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Background & Aims: Mice that express a dominant-negative form of transforming growth factor-β receptor restricted to T cells (dnTGF-βRII) develop antimitochondrial antibodies and liver inflammation similar to human primary biliary cirrhosis. Methods: To address the role of B cells in this model of primary biliary cirrhosis, we bred B cell–deficient mice (Igμ–/–) with dnTGF-βRII mice, creating Igμ–/–dnTGF-βRII mice, and compared the resulting disease phenotype with that of dnTGF-βRII mice (controls). We also performed adoptive transfer of dnTGF-βRII CD8+ splenocytes, with or without B cells, to 8-week-old female Rag-1–/– mice to assess the role of B cells in the inflammatory response. Results: The B cell–deficient Igμ–/–dnTGF-βRII mice unexpectedly developed a more severe form of cholangitis than controls (dnTGF-βRII mice) and had a significantly greater frequency of activated CD4+ and CD8+ T cells in the liver. They also had reduced frequency of Foxp3+ regulatory T cells in the hepatic CD4+ T-cell population and natural killer (NK) T cells (NK1.1+ CD3+) in hepatic inflammatory cell infiltrates. The Igμ–/–dnTGF-βRII mice had increased levels of proinflammatory cytokines (tumor necrosis factor-α and interleukin-6) and developed a more severe form of colitis than controls. Adoptive transfer of CD8+ splenocytes from dnTGF-βRII mice and peritoneal cavity–derived, but not spleen-derived, CD19+ B cells into Rag-1–/– mice resulted in decreased amounts of liver inflammation and bile duct damage, compared with Rag-1–/– mice in which only CD8+ splenocytes were transferred. Conclusion: B cells have a suppressive effect on the inflammatory response in the dnTGF-βRII model of primary biliary cirrhosis. [Copyright &y& Elsevier]

Abstract: The crucial role of regulatory cells in self-tolerance and autoimmunity has been clearly established in numerous types of regulatory cells, the majority of which are CD4+ T cells. Much focus has been placed on thymically derived CD4+CD25+ regulatory T cells, given that the depletion of this subset in murine models results in the spontaneous development of autoimmune diseases. These naturally occurring regulatory T cells are found to be functionally mature in the thymus, and exert suppression in a contact-dependent manner. Another important category of immunosuppressive cells consists of conditionally induced regulatory T cells such as Tr1, Th3, and various other CD4+ lymphocytes. Understanding the development and regulatory functions of immunoregulatory cells may elucidate the etiology for loss of self-tolerance. This review will summarize the characteristics, developmental pathways, and functions of regulatory T cells, as well as their role in human autoimmune diseases including multiple sclerosis, rheumatoid arthritis, Myasthenia Gravis, Kawasaki disease, autoimmune polyglandular syndrome type II, type 1 diabetes, autoimmune lymphoproliferative syndrome, and systemic lupus erythematosus. [Copyright &y& Elsevier]

Abstract: Autoimmune antibodies and autoimmune responses have been characterized in both human HIV infection and the rhesus macaque (RM) non-human primate model of SIV infection and reasoned to contribute to the pathogenesis of AIDS. Many theories for the induction and maintenance of such responses have been entertained including molecular mimicry between HIV proteins and self molecules, CD4+ T cell loss accompanied by loss of normal immune regulation that dictate self–non-self-reactivity, defective negative/positive selection of T cells to name a few. The precise mechanisms that lead to such immune dysfunction is difficult to study in humans. Our lab has been studying such autoimmune responses in both SIV-infected RM and sooty mangabeys (SM), a species from Africa that are naturally infected with SIV but do not display any detectable signs of immune deficiency or autoimmunity. We submit that this model is an important model since it allows for narrowing down those mechanisms and pathways that are a result of lentiviral infection per se from those that specifically cause disease including autoimmunity. During the course of these studies, we have ruled out a role for plasma and cellular viral loads, anti-viral humoral responses and a variety of cell signaling pathways. We have identified select pathways that appear to play roles in the pathogenesis of lentiviral infection and disease. These include pathways involved in innocent bystander killing by apoptosis of CD4+ T cells, role for differential regulation of the cell cycle, and a role for distinct host proteins that get incorporated by the virions as they are assembled and either bud out of CD4+ T cells or exit the cells in the form of multi-vesicular endosomal particles from monocytes/macrophages from SIV-infected disease susceptible RM and disease-resistant SM. We present our current working model and hypotheses that are designed to elucidate differences that are responsible for such distinct outcomes of lentiviral infection, autoimmunity and disease. We believe that such findings have important implications for the design of vaccines against human HIV infection. [Copyright &y& Elsevier]

Background: Undernutrition is widely perceived to affect the development of an effective immune system. Objective:We used a mini-analysis system to quantitate antibody titers and evaluate the sera of 200 Kenyan schoolchildren for antibodies to Helicobacter pylori [isotypes of immunoglobulins A (IgA), G (IgG), and M (IgM)], hepatitis A virus, rotavirus, tetanus toxoid (IgG), and a panel of recombinant malarial antigens (MSP119, MSP2, Ag512, MSP4, and MSP5). Design: Children participated in a school-based feeding intervention with meat, milk, or nonanimal-source foods or in a nonintervention control group. Microvolumes (200 mL) of sera were analyzed at baseline and after 1 y. Results: Nearly all children had elevated titers of antibody to H. pylori, hepatitis A virus, rotavirus, and malaria at the outset, despite a high prevalence of apparent biochemical micronutrient deficiencies and stunting, but many had titers of tetanus toxoid IgG antibodies below the protective concentration. Children with low hemoglobin had a greater proportion of elevated H. pylori IgM antibody titers at baseline, which suggests that current infection with H. pylori may be associated with anemia. Compared with the control subjects, only the group eating meat had a significant increase in H. pylori IgM antibodies during the intervention (P = 0.019). No other group comparisons with the control subjects were statistically significant. The additional finding that the sera of some children showed inadequate tetanus-protective antibodies, despite immunization, suggests that the vaccination program was suboptimal. Conclusions: A large battery of immune assays can be performed on microvolumes of sera. Furthermore, despite evidence of malnutrition, children do develop significant antibody-mediated responses to common pathogens. [ABSTRACT FROM AUTHOR]

Background: Increased incidence and prevalence of peripartum cardiomyopathy (PPCM) have been documented in the Hospital Albert Schweitzer (HAS) District of Haiti. Although the basis for this increased incidence of PPCM remains unclear, there is growing evidence for an underlying autoimmune process. One potential risk factor for increased autoreactivity is a micronutrient deficiency. In Africa, low plasma selenium (Se) level has been reported as a possible risk factor for PPCM. This report details results of initial studies to test the hypothesis that plasma levels of Se and/or other micronutrients may be related to PPCM risk in this population. Methods: Under the direction of the Institutional Review Board (HAS Ethics Committee) and with informed consent, levels of Se and other micronutrients were measured in plasma samples obtained from PPCM mothers and parity-matched control mothers from the HAS District of Haiti. Results: Mean plasma Se level in 18 PPCM patients was 110 ng/ml (range 67–145) compared to mean plasma Se level in 34 control mothers of 121 ng/ml (range 98–172) (P=0.1748). These levels are substantially greater than those reported for pediatric patients with Keshan cardiomyopathy, which can be prevented by Se prophylaxis. No deficiency or significant difference was found in any other micronutrient tested (Vitamin A (retinol), Vitamin B12, Vitamin C, Vitamin E, and B-Carotene) for these PPCM and control mothers. Conclusion: Although there are several possible mechanisms by which Se could play a role in the pathobiology of PPCM, there is no evidence that Se deficiency is a cause of PPCM or a risk factor for the development of PPCM in this district of Haiti. The results of this investigation indicate that future studies of PPCM in this population should focus on other potential etiologic and risk factors. [Copyright &y& Elsevier]

Abstract: Homeostasis of the immune system is achieved through refined regulation and communication between immunologically relevant receptor and their cognate ligands amongst mononuclear cells during ontogeny and day to day immune responses. An aberrance in not only the kinetics of receptor expression but also the relative diversity of expression alter these events. More importantly, improper modulation of ligand binding affinity can be a triggering event that results in autoimmunity. As one of the most common post-translational modifications, tyrosine sulfation possesses the ability to regulate mononuclear cell function at various stages of the immune response. For example, removal of sulfated tyrosine residues consistently decreases the binding affinity of the ligand to its corresponding receptor as exemplified by studies of several tyrosine sulfated proteins such as PSGL-1, CD44v5, CCR5, and CXCR4, all known to play a role in a variety of autoimmune diseases. This review defines possible roles that tyrosine sulfated proteins may play in the pathogenesis of autoimmune diseases. [Copyright &y& Elsevier]

Abstract: The role of adaptive as well as innate immune responses in the pathology of primary biliary cirrhosis (PBC) has been a major subject of investigation. Primary biliary cirrhosis is an autoimmune liver disease involving the destruction of small bile ducts, which eventually leads to liver cirrhosis. Adaptive immune responses involving autoantibody production by B cells and autoreactive T cells have been labeled as the most probable mediators of tissue destruction. Autoantibody production against mitochondrial antigens is used as a key diagnostic marker in PBC, being present in 90–95% of patient sera. Besides blood, these antimitochondrial antibodies are found in liver, bile, saliva, and urine of patients and target mitochondrial autoantigens that are well conserved between species. One possible mechanism of antibody-mediated tissue destruction is via the transcytosis of immunoglobulin A antimitochondrial antibodies through biliary epithelium. Another mechanism may involve the recognition by antimitochondrial antibodies of the mitochondrial autoantigens abnormally expressed on patient biliary epithelium. The second component of the adaptive immune response in PBC involves T cells, which comprise a large fraction of infiltrating leukocytes in diseased livers. Autoreactive CD4+ and CD8+ T cells recognizing mitochondrial antigens targeted by antimitochondrial antibodies have been isolated with specificity for epitopes that overlap with those of B cells. Cytokines production of such infiltrates indicates the involvement of both TH1 and TH2 responses in the diseased tissue. Besides adaptive responses, innate immunity effector mechanisms involving eosinophils, macrophages, and B cells hyperresponsive to bacterial DNA CpG motifs has been implicated in the pathology of PBC. Despite research efforts, the etiology of PBC still remains elusive, although theories involving the participation of genetic factors, molecular mimicry due to microorganisms, and a role for modification of native autoantigens by xenobiotics have been proposed. [Copyright &y& Elsevier]

The adjuvant effect of recombinant Rhesus macaque interleukin-12 (RhIL-12) on the induction of cellular and humoral immune responses elicited by the HIV-1 subunit vaccine protein gp120 in Rhesus macaques was examined. RhIL-12 in conjunction with gp120 was given at day 0, 28 and 84 intramuscularly. Coadministration resulted in an approximate 10-fold increase in plasma anti-gp120 antibody levels as compared to levels generated in control monkeys receiving gp120 alone. Potentiation of the humoral arm of the immune response was evident by both ELISA and an antiviral bioassay. In addition, RhIL-12 was found to produce a significant increase in gp120-specific proliferative responses and in the frequency of antigen-specific IFN-γ and IL-2 producing T cells after restimulation of PBMC with gp120 in vitro indicating that RhIL-12 potentiates cell-mediated immune responses as well. A critical finding was that during the course of the study, RhIL-12 did not induce a neutralizing antibody response to the administered cytokine. The doses of RhIL-12 were well tolerated and no detectable adverse side-effects on hematopoietic and hepatic parameters were noted. The data revealed that IL-12, when coadministered intramuscularly, acts as a potent adjuvant which is able to enhance not only cellular but also humoral immune responses to gp120 in non-human primates and may have to be considered in future HIV vaccine strategies. [Copyright &y& Elsevier]

Purpose Although the role of integrins has been described in a variety of diseases, these roles seem to be distinct. To date, no study has attempted to provide links to the various pathways by which such integrins can be involved in these diverse disease settings. The purpose of this review was to address this gap in our knowledge with the hypothesis that there is, in fact, a common pathway by which integrins may function. Methods This article provides an in-depth perspective on the discovery, development, and design of therapeutics that modulate cellular function by targeting integrin:ligand interactions by reviewing the literature on this subject; the review included the most recent results of clinical and subclinical studies. A MEDLINE search was conducted for articles pertaining to the various issues related to integrins, and the most relevant articles are discussed (ie, not only those published in journals with a higher impact factor). Findings It seems that the ligation of the integrins with their cognate ligands plays a major role in translating membrane dialogue into biological function. In addition, they also seem to play a major regulatory role that can enhance or inhibit biological function depending on the context within which such receptor:ligand interactions occur and the organ and tissues at which interactions occurs and is manipulated. Those studies that used statistical analyses have been included where appropriate. Implications Our findings show that anti-integrin treatment has the potential to become a valid coadjuvant in the treatment of several diseases including cancer, inflammatory diseases, HIv infection and cardiovascular diseases. [ABSTRACT FROM AUTHOR]

Abstract: In an attempt to simplify the protocol of DC generation in vitro, studies conducted herein show that functional DCs could be generated from bulk peripheral blood mononuclear cells (PBMCs) in media containing GM-CSF and IL-4. Interestingly, when PBMCs, but not purified monocytes, were exposed to either CCR5- or CXCR4-tropic inactivated HIV-1 isolates (iHIV-1) at the initiation of the culture, DC yields were significantly reduced in a dose-dependent manner because of monocyte apoptosis. Similar impairment of DC generation was noted using type I IFNs and poly IC not only in cultures of PBMCs but also using highly enriched monocytes. This effect was reversed by antihuman type I IFN receptor, but not by anti-FasL, anti-TRAIL, anti-TNF, or a mixture of these antibodies. iHIV-1–exposed PBMCs, but not monocytes, produced high levels of IFN-α but not IFN-β. PBMCs depleted of CD123+ plasmacytoid DCs produced low levels of IFN-α and were resistant to iHIV-1–mediated DC impairment. Interestingly, exogenously added TNF reversed the impairment by iHIV-1 in the PBMC cultures. In conclusion, the present results indicate that iHIV-1 impairs the in vitro generation of functional DCs from PBMCs through the induction of IFN-α from plasmacytoid DCs in a CD4-dependent fashion in the absence of TNF. [Copyright &y& Elsevier]

Summary: We have previously demonstrated that normal human T cells either long-term repeatedly stimulated or freshly activated in vitro in the presence of TGF-β express the cell surface T-cell costimulating molecule OX40 ligand (OX40L). To further elucidate the kinetics of OX40L expression by human T cells, we have examined whether cell proliferation was required for the expression of OX40L. Thus, normal fresh peripheral blood mononuclear cells were stimulated with immobilized anti-CD3 antibody in the presence of the DNA synthesis-blocking agents such as mitomycin C, 5-fluorouracil, or X-ray irradiation. Flow cytometric analyses demonstrated that a significant frequency of these DNA-damaged activated primary CD4+ and CD8+ T cells became OX40L+ as early as 1 hour after treatment. The OX40L induction on the DNA-damaged activated T cells was inhibited by treatment with either RNA or protein synthesis inhibitors, actinomycin D, or cycloheximide, respectively. Induced OX40L on T cells was functional because it bound recombinant OX40. These data indicate that human primary T cells are programmed to rapidly express functional OX40L molecules after stimulation under DNA-damaging conditions, demonstrating that the induction of OX40L by T cells is independent of cell proliferation. The clinical implications of these new findings are discussed. [Copyright &y& Elsevier]

Summary: Interaction between OX40 expressed on activated T cells and its ligand (OX40L) on antigen presenting cells (APC) provides a co-stimulatory signal for T cells to promote acquired immunity. In the present study, we have examined various culture conditions for optimum OX40L expression on T cells stimulated with immobilized anti-CD3/CD28 monoclonal antibodies (mAbs). Although the day 3 primed T cells expressed minimal OX40L, after repeated stimulations both the CD4+ and CD8+ T cells became OX40L positive as determined by flow cytometry. Interleukin (IL)–12 interfered with the OX40L expression. Among activated T cells, a higher frequency of CD8+ T cells expressed OX40L than CD4+ T cells. By blocking OX40L-OX40 interaction by an anti-OX40 mAb, the number of OX40L+ T cells significantly increased. Screening of various cytokines showed that transforming growth factor (TGF)–β1 was capable of induction of OX40L on the activated T cells within 3 days. The OX40L expressed on T cells was functional, as they bound soluble OX40 and stimulated human immunodeficiency virus–1 (HIV-1) production from cell lines chronically infected with HIV-1 and expressing OX40. Altogether the present study findings indicate that functional OX40L is inducible on human activated CD4+ and CD8+ T cells, and that the expression is enhanced by TGF-β1. [Copyright &y& Elsevier]

Abstract: We tested the hypothesis that removal of viral lipids using diisopropylether can enhance antigenicity of SIVmac251. DIPE delipidation removed cholesterol from SIVmac251 without significant loss of viral protein or RNA. Mice immunized with the same SIV preparation but boosted with delipidated SIVmac251 exhibited significantly broader and higher cellular and humoral immune responses compared to live or AT-2-inactivated virus. As little as 1μg (total protein) of delipidated virus was sufficient to induce such enhanced immune responses. Thus, solvent treated lentivirus may provide a novel strategy to generate immune responses to additional viral epitopes. [Copyright &y& Elsevier]

Abstract: TGF-β1 deficient mice develop multifocal inflammatory autoimmune disease and serve as a valuable animal model of autoimmunity. Transgenic expression of a dominant negative form of TGF-β receptor type II in T cells have enabled the study of cell lineage specific effects of TGF-β providing clues to the potential etiology of autoimmunity. These studies suggest that TGF-β deficiency may induce autoimmune disease by influencing a number of immunological phenomena including lymphocyte activation and differentiation, cell adhesion molecule expression, regulatory T cell function, the expression of MHC molecules and cytokines, and cell apoptosis. The spectrum of effects appears to be significant in mucosal immunity and may contribute to the pathogenesis of inflammatory bowel disease. [Copyright &y& Elsevier]

Abstract: The NOD mouse has been an important model of type 1 diabetes and autoimmune diseases for over 20 years. Experimental and genetic manipulations of the NOD mouse have demonstrated a broad susceptibility to multiple autoimmune syndromes. This predisposition to autoimmunity is due to defects in both central and peripheral tolerance. The defect of central tolerance is likely secondary to improper negative selection mediated by the unique MHC Class II molecule, I-Ag7 as well as intrinsic T cell signaling defects. The genetic basis for impaired peripheral tolerance is controlled by over 20 susceptibility loci termed insulin-dependent diabetes (idd) loci. The maintenance of peripheral tolerance is impaired by alterations in T cell signaling and apoptosis. In addition, insufficient co-stimulation from accessory cells, and defective regulatory T cells, may promote the production of autoreactive T cells. [Copyright &y& Elsevier]

Abstract: Primary biliary cirrhosis is an enigmatic autoimmune liver disease that predominantly affects women and is characterized by antimitochondrial antibodies and specific destruction of small bile ducts. Interestingly, patients with this disease not only have high titer antibodies to mitochondria, but also highly directed, liver-specific CD4 and CD8 cells directed at the same mitochondrial autoantigens. These mitochondrial autoantigens are all members of the 2-oxo dehydrogenase complex family and include the E2 component of pyruvate dehydrogenase as the major autoantigen. Moreover, the epitopes recognized by CD4, CD8 T cells and autoantibody, are all directed within the same region, namely the lipoyl domain of pyruvate dehydrogenase complex-E2. All cells in the body have mitochondria but there appear to be specific destruction of biliary cells. We believe that this specific destruction is secondary to a highly directed mucosal response that focuses on biliary cells because of the involvement of a polymeric immunoglobulin receptor, the presence of immunoglobulin A in mucosal secretions, and the unique apoptotic properties of biliary epithelium. [Copyright &y& Elsevier]

Evaluation of cytokine production in macaques has been hampered by a lack of availability of optimized and standardized immunoassays such as ELISA and enzyme-linked immune spot assay (ELISpot); only a limited number of macaque cytokines have been assessed by ELISpot. Using monoclonal antibodies (mAb) to human cytokines that cross-react with cynomolgus and rhesus macaque interferon-γ (IFN-γ), interleukin (IL)-2, IL-4, IL-5, IL-6, IL-12, IL-13 and granulocyte monocyte colony-stimulating factor, we measured macaque cytokine production by ELISA and ELISpot. Quantitation of spontaneous as well as phytohemagglutinin (PHA)-induced cytokine production in peripheral blood mononuclear cells (PBMC) from rhesus and cynomolgus macaques and humans were compared. The proportional distribution of the different cytokines, in terms of PBMC synthesizing different cytokines as well as the levels of the different cytokines produced, were similar in all species. Spontaneous- and PHA-induced cytokine productions thus appear to be similarly regulated in macaques and man. ELISpot and ELISA assays for macaque IFN-γ were further used to measure antigen-specific immune responses of PBMC from cynomolgus macaques exposed to, or vaccinated against, simian immunodeficiency virus (SIV). The establishment of reliable immunoassays for detection of macaque cytokines is of importance for future progress of research utilizing macaques as experimental animals. [Copyright &y& Elsevier]

Peripartum cardiomyopathy (PPCM) is a rare and serious heart disease that exclusively afflicts women during childbearing years. Symptoms include rapid onset of cardiovascular insufficiency occurring during pregnancy, initiated anytime between the third trimester until 5 months post-partum in the absence of any other signs or history of heart disease. The rare incidence of PPCM and the absence of any relevant animal models have limited research and understanding of the pathogenic mechanisms involved. Several compelling sets of data support the view that PPCM is a form of autoimmune IDCM. However, PPCM differs from autoimmune IDCM in that (a) it is associated with unique sets of autoantibodies and autoantigens, (b) it has a relatively rapid onset, and (c) it exclusively affects pregnant women. Furthermore, the etiology of PPCM is dependent on the interaction of pregnancy associated factors, e.g. increased hemodynamic stress, vasoactive hormones and fetal microchimerism, that co-operate in the context of essential immune and genetic environments for disease progression. Our model of PPCM attempts to represent how multiple factors, e.g. pregnancy, genetics, immune dysregulation, and fetal microchimerism are held in a complex dynamic balance that can co-operate towards the maintenance of cardiovascular health or disease in the mother (Fig. 1Fig. 1Dynamic balance between the immune environment, pregnancy associated factors, e.g. vasoactive hormone levels and hemodynamic stress, genetics, and fetal microchimerism in the development of PPCM.). A more thorough study of the precise nature of the cardiac tissue autoantigens may lead to the identification of the mechanisms of breakdown of self-tolerance and perhaps also the putative etiologic agent(s). Further studies of the precise nature of the cardiac tissue autoantigens and the specific factors governing the balance between tolerance and autoimmunity in the periphery, e.g. expression of PD-L1 on cardiac tissues and the role of regulatory T cells, may help to elucidate the autoimmune mechanisms of PPCM. [Copyright &y& Elsevier]

Abnormal bone marrow (BM) suppression is one of the hallmarks of dengue virus (DENV) infection in patients. Although the etiology remains unclear, direct viral targeting of the BM has been reasoned to be a contributing factor. The present studies were carried out in an effort to determine the potential effect of DENV infection on the cellularity of BM using a previously established nonhuman primate model of DENV-induced coagulopathy. BM aspirates were collected at various times from the infected nonhuman primate and cells were phenotypically defined and isolated using standard flow cytometry (fluorescence-activated cell sorting). These isolated cells were subjected to detection of DENV utilizing quantitative real-time reverse transcription polymerase chain reaction, electron microscopy, and immunostaining techniques. DENV RNA was detectable by quantitative real-time reverse transcription polymerase chain reaction in BM specimens and the presence of DENV-like particles within platelet was confirmed by electron microscopy. Enumeration of BM cells revealed a transient surge in cellularity at day 1, followed by a gradual decline from days 2 to 10 post infection. Detailed phenotypic studies showed similar kinetics in the frequencies of CD41+CD61+ cells, regardless of CD34 and CD45 expression. The CD61+ cells were not only the predominant cells that stained for DENV antigen but fluorescence-activated cell sorting–assisted isolation of CD61+ cells from the BM were shown to contain infectious DENV by coculture with Vero cells. These data support the view that intravenous infection of nonhuman primate with DENV leads to direct infection of the BM, which is likely to be a contributing factor for transient cell suppression in the peripheral blood characteristic of acute DENV infection. [ABSTRACT FROM AUTHOR]