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Central to protective humoral immunity is the activation of B cells and their terminal differentiation into antibody‐secreting plasma cells. Long‐lived plasma cells (LLPC) may survive for years to decades. Such long‐lived plasma cells are also responsible for producing pathogenic antibodies that cause a variety of challenges such as autoimmunity, allograft rejection, and drug neutralization. Up to now, various therapeutic strategies aimed at durably eliminating pathogenic antibodies have failed, in large part due to their inability to efficiently target LLPCs. Several antibody‐based therapies have recently gained regulatory approval or are in clinical phases of development for the treatment of multiple myeloma, a malignancy of plasma cells. We discuss the exciting potential of using these emerging cancer immunotherapies to solve the antibody problem. [ABSTRACT FROM AUTHOR]

Nonhuman primates are the closest animal models to humans with respect to genetics and physiology. Consequently, a critical component of immunogenetics research relies on drawing inferences from the cynomolgus macaque to inform human trials. Despite the conserved organization of the Major Histocompatibility Complex (MHC) between cynomolgus macaques and humans, MHC genotyping of cynomolgus macaques is challenging due to high rates of copy number variants, duplications, and rearrangements, particularly at the MHC class I loci. Furthermore, the limited availability of commercial reagents specific to cynomolgus macaques that can be used to characterize anti‐MHC class I and class II antibody (Ab) specificities in cynomolgus macaques presents a major bottleneck in translational research. Here we successfully characterized cynomolgus macaque Mafa class I and class II serologic specificities in 86 animals originating from various geographical regions using the complement dependent cytotoxicity (CDC) assay with human HLA class I and class II monoclonal antibody (mAb) typing trays. Further, we successfully induced and characterized anti‐Mafa class I and class II alloantibody specificity using HLA single antigen bead assays. We also subsequently tracked the alloAb burden in the animals during treatment with anti‐B lymphocyte stimulator (BLyS) treatment. Altogether, these methods can be easily used in translational research to serotype MHC class I and class II specificity in macaques, characterize their alloAb specificity, and evaluate the efficacy of novel therapeutic modalities in depleting circulating alloAbs in these animals. [ABSTRACT FROM AUTHOR]

The mechanisms underlying the maintenance of long-lasting humoral immunity are not well understood. Studies in mice indicate that plasma cells (PCs) can survive up to a lifetime, even in the absence of regeneration by B cells, implying the presence of long-lived PCs as a mechanism for long-lasting immunity. Evidence from humans treated with anti-CD20, which depletes circulating B cells, also suggests B–cell-independent long-term survival of some PCs. On the other hand, antibody responses may be sustained solely by short-lived PCs with repopulation from clonally related memory B cells. To explore PC longevity and humoral immunity in humans, we investigated the fate of PCs and their antibodies in adult and pediatric patients who received chimeric antigen receptor–based adoptive T-cell immunotherapy targeting CD19 to treat B-cell lineage malignancies (CTL019). Treatment with CTL019 is frequently associated with B-cell aplasia that can persist for years. Serum antibody titers to vaccine-related antigens were measured, and quantitative assessment ofBcells and PCs in blood and bone marrow was performed at various time points before and after CTL019 therapy. While total serum immunoglobulin concentrations decline following CTL019-induced B-cell aplasia, several vaccine/pathogen-specific serum immunoglobulin G and A (IgG and IgA) titers remain relatively stable for at least 6 and 12 months posttreatment, respectively. Analysis of bone marrow biopsies after CTL019 revealed 8 patients with persistence of antibody-secreting PCs at least 25 months post-CTL019 infusion despite absence of CD19+CD20+ B cells. These results provide strong evidence for the existence of memory B-cell—independent, long-lived PCs in humans that contribute to long-lasting humoral immunity. [ABSTRACT FROM AUTHOR]

Ideally, therapy for autoimmune diseases should eliminate pathogenic autoimmune cells while sparing protective immunity, but feasible strategies for such an approach have been elusive. Here, we show that in the antibody-mediated autoimmune disease pemphigus vulgaris (PV), autoantigen-based chimeric immunoreceptors can direct T cells to kill autoreactive B lymphocytes through the specificity of the B cell receptor (BCR).We engineered human T cells to express a chimeric autoantibody receptor (CAAR), consisting of the PV autoantigen, desmoglein (Dsg) 3, fused to CD137-CD3z signaling domains. Dsg3 CAAR-T cells exhibit specific cytotoxicity against cells expressing anti-Dsg3 BCRs in vitro and expand, persist, and specifically eliminate Dsg3-specific B cells in vivo. CAAR-T cells may provide an effective and universal strategy for specific targeting of autoreactive B cells in antibody-mediated autoimmune disease. [ABSTRACT FROM AUTHOR]

