Rituximab-induced gut microbiota changes in Chinese neuromyelitis optica spectrum disorders

BACKGROUND

Recent evidence shows that immunosuppressive agents can affect the gut microbiota in autoimmune diseases. However, the relationship between the gut microbiome and B-cell depletion immunotherapy in neuromyelitis optica spectrum disorder (NMOSD) remains poorly understood.

OBJECTIVES

To evaluate the distinct intestinal microbial patterns and serum cytokine levels after short-term rituximab treatment (three months) in patients with NMOSD.

METHODS

Firstly, we conducted a cross-sectional study involving 46 treatment-naïve NMOSD patients and 48 matched healthy controls. We collected fecal specimens, which were then analyzed using next-generation sequencing, and quantified serum cytokines. Subsequently, fecal and serum samples were re-collected and re-evaluated in 31 of the 46 treatment-naïve NMOSD patients after RTX treatment.

RESULTS

Comparing the gut microbiome of treatment-naïve NMOSD patients to that of healthy controls revealed low α-diversity and distinct microbial compositions in the former. The microbial composition in NMOSD patients underwent changes following three months of RTX treatment. Specifically, the levels of IL-17F and IL-6 decreased, while those of IL-10 and TNFα increased after RTX treatment. LEfSe analysis identified 27 KEGG categories with significantly differential abundances between NMOSD patients and RTX treatment group.

CONCLUSIONS

Our study provides a comprehensive understanding of the gut microbiota landscape in the context of B-cell depletion immunotherapy. We observed dysbiosis in the gut microbiome of NMOSD patients, which was partially alleviated by three months of RTX treatment. This suggests that B-cell depletion may play a crucial role in driving changes in the gastrointestinal environment.

Immunosuppression withdrawal in living-donor renal transplant recipients following induction with antithymocyte globulin and rituximab: Results of a prospective clinical trial

Durable tolerance in kidney transplant recipients remains an important but elusive goal. We hypothesized that adding B cell depletion to T cell depletion would generate an immune milieu postreconstitution dominated by immature transitional B cells, favoring tolerance. The Immune Tolerance Network ITN039ST Research Study of ATG and Rituximab in Renal Transplantation was a prospective multicenter pilot study of live donor kidney transplant recipients who received induction with rabbit antithymocyte globulin and rituximab and initiated immunosuppression (IS) withdrawal (ISW) at 26 weeks. The primary endpoint was freedom from rejection at 52 weeks post-ISW. Six of the 10 subjects successfully completed ISW. Of these 6 subjects, 4 restarted immunosuppressive medications due to acute rejection or recurrent disease, 1 remains IS-free for over 9 years, and 1 was lost to follow-up after being IS-free for 42 weeks. There were no cases of patient or graft loss. CD19+ B cell frequencies returned to predepletion levels by 26 weeks posttransplant; immunoglobulin D+CD27--naïve B cells predominated. In contrast, memory cells dominated the repopulation of the T cell compartment. A regimen of combined B and T cell depletion did not generate the tolerogenic B cell profile observed in preclinical studies and did not lead to durable tolerance in the majority of kidney transplant recipients.

Ofatumumab subcutaneous injection successfully treated patients with pemphigus vulgaris relapse post rituximab

The therapeutic strategy for the treatment of pemphigus vulgaris (PV) still needs optimization because of the multiple deficiencies of glucocorticoid and rituximab. Ofatumumab, another CD20 monoclonal antibody administrated subcutaneously, provides a possible alternative option. In this study, three patients experienced PV relapse after clinical remission induced by rituximab. With written informed consent, they received an ofatumumab (20 mg) subcutaneous injection twice (2 weeks apart) in combination with a prednisone dose adjusted according to their weight and disease severity. Over the 24-week observation, two of three patients achieved lesion clear-up under prednisone (0.2 mg/kg per day), and the other patient's pemphigus disease area index dropped from 39 to 3 with prednisone (15 mg/day). The anti-desmoglein antibody levels and CD19+ B cell counts declined compared to those at baseline. No severe adverse events were observed within the 24-week follow-up. In summary, we propose a protocol of ofatumumab for patients with refractory PV and report positive treatment outcomes of three patients who received this regimen.

B cell depletion attenuates CD27 signaling of T helper cells in multiple sclerosis

Multiple sclerosis is a chronic inflammatory disease of the central nervous system. Whereas T cells are likely the main drivers of disease development, the striking efficacy of B cell-depleting therapies (BCDTs) underscore B cells' involvement in disease progression. How B cells contribute to multiple sclerosis (MS) pathogenesis-and consequently the precise mechanism of action of BCDTs-remains elusive. Here, we analyze the impact of BCDTs on the immune landscape in patients with MS using high-dimensional single-cell immunophenotyping. Algorithm-guided analysis reveals a decrease in circulating T follicular helper-like (Tfh-like) cells alongside increases in CD27 expression in memory T helper cells and Tfh-like cells. Elevated CD27 indicates disrupted CD27/CD70 signaling, as sustained CD27 activation in T cells leads to its cleavage. Immunohistological analysis shows CD70-expressing B cells at MS lesion sites. These results suggest that the efficacy of BCDTs may partly hinge upon the disruption of Th cell and B cell interactions.

Hepatitis B virus reactivation in seronegative occult hepatitis B patient receiving ibrutinib therapy

BACKGROUND

Ibrutinib is a Bruton's tyrosine kinase (BTK) inhibitor approved for the treatment for several mature B-cell malignancies. Reactivation of hepatitis B virus (HBV) is a well-described complication in patients with chronic HBV infection or prior HBV exposure undergoing cytotoxic or immunosuppressive chemotherapy for hematologic malignancies. This phenomenon has been frequently reported with rituximab. However, published data on the risk of HBV reactivation induced by ibrutinib are scarce. Cases of HBV reactivation in hematologic patients receiving ibrutinib therapy have recently been described, but limited only to overt hepatitis B patients or seropositive occult hepatitis B patients.

CASE PRESENTATION

We report the first case of HBV reactivation during ibrutinib treatment in an asymptomatic 82-year-old woman with seronegative occult hepatitis B patient (i.e., negative for HBsAg, anti-HBc and anti-HBs). Four months after ibrutinib treatment, her liver function test (LFT) was deranged, with seroconversion to HBsAg positivity. Serum hepatitis B virus DNA was quantified to be 1.92 × 10⁸ IU/ml. Antiviral treatment was initiated, and viral load was gradually suppressed with improvement in LFT.

CONCLUSIONS

Our case illustrated that in populations with a high incidence of HBV exposure, systematic screening for HBV exposure is essential prior to ibrutinib treatment, followed by serial monitoring of serologic and molecular markers of hepatitis B. There is a need for an international consensus to support the recommendation of antiviral prophylaxis against HBV reactivation in patients using ibrutinib.

Impact of extended interval dosing of ocrelizumab on immunoglobulin levels in multiple sclerosis

BACKGROUND

Long-term B cell depletion with ocrelizumab in multiple sclerosis (MS) is associated with severe side effects such as hypogammaglobulinemia and infections. Our study therefore aimed to assess immunoglobulin levels under treatment with ocrelizumab and implement an extended interval dosing (EID) scheme.

METHODS

Immunoglobulin levels of 51 patients with ≥24 months of treatment with ocrelizumab were analyzed. After ≥4 treatment cycles, patients chose to either continue on the standard interval dosing (SID) regimen (n = 14) or, in the case of clinically and radiologically stable disease, switch to B cell-adapted EID (n = 12, next dose at CD19⁺ B cells >1% of peripheral blood lymphocytes).

FINDINGS

Levels of immunoglobulin M (IgM) declined rapidly under ocrelizumab treatment. Risk factors for IgM and IgA hypogammaglobulinemia were lower levels at baseline and more previous disease-modifying therapies. B cell-adapted EID of ocrelizumab increased the mean time until next infusion from 27.3 to 46.1 weeks. Ig levels declined significantly in the SID group over 12 months but not in the EID group. Previously stable patients remained stable under EID as measured by expanded disability status scale (EDSS), neurofilament light chain, timed 25-foot walk (T25-FW), 9-hole peg test (9-HPT), symbol digit modalities test (SDMT), and multiple sclerosis impact scale (MSIS-29).

CONCLUSIONS

In our pilot study, B cell-adapted EID of ocrelizumab prevented the decline of Ig levels without affecting disease activity in previously stable patients with MS. Based on these findings, we propose a new algorithm for long-term ocrelizumab treatment.

FUNDING

This study was supported by the Deutsche Forschungsgemeinschaft (SFB CRC-TR-128, SFB 1080, and SFB CRC-1292) and the Hertie Foundation.

Novel Immunotherapies for Myasthenia Gravis

Myasthenia gravis (MG), a prototype autoimmune neurological disease, had its therapy centred on corticosteroids, non-steroidal broad-spectrum immunotherapy and cholinesterase inhibitors for several decades. Treatment-refractory MG and long-term toxicities of the medications have been major concerns with the conventional therapies. Advances in the immunology and pathogenesis of MG have ushered in an era of newer therapies which are more specific and efficacious. Complement inhibitors and neonatal Fc receptor blockers target disease-specific pathogenic mechanisms linked to myasthenia and have proven their efficacy in pivotal clinical studies. B cell-depleting agents, specifically rituximab, have also emerged as useful for the treatment of severe MG. Many more biologicals are in the pipeline and in diverse stages of development. This review discusses the evidence for the novel therapies and the specific issues related to their clinical use.

Hypogammaglobulinemia secondary to B-cell depleting therapies in neuroimmunology: Comparing management strategies

Background

Anti-CD20 agents are commonly used in MS, NMOSD, and MOGAD. Few studies have compared strategies to address hypogammaglobulinemia.

Objective

To compare strategies to manage secondary hypogammaglobulinemia in neuroimmunology patients, including reducing anti-CD20 dose and dosing frequency, IVIG/SCIG, anti-CD20 cessation, and DMT switches.

Methods

All MS, NMOSD, and MOGAD patients at our institution with hypogammaglobulinemia on anti-CD20 agents from 2001 to 2022 were analyzed. The median change in IgG, infection frequency, and infection severity before and after the treatment was calculated.

Results

In total, 257 patients were screened, and 30 had a treatment for hypogammaglobulinemia. IVIG/SCIG yielded the largest increase in IgG per year (674.0 mg/dL), followed by B-cell therapy cessation (34.7 mg/dL), and DMT switch (5.9 mg/dL). Dose reduction had the largest decrease in yearly infection frequency (2.7 fewer infections), followed by IVIG/SCIG (2.5 fewer), DMT switch (2 fewer), and reduced dosing frequency (0.5 fewer). Infection grade decreased by 1.9 for reduced dosing frequency (less severe infections), by 1.3 for IVIG/SCIG, and by 0.6 for DMT switch.

Conclusion

This data suggests that IVIG/SCIG may yield the greatest recovery in IgG while also reducing infection frequency and severity. Stopping anti-CD20 therapy and/or switching DMTs also increase IgG and may lower infection risk.

Successful AAV8 re-administration: Suppression of capsid-specific neutralizing antibodies by a combination treatment of bortezomib and CD20 mAb in a mouse model of Pompe disease

BACKGROUND

A major challenge to AAV mediated gene therapy is the presence of anti-AAV capsid neutralizing antibodies (NAbs), which can block viral vector transduction even at very low titers. Here we examined the ability of a combination immunosuppression (IS) treatment with bortezomib and a mouse-specific CD20 mAb to suppress anti-AAV NAbs and enable re-administration of AAV vectors of the same capsid in mice.

METHODS

An AAV8 vector (AAV8-CB-hGAA) that ubiquitously expresses human α-glucosidase was used for initial gene therapy and a second AAV8 vector (AAV8-LSP-hSEAP) that contains a liver-specific promoter to express human secreted alkaline phosphatase was used for AAV re-administration. Plasma samples were used for determination of anti-AAV8 NAb titers. Cells isolated from whole blood, spleen, and bone marrow were analyzed for B-cell depletion by flow cytometry. The efficiency of AAV re-administration was determined by the secretion of hSEAP in blood.

RESULTS

In näive mice, an eight-week IS treatment along with AAV8-CB-hGAA injection effectively depleted CD19⁺ B220⁺ B cells from blood, spleen, and bone marrow and prevented the formation of anti-AAV8 NAbs. Following administration of AAV8-LSP-hSEAP, increasing levels of hSEAP were detected in blood for up to 6 weeks, indicating successful AAV re-administration. In mice pre-immunized with AAV8-CB-hGAA, comparison of IS treatment for 8, 12, 16, and 20 weeks revealed that the 16-week IS treatment demonstrated the highest plasma hSEAP level following AAV8-LSP-hSEAP re-administration.

CONCLUSIONS

Our data suggest that this combination treatment is an effective IS approach that will allow retreatment of patients with AAV mediated gene therapy.

B cell targeted therapies in inflammatory autoimmune disease of the central nervous system

Cumulative evidence along several lines indicates that B cells play an important role in the pathological course of multiple sclerosis (MS), neuromyelitisoptica spectrum disorders (NMOSD) and related CNS diseases. This has prompted extensive research in exploring the utility of targeting B cells to contain disease activity in these disorders. In this review, we first recapitulate the development of B cells from their origin in the bone marrow to their migration to the periphery, including the expression of therapy-relevant surface immunoglobulin isotypes. Not only the ability of B cells to produce cytokines and immunoglobulins seems to be essential in driving neuroinflammation, but also their regulatory functions strongly impact pathobiology. We then critically assess studies of B cell depleting therapies, including CD20 and CD19 targeting monoclonal antibodies, as well as the new class of B cell modulating substances, Bruton´s tyrosinekinase (BTK) inhibitors, in MS, NMOSD and MOGAD.

B cell depletion therapies in autoimmune diseases: Monoclonal antibodies or chimeric antigen receptor-based therapy?

Immune system detects foreign pathogens, distinguishes them from self-antigens and responds to defend human body. When this self-tolerance is disrupted, the overactive immune system attacks healthy tissues or organs and the autoimmune diseases develop. B cells and plasma cells contribute a lot to pathogenesis and persistence of autoimmune diseases in both autoantibody-dependent and autoantibody-independent ways. Accumulating data indicates that treatments aiming to eliminate antibody-secreting cells (B cells or plasma cells) are effective in a wide spectrum of autoimmune diseases. Monoclonal antibodies (mAbs) deplete B cell lineage or plasma cells by signaling disruption, complement-dependent cytotoxicity (CDC) and antibody-dependent cellular cytotoxicity (ADCC). Engineered-T cells armed with chimeric antigen receptors (CARs) have been adopted from field of hematological malignancies as a method to eliminate B cells or plasma cells. In this review, we update our understanding of B cell depletion therapies in autoimmune diseases, review the mechanism, efficacy, safety and application of monoclonal antibodies and CAR-based immunotherapies, and discuss the strengths and weaknesses of these treatment options for patients.

The concentrations of antibodies to Epstein-Barr virus decrease during ocrelizumab treatment

BACKGROUND

Epstein-Barr Virus (EBV) is strongly associated with multiple sclerosis (MS). After initial infection, EBV maintains a life-long latent infection in B lymphocytes. Depletion of B lymphocytes from the blood with the anti-CD20 antibody ocrelizumab (OCR) markedly reduces disease activity in MS. Our objective was to measure the effect of OCR treatment on the antibody response to EBV and human antigens that are cross-reactive with EBV.

METHODS

Blood was collected from MS patients before and during OCR treatment. Antibodies to three EBV antigens (EBNA-1, BFRF3, and gp350) and three human proteins that are cross-reactive with EBV (septin-9, DLST, and HNRNPL) were quantified with Western blots. Antibodies to EBNA-1 and BFRF3 were also quantified with ELISA.

RESULTS

Antibodies to the EBV proteins BFRF3 and EBNA-1 measured on Western blot were significantly decreased after 12 months on OCR. Subsequent testing with ELISA confirmed the decrease for both BFRF3 and EBNA-1. With Western blots, there was a trend to decreased antibody response to septin-9 and DLST, but not HNRNPL. Total IgG concentration did not change.

CONCLUSION

The antibody response to some EBV antigens decreases in OCR treated patients. The benefit of OCR for MS may be through removal of EBV antigenic stimulus.

Retrospective analysis of the long-term therapeutic effectiveness and safety profile of rituximab in the treatment of mucous membrane pemphigoid in a German university center between 2008 and 2019

Background

The B-cell-depleting anti-CD20 antibody rituximab (RTX) is often used as an adjuvant drug for the treatment of refractory cases of mucous membrane pemphigoid (MMP).

Objective

This study aims to determine the therapeutic effectiveness and the safety profile of RTX in MMP.

Methods

The medical records of all cases of MMP treated with RTX between 2008 and 2019 in our university medical center located in northern Germany, which specialized in autoimmune blistering skin diseases, were retrieved and systemically analyzed for treatment responses and potential adverse events over a median period of 27 months.

Results

We identified 18 MMP patients who received at least one cycle of RTX to treat MMP. RTX was always used as an adjuvant treatment, and its application did not change concomitant treatments. Under treatment with RTX, 67% of the patients achieved an improvement in their disease activity within 6 months. This was also reflected in a statistically significant reduction in the Mucous Membrane Pemphigoid Disease Index (MMPDAI) activity score. The frequency of infections under RTX treatment increased only slightly.

Conclusions

The use of RTX is associated with an attenuation of MMP in a large proportion of MMP patients in our study. At the same time, its application was not found to further increase the susceptibility of the most strongly immunocompromised population of MMP patients to opportunistic infections. Collectively, our results suggest that the potential benefits of RTX outweigh its risks in patients with refractory MMP.

Disparity in peripheral and renal B-cell depletion with rituximab in systemic lupus erythematosus: an opportunity for obinutuzumab?

OBJECTIVES

To investigate key factors that may contribute to the variability of rituximab-mediated peripheral and renal B cell depletion (BCD) in SLE.

METHODS

We analysed: (i) CD19+ B cell counts in patients with SLE before and 1, 2, 3 and 6 months after treatment with rituximab, comparing them with RA patients; (ii) the presence of B cells in renal biopsies after rituximab therapy; (iii) whether the duration of BCD correlated with patient demographics and B cell expression of CD20 and FcγRIIb; and (iv) the effect of B cell activation factor (BAFF) on the efficiency of rituximab and obinutuzumab at inducing BCD in whole blood assays, in vitro.

RESULTS

In SLE (n = 71), the duration of BCD was shorter compared with RA (n = 27). B cells were detectable in renal biopsy samples (n = 6) after treatment with rituximab in all patients with poor response while peripheral blood B cells remained low or undetectable in the same patients. There were no significant relationships between peripheral BCD and patient age, disease duration, serum C3 levels or the level of expression of B cell surface proteins CD20 and FcγRIIb. Obinutuzumab was more efficient than rituximab at inducing BCD in whole blood assays, regardless of excess BAFF.

CONCLUSIONS

BCD in SLE is less efficient than in RA. Renal B cell presence following rituximab treatment was associated with poor outcomes. No significant relationships between any measured B cell related, clinical or laboratory parameters and the efficiency of BCD by rituximab was found. Obinutuzumab was superior to rituximab at inducing BCD.

Prospects for CAR T cell immunotherapy in autoimmune diseases: clues from Lupus

INTRODUCTION

Medicine stands at the threshold of a new era heralded by the vast potential of cell engineering. Like advances made possible by genetic engineering, current prospects for purposeful control of cell functions through cell engineering may bring breakthroughs in the treatment of previously intractable diseases.

AREAS COVERED

Engineering of cytotoxic T cells for expression of chimeric antigen receptors (CARs) instructs them to attack and destroy malignant cells and thus provides an exciting new approach in oncology. A decade of practical experience and first-in-human trials encourage the search for new and broader uses of CAR technology, including in autoimmune diseases.

EXPERT OPINION

Systemic lupus erythematosus is an example of a broader category of autoimmune diseases, for which cell engineering will provide a powerful new therapeutic approach. This article describes different types of CAR T cell strategies that will provide new treatment options for patients with autoimmune diseases and replace conventional therapies.

Humoral Immune Response after the Third SARS-CoV-2 mRNA Vaccination in CD20 Depleted People with Multiple Sclerosis

CD20 depletion is a risk factor for unfavorable outcomes of COVID-19 in people with MS (pwMS). Evidence suggests that protective IgG response to mRNA-based vaccines in B cell-depleted individuals is limited. We studied the seroconversion after the third mRNA SARS-CoV-2 vaccine in B cell-depleted pwMS with limited or no IgG response after the standard immunization. Sixteen pwMS treated with ocrelizumab or rituximab received a third homologous SARS-CoV-2 mRNA vaccine, either the Moderna mRNA-1273 or Pfizer-BioNTech’s BNT162b2 vaccine. We quantified the response of IgG antibodies against the spike receptor-binding domain of SARS-CoV-2 four weeks later. An antibody titer of 100 AU/mL or more was considered clinically relevant. The median time between the last infusion of the anti-CD20 treatment and the third vaccination was 22.9 weeks (range 15.1–31.3). After the third vaccination, one out of 16 patients showed an IgG titer deemed clinically relevant. Only the seroconverted patient had measurable B-cell counts at the time of the third vaccination. The development of a humoral immune response remains rare in pwMS on anti-CD20 therapy, even after third dose of the homologous SARS-CoV-2 mRNA vaccine. It remains to be determined whether T-cell responses can compensate for the lack of seroconversion and provide sufficient protection against CoV-2 infections.

B cell depletion treatment decreases Th17 cells in patients with rheumatoid arthritis

INTRODUCTION

We aimed to evaluate for any possible effects of treatment with rituximab (RTX) on the peripheral Th17 and Treg subpopulations in patients with rheumatoid arthritis (RA).

PATIENTS AND METHODS

We analyzed 16 patients with RA initiating RTX treatment, 11 patients with RA initiating abatacept treatment, 11 patients with RA treated with other medications, 8 patients with other autoimmune rheumatic diseases initiating RTX, and 14 healthy volunteers. Th17 cells (CD4⁺IL23R⁺IL17A⁺) and Treg cells (CD4⁺CD25^hiFoxP3⁺) were evaluated flow-cytometrically.

RESULTS

Th17 cells from patients treated with RTX decreased significantly at weeks 8 and 16 (mean ± SEΜ: 3.01% ± 0.54℅ CD4⁺ cells at week 0 vs. 1.53% ± 0.24℅ at week 8 vs 1.10% ± 0.20℅ at week 16, p = 0.0004). Reductions of Th17 cells were evident in clinical responders (DAS28 score ≤ 3.2), ACPA (+) and RF (-) patients; circulating Tregs remained stable. Th17 and Tregs were not affected by ABA treatment or by changes in disease activity. Tregs, but not Th17 cells, decreased following treatment with RTX in patients with other autoimmune diseases (0.75% ± 0.16% at week 0 vs. 0.43% ± 0.16% at week 8, p = 0.033).

CONCLUSION

RTX-induced B cell depletion results in a significant reduction of circulating Th17 cell percentages, whereas it has no effect on Tregs of patients with RA. This reduction of Th17 cells was evident particularly in responders to RTX treatment, ACPA+ and RF (-) patients with RA.

Case Report: Sustained Remission Due to PD-1-Inhibition in a Metastatic Melanoma Patient With Depleted B Cells

Introduction

Checkpoint-Inhibition (CPI) with PD-1- and PD-L1-inhibitors is a well-established therapy for advanced stage melanoma patients. CPI mainly acts via T-lymphocytes. However, recent literature suggests also a role for B cells modulating its efficacy and tolerability of CPI.

Case Report

We report a 48-year-old female patient with metastatic melanoma affecting brain, lung, skin and lymph nodes. A preexisting granulomatosis with polyangiitis was treated with rituximab over five years prior to the diagnosis of melanoma, resulting in a complete depletion of B cells both in peripheral blood as well as the tumor tissue. In the absence of the mutation of the proto-oncogene b-raf, treatment with the PD-1 inhibitor nivolumab was initiated. This therapy was well tolerated and resulted in a deep partial response, which is ongoing for 14+ months. Flow cytometric analysis of peripheral blood mononuclear cells revealed 15% IL-10 producing and 14% CD24 and CD38 double positive regulatory B cells.

Conclusion

The exceptional clinical response to nivolumab monotherapy in our patient with depleted B cells sheds a new light on the relevance of B cells in the modulation of immune responses to melanoma. Obviously, B cells were not required for the efficacy of CPI in our patient. Moreover, the depletion of regulatory B cells may have improved efficacy of CPI.

The cellular immune response against Epstein-Barr virus decreases during ocrelizumab treatment

BACKGROUND

Epstein-Barr Virus (EBV) is strongly associated with multiple sclerosis (MS). After initial infection, EBV maintains a life-long latent infection in B lymphocytes. Depletion of B lymphocytes from the blood with the anti-CD20 antibody ocrelizumab markedly reduces disease activity in MS. Our objective was to measure the effect of ocrelizumab treatment on the cellular immune response to EBV.

METHODS

Blood was collected from MS patients before and during ocrelizumab treatment. Peripheral blood mononuclear cells were stimulated with various antigens, and the response was measured using tritiated thymidine for proliferation and ELIspot for number of interferon-γ producing cells.

RESULTS

The proliferation to autologous EBV-infected cells (LCL) was decreased after both 6 and 12 months of treatment. The number of interferon-γ producing cells on ELIspot in response to stimulation with either LCL or EBV also decreased. Responses to varicella zoster virus, influenza virus, and a mitogen did not change significantly.

CONCLUSION

The cellular immune response to EBV and LCL decreases during treatment with ocrelizumab. The benefit of ocrelizumab for MS may be through removal of EBV antigenic stimulus.

BLyS neutralization results in selective anti-HLA alloantibody depletion without successful desensitization

Pre-existing anti-HLA allo-antibodies (allo-Abs) are a major barrier to successful kidney transplantation, resulting in an elevated risk for antibody-mediated rejection (AMR) and eventual graft loss. The cytokine B lymphocyte stimulator (BLyS) promotes B cell maturation and plasma cell survival; consequently, anti-BLyS therapy represents a potential therapeutic opportunity in diminishing pre-existing allo-Abs. Here we report that in our 1-year pilot trial, BLyS neutralization failed to reduce total anti-HLA allo-Ab levels in highly sensitized candidates awaiting kidney transplant in a clinically meaningful way. Additionally, we performed a post hoc analysis using sera from trial candidates which revealed selective depletion of anti-HLA class I and class II Abs in response to belimumab treatment, restricted to certain allele specificities and IgG subclasses. Altogether, we observed that BLyS blockade only results in selective depletion of anti-HLA Abs recognizing a few discrete HLA allele specificities.

B cells promote CD8 T cell primary and memory responses to subunit vaccines

The relationship between B cells and CD4 T cells has been carefully studied, revealing a collaborative effort in which B cells promote the activation, differentiation, and expansion of CD4 T cells while the so-called “helper” cells provide signals to B cells, influencing their class switching and fate. Interactions between B cells and CD8 T cells are not as well studied, although CD8 T cells exhibit an accelerated contraction after certain infections in B-cell-deficient mice. Here, we find that B cells significantly enhance primary CD8 T cell responses after vaccination. Moreover, memory CD8 numbers and function are impaired in B-cell-deficient animals, leading to increased susceptibility to bacterial challenge. We also show that interleukin-27 production by B cells contributes to their impact on primary, but not memory, CD8 responses. Better understanding of the interactions between CD8 T cells and B cells may aid in the design of more effective future vaccine strategies.

Generating cytotoxic CD8 T cell responses with vaccines can greatly improve their efficacy, but inducing adequate numbers of these cells can be challenging. Klarquist et al. reveal that the magnitude, persistence, and function of CD8 T cell vaccine responses depend on B cells.

B Cells in Systemic Lupus Erythematosus: From Disease Mechanisms to Targeted Therapies

B cells exert a prominent contribution to the pathogenesis of systemic lupus erythematosus (SLE). Here, we review the immune mechanisms underlying autoreactive B cell activation in SLE, focusing on how B cell receptor and Toll-like receptor signals integrate to drive breaks in tolerance to nuclear antigens. In addition, we discuss autoantibody-dependent and autoantibody-independent B cell effector functions during lupus pathogenesis. Finally, we address efforts to target B cells therapeutically in human SLE. Despite initial disappointing clinical trials testing B cell depletion in lupus, more recent studies show promise, emphasizing how greater understanding of underlying immune mechanisms can yield clinical benefits.

Biological Therapy in Primary Sjögren's Syndrome: Effect on Salivary Gland Function and Inflammation

Primary Sjögren's syndrome (pSS) is a chronic, systemic autoimmune disease. It is the second most common rheumatic autoimmune disorder, affecting 0.7% of European Americans and up to 1% of people globally. pSS is characterized by the impaired secretory function of exocrine glands, including salivary and lachrymal glands. A lymphocytic infiltration of these organs leads to the common and debilitating symptoms of oral and ocular dryness, majorly affecting the quality of life of these patients. Currently, no disease-modifying drug has been approved for the treatment of pSS, with therapies largely aimed at relieving symptoms of dry mouth and dry eyes. In particular, management of oral dryness still represents a major unmet clinical need in pSS and a significant burden for patients with this condition. Recently, several randomized clinical trials in pSS with biological therapies targeting specific mechanistic pathways implicated in the disease pathogenesis, including B-cell hyperactivity, T-cell co-stimulation and the aberrant role of cytokines, have been completed with mixed results. In this review, we summarize evidence from recent clinical trials investigating biological therapy in pSS, specifically highlighting efficacy, or lack thereof, in modulating local inflammation and improving salivary gland function.

COVID-19 pneumonia in a patient with granulomatosis with polyangiitis on rituximab: case-based review

A 77-year-old man with past medical history of granulomatosis with polyangiitis (GPA) on rituximab and prednisone, presented to the hospital with worsening cough and shortness of breath. He had tested positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection by nasal swab polymerase chain reaction (PCR) while asymptomatic, 6 weeks earlier. He started with cough and shortness of breath 2 weeks after his initial positive test. After developing symptoms, he tested negative twice by nasal swab PCR, but the PCR of his bronchioloalveolar lavage was positive for SARS-CoV-2. He did not develop antibodies against coronavirus. Prednisone 15 mg daily was continued, and he received remdesivir, and convalescent plasma with quick recovery. We reviewed the literature to search for similar cases. Our case suggests that SARS-CoV-2 infection in patients on rituximab may have an atypical presentation and the diagnosis may be delayed due to negative PCR testing in the nasal swab. Patients may benefit from treatment with convalescent plasma.

B cell depletion inhibits fibrosis via suppressing pro-fibrotic macrophage differentiation in a mouse model of systemic sclerosis

OBJECTIVE

We investigated the effect of B cell depletion on fibrosis in systemic sclerosis (SSc) and its mechanism of action.

METHODS

Bleomycin-induced SSc (BLM-SSc) model mice were treated with anti-CD20 antibody, and skin and lung fibrosis was evaluated histopathologically. T cells and macrophages were co-cultured with B cells, and the effect of B cells on their differentiation was assessed by flow cytometry. We also co-cultured B cells and monocytes from SSc patients and analyzed the correlation between fibrosis and pro-fibrotic macrophage induction by B cells.

RESULTS

B cell depletion inhibited fibrosis in BLM-SSc mice. B cells from BLM-SSc mice increased pro-inflammatory cytokine producing T cells in co-culture. In BLM-SSc mice, B cell depletion before BLM treatment (pre-depletion) inhibited fibrosis more strongly than B cell depletion after BLM treatment (post-depletion). However, the frequencies of pro-inflammatory T cells were lower in the post-depletion group than in the pre-depletion group. This discrepancy suggests that the effect of B cell depletion on fibrosis cannot be explained by its effect on T cell differentiation. On the other hand, pro-fibrotic macrophages were markedly decreased in the pre-depletion group than in the post-depletion group. Furthermore, B cells from BLM-SSc mice increased pro-fibrotic macrophage differentiation in co-culture. In SSc patients, the extent of pro-fibrotic macrophage induction by B cells correlated with the severity of fibrosis.

CONCLUSION

These findings suggest that B cell depletion inhibits tissue fibrosis via suppressing pro-fibrotic macrophage differentiation in BLM-SSc mice, providing a new rationale for B cell depletion therapy in SSc.

[Rituximab treatment in pediatric patients with steroid-dependent nephrotic syndrome: a tertiary hospital]

BACKGROUND

Corticosteroids have had a central role in the treatment of nephrotic syndrome. The management of these patients who become dependent to steroids is complex, involving different immunosuppressive drugs patterns. The monoclonal antibody anti CD20, Rituximab, is likely to have beneficial effects in cases of steroid-dependent nephrotic syndrome patients with no easy resolution, even when we cannot make a statement about the specific role in the impact. We bring our personal experience in pediatric patients treated with this medication during the last years, to provide a thorough overview and useful information about the role of Rituximab in this pathology.

METHODS

Retrospective study in patients with steroid-dependent idiopathic nephrotic syndrome controlled in the division of Pediatric Nephrology of a spanish tertiary hospital in those patients who had received at least one treatment cycle of Rituximab, at any moment along the evolution of the disease.

RESULTS

The study involved 8 patients. All of them previously received immunosuppressive therapy. The Rituximab were administered as an intravenous infusion, in a dose of 375 mg/m2, and all doses were administered in a period during which the disease was in remission. The depletion of lymphocytes B (CD 19%) were confirmed after the first dose of Rituximab except for one, with a lymphocyte count of 1%. The period of depletion lasts 10.3 months (median; range 6.5-16 months), and only one of the patients registered a relapse of the disease in this period. A reduction of relapses suffered by patients has been shown after the treatment began (3.6 relapses/year in the previous year to the start of the treatment vs. 0.1 relapses/year during the first year post-rituximab). The relapse-free survival in the first year reached 83.3% in patients who suffered more than one relapse (75% of patients), and without a relapse after the treatment began in 2 cases. One or more drugs could be removed in 87.5% of patients after the first cycle of rituximab. After the rituximab treatment, we reached a 96.5% decrease in the corticosteroids doses administered (28.5 mg/m2/day during the 3 months pre-treatment vs. 1 mg/m2/day in the last 3 months of patient monitoring). Not a significant observed adverse effect attributed to the drug after the post-rituximab monitoring period (median 46.5 months, range 5-97 months).

CONCLUSION

The favorable results reported after rituximab treatment in our patients seems to confirm the effectiveness of this drug in the steroid-dependent nephrotic syndrome, making that therapeutic option into consideration and legitimating the use of the drug in complex cases involving pediatric patients. Even so, it seems recommendable to design pertinent studies to clarify, among others, the optimum regimen of the treatment (dose, interval and cycles), clinical repercussion and potential adverse effects in long terms.

The Influence of B Cell Depletion Therapy on Naturally Acquired Immunity to Streptococcus pneumoniae

The anti-CD20 antibody Rituximab to deplete CD20+ B cells is an effective treatment for rheumatoid arthritis and B cell malignancies, but is associated with an increased incidence of respiratory infections. Using mouse models we have investigated the consequences of B cell depletion on natural and acquired humoral immunity to Streptococcus pneumoniae. B cell depletion of naïve C57Bl/6 mice reduced natural IgM recognition of S. pneumoniae, but did not increase susceptibility to S. pneumoniae pneumonia. ELISA and flow cytometry assays demonstrated significantly reduced IgG and IgM recognition of S. pneumoniae in sera from mice treated with B cell depletion prior to S. pneumoniae nasopharyngeal colonization compared to untreated mice. Colonization induced antibody responses to protein rather than capsular antigen, and when measured using a protein array B cell depletion prior to colonization reduced serum levels of IgG to several protein antigens. However, B cell depleted S. pneumoniae colonized mice were still partially protected against both lung infection and septicemia when challenged with S. pneumoniae after reconstitution of their B cells. These data indicate that although B cell depletion markedly impairs antibody recognition of S. pneumoniae in colonized mice, some protective immunity is maintained, perhaps mediated by cellular immunity.

A Retrospective Analysis of Rituximab Treatment for B Cell Depletion in Different Pediatric Indications

Background: Rituximab (RTX) is used in cancer therapy as well as in the treatment of autoimmune diseases and alloimmune responses after transplantation. It depletes the disease-causing B cells by binding to the CD (cluster of differentiation) 20 antigen. We evaluate different pediatric treatment protocols (via fixed treatment schedule, B cell- or symptom-controlled) and their therapeutic effects. Methods: Demographic information, clinical and laboratory characteristics, and special laboratory values such as immunoglobulin G (IgG), CD19 positive B cells and Epstein-Barr viral load were retrospectively analyzed in children treated with RTX between 2008 and 2016. Results: Seventy-six patients aged 1 to 19 (median 13) years were treated with 259 RTX infusions. The spectrum of diseases was very heterogeneous. RTX led to a complete depletion of the B cells. The reconstitution time varied between patients and was dependent on the application schedule (median 11.8 months). Fourteen out of 27 (52%) patients developed hypogammaglobulinaemia. The risk of IgG deficiency was 2.6 times higher in children under 4 years of age than in olderones. In the last group IgG deficiency developed in only 38% of the cases (n = 8). Recurrent and severe infections were observed each in 11/72 (15%) patients. Treatment-related reactions occurred in 24/76 (32%) cases; however, treatment had to be discontinued in only 1 case. In 16/25 (76%), the Epstein-Barr viral load dropped below the detection limit after the first RTX infusion. Conclusion: RTX is an effective and well-tolerated drug for the treatment of oncological diseases as well as autoimmune and alloimmune conditions in children. B cell depletion and reconstitution varies both intra- und interindividually, suggesting that symptom-oriented and B cell-controlled therapy may be favorable. Treatment-related reactions, IgG deficiency and infections must be taken into account.

Anti-CD20-Mediated B Cell Depletion Is Associated With Bone Preservation in Lymphoma Patients and Bone Mass Increase in Mice

Immunotherapy with anti-CD20-specific antibodies (rituximab), has become the standard of care for B cell lymphoproliferative disorders and many autoimmune diseases. In rheumatological patients the effect of rituximab on bone mass yielded conflicting results, while in lymphoma patients it has not yet been described. Here, we used cross-sectional X-ray imaging (CT/PET-CT) to serially assess bone density in patients with follicular lymphoma receiving rituximab maintenance therapy. Remarkably, this treatment prevented the decline in bone mass observed in the control group of patients who did not receive active maintenance therapy. In accordance with these data, anti-CD20-mediated B cell depletion in normal C57BL/6J female mice led to a significant increase in bone mass, as reflected by a 7.7% increase in bone mineral density (whole femur), and a ~5% increase in cortical as well as trabecular tissue mineral density. Administration of anti-CD20 antibodies resulted in a significant decrease in osteoclastogenic signals, including RANKL, which correlated with a reduction in osteoclastogenic potential of bone marrow cells derived from B-cell-depleted animals. Taken together, our data suggest that in addition to its anti-tumor activity, anti-CD20 treatment has a favorable effect on bone mass. Our murine studies indicate that B cell depletion has a direct effect on bone remodeling.

A review of advances in the understanding of lupus nephritis pathogenesis as a basis for emerging therapies

Lupus nephritis is an important cause of both acute kidney injury and chronic kidney disease that can result in end-stage renal disease. Its pathogenic mechanisms are characterized by aberrant activation of both innate and adaptive immune responses, dysregulation of inflammatory signaling pathways, and increased cytokine production. Treatment of lupus nephritis remains a challenging issue in the management of systemic lupus erythematosus since the clinical presentation, response to treatment, and prognosis all vary considerably between patients and are influenced by ethnicity, gender, the degree of chronic kidney damage, pharmacogenomics, and non-immunological modulating factors. Elucidation of the various immunopathogenic pathways in lupus nephritis has resulted in the development of novel therapies, including biologics that target specific antigens on B lymphocytes to achieve B cell depletion, agents that modulate B cell proliferation and development, drugs that block co-stimulatory pathways, drugs that target T lymphocytes primarily, and therapies that target complement activation, signaling pathways, pro-inflammatory cytokines, and neutrophil extracellular traps. This review will discuss recent advances in the understanding of disease pathogenesis in lupus nephritis in the context of potential emerging therapies.

Current protocols and outcomes of ABO-incompatible kidney transplantation

One of the principal obstacles in transplantation from living donors is that approximately 30% are immunologically incompatible because of the presence in the recipient of antibodies directed against the human leukocyte antigen system of the donor or because of the incompatibility of the ABO system. The aim of this review is to describe the more recent data from the literature on the different protocols used and the clinical outcomes of ABO-incompatible kidney transplantation. Two different strategies are used to overcome these barriers: desensitization of the recipient to remove the antibodies and to prevent their rebound after transplantation and the exchange of organs between two or more pairs. The largest part of this review is dedicated to describing the techniques of desensitization. Even if the first reports of successful renal transplantation between ABO-incompatible pairs have been published by 1980, the number of ABO-incompatible transplants increased substantially in this century because of our improved knowledge of the immune system and the availability of new drugs. Rituximab has substantially replaced splenectomy. The technique of apheresis has improved and more recently a tailored desensitization proved to be the more efficient strategy avoiding an excess of immunosuppression with the related side effects. Recent reports document outcomes for such transplantation similar to the outcomes of standard transplantation.

Belimumab and Rituximab in Systemic Lupus Erythematosus: A Tale of Two B Cell-Targeting Agents

Given the centrality of B cells to systemic lupus erythematosus (SLE), it stands to reason that a candidate therapeutic agent that targets B cells could be efficacious. Both rituximab, a monoclonal antibody (mAb) that binds to CD20 on the surface of B cells, and belimumab, a mAb that binds and neutralizes the B cell survival factor BAFF, have been extensively studied for the treatment of SLE. Despite the greater ability of rituximab to deplete B cells than that of belimumab, randomized controlled trials of rituximab in SLE failed to reach their primary clinical endpoints, whereas the primary clinical endpoints were reached in four independent phase-III clinical trials of belimumab in SLE. Accordingly, belimumab has been approved for treatment of SLE, whereas use of rituximab in SLE remains off-label. Nevertheless, several case series of rituximab have pointed to some utility for rituximab in treating SLE. In this review, we provide a concise summary of the factors that led to belimumab's success in SLE as well an analysis of the elements that may have contributed to the lack of success seen in the rituximab randomized controlled trials in SLE.

The effects of B cell depletion on immune related adverse events associated with immune checkpoint inhibition

This letter describes the potential effect of B cell depletion on immune related adverse events associated with immune checkpoint inhibition. B cell depleting agents such as rituximab reduce B cell to plasma cell differentiation and antibody production. This treatment strategy is used in several immune mediated inflammatory diseases such as rheumatoid arthritis and small vessel vasculitis. The immune related adverse events associated with immune checkpoint inhibition resemble immune mediated inflammatory diseases. Here, we report a lower incidence of hypothyroidism in a trial of combined B cell depletion and immune checkpoint inhibitor treatment compared with studies of immune checkpoint inhibitor monotherapy. This letter aims to increase awareness of the immune related adverse events associated with immune checkpoint inhibition in future clinical trials of immune checkpoint inhibition together with B cell depletion (primarily trials of B cell lymphomas). Hopefully, observations from these clinical trials can guide future treatment strategies to treat or prevent immune related adverse events associated with immune checkpoint inhibition.

Exploration and Evaluation of Therapeutic Efficacy of Drug-Free Macromolecular Therapeutics in Collagen-Induced Rheumatoid Arthritis Mouse Model

Monoclonal antibodies (mAbs) against B cell antigens are extensively used in the treatment of rheumatoid arthritis (RA). The B cell depletion therapy prevents RA symptoms and/or alleviates existing inflammation. The previously established two-step drug-free macromolecular therapeutics (DFMT) is applied in the treatment of collagen-induced rheumatoid arthritis in a collagen-induced rheumatoid arthritis mouse model. DFMT is a B cell depletion strategy utilizing Fab' fragment of anti-CD20 mAb for biorecognition and receptor crosslinking to induce B cell apoptosis. DFMT is composed from two nanoconjugates: 1) bispecific engager, Fab'-MORF1 (anti-CD20 Fab' fragment conjugated with morpholino oligonucleotide MORF1), and 2) a crosslinking (effector) component P-(MORF2)X (N-(2-hydroxypropyl)methacrylamide copolymer grafted with multiple copies of complementary morpholino oligonucleotide MORF2). The absence of Fc fragment has the potential to avoid development of resistance and infusion-related reactions. DFMT produces B cell depletion, keeps the RA score low for more than 100 days, and shows minimal cartilage and bone erosion and inflammatory cell infiltration. Further improvements will be explored to optimize DFMT strategy in autoimmune disease treatment.

Successful Treatment of Patients With Refractory PLA2R-Associated Membranous Nephropathy With Obinutuzumab: A Report of 3 Cases

Membranous nephropathy (MN) is a common cause of nephrotic syndrome in adults. Rituximab, a type I anti-CD20 antibody, has been shown to be an effective therapy in treatment of patients with MN associated with M-type phospholipase A₂ receptor (PLA₂R) antibodies. Despite its effectiveness, up to 40% of patients may fail to respond to rituximab, which may be related to higher PLA₂R antibody titers. Obinutuzumab, a type II anti-CD20 depleter, has been shown to produce a more profound CD20 depletion and be more efficacious in treating certain hematologic malignancies compared with rituximab. We report 3 patients with PLA₂R-associated MN for whom rituximab failed to induce immunologic or clinical remisison, but who were successfully treated with obinutuzumab. Obinutuzumab resulted in complete immunologic remission in all 3 cases and was followed by partial remission in 2 of the cases. Obinutuzumab appears to be a promising treatment strategy for PLA₂R-associated MN that fails to respond to rituximab.

Differential response to rituximab in anti-AChR and anti-MuSK positive myasthenia gravis patients: a single-center retrospective study

BACKGROUND

B-cell targeted therapy with rituximab has shown durable response in treating refractory myasthenia gravis (MG). This study compares the response to rituximab between patients with acetylcholine receptor autoantibody positive (AChR+) and muscle-specific kinase autoantibody positive (MuSK+) MG.

METHODS

This retrospective study included 33 patients with either AChR+ or MuSK+ MG who were treated with rituximab from 05/31/2003 to 05/31/2017. Pretreatment and post-treatment immunotherapy regimens, clinical symptoms, and examination findings were evaluated.

RESULTS

Median MGFA Class of II at baseline improved to an asymptomatic median classification at 12-months and last follow-up (p-values <.001) post-rituximab. Improvement in MGFA class was not significantly different between the groups. Twenty-one patients achieved clinical remission (12/17 AChR+, 9/16 MuSK+) with time to remission of 441.4 ± 336.6 days for AChR+ versus 230 ± 180.8 days for MuSK+ patients (p-value 0.049). The mean prednisone dosage requirement decreased significantly in both groups post-rituximab. AChR+ patients required more hospitalizations for exacerbation post-rituximab (p-value 0.046).

CONCLUSION

Rituximab treatment response is observed in both AChR+ and MuSK+ patients supporting the role of B cell depletion in the management of MG. While there was no significant difference between these groups in terms of clinical improvement, symptom-free state, and prednisone burden, MuSK+ MG patients may experience greater benefits, including earlier time to remission, fewer exacerbations and hospitalizations post-treatment.

Activation of natural killer cells by rituximab in granulomatosis with polyangiitis

Objective

In the last few years, anti-CD20 antibody rituximab profoundly changed the therapeutic landscape of granulomatosis with polyangiitis (GPA). Here, we investigated whether natural killer (NK) cells may play a role in rituximab’s mechanism of action in GPA.

Methods

B cell depletion, NK cell degranulation, and the expression of CD69 and CD16 on NK cells were measured in a series of in vitro experiments using peripheral blood mononuclear cells (PBMCs). In vivo activation of NK cells was investigated in patients receiving rituximab infusions. Cells were analyzed by seven-color flow cytometry.

Results

NK cells from GPA patients were activated by immobilized rituximab. Also soluble rituximab activated NK cells, provided that B cells were present. NK cells degranulated and expressed the activation marker CD69 while CD16 expression was decreased. This activation of NK cells by soluble rituximab was accompanied by a reduction of B cells. The next-generation anti-CD20 antibody obinutuzumab showed stronger effects compared to rituximab on both the reduction of B cells and the activation of NK cells. Finally, we found that rituximab led to the activation of NK cells in vivo, provided that B cells were not depleted due to prior rituximab infusions.

Conclusion

B cell-bound rituximab activates NK cells in GPA. While NK cells therefore participate in rituximab’s mechanism of action in humans, their potential may be more efficiently exