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Background and Aims: There is increased interest in utilizing dietary interventions to alter the progression of autoimmune diseases. These efforts are driven by associations of gut microbiota/metabolites with levels of short-chain fatty acids (SCFAs). Propionate is a key SCFA that is commonly used as a food preservative and is endogenously generated by bacterial fermentation of non-digestible carbohydrates in the gut. A thesis has suggested that a diet rich in propionate and other SCFAs can successfully modulate autoimmunity. Herein, we investigated the effect of long-term administration of propionylated high-amylose resistant starches (HAMSP) on the course of murine primary biliary cholangitis., Materials and Methods: Groups of female ARE-Del mice were fed an HAMSP diet either before or after disease onset. A detailed immunobiological analysis was performed involving autoantibodies and rigorous T-cell phenotyping, including enumeration of T-cell subsets in the spleen, liver, intestinal intraepithelial lymphocytes and lamina propria by flow cytometry. Histopathological scores were used to assess the frequency and severity of liver inflammation and damage to hepatocytes and bile ducts., Results: Our results demonstrate that a long-term propionate-yielding diet re-populated the T-cell pool with decreased naïve and central memory T-cell subsets and an increase in the effector memory T cells in mice. Similarly, long-term HAMSP intake reduced CD4 + CD8 + double-positive T cells in intraepithelial lymphocytes and the intestinal lamina propria. Critically, HAMSP consumption led to moderate-to-severe hepatocellular steatosis in ARE-Del mice, independent of the stage of autoimmune cholangitis., Conclusions: Our data suggest that administration of HAMSP induces both regulatory and effector T cells. Furthermore, HAMSP administration resulted in hepatocellular steatosis. Given the interest in dietary modulation of autoimmunity and because propionate is widely used as a food preservative, these data have significant implications. This study also provides new insights into the immunological and pathological effects of chronic propionate exposure., (© 2024 The Author(s). Liver International published by John Wiley & Sons Ltd.)

The gastrointestinal tract is home to the largest microbial population in the human body. The gut microbiota plays significant roles in the development of the gut immune system and has a substantial impact on the maintenance of immune tolerance beginning in early life. These microbes interact with the immune system in a dynamic and interdependent manner. They generate immune signals by presenting a vast repertoire of antigenic determinants and microbial metabolites that influence the development, maturation and maintenance of immunological function and homeostasis. At the same time, both the innate and adaptive immune systems are involved in modulating a stable microbial ecosystem between the commensal and pathogenic microorganisms. Hence, the gut microbial population and the host immune system work together to maintain immune homeostasis synergistically. In susceptible hosts, disruption of such a harmonious state can greatly affect human health and lead to various auto-inflammatory and autoimmune disorders. In this review, we discuss our current understanding of the interactions between the gut microbiota and immunity with an emphasis on: a) important players of gut innate and adaptive immunity; b) the contribution of gut microbial metabolites; and c) the effect of disruption of innate and adaptive immunity as well as alteration of gut microbiome on the molecular mechanisms driving autoimmunity in various autoimmune diseases., Competing Interests: Declaration of competing interest All authors declare that they have no competing interests., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Autoimmune regulator (Aire) and TGF-β signaling play important roles in central tolerance and peripheral tolerance, respectively, by eliminating or suppressing the activity of autoreactive T cells. We previously demonstrated that dnTGFβRII mice develop a defect in peripheral tolerance and a primary biliary cholangitis (PBC)-like disease. We hypothesized that by introducing the Aire gene to this model, we would observe a more severe PBC phenotype. Interestingly, however, we demonstrated that, while dnTGFβRII Aire -/- mice do manifest key histological and serological features of autoimmune cholangitis, they also develop mild to moderate interface hepatitis and show high levels of alanine transaminase (ALT) and antinuclear antibodies (ANA), characteristics of autoimmune hepatitis (AIH). To further understand this unique phenotype, we performed RNA sequencing (RNA-seq) and flow cytometry to explore the functional pathways and immune cell pathways in the liver of dnTGFβRII Aire -/- mice. Our data revealed enrichments of programmed cell death pathways and predominant CD8 + T cell infiltrates. Depleting CD8 + T cells using an anti-CD8α antibody significantly alleviated hepatic inflammation and prolonged the life span of these mice. Finally, RNA-seq data indicated the clonal expansion of hepatic CD8 + T cells. In conclusion, these mice developed an autoreactive CD8 + T-cell-mediated autoimmune cholangitis with concurrent hepatitis that exhibited key histological and serological features of the AIH-PBC overlap syndrome, representing a novel model for the study of tolerance and autoimmune liver disease. © 2023 The Pathological Society of Great Britain and Ireland., (© 2023 The Pathological Society of Great Britain and Ireland.)

The interferon (IFN) signaling pathways are major immunological checkpoints with clinical significance in the pathogenesis of autoimmunity. We have generated a unique murine model named ARE-Del, with chronic overexpression of IFNγ, by altering IFNγ metabolism. Importantly, these mice develop an immunologic and clinical profile similar to patients with primary biliary cholangitis, including high titers of autoantibodies and portal inflammation. We hypothesized that the downregulation of IFN signaling pathways with a JAK1/2 inhibitor would inhibit the development and progression of cholangitis. To study this hypothesis, ARE-Del +/- mice were treated with the JAK1/2 inhibitor ruxolitinib and serially studied. JAK inhibition resulted in a significant reduction in portal inflammation and bile duct damage, associated with a significant reduction in splenic and hepatic CD4 + T cells and CD8 + T cells. Functionally, ruxolitinib inhibited the secretion of the proinflammatory cytokines IFNγ and TNF from splenic CD4 + T cells. Additionally, ruxolitinib treatment also decreased the frequencies of germinal center B (GC B) cells and T follicular helper (Tfh) cells and led to lower serological AMA levels. Of note, liver and peritoneal macrophages were sharply decreased and polarized from M1 to M2 with a higher level of IRF4 expression after ruxolitinib treatment. Mechanistically, ruxolitinib inhibited the secretion of IL-6, TNF and MCP1 and the expression of STAT1 but promoted the expression of STAT6 in macrophages in vitro, indicating that M1 macrophage polarization to M2 occurred through activation of the STAT6-IRF4 pathway. Our data highlight the significance, both immunologically and clinically, of the JAK/STAT signaling pathway in autoimmune cholangitis., (© 2022. The Author(s).)

Primary biliary cholangitis (PBC), an organ-specific autoimmune disease, is characterized by injury to small bile ducts, inflammatory cell infiltrates within the liver, progressive cholestasis, and in some cases, cirrhosis with unclear pathogenesis. We aimed to clarify the importance role of hepatic immunce cells in the pathogenesis of human and experimental PBC.The dominant-negative TGFβ receptor type II transgenic (dnTGFβRII) mice, a well-studied and established murine model of PBC were used to identify changes of immune cells, especially the pathogenic CD8 + T cells. The high-throughput single-cell RNA sequencing technology were applied and found functional heterogeneity among the hepatic CD8 + T cells subsets in dnTGFβRII mice. CD8 + T cells were confirmed the key cells leading to the pathogenesis of PBC in dnTGFβRII mice, and identified the terminally differentiated CD8αα T cells and CD8αβ T cell subsets in the liver of dnTGFβRII mice. While terminally differentiated CD8αα T cells have higher cytokine production ability and cytotoxicity, the terminally differentiated CD8αβ T cells retain their proliferative profile. Our work suggests that there are developmental and differentiated trajectories of pathogenic CD8 + T cell subsets in the pathogenesis of PBC. A further clarification of their roles would be helpful to our understanding of the pathogenesis of PBC and may potentially lead to identifying novel therapeutic modalities., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Han, Bian, Yang, Wang, Li, Yang, Ansari, Gershwin, Zeng, Lian and Zhao.)

Background and Aims: The increased frequency of urinary tract infections in patients with primary biliary cholangitis (PBC) and the cross-reactivity between the lipoyl domains (LD) of human pyruvate dehydrogenase complex (hPDC-E2) and Escherichia coli PDC-E2 (ePDC-E2) have long suggested a role of E. coli in causality of PBC. This issue, however, has remained speculative. We hypothesized that by generating specific constructs of human and E. coli PDC-E2, we would be able to assess the specificity of autoantibody responses and define whether exposure to E. coli in susceptible hosts is the basis for the antimitochondrial antibody (AMA) response., Approach and Results: Importantly, the reactivity of hPDC-E2 LD (hPDC-E2LD) affinity-purified antibodies against hPDC-E2LD could only be removed by prior absorption with hPDC-E2LD and not ePDC-E2, suggesting the presence of unique human PDC-E2 epitopes distinct from E. coli PDC-E2. To identify the autoepitope(s) present in hPDC-E2LD, a more detailed study using a variety of PDC-E2 constructs was tested, including the effect of lipoic acid (LA) on ePDC-E2 conformation and AMA recognition. Individual recombinant ePDCE2 LD domains LD1, LD2 and LD3 did not react with either AMA or antibodies to LA (anti-LA), but in contrast, anti-LA was readily reactive against purified recombinant LD1, LD2, and LD3 expressed in tandem (LP); such reactivity increased when LP was precultured with LA. Moreover, when the three LD (LD1, LD2, LD3) domains were expressed in tandem in pET28a or when LD1 was expressed in another plasmid pGEX, they were lipoylated and reactive to PBC sera., Conclusions: In conclusion, our data are consistent with an exposure to E. coli that elicits specific antibody to ePDC-E2 resulting in determinant spreading and the classic autoantibody to hPDC-E2LD. We argue this is the first step to development of human PBC., (© 2021 by the American Association for the Study of Liver Diseases.)

Monocytes, one of the main target cells for dengue virus (DENV) infection, contribute to the resolution of viremia and to pathogenesis. We performed a longitudinal study by a detailed phenotypic comparison of classical (CD14++CD16-, non-classical (CD14+CD16++) and intermediate (CD14++CD16+) monocyte subsets in blood samples from dengue fever (DF) to the severe dengue hemorrhagic fever (DHF) and healthy individuals. Various costimulatory molecules of CD40, CD80, CD86 and inducible costimulatory ligand (ICOSL) expressed on these three monocyte subsets were also analyzed. DENV-infected patients showed an increase in the frequency of intermediate monocytes and a decrease in the classical monocytes when compared to healthy individuals. Although these differences did not correlate with disease severity, changes during the early phase of infection gradually returned to normal in the defervescence phase. Moreover, decreased frequency of classical monocytes was associated with a significant up-regulation of co-stimulatory molecules CD40, CD86 and ICOSL. Kinetics of these co-stimulatory molecule-expressing classical monocytes showed different patterns throughout the sampling times of acute DENV infection. Different distribution of monocyte subsets and their co-stimulatory molecules in the peripheral blood during acute infection might exacerbate immune responses like cytokine storms and ADE, and future studies on intracellular molecular pathways utilized by these monocyte linages are warranted.

Objective: The aim of this study was to investigate the kinetics of Env (gp140)-specific antibody-secreting cells (ASCs) during acute and early chronic simian immunodeficiency virus (SIV) infection, and prior to and postantiretroviral therapy (ART) in rhesus macaques., Design and Methods: At week 0, rhesus macaques were inoculated intravenously with SIVmac239 and the viral loads were allowed to develop. Daily ART was initiated at week 5 post infection until week 18, though the animals were monitored until week 28 for the following parameters: enumeration of SIV gp140-specific ASCs by ELISPOT; quantification of viremia and SIV gp140-specific IgG titres through qRT-PCR and ELISA, respectively; estimation of monocytes, follicular helper T cells (Tfh) and memory B cell frequencies using polychromatic flow cytometry., Results: Direct correlations were consistently found between blood SIV gp140-specific ASC responses and viremia or SIV Env-specific IgG titres. In contrast, SIV gp140-specific ASC responses showed inverse correlations with the percentage of total memory B cells in the blood. In lymph nodes, the magnitude of the SIV gp140-specific ASC responses also followed the viral load kinetics. In contrast, the number of SIV gp140-specific ASCs presented did not correlate with frequencies of circulating activated monocyte (CD14+CD16+) or Tfh cells., Conclusion: Blood and/or lymph node viral loads may regulate the onset and magnitude of SIV gp140-specific ASCs during SIV infection and following ART in rhesus macaques., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Treating macaques with an anti-α4β7 antibody under the umbrella of combination antiretroviral therapy (cART) during early SIV infection can lead to viral remission, with viral loads maintained at < 50 SIV RNA copies/ml after removal of all treatment in a subset of animals. Depletion of CD8+ lymphocytes in controllers resulted in transient recrudescence of viremia, suggesting that the combination of cART and anti-α4β7 antibody treatment led to a state where ongoing immune responses kept the virus undetectable in the absence of treatment. A previous mathematical model of HIV infection and cART incorporates immune effector cell responses and exhibits the property of two different viral load set-points. While the lower set-point could correspond to the attainment of long-term viral remission, attaining the higher set-point may be the result of viral rebound. Here we expand that model to include possible mechanisms of action of an anti-α4β7 antibody operating in these treated animals. We show that the model can fit the longitudinal viral load data from both IgG control and anti-α4β7 antibody treated macaques, suggesting explanations for the viral control associated with cART and an anti-α4β7 antibody treatment. This effective perturbation to the virus-host interaction can also explain observations in other nonhuman primate experiments in which cART and immunotherapy have led to post-treatment control or resetting of the viral load set-point. Interestingly, because the viral kinetics in the various treated animals differed-some animals exhibited large fluctuations in viral load after cART cessation-the model suggests that anti-α4β7 treatment could act by different primary mechanisms in different animals and still lead to post-treatment viral control. This outcome is nonetheless in accordance with a model with two stable viral load set-points, in which therapy can perturb the system from one set-point to a lower one through different biological mechanisms., Competing Interests: The authors have declared that no competing interests exist.

The diverse clinical manifestations of COVID-19 is emerging as a hallmark of the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) infection. While the initial target of SARS-CoV-2 is the respiratory tract, it is becoming increasingly clear that there is a complex interaction between the virus and the immune system ranging from mild to controlling responses to exuberant and dysfunctional multi-tissue directed autoimmune responses. The immune system plays a dual role in COVID-19, being implicated in both the anti-viral response and in the acute progression of the disease, with a dysregulated response represented by the marked cytokine release syndrome, macrophage activation, and systemic hyperinflammation. It has been speculated that these immunological changes may induce the loss of tolerance and/or trigger chronic inflammation. In particular, molecular mimicry, bystander activation and epitope spreading are well-established proposed mechanisms to explain this correlation with the likely contribution of HLA alleles. We performed a systematic literature review to evaluate the COVID-19-related autoimmune/rheumatic disorders reported between January and September 2020. In particular, we investigated the cases of incident hematological autoimmune manifestations, connective tissue diseases, antiphospholipid syndrome/antibodies, vasculitis, Kawasaki-like syndromes, acute arthritis, autoimmune-like skin lesions, and neurologic autoimmune conditions such as Guillain-Barré syndrome. We screened 6263 articles and report herein the findings of 382 select reports which allow us to conclude that there are 2 faces of the immune response against SARS-CoV-2, that include a benign virus controlling immune response and a many faceted range of dysregulated multi-tissue and organ directed autoimmune responses that provides a major challenge in the management of this viral disease. The number of cases for each disease varied significantly while there were no reported cases of adult onset Still disease, systemic sclerosis, or inflammatory myositis., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Coronavirus disease 2019 (COVID-19) has been categorized as evolving in overlapping phases. First, there is a viral phase that may well be asymptomatic or mild in the majority, perhaps 80% of patients. The pathophysiological mechanisms resulting in minimal disease in this initial phase are not well known. In the remaining 20% of cases, the disease may become severe and/or critical. In most patients of this latter group, there is a phase characterized by the hyperresponsiveness of the immune system. A third phase corresponds to a state of hypercoagulability. Finally, in the fourth stage organ injury and failure occur. Appearance of autoinflammatory/autoimmune phenomena in patients with COVID-19 calls attention for the development of new strategies for the management of life-threatening conditions in critically ill patients. Antiphospholipid syndrome, autoimmune cytopenia, Guillain-Barré syndrome and Kawasaki disease have each been reported in patients with COVID-19. Here we present a scoping review of the relevant immunological findings in COVID-19 as well as the current reports about autoinflammatory/autoimmune conditions associated with the disease. These observations have crucial therapeutic implications since immunomodulatory drugs are at present the most likely best candidates for COVID-19 therapy. Clinicians should be aware of these conditions in patients with COVID-19, and these observations should be considered in the current development of vaccines., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Glycosylation of antibodies, particularly in the Fc domain, critically modulate the ability of antibodies to bind to FcRs, maintaining immune quiescence to achieve a finely orchestrated immune response. The removal of sialic acid and galactose residues dramatically alters the physiological function of IgGs, and alterations of Ig glycosylation have been associated with several autoimmune disorders. However, Ig glycosylation has not been extensively studied in autoimmune cholangitis. We applied triple quadruple mass spectroscopy with subsequent multiple reaction monitoring to elucidate the profile, composition and linkage of sugar residues of antibody glycans in patients with primary biliary cholangitis (PBC), primary sclerosing cholangitis (PSC) and healthy controls (HC). Agalactosylated, HexNAc terminated IgG1 glycoforms were enriched in both PBC and PSC. Levels of IgM glycans at site N439 and fucosylated glycans in J chain, were significantly decreased in PBC compared to PSC and HC. PSC patients had decreased bisecting glycoforms and increased biantennary glycoforms on IgA compared to PBC. Importantly, our data demonstrate the association of distinct branching and composition patterns of Ig glycoforms with disease severity and liver cirrhosis, which highlight the importance of glycan biology as a potential mechanism and/or a disease specific signal of inflammation., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Deglycosylated, live-attenuated SIV vaccines elicited protective immune responses against heterologous SIVsmE543-3, which differs from the vaccine strain SIVmac239 to levels similar to those across HIV-1 clades. Two thirds of the vaccinees contained the chronic SIVsmE543-3 infection (controllers), whereas one third did not (noncontrollers). In this study, we investigated immune correlates of heterologous challenge control in rhesus macaques of Burmese origin. Because depletion of CD8 + cells in the controllers by administration of anti-CD8α Ab abrogated the control of viral replication, CD8 + cells were required for the protective immune response. However, classical SIV-specific CD8 + T cells did not account for the protective immune response in all controllers. Instead, IL-15-responding CD8α + cells, including CD8 + T and NK cells, were significantly higher in the controllers than those in the noncontrollers, before and after vaccination with deglycosylated SIV. It is well established that IL-15 signal transduction occurs through " trans -presentation" in which IL-15 complexed with IL-15Rα on monocytes, macrophages, and dendritic cells binds to IL-15 Rβ/γ expressed on CD8 + T and NK cells. Accordingly, levels of IL-15 stimulation were strongly affected by the depletion of monocytes from PBMCs, implying key roles of innate immune cells. These results suggest that intrinsic IL-15 responsiveness may dictate the outcome of protective responses and may lead to optimized formulations of future broadly protective HIV vaccines., (Copyright © 2020 by The American Association of Immunologists, Inc.)

The Coronavirus-associated disease, that was first identified in 2019 in China (CoViD-19), is a pandemic caused by a bat-derived beta-coronavirus, named SARS-CoV2. It shares homology with SARS and MERS-CoV, responsible for past outbreaks in China and in Middle East. SARS-CoV2 spread from China where the first infections were described in December 2019 and is responsible for the respiratory symptoms that can lead to acute respiratory distress syndrome. A cytokine storm has been shown in patients who develop fatal complications, as observed in past coronavirus infections. The management includes ventilatory support and broad-spectrum antiviral drugs, empirically utilized, as a targeted therapy and vaccines have not been developed. Based upon our limited knowledge on the pathogenesis of CoViD-19, a potential role of some anti-rheumatic drugs may be hypothesized, acting as direct antivirals or targeting host immune response. Antimalarial drugs, commonly used in rheumatology, may alter the lysosomal proteases that mediates the viral entry into the cell and have demonstrated efficacy in improving the infection. Anti-IL-1 and anti-IL-6 may interfere with the cytokine storm in severe cases and use of tocilizumab has shown good outcomes in a small cohort. Baricitinib has both antiviral and anti-inflammatory properties. Checkpoints inhibitors such as anti-CD200 and anti-PD1 could have a role in the treatment of CoViD-19. Rheumatic disease patients taking immunosuppressive drugs should be recommended to maintain the chronic therapy, prevent infection by avoiding social contacts and pausing immunosuppressants in case of infection. National and international registries are being created to collect data on rheumatic patients with CoViD-19., (Copyright © 2020. Published by Elsevier Ltd.)

The genus Ebolavirus from the family Filoviridae is composed of five species including Sudan ebolavirus, Reston ebolavirus, Bundibugyo ebolavirus, Taï Forest ebolavirus, and Ebola virus (previously known as Zaire ebolavirus). These viruses have a large non-segmented, negative-strand RNA of approximately 19 kb that encodes for glycoproteins (i.e., GP, sGP, ssGP), nucleoproteins, virion proteins (i.e., VP 24, 30,40) and an RNA dependent RNA polymerase. These viruses have become a global health concern because of mortality, their rapid dissemination, new outbreaks in West-Africa, and the emergence of a new condition known as "Post-Ebola virus disease syndrome" that resembles inflammatory and autoimmune conditions such as rheumatoid arthritis, systemic lupus erythematosus and spondyloarthritis with uveitis. However, there are many gaps in the understanding of the mechanisms that may induce the development of such autoimmune-like syndromes. Some of these mechanisms may include a high formation of neutrophil extracellular traps, an uncontrolled "cytokine storm", and the possible formation of auto-antibodies. The likely appearance of autoimmune phenomena in Ebola survivors suppose a new challenge in the management and control of this disease and opens a new field of research in a special subgroup of patients. Herein, the molecular biology, pathogenesis, clinical manifestations, and treatment of Ebola virus disease are reviewed and some strategies for control of disease are discussed., (Copyright © 2019 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Molecular mimicry is one of the leading mechanisms by which infectious or chemical agents may induce autoimmunity. It occurs when similarities between foreign and self-peptides favor an activation of autoreactive T or B cells by a foreign-derived antigen in a susceptible individual. However, molecular mimicry is unlikely to be the only underlying mechanism for autoimmune responses; other factors such as breach in central tolerance, non-specific bystander activation, or persistent antigenic stimuli (amongst others) may also contribute to the development of autoimmune diseases. Host genetics, exposure to microbiota and environmental chemicals are additional links to our understanding of molecular mimicry. Our current knowledge of the detailed mechanisms of molecular mimicry is limited by the issues of prolonged periods of latency before the appearance of disease, the lack of enough statistical power in epidemiological studies, the limitations of the potential role of genetics in human studies, the relevance of inbred murine models to the diverse human population and especially the limited technology to systematically dissect the human T-cell repertoire and B-cell responses. Nevertheless, studies on the role of autoreactive T-cells that are generated secondary to molecular mimicry, the diversity of the T-cell receptor repertoires of auto-reactive T-cells, the role of exposure to cryptic antigens, the generation of autoimmune B-cell responses, the interaction of microbiota and chemical adjuvants with the host immune systems all provide clues in advancing our understanding of the molecular mechanisms involved in the evolving concept of molecular mimicry and also may potentially aid in the prevention and treatment of autoimmune diseases., (Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Human gut-associated lymphoid tissues (GALT) play a key role in the acute phase of HIV infection. The propensity of HIV to replicate in these tissues, however, is not fully understood. Access and migration of naive and memory CD4 + T cells to these sites is mediated by interactions between integrin α 4 β 7 , expressed on CD4 + T cells, and MAdCAM, expressed on high endothelial venules. We report here that MAdCAM delivers a potent costimulatory signal to naive and memory CD4 + T cells following ligation with α 4 β 7 . Such costimulation promotes high levels of HIV replication. An anti-α 4 β 7 mAb that prevents mucosal transmission of SIV blocks MAdCAM signaling through α 4 β 7 and MAdCAM-dependent viral replication. MAdCAM costimulation of memory CD4 + T cells is sufficient to drive cellular proliferation and the upregulation of CCR5, while naive CD4 + T cells require both MAdCAM and retinoic acid to achieve the same response. The pairing of MAdCAM and retinoic acid is unique to the GALT, leading us to propose that HIV replication in these sites is facilitated by MAdCAM-α 4 β 7 interactions. Moreover, complete inhibition of MAdCAM signaling by an anti-α 4 β 7 mAb, an analog of the clinically approved therapeutic vedolizumab, highlights the potential of such agents to control acute HIV infection.

The GI tract is preferentially targeted during acute/early HIV-1 infection. Consequent damage to the gut plays a central role in HIV pathogenesis. The basis for preferential targeting of gut tissues is not well defined. Recombinant proteins and synthetic peptides derived from HIV and SIV gp120 bind directly to integrin α4β7, a gut-homing receptor. Using both cell-surface expressed α4β7 and a soluble α4β7 heterodimer we demonstrate that its specific affinity for gp120 is similar to its affinity for MAdCAM (its natural ligand). The gp120 V2 domain preferentially engages extended forms of α4β7 in a cation -sensitive manner and is inhibited by soluble MAdCAM. Thus, V2 mimics MAdCAM in the way that it binds to α4β7, providing HIV a potential mechanism to discriminate between functionally distinct subsets of lymphocytes, including those with gut-homing potential. Furthermore, α4β7 antagonists developed for the treatment of inflammatory bowel diseases, block V2 binding to α4β7. A 15-amino acid V2 -derived peptide is sufficient to mediate binding to α4β7. It includes the canonical LDV/I α4β7 binding site, a cryptic epitope that lies 7-9 amino acids amino terminal to the LDV/I, and residues K169 and I181. These two residues were identified in a sieve analysis of the RV144 vaccine trial as sites of vaccine -mediated immune pressure. HIV and SIV V2 mAbs elicited by both vaccination and infection that recognize this peptide block V2-α4β7 interactions. These mAbs recognize conformations absent from the β- barrel presented in a stabilized HIV SOSIP gp120/41 trimer. The mimicry of MAdCAM-α4β7 interactions by V2 may influence early events in HIV infection, particularly the rapid seeding of gut tissues, and supports the view that HIV replication in gut tissue is a central feature of HIV pathogenesis., Competing Interests: I have read the journal's policy and the authors of this manuscript have the following competing interests: JA, CC and ASF are inventors of patent 20160075786 submitted by the NIAID, NIH that covers the study of reagents that serve as antagonists of the interaction between HIV gp120 and α4β7 mAb. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Dengue virus (DENV) is the most prevalent arthropod-borne viral disease in humans. DENV causes a spectrum of illness ranging from mild to potentially severe complications. Dendritic cells (DCs) play a critical role in initiating and regulating highly effective antiviral immune response that include linking innate and adaptive immune responses. This study was conducted to comparatively characterize in detail the relative proportion, phenotypic changes, and maturation profile of subsets of both myeloid DCs (mDCs) and plasmacytoid DCs (pDCs) in children with dengue fever (DF), dengue hemorrhagic fever (DHF) and for purposes of control healthy individuals. The mDCs (Lin-CD11c+CD123lo), the pDCs (Lin-CD11c-CD123+) and the double negative (DN) subset (Lin-/HLA-DR+/CD11c-CD123-) were analyzed by polychromatic flow cytometry. The data were first analyzed on blood samples collected from DENV-infected patients at various times post-infection. Results showed that the relative proportion of mDCs were significantly decreased which was associated with an increase in disease severity in samples from DENV-infected patients. While there was no significant difference in the relative proportion of pDCs between healthy and DENV-infected patients, there was a marked increase in the DN subset. Analysis of the kinetics of changes of pDCs showed that there was an increase but only during the early febrile phase. Additionally, samples from patients during acute disease showed marked decreases in the relative proportion of CD141+ and CD16+ mDC subsets that were the major mDC subsets in healthy individuals. In addition, there was a significant decrease in the level of CD33-expressing mDCs in DENV patients. While the pDCs showed an up-regulation of maturation profile during acute DENV infection, the mDCs showed an alteration of maturation status. This study suggests that different relative proportion and phenotypic changes as well as alteration of maturation profile of DC subsets may play a critical role in the dengue pathogenesis and disease outcome., Competing Interests: The authors have declared that no competing interests exist.

Mucosal-associated invariant T (MAIT) cells are novel innate-like T cells constituting a significant proportion of circulating and hepatic T cells. Herein, we extensively examine the phenotypical and functional alterations of MAIT cells and their regulation in a cohort of 56 patients with Primary Biliary Cholangitis (PBC) and 53 healthy controls (HC). Additionally alterations of MAIT cells were assessed before and after UDCA treatment. Finally the localization of MAIT cell in liver was examined using specific tetramer staining and the underlying mechanisms of these alterations in PBC were explored. Our data demonstrated that the frequency and number of circulating MAIT cells were decreased, whereas hepatic MAIT cells were increased in PBC compared to HC. Moreover, circulating MAIT cells were more activated in PBC than HC, reflected by elevated expression levels of granzyme B. Six months of UDCA treatment significantly attenuated the circulating MAIT cells differences in PBC. Of note, the expression levels of IL-7 were significantly increased in both plasma and liver from PBC as compared to HC, which promoted the production of inflammatory cytokines and granzyme B by inducing signal transduction and activation of transcription 5 (STAT5) phosphorylation in MAIT cells. Finally, cholic acid, one of the major bile acids in liver, upregulated IL-7 expression in hepatocyte cell line L02 by inducing Farnesoid X Receptor (FXR) binding to the IL-7 promoter. Hence MAIT cells are activated and enriched in the liver of PBC. Cholic acid-induced IL-7 production in hepatocytes plays a critical role in regulating MAIT cell function, highlighting that hepatocytes may bridge cholangiocyte injury and innate immunity through a bile acid signaling pathway., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Cerebrospinal fluid (CSF) drains via the lymphatic drainage pathway. This lymphatic pathway connects the central nervous system (CNS) to the cervical lymph node (CLN). As the CSF drains to CLN via the dural and nasal lymphatics, T cells and antigen presenting cells pass along the channels from the subarachnoid space through the cribriform plate. Human immunodeficiency virus (HIV) may also egress from the CNS along this pathway. As a result, HIV egressing from the CNS may accumulate within the CLN. Towards this objective, we analyzed CLNs isolated from rhesus macaques that were chronically-infected with simian immunodeficiency virus (SIV). We detected significant accumulation of SIV within the CLNs. SIV virion trapping was observed on follicular dendritic cells (FDCs) localized within the follicular regions of CLNs. In addition, SIV antigens formed immune complexes when FDCs interacted with B cells within the germinal centers. Subsequent interaction of these B cells with CD4+ T follicular helper cells (T FHs ) resulted in infection of the latter. Of note, 73% to 90% of the T FHs cells within CLNs were positive for SIV p27 antigen. As such, it appears that not only do the FDCs retain SIV they also transmit them (via B cells) to T FHs within these CLNs. This interaction results in infection of T FHs in the CLNs. Based on these observations, we infer that FDCs within the CLNs have a novel role in SIV entrapment with implications for viral trafficking.

Dengue virus (DENV) infection is considered one of the most important mosquito-borne diseases. It causes a spectrum of illness that could be due to qualitative and/or quantitative difference(s) of the natural killer (NK) cell responses during acute DENV infection. This view prompted us to perform a detailed phenotypic comparative characterization of NK cell subsets from DENV-infected patients with dengue fever (DF), patients with dengue haemorrhagic fever (DHF) and healthy controls. The activation/differentiation molecules, CD69 and CD57 and a variety of tissue homing molecules were analysed on the CD56 hi CD16 - and CD56 lo CD16 + NK cells. Although there was no increase in the frequency of the total NK cells during DENV infection compared with the healthy individuals, there was a significant increase in the frequency of the CD56 hi CD16 - subset and the frequency of CD69 expression by both NK cell subsets during the febrile phase of infection. We also found an increase in the frequencies of cells expressing CD69 and CD57 in the CD56 lo CD16 + subset compared with those in the CD56 hi CD16 - subset. Moreover, although the CD56 lo CD16 + subset contained a high frequency of cells expressing skin-homing markers, the CD56 hi CD16 - subset contained a high frequency of cells expressing bone marrow and lymph node trafficking markers. Interestingly, no differences of these NK cell subsets were noted in samples from patients with DF versus those with DHF. These findings suggest that activation and differentiation and the patterns of tissue homing molecules of the two major NK cell subsets are different and that these might play a critical role in the immune response against acute DENV infection., (© 2017 John Wiley & Sons Ltd.)

Purpose of Review: Acute HIV infection is characterized by high-level viral replication throughout the body's lymphoid system, particularly in gut-associated lymphoid tissues resulting in damage to structural components of gut tissue. This damage is irreversible and believed to contribute to the development of immune deficiencies. Antiretroviral therapy (ART) does not restore gut structure and function. Studies in macaques point to an alternative treatment strategy that may ameliorate gut damage. Integrin α 4 β 7 mediates the homing of lymphocytes to gut tissues. Vedolizumab, a monoclonal antibody (mAb) antagonist of α 4 β 7 , has demonstrated efficacy and has been approved for the treatment of inflammatory bowel disease in humans. Here, we describe our current knowledge, and the gaps in our understanding, of the role of α 4 β 7 in HIV pathogenesis and treatment., Recent Findings: When administered to macaques prior to infection, a nonhuman primate analogue of vedolizumab prevents transmission of SIV. In combination with ART, this mAb facilitates durable virologic control following treatment interruption. Targeting α 4 β 7 represents a novel therapeutic approach to prevent and treat HIV infection.

Infusion of a simianized anti-α 4 β 7 mAb (Rh-α 4 β 7 ) just before and following SIV infection protected rhesus macaques from developing AIDS and partially from vaginal SIV acquisition. Recently, short-term treatment with Rh-α 4 β 7 in combination with cART was found to lead to prolonged viral suppression after withdrawal of all therapeutic interventions. The humanized form of Rh-α 4 β 7 , vedolizumab, is a highly effective treatment for inflammatory bowel disease. To clarify the mechanism of action of Rh-α 4 β 7 , naive macaques were infused with Rh-α 4 β 7 and sampled in blood and tissues before and after treatment to monitor several immune cell subsets. In blood, Rh-α 4 β 7 increased the CD4 + and CD8 + T cell counts, but not B cell counts, and preferentially increased CCR6 + subsets while decreasing CD103 + and CD69 + lymphocytes. In mucosal tissues, surprisingly, Rh-α 4 β 7 did not impact integrin α 4 + cells, but decreased the frequencies of CCR6 + and CD69 + CD4 + T cells and, in the gut, Rh-α 4 β 7 transiently decreased the frequency of memory and IgA + B cells. In summary, even in the absence of inflammation, Rh-α 4 β 7 impacted selected immune cell subsets in different tissues. These data provide new insights into the mechanisms by which Rh-α 4 β 7 may mediate its effect in SIV-infected macaques with implications for understanding the effect of treatment with vedolizumab in patients with inflammatory bowel disease., (Copyright © 2018 by The American Association of Immunologists, Inc.)

Background: Pertussis toxin (PTX) blocks GPCR signaling resulting in the inhibition of chemotaxis/cell adhesion. It was reasoned that inhibition of cell trafficking may be an approach to prevent HIV/SIV transmission., Methods: In this study, PTX in HEC gel was applied to the vaginal wall of monkeys that were then challenged intravaginally with SIVmac251., Results: Results of these studies showed that 2 of 4 animals were resistant to infection. Furthermore, infection was correlated with a marked increase in the plasma and cervicovaginal lavage levels of select chemokines and cytokines., Conclusions: Results from this preliminary feasibility study dictate that further studies that include a larger number of animals are required to optimize this protocol and establish the efficacy of this approach. In addition, such future studies will provide important information on the role of specific chemokines that play a role in lymphocyte trafficking within the genital tract and serve as additional therapeutic targets., (© 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Objective: Germinal center resident follicular helper T (TFH) cells in lymphoid follicles are a potential sanctuary for HIV/simian immunodeficiency virus (SIV) replication. But the dynamics of germinal centers upon early initiation of antiretroviral therapy (ART) and their potential role in the formation of viral sanctuaries post-SIV infection are not fully understood., Design: Sequential lymph node biopsies (n = 10) were collected from SIVmac239-infected rhesus macaques before infection, at 5 weeks postinfection/pre-ART, 6 and 12 weeks following ART initiation. These tissues and cells were analyzed for frequencies of TFH cells and assignment of germinal center scores., Results: Modest but significant increases in TFH cells and hyperplastic follicles with large germinal centers were noted during the acute phase of SIV infection (week 5/pre-ART). However, 6 weeks after ART initiation, substantial increases in germinal center TFH cells, germinal center B cells, hyperplastic follicles with large germinal centers, and abundant local IL-21 production were observed, whereas levels of SIV RNA and DNA of lymph nodes had decreased to barely detectable values along with barely detectable levels of SIV antibody-producing cells. An additional 6 weeks of ART did not appreciably decrease germinal center TFH or germinal center scores., Conclusion: Thus, although early ART rapidly controls SIV replication, it does not regulate early lymphoid activation, which may contribute to the seeding and magnitude of viral reservoirs.

Glycosylation of Env defines pathogenic properties of simian immunodeficiency virus (SIV). We previously demonstrated that pathogenic SIVmac239 and a live-attenuated, quintuple deglycosylated Env mutant (Δ5G) virus target CD4 + T cells residing in different tissues during acute infection. SIVmac239 and Δ5G preferentially infected distinct CD4 + T cells in secondary lymphoid organs (SLOs) and within the lamina propria of the small intestine, respectively (C. Sugimoto et al., J Virol 86:9323-9336, 2012, https://doi.org/10.1128/JVI.00948-12). Here, we studied the host responses relevant to SIV targeting of CXCR3 + CCR5 + CD4 + T cells in SLOs. Genome-wide transcriptome analyses revealed that Th1-polarized inflammatory responses, defined by expression of CXCR3 chemokines, were distinctly induced in the SIVmac239-infected animals. Consistent with robust expression of CXCL10, CXCR3 + T cells were depleted from blood in the SIVmac239-infected animals. We also discovered that elevation of CXCL10 expression in blood and SLOs was secondary to the induction of CD14 + CD16 + monocytes and MAC387 + macrophages, respectively. Since the significantly higher levels of SIV infection in SLOs occurred with a massive accumulation of infiltrated MAC387 + macrophages, T cells, dendritic cells (DCs), and residential macrophages near high endothelial venules, the results highlight critical roles of innate/inflammatory responses in SIVmac239 infection. Restricted infection in SLOs by Δ5G also suggests that glycosylation of Env modulates innate/inflammatory responses elicited by cells of monocyte/macrophage/DC lineages. IMPORTANCE We previously demonstrated that a pathogenic SIVmac239 virus and a live-attenuated, deglycosylated mutant Δ5G virus infected distinct CD4 + T cell subsets in SLOs and the small intestine, respectively (C. Sugimoto et al., J Virol 86:9323-9336, 2012, https://doi.org/10.1128/JVI.00948-12). Accordingly, infections with SIVmac239, but not with Δ5G, deplete CXCR3 + CCR5 + CD4 + T (Th1) cells during the primary infection, thereby compromising the cellular immune response. Thus, we hypothesized that distinct host responses are elicited by the infections with two different viruses. We found that SIVmac239 induced distinctly higher levels of inflammatory Th1 responses than Δ5G. In particular, SIVmac239 infection elicited robust expression of CXCL10, a chemokine for CXCR3 + cells, in CD14 + CD16 + monocytes and MAC387 + macrophages recently infiltrated in SLOs. In contrast, Δ5G infection elicited only modest inflammatory responses. These results suggest that the glycosylation of Env modulates the inflammatory/Th1 responses through the monocyte/macrophage subsets and elicits marked differences in SIV infection and clinical outcomes., (Copyright © 2017 American Society for Microbiology.)

The identification of environmental factors that lead to loss of tolerance has been coined the holy grail of autoimmunity. Our work has focused on the reactivity of antimitochondrial autoantibodies (AMA) to chemical xenobiotics and has hypothesized that a modified peptide within PDC-E2, the major mitochondrial autoantigen, will have been immunologically recognized at the time of loss of tolerance. Herein, we successfully applied intein technology to construct a PDC-E2 protein fragment containing amino acid residues 177-314 of PDC-E2 by joining a recombinant peptide spanning residues 177-252 (PDC-228) with a 62-residue synthetic peptide from 253 to 314 (PP), which encompasses PDC-E2 inner lipoyl domain (ILD). We named this intein-constructed fragment PPL. Importantly, PPL, as well as lipoic acid conjugated PPL (LA-PPL) and xenobiotic 2-octynoic acid conjugated PPL (2OA-PPL), are recognized by AMA. Of great importance, AMA has specificity for the 2OA-modified PDC-E2 ILD peptide backbone distinct from antibodies that react with native lipoylated PDC-E2 peptide. Interestingly, this unique AMA subfraction is of the immunoglobulin M isotype and more dominant in early-stage primary biliary cholangitis (PBC), suggesting that exposure to 2OA-PPL-like compounds occurs early in the generation of AMA. To understand the structural basis of this differential recognition, we analyzed PPL, LA-PPL, and 2OA-PPL using electron paramagnetic resonance spectroscopy, with confirmations by enzyme-linked immunosorbent assay, immunoblotting, and affinity antibody analysis. We demonstrate that the conformation of PDC-E2 ILD is altered when conjugated with 2OA, compared to conjugation with lipoic acid., Conclusion: A molecular understanding of the conformation of xenobiotic-modified PDC-E2 is critical for understanding xenobiotic modification and loss of tolerance in PBC with widespread implications for a role of environmental chemicals in the induction of autoimmunity. (Hepatology 2017;65:1670-1682)., (© 2017 by the American Association for the Study of Liver Diseases.)

CXC Chemokine Receptor 3 (CXCR3) is functionally pleiotropic and not only plays an important role in chemotaxis, but also participates in T cell differentiation and may play a critical role in inducing and maintaining immune tolerance. These observations are particularly critical for autoimmune cholangitis in which CXCR3 positive T cells are found around the portal areas of both humans and mouse models of primary biliary cholangitis (PBC). Herein, we investigated the role of CXCR3 in the pathogenesis of autoimmune cholangitis. We have taken advantage of a unique CXCR3 knockout dnTGFβRII mouse to focus on the role of CXCR3, both by direct observation of its influence on the natural course of disease, as well as through adoptive transfer studies into Rag-/- mice. We report herein that not only do CXCR3 deficient mice develop an exacerbation of autoimmune cholangitis associated with an expanded effector memory T cell number, but also selective adoptive transfer of CXCR3 deficient CD8 + T cells induces autoimmune cholangitis. In addition, gene microarray analysis of CXCR3 deficient CD8 + T cells reveal an intense pro-inflammatory profile. Our data suggests that the altered gene profiles induced by CXCR3 deficiency promotes autoimmune cholangitis through pathogenic CD8 + T cells. These data have significance for human PBC and other autoimmune liver diseases in which therapeutic intervention might be directed to chemokines and/or their receptors., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

We have focused on the epidemiology and immunobiology of Zika virus (ZIKV) infection and factors associated with the development of Guillain-Barré syndrome (GBS) and other neurological syndromes in Cúcuta, the capital of North Santander department, Colombia. Data of patients with ZIKV disease reported to the national population-based surveillance system were used to calculate the basic reproduction number (R 0 ) and the attack rates (ARs) as well as to develop epidemiological maps. Patients with neurological syndromes were contacted and their diagnoses were confirmed. A case-control study in which 29 patients with GBS associated with ZIKV compared with 74-matched control patients with ZIKV infection alone was undertaken. Antibodies against arboviruses and other infections that may trigger GBS were evaluated. The estimated value of R 0 ranged between 2.68 (95% CI 2.54-2.67) to 4.57 (95% CI 4.18-5.01). The sex-specific ARs were 1306 per 100,000 females, and 552 per 100,000 males. A non-linear interaction between age and gender on the ARs was observed. The incidence of GBS in Cúcuta increased 4.41 times secondary to ZIKV infection. The lag time between ZIKV infection and neurological symptoms was 7 days (interquartile range 2-14.5). Patients with GBS appeared to represent a lower socioeconomic status and were living near to environmentally contaminated areas. All GBS patients were positive for IgG antibodies against both ZIKV and Dengue virus, and 69% were positive for Chikungunya virus. Noteworthy, GBS was associated with a previous infection with M. pneumoniae (OR: 3.95; 95% CI 1.44-13.01; p = 0.006). No differences in antibody levels against C. jejuni, Epstein-Barr virus and cytomegalovirus were observed. High rates of cranial nerves involvement and dysautonomia were present in 82% and 75.9%, respectively. Intensive care unit (ICU) admission was necessary in 69% of the GBS patients. Most of the patients disclosed a high disability condition (Hughes grade 4). Dysautonomia was the main risk factor of poor GBS prognosis (i.e., ICU admission and disability). Thirteen patients were diagnosed with other neurological syndromes different to GBS (6 with transverse myelitis, 3 with encephalitis, 3 with peripheral facial palsy and one with thoraco-lumbosacral myelopathy). Our data confirm an increased transmission of ZIKV in Cúcuta, and provide support to the view that severe neurological syndromes are related to ZIKV disease. The complex ways by which previous infections and socioeconomic status interact to increase the risk of GBS in people infected by ZIKV should be further investigated., (Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Antiretroviral drug therapy (ART) effectively suppresses replication of both the immunodeficiency viruses, human (HIV) and simian (SIV); however, virus rebounds soon after ART is withdrawn. SIV-infected monkeys were treated with a 90-day course of ART initiated at 5 weeks post infection followed at 9 weeks post infection by infusions of a primatized monoclonal antibody against the α 4 β 7 integrin administered every 3 weeks until week 32. These animals subsequently maintained low to undetectable viral loads and normal CD4 + T cell counts in plasma and gastrointestinal tissues for more than 9 months, even after all treatment was withdrawn. This combination therapy allows macaques to effectively control viremia and reconstitute their immune systems without a need for further therapy., (Copyright © 2016, American Association for the Advancement of Science.)

The environmental factors that lead to the reactivation of human T cell leukemia virus type-1 (HTLV-I) in latently infected T cells in vivo remain unknown. It has been previously shown that heat shock (HS) is a potent inducer of HTLV-I viral protein expression in long-term cultured cell lines. However, the precise HTLV-I protein(s) and mechanisms by which HS induces its effect remain ill-defined. We initiated these studies by first monitoring the levels of the trans-activator (Tax) protein induced by exposure of the HTLV-I infected cell line to HS. HS treatment at 43 °C for 30 min for 24 h led to marked increases in the level of Tax antigen expression in all HTLV-I-infected T cell lines tested including a number of HTLV-I-naturally infected T cell lines. HS also increased the expression of functional HTLV-I envelope gp46 antigen, as shown by increased syncytium formation activity. Interestingly, the enhancing effect of HS was partially inhibited by the addition of the heat shock protein 70 (HSP70)-inhibitor pifithlin-μ (PFT). In contrast, the HSP 70-inducer zerumbone (ZER) enhanced Tax expression in the absence of HS. These data suggest that HSP 70 is at least partially involved in HS-mediated stimulation of Tax expression. As expected, HS resulted in enhanced expression of the Tax-inducible host antigens, such as CD83 and OX40. Finally, we confirmed that HS enhanced the levels of Tax and gp46 antigen expression in primary human CD4⁺ T cells isolated from HTLV-I-infected humanized NOD/SCID/γc null (NOG) mice and HTLV-I carriers. In summary, the data presented herein indicate that HS is one of the environmental factors involved in the reactivation of HTLV-I in vivo via enhanced Tax expression, which may favor HTLV-I expansion in vivo.

In this review we have summarized the role of gut homing molecules with a focus on the heterodimeric integrin α4β7 since the α4β7 has been shown to be important in modulating SIV transmission, disease susceptibility and progression. This review provides an overview of integrins, their structure and function to provide a general background upon which the role of the α4β7 integrin can best be understood. We also describe integrins and their cognate receptors and their potential role in modulating disease that we hope provides some food for thought on how such knowledge can be utilized for vaccine formulation.

Natural killer lymphocytes are essentially involved as the first line of defense against agents such as viruses and malignant cells. The activity of these cells is regulated via interaction of specific and diverse killer cell immunoglobulin-like receptors (KIR) with the highly polymorphic cognate MHC class I proteins on target cells. Genetic variability of both KIR and MHC-I ligands has been shown to be associated with resistance to many diseases, including infection with the immunodeficiency virus. Disease course and progression to AIDS after infection with human immunodeficiency virus-1 (HIV-1) is essentially influenced by the presence of the stimulatory KIR3DS1 receptor in combination with HLA-Bw4. Knowledge of such genetic interactions that contribute to not only disease resistance but also susceptibility are just as important. Such combined genetic factors were recently reported in the rhesus macaque AIDS model. Here, we review the rhesus macaque MHC class I and KIR gene systems and the role of their polymorphisms in the SIV infection model.

Lectin-like molecules and their receptors are cell surface molecules that have been shown to play a role in either facilitating infection or serving as transporters of HIV/SIV in vivo. The role of these lectin-like molecules in the pathogenesis of HIV/SIV infection continues to be defined. In efforts to gain further insight on the potential role of these lectin-like molecules, our laboratory generated monoclonal antibodies (mAb) against the human analogs of rhesus macaque CD200, CD200R and Mincle, since the rhesus macaques are accepted as the most reliable animal model to study human HIV infection. The characterization of the cell lineages from the blood and various tissues of rhesus macaques that express these lectin-like molecules are described herein. Among the mononuclear cells, the cells of the myeloid lineage of rhesus macaques are the predominant cell lineages that express readily detectable levels of CD200, CD200R and Mincle that is similar to the expression of Siglec-1 and Siglec-3 reported by our laboratory earlier. Subset analysis revealed that a higher frequency of the CD14+/CD16- subset from normal rhesus macaques express CD200, CD200R and Mincle. Differences in the frequencies and density of expression of these molecules by the gated population of CD14+ cells from various tissues are noted with PBMC and bone marrow expressing the highest and the mononuclear cells isolated from the colon and ileum expressing the lowest levels. While a significant frequency of pDCs and mDCs express Siglec-1/Siglec-3, a much lower frequency expresses CD200, CD200R and Mincle in PBMCs from rhesus macaques. The mAb against CD200 and CD200R but not Mincle appear to inhibit the infection of macrophage tropic SIV/SHIV in vitro. We conclude that these mAbs may have potential to be used as adjunctive therapeutic agents to control/inhibit SIV/HIV infection.

Varying susceptibility during menstrual cycling could be a factor for S(H)IV infection risk in female rhesus macaques. We retrospectively determined vaginal SIV infection time points relative to the menstrual cycle in a group of rhesus macaques (n=11) enrolled in an HIV transmission trial. Eight of nine rhesus macaques became infected around menstruation time., (© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Designed molecular scaffolds have been proposed as alternative therapeutic agents against HIV-1. The ankyrin repeat protein (Ank(GAG)1D4) and the zinc finger protein (2LTRZFP) have recently been characterized as intracellular antivirals, but these molecules, used individually, do not completely block HIV-1 replication and propagation. The capsid-binder Ank(GAG)1D4, which inhibits HIV-1 assembly, does not prevent the genome integration of newly incoming viruses. 2LTRZFP, designed to target the 2-LTR-circle junction of HIV-1 cDNA and block HIV-1 integration, would have no antiviral effect on HIV-1-infected cells. However, simultaneous expression of these two molecules should combine the advantage of preventive and curative treatments. To test this hypothesis, the genes encoding the N-myristoylated Myr(+)Ank(GAG)1D4 protein and the 2LTRZFP were introduced into human T-cells, using a third-generation lentiviral vector. SupT1 cells stably expressing 2LTRZFP alone or with Myr(+)Ank(GAG)1D4 showed a complete resistance to HIV-1 in viral challenge. Administration of the Myr(+)Ank(GAG)1D4 vector to HIV-1-preinfected SupT1 cells resulted in a significant antiviral effect. Resistance to viral infection was also observed in primary human CD4+ T-cells stably expressing Myr(+)Ank(GAG)1D4, and challenged with HIV-1, SIVmac, or SHIV. Our data suggest that our two anti-HIV-1 molecular scaffold prototypes are promising antiviral agents for anti-HIV-1 gene therapy.

Thymic CD4(+) FoxP3(+) regulatory T (Treg) cells are critical for the development of immunological tolerance and immune homeostasis and requires contributions of both thymic dendritic and epithelial cells. Although B cells have been reported to be present within the thymus, there has not hitherto been a definition of their role in immune cell development and, in particular, whether or how they contribute to the Treg cellular thymic compartment. Herein, using both phenotypic and functional approaches, we demonstrate that thymic B cells contribute to the maintenance of thymic Treg cells and, using an in vitro culture system, demonstrate that thymic B cells contribute to the size of the thymic Treg compartment via cell-cell MHC II contact and the involvement of two independent co-stimulatory pathways that include interactions between the CD40/CD80/CD86 co-stimulatory molecules. Our data also suggest that thymic B cells promote the generation of thymic Treg cell precursors (pre-Treg cells), but not the conversion of FoxP3(+) Treg cells from pre-Treg cells. In addition, thymic B cells directly promote the proliferation of thymic Treg cells that is MHC II contact dependent with a minimal if any role for co-stimulatory molecules including CD40/CD80/CD86. Both pathways are independent of TGFβ. In conclusion, we rigorously define the critical role of thymic B cells in the development of thymic Treg cells from non-Treg to precursor stage and in the proliferation of mature thymic Treg cells., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Background: CD83, a cell surface glycoprotein that is stably expressed on mature dendritic cells, can be transiently induced on other hematopoietic cell lineages upon cell activation. In contrast to the membrane form of CD83, soluble CD83 appears to be immunosuppressive. In an analysis of the phenotype of leukemic CD4(+) T cells from patients with adult T-cell leukemia (ATL), we found that a number of primary CD4(+) T cells became positive for cell surface CD83 after short-term culture, and that most of these CD83(+) CD4(+) T cells were positive for human T-cell leukemia virus type-I (HTLV-I) Tax (Tax1). We hypothesized that Tax1 is involved in the induction of CD83., Result: We found that CD83 was expressed selectively on Tax1-expressing human CD4(+) T cells in short-term cultured peripheral blood mononuclear cells (PBMCs) isolated from HTLV-I(+) donors, including ATL patients and HTLV-I carriers. HTLV-I-infected T cell lines expressing Tax1 also expressed cell surface CD83 and released soluble CD83. CD83 can be expressed in the JPX-9 cell line by cadmium-mediated Tax1 induction and in Jurkat cells or PBMCs by Tax1 introduction via infection with a recombinant adenovirus carrying the Tax1 gene. The CD83 promoter was activated by Tax1 in an NF-κB-dependent manner. Based on a previous report showing soluble CD83-mediated prostaglandin E2 (PGE2) production from human monocytes in vitro, we tested if PGE2 affected HTLV-I propagation, and found that PGE2 strongly stimulated expression of Tax1 and viral structural molecules., Conclusions: Our results suggest that HTLV-I induces CD83 expression on T cells via Tax1 -mediated NF-κB activation, which may promote HTLV-I infection in vivo.

Among nonhuman primates, SIV-infected Asian pigtailed macaques (PM) are relatively more susceptible to infection and disease progression than SIV-infected rhesus macaques (RM). In addition, SIV-infected African natural hosts such as the sooty mangabeys (SM) are resistant to disease. The mechanisms associated with such species-related variable clinical outcomes remain ill-defined but hold the potential to provide insights into the underlying mechanisms surrounding HIV pathogenesis. Recent findings indicate that the expression of the heterodimeric gut homing integrin α4β7 can influence both susceptibility and disease progression in RM. It was reasoned that differences in the frequencies/surface densities of α4β7-expressing lymphocytes might contribute to the differences in the clinical outcome of SIV infection among NHPs. In this article, we report that CD4(+) T cells from PM constitutively express significantly higher levels of α4β7 than RM or SM. Retinoic acid, a key regulator of α4β7 expression, was paradoxically found at higher levels in the plasma of SM versus RM or PM. We also observed pairing of β7 with αE (αEβ7) on CD4(+) T cells in the peripheral blood of SM, but not PM or RM. Finally, the differential mean density of expression of α4β7 in RM versus SM versus PM was predominantly dictated by species-specific sequence differences at the level of the β7 promoters, as determined by in vitro reporter/promoter construct transfection studies. We propose that differences in the regulation and expression of α4β7 may explain, in part, the differences in susceptibility and SIV disease progression in these NHP models., (Copyright © 2015 by The American Association of Immunologists, Inc.)

The detection of viral dynamics and localization in the context of controlled HIV infection remains a challenge and is limited to blood and biopsies. We developed a method to capture total-body simian immunodeficiency virus (SIV) replication using immunoPET (antibody-targeted positron emission tomography). The administration of a poly(ethylene glycol)-modified, (64)Cu-labeled SIV Gp120-specific antibody led to readily detectable signals in the gastrointestinal and respiratory tract, lymphoid tissues and reproductive organs of viremic monkeys. Viral signals were reduced in aviremic antiretroviral-treated monkeys but detectable in colon, select lymph nodes, small bowel, nasal turbinates, the genital tract and lung. In elite controllers, virus was detected primarily in foci in the small bowel, select lymphoid areas and the male reproductive tract, as confirmed by quantitative reverse-transcription PCR (qRT-PCR) and immunohistochemistry. This real-time, in vivo viral imaging method has broad applications to the study of immunodeficiency virus pathogenesis, drug and vaccine development, and the potential for clinical translation.

Objective: Understanding the role of T-cell immunoglobulin and mucin domain-containing molecule 3 (Tim-3) on T cells and dendritic cells during the course of simian immunodeficiency virus (SIV) infection., Design: Sequentially collected PBMCs from uninfected and SIVmac239-infected rhesus macaques were evaluated for Tim-3 expression by flow cytometry and antigen-specific responses., Results: Blood innate immune cells (dendritic cells) and B cells showed high constitutive expression of Tim-3, whereas, compared to humans, only a minority of macaque T cells did. However, TIM-3 expression was transiently up-regulated on both CD4 and CD8 T cells during acute SIV infection, correlating with plasma viral loads, CD4 cell counts, and Ki67 expression up to 6 weeks postinfection and returned to baseline values by 8 weeks postinfection. Upon antigen-specific stimulation, most Tim-3 T cells produced various cytokines, suggesting that this marker is up-regulated on effector antigen-specific T cells and not associated with T-cell exhaustion. Among myeloid dendritic cells (mDCs), a clear separation was seen between blood mDCs expressing Tim-3 and those expressing PD-L2 - a ligand for inhibitory receptor programmed death 1., Conclusion: Rhesus macaques show constitutive expression of Tim-3 primarily on innate immune cells, but markedly lower levels on T cells compared to humans. Nevertheless, Tim-3 expression on T cells is transiently up-regulated during acute, but not chronic, SIV infection, and appears to be a marker of antigen-specific effector cells. The exact role and contribution of Tim-3 to the modulation of antiviral responses in vivo will require additional investigation.

There has clearly been a deluge of international press coverage of the recent outbreak of Ebolavirus in Africa and is partly related to the "fear factor" that comes across when one is confronted with the fact that once infected, not only is the speed of death in a majority of cases rapid but also the images of the cause of death such as bleeding from various orifices gruesome and frightening. The fact that it leads to infection and death of health care providers (10% during the current epidemic) and the visualization of protective gear worn by these individuals to contain such infection adds to this "fear factor". Finally, there is a clear perceived notion that such an agent can be utilized as a bioterrorism agent that adds to the apprehension. Thus, in efforts to gain an objective view of the growing threat Ebolavirus poses to the general public, it is important to provide some basic understanding for the lethality of Ebolavirus infection that is highlighted in Fig. 1. This virus infection first appears to disable the immune system (the very system needed to fight the infection) and subsequently disables the vascular system that leads to blood leakage (hemorrhage), hypotension, drop in blood pressure, followed by shock and death. The virus appears to sequentially infect dendritic cells disabling the interferon system (one of the major host anti-viral immune systems) then macrophages (that trigger the formation of blood clots, release of inflammatory proteins and nitric oxide damaging the lining of blood vessels leading to blood leakage) and finally endothelial cells that contribute to blood leakage. The virus also affects organs such as the liver (that dysregulates the formation of coagulation proteins), the adrenal gland (that destroys the ability of the patient to synthesize steroids and leads to circulation failure and disabling of regulators of blood pressure) and the gastro-intestinal tract (leading to diarrhea). The ability of the virus to disable such major mechanisms in the body facilitates the ability of the virus to replicate in an uncontrolled fashion leading to the rapidity by which the virus can cause lethality. Various laboratories have been working on defining such mechanisms utilizing in vitro culture systems, a variety of animal models including inbred strains of normal and select gene knock out mice, guinea pigs and nonhuman primates that have led to a better understanding of the potential mechanisms involved. There have also been some major advances made in the identification of therapies from the very simple (major supportive type of therapy), to the identification of a number of highly effective chemotherapeutic agents, a variety of highly effective preventive (demonstrating 100% effectiveness in nonhuman primate models) recombinant formulations (adenovirus based, VSV-based, rabies virus based), therapeutic candidate vaccines (cocktail of monoclonal antibodies such as ZMAPP) and alternate approaches (RNAi-based such as TKM-Ebola and antisense based such as AVI-7537) that show great promise and at an unprecedented rate of discovery that speaks well for the scientific research community at large., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

α4β7 integrin-expressing CD4(+) T cells preferentially traffic to gut-associated lymphoid tissue (GALT) and have a key role in HIV and simian immunodeficiency virus (SIV) pathogenesis. We show here that the administration of an anti-α4β7 monoclonal antibody just prior to and during acute infection protects rhesus macaques from transmission following repeated low-dose intravaginal challenges with SIVmac251. In treated animals that became infected, the GALT was significantly protected from infection and CD4(+) T cell numbers were maintained in both the blood and the GALT. Thus, targeting α4β7 reduces mucosal transmission of SIV in macaques.

Killer cell immunoglobulin-like receptors (KIR) regulate the activity of natural killer (NK) cells and have been shown to be associated with susceptibility to a number of human infectious diseases. Here, we analyzed NK cell function and genetic associations in a cohort of 52 rhesus macaques experimentally infected with SIVmac and subsequently stratified into high viral load (HVL) and low viral load (LVL) plasma viral loads at set point. This stratification coincided with fast (HVL) and slow (LVL) disease progression indicated by the disease course and critical clinical parameters including CD4+ T cell counts. HVL animals revealed sustained proliferation of NK cells but distinct loss of peripheral blood NK cell numbers and lytic function. Genetic analyses revealed that KIR genes 3DL05, 3DS05, and 3DL10 as well as 3DSW08, 3DLW03, and 3DSW09 are correlated, most likely due to underlying haplotypes. SIV-infection outcome associated with presence of transcripts for two inhibitory KIR genes (KIR3DL02, KIR3DL10) and three activating KIR genes (KIR3DSW08, KIR3DS02, KIR3DS05). Presence of KIR3DL02 and KIR3DSW08 was associated with LVL outcome, whereas presence of KIR3DS02 was associated with HVL outcome. Furthermore, we identified epistasis between KIR and MHC class I alleles as the transcript presence of the correlated genes KIR3DL05, KIR3DS05, and KIR3DL10 increased HVL risk when Mamu-B*012 transcripts were also present or when Mamu-A1*001 transcripts were absent. These genetic associations were mirrored by changes in the numbers, the level of proliferation, and lytic capabilities of NK cells as well as overall survival time and gastro-intestinal tissue viral load.

Unlabelled: The serologic hallmark of primary biliary cirrhosis (PBC), the antimitochondrial response to the E2 component of the pyruvate dehydrogenase complex (PDC-E2), has unique features, including continuous high titers of immunoglobulin M (IgM) and IgG reactivity throughout all stages of disease, capable not only of target enzyme inhibition, but also crossreactive with chemical xenobiotics that share molecular homology with the inner lipoyl domain of PDC-E2; such chemicals have been proposed as potential etiological agents. We used flow cytometry and enzyme-linked immunospot assay (ELISPOT) to examine B-cell subsets in 59 subjects, including 28 with PBC, 13 with primary sclerosing cholangitis (PSC), and 18 healthy controls. Strikingly, in PBC, although there were no significant differences in B-cell phenotype subpopulations, 10% of the total IgG and IgA plasmablast population and 23% of the IgM plasmablast population were uniquely reactive with PDC-E2, detected in the CXCR7+ CCR10low plasmablast population. In contrast, plasmablast reactivity to a control antigen, tetanus toxoid, was minimal and similar in all groups. Additionally, we isolated plasmablast-derived polyclonal antibodies and compared reactivity with plasma-derived antibodies and noted a distinct noncirculating tissue source of xenobiotic crossreacting antibodies. The high levels of autoantigen specific peripheral plasmablasts indicate recent activation of naive or memory B cells and a continuous and robust activation. The presence of CXCR7+ CCR10low PDC-E2-specific ASCs suggests a mechanistic basis for the migration of circulating antigen specific plasmablasts to the mucosal epithelial ligands CXCL12 and CCL28., Conclusion: Our findings suggest a sustained rigorous B-cell response in PBC, likely activated and perpetuated by cognate autoantigen., (© 2014 by the American Association for the Study of Liver Diseases.)

Unlabelled: Shotgun proteomics is a powerful analytic method to characterize complex protein mixtures in combination with multidimensional liquid chromatography-tandem mass spectrometry (LC-MS/MS). We used this platform for proteomic characterization of apoptotic bodies in an effort to define the complex protein mixtures found in primary cultures of human intrahepatic biliary epithelial cells (HiBEC), human renal proximal tubular epithelial cells, human bronchial epithelial cells, isolated intrahepatic biliary epithelial cells from explanted primary biliary cirrhosis (PBC), and control liver using a total of 24 individual samples. Further, as additional controls and for purposes of comparison, proteomic signatures were also obtained from intact cells and apoptotic bodies. The data obtained from LC-MS/MS, combined with database searches and protein assembly algorithms, allowed us to address significant differences in protein spectral counts and identify unique pathways that may be a component of the induction of the signature inflammatory cytokine response against BECs, including the Notch signaling pathway, interleukin (IL)8, IL6, CXCR2, and integrin signaling. Indeed, there are 11 proteins that localize specifically to apoptotic bodies of HiBEC and eight proteins that were specifically absent in HiBEC apoptotic bodies., Conclusion: Proteomic analysis of BECs from PBC liver compared to normal liver are significantly different, suggesting that an immunological attack affects the repertoire of proteins expressed and that such cells should be thought of as living in an environment undergoing continuous selection secondary to an innate and adaptive immune response, reflecting an almost "Darwinian" bias., (© 2014 by the American Association for the Study of Liver Diseases.)

We have investigated the dynamics of germinal center (GC) formation in lymphoid tissues following acute SIV infection. SIV induces a marked follicular hyperplasia, associated with an aberrant accumulation of nonproliferating T follicular helper cells within GCs, but with an abundance of cells producing IL-21, demonstrating that the mechanisms involved for these two events appear independent. IL-21-stimulated T follicular helper cells are considered a critical element for GC formation, a physiological process that seems dysregulated and excessive during HIV/SIV infection, contributing to lymphoid pathogenesis. However, the data suggest that the kinetics by which such GCs are formed may be an important predictor of the host-pathogen equilibrium, as early GC hyperplasia was associated with better control of viral replication. In contrast, monkeys undergoing fast disease progression upon infection exhibited an involution of GCs without local IL-21 production in GCs. These results provide important clues regarding GC-related hyperimmune responses in the context of disease progression within various individuals during HIV/SIV infection and may open novel therapeutic avenues to limit lymphoid dysfunction, postinfection., (Copyright © 2014 by The American Association of Immunologists, Inc.)

Immunochromatographic strip test is a unique type of rapid test that has been developed for use as part of a diagnostic kit for the rapid detection of antibodies and/or other proteins of interest. For the detection of target proteins, most of the commercial tests are assembled based on the conjugation of colloidal gold particles to monoclonal antibodies embedded within the conjugate pad of a strip test. In this study, we tested the novel concept of using an artificial non-antibody structure for generating a colloidal gold conjugate (CGC). We exploited the property of an ankyrin repeat protein that specifically binds to the HIV-1 capsid protein termed Ank(GAG)1D4. This construct was applied as a model structure to create Ank1D4-CGC and used as a new type of visible detector system and termed it ankyrin-based immunochromatographic strip (ABIS) test. The ABIS test was shown to be highly sensitive with a lower limit of detection of the target protein at 0.1 μg/ml. Moreover, the ABIS test was not only highly sensitive but also shared a level of specificity within the same range of the commercial test kit. The results of the studies presented herein therefore demonstrate the novel application of an artificial non-immunoglobulin structure (ankyrin repeat protein) as the new line of a visible detector using a rapid diagnostic test with characteristics that have the potential to be superior to those that utilize antibody-based tests.