Protein ubiquitylation has emerged as a key mechanism that regulates immune responses. Much like phosphorylation, ubiquitylation is a reversible covalent modification that regulates the stability, activity and localization of target proteins. As such, ubiquitylation regulates the development of the immune system and many phases of the immune response, including its initiation, propagation and termination. Recent work has shown that several ubiquitin ligases help to prevent the immune system from attacking self tissues. The dysfunction of several ubiquitin ligases has been linked to autoimmune diseases. [ABSTRACT FROM AUTHOR]

Infection by RNA viruses is detected by the host through Toll-like receptors or RIG-I-like receptors. Toll-like receptors and RIG-I-like receptors signal through the adaptors MyD88 and MAVS, respectively, to induce type I IFNs (IFN-I) and other antiviral molecules, which are thought to be essential for activating the adaptive immune system. We investigated the role of these adaptors in innate and adaptive immune responses against respiratory syncytial virus (RSV), a common human pathogen. Deletion of Mavs abolished the induction of IFN-l and other proinflammatory cytokines by RSV. Genome-wide expression profiling in the lung showed that the vast majority of RSV-induced genes depended on MAVS. Although Myd88 deficiency did not affect most RSV-induced genes, mice lacking both adaptors harbored a higher and more prolonged viral load and exhibited more severe pulmonary disease than those lacking either adaptor alone. Surprisingly, Myd88-/-/Mavs-/- mice were able to activate a subset of pulmonary dendritic cells that traffic to the draining lymph node in response to RSV. These mice subsequently mounted a normal cytotoxic T-lymphocyte response and demonstrated delayed but effective viral clearance. These results provide an example of a normal and effective adaptive immune response in the absence of innate immunity mediated by MAVS and MyD88. [ABSTRACT FROM AUTHOR]

Precision Medicine is an emerging approach for disease treatment and prevention that takes into account individual variability in genes, environment, and lifestyle. Autoimmune diseases are those in which the body's natural defense system loses discriminating power between its own cells and foreign cells, causing the body to mistakenly attack healthy tissues. These conditions are very heterogeneous in their presentation and therefore difficult to diagnose and treat. Achieving precision medicine in autoimmune diseases has been challenging due to the complex etiologies of these conditions, involving an interplay between genetic, epigenetic, and environmental factors. However, recent technological and computational advances in molecular profiling have helped identify patient subtypes and molecular pathways which can be used to improve diagnostics and therapeutics. This review discusses the current understanding of the disease mechanisms, heterogeneity, and pathogenic autoantigens in autoimmune diseases gained from genomic and transcriptomic studies and highlights how these findings can be applied to better understand disease heterogeneity in the context of disease diagnostics and therapeutics. [ABSTRACT FROM AUTHOR]

In this issue, report a mechanism by which host cells avert an autoimmune response to self-nucleic acids. They show that the nuclease Trex1 prevents the accumulation of DNA derived from endogenous retroelements that, if left unchecked, trigger elevated production of type I interferons leading to autoimmunity. [Copyright &y& Elsevier]

Chimeric antigen receptor (CAR) T cells have induced remarkable antitumor responses in B cell malignancies. Some patients do not respond because of T cell deficiencies that hamper the expansion, persistence, and effector function of these cells. We used longitudinal immune profiling to identify phenotypic and pharmacodynamic changes in CD19-directed CAR T cells in patients with chronic lymphocytic leukemia (CLL). CAR expression maintenance was also investigated because this can affect response durability. CAR T cell failure was accompanied by preexisting T cell-intrinsic defects or dysfunction acquired after infusion. In a small subset of patients, CAR silencing was observed coincident with leukemia relapse. Using a small molecule inhibitor, we demonstrated that the bromodomain and extra-terminal (BET) family of chromatin adapters plays a role in downregulating CAR expression. BET protein blockade also ameliorated CAR T cell exhaustion as manifested by inhibitory receptor reduction, enhanced metabolic fitness, increased proliferative capacity, and enriched transcriptomic signatures of T cell reinvigoration. BET inhibition decreased levels of the TET2 methylcytosine dioxygenase, and forced expression of the TET2 catalytic domain eliminated the potency-enhancing effects of BET protein targeting in CAR T cells, providing a mechanism linking BET proteins and T cell dysfunction. Thus, modulating BET epigenetic readers may improve the efficacy of cell-based immunotherapies. [ABSTRACT FROM AUTHOR]

• Immunoreceptor-engineered T cells demonstrate remarkable therapeutic potential. • Gene-engineering and editing have broadened the applications of T cell therapies. • Engineered Tconv cells have paved a way for engineered Treg therapies. Approaches to harness the immune system to alleviate disease have become remarkably sophisticated since the crude, yet impressively-effective, attempts using live bacteria in the late 1800s. Recent evidence that engineered T cell therapy can deliver durable results in patients with cancer has spurred frenzied development in the field of T cell therapy. The myriad approaches include an innumerable variety of synthetic transgenes, multiplex gene-editing, and broader application to diseases beyond cancer. In this article, we review the preclinical studies and over a decade of clinical experience with engineered conventional T cells that have paved the way for translating engineered regulatory T cell therapies. [ABSTRACT FROM AUTHOR]

Background: Patients with diffuse large B-cell lymphoma or follicular lymphoma that is refractory to or that relapses after immunochemotherapy and transplantation have a poor prognosis. High response rates have been reported with the use of T cells modified by chimeric antigen receptor (CAR) that target CD19 in B-cell cancers, although data regarding B-cell lymphomas are limited.Methods: We used autologous T cells that express a CD19-directed CAR (CTL019) to treat patients with diffuse large B-cell lymphoma or follicular lymphoma that had relapsed or was refractory to previous treatments. Patients were monitored for response to treatment, toxic effects, the expansion and persistence of CTL019 cells in vivo, and immune recovery.Results: A total of 28 adult patients with lymphoma received CTL019 cells, and 18 of 28 had a response (64%; 95% confidence interval [CI], 44 to 81). Complete remission occurred in 6 of 14 patients with diffuse large B-cell lymphoma (43%; 95% CI, 18 to 71) and 10 of 14 patients with follicular lymphoma (71%; 95% CI, 42 to 92). CTL019 cells proliferated in vivo and were detectable in the blood and bone marrow of patients who had a response and patients who did not have a response. Sustained remissions were achieved, and at a median follow-up of 28.6 months, 86% of patients with diffuse large B-cell lymphoma who had a response (95% CI, 33 to 98) and 89% of patients with follicular lymphoma who had a response (95% CI, 43 to 98) had maintained the response. Severe cytokine-release syndrome occurred in 5 patients (18%). Serious encephalopathy occurred in 3 patients (11%); 2 cases were self-limiting and 1 case was fatal. All patients in complete remission by 6 months remained in remission at 7.7 to 37.9 months (median, 29.3 months) after induction, with a sustained reappearance of B cells in 8 of 16 patients and with improvement in levels of IgG in 4 of 10 patients and of IgM in 6 of 10 patients at 6 months or later and in levels of IgA in 3 of 10 patients at 18 months or later.Conclusions: CTL019 cells can be effective in the treatment of relapsed or refractory diffuse large B-cell lymphoma and follicular lymphoma. High rates of durable remission were observed, with recovery of B cells and immunoglobulins in some patients. Transient encephalopathy developed in approximately one in three patients and severe cytokine-release syndrome developed in one in five patients. (Funded by Novartis and others; ClinicalTrials.gov number, NCT02030834 .). [ABSTRACT FROM AUTHOR]

Background: Respiratory Syncytial Virus (RSV) infection is usually restricted to the respiratory epithelium. Few studies have documented the presence of RSV in the systemic circulation, however there is no consistent information whether virus detection in the blood correlates with disease severity.Methods: Balb/c mice were inoculated with live RSV, heat-inactivated RSV or medium. A subset of RSV-infected mice was treated with anti-RSV antibody 72 h post-inoculation. RSV RNA loads were measured by PCR in peripheral blood from day 1-21 post-inoculation and were correlated with upper and lower respiratory tract viral loads, the systemic cytokine response, lung inflammation and pulmonary function. Immunohistochemical staining was used to define the localization of RSV antigens in the respiratory tract and peripheral blood.Results: RSV RNA loads were detected in peripheral blood from day 1 to 14 post-inoculation, peaked on day 5 and significantly correlated with nasal and lung RSV loads, airway obstruction, and blood CCL2 and CXCL1 expression. Treatment with anti-RSV antibody reduced blood RSV RNA loads and improved airway obstruction. Immunostaining identified RSV antigens in alveolar macrophages and peripheral blood monocytes.Conclusions: RSV RNA was detected in peripheral blood upon infection with live RSV, followed a time-course parallel to viral loads assessed in the respiratory tract and was significantly correlated with RSV-induced airway disease. [ABSTRACT FROM AUTHOR]

Background. Previous studies in mice showed that respiratory syncytial virus (RSV) infection was associated with RSV RNA persistence. This study was designed to characterize the significance of RSV RNA persistence and its relation to RSV-induced chronic airway disease. Methods. Mice were inoculated with live RSV, UV light-treated RSV, heat-inactivated RSV, or medium. Bronchoalveolar lavage fluid samples were obtained and lung specimens were harvested on days 1, 5, and 42 after inoculation to assess lung inflammation, lung mRNA expression of interleukin (IL)-4, IL-5, IL-15, and interferon (IFN)-γ; RSV loads were assessed by culture and real-time polymerase chain reaction (PCR) and correlated with pulmonary function. Results. During the acute phase of infection, RSV loads as indicated by culture and PCR were significantly higher in mice inoculated with live RSV. On day 42, RSV RNA remained detectable only in mice inoculated with live or UV light-treated RSV. Lung inflammation, IFN-γ:IL-4 mRNA expression ratios, airway obstruction (AO), and airway hyperreactivity (AHR) were significantly increased in mice inoculated with live RSV. AO on day 5 and AHR on day 42 were significantly correlated with RSV RNA copy number in lung samples. Conclusions. Infection with live RSV induced acute and chronic airway disease that was associated with a predominantly Th-1 immune response and RSV RNA persistence that significantly correlated with pulmonary function abnormalities. [ABSTRACT FROM AUTHOR]

CD19-directed immunotherapies are clinically effective for treating B cell malignancies but also cause a high incidence of neurotoxicity. A subset of patients treated with chimeric antigen receptor (CAR) T cells or bispecific T cell engager (BiTE) antibodies display severe neurotoxicity, including fatal cerebral edema associated with T cell infiltration into the brain. Here, we report that mural cells, which surround the endothelium and are critical for blood-brain-barrier integrity, express CD19. We identify CD19 expression in brain mural cells using single-cell RNA sequencing data and confirm perivascular staining at the protein level. CD19 expression in the brain begins early in development alongside the emergence of mural cell lineages and persists throughout adulthood across brain regions. Mouse mural cells demonstrate lower levels of Cd19 expression, suggesting limitations in preclinical animal models of neurotoxicity. These data suggest an on-target mechanism for neurotoxicity in CD19-directed therapies and highlight the utility of human single-cell atlases for designing immunotherapies. • Single-cell RNA-seq reveals CD19 expression in human brain mural cells • Mural cells line blood vessels and maintain blood-brain barrier integrity • Brain mural cell CD19 expression is present across brain regions and human age • Targeting CD19+ mural cells may contribute to neurotoxicity of CAR-T therapy Single-cell RNA sequencing analysis shows that CD19, primarily considered as a B cell-specific surface antigen, is expressed in human brain mural cells that are critical for blood-brain-barrier integrity, suggesting that this cell population may contribute to the neurotoxicity of CD19-directed immunotherapy including CAR-T. [ABSTRACT FROM AUTHOR]

Skin keratinocytes provide a first line of defense against invading microorganisms in two ways: (i) by acting as a physical barrier to pathogen entry and (ii) by initiating a vigorous innate immune response upon sensing danger signals. How keratinocytes detect virus infections and generate antiviral immune responses is not well understood. Orthopoxviruses are dermatotropic DNA viruses that cause lethal disease in humans. Virulence in animal models depends on the virus-encoded bifunctional Z-DNA/double-stranded RNA (dsRNA)-binding protein E3. Here, we report that infection of mouse primary keratinocytes with a vaccinia Δ E3L mutant virus triggers the production of beta interferon (IFN-β), interleukin-6 (IL-6), CCL4, and CCL5. None of these immune mediators is produced by keratinocytes infected with wild-type vaccinia virus. The dsRNA-binding domain of E3 suffices to prevent activation of the innate immune response. Δ E3L induction of IFN-β, IL-6, CCL4, and CCL5 secretion requires mitochondrial antiviral signaling protein (MAVS; an adaptor for the cytoplasmic viral RNA sensors RIG-I and MDA5) and the transcription factor IRF3. IRF3 phosphorylation is induced in keratinocytes infected with Δ E3L, an event that depends on MAVS. The response of keratinocytes to Δ E3L is unaffected by genetic ablation of Toll-like receptor 3 (TLR3), TRIF, TLR9, and MyD88. [ABSTRACT FROM AUTHOR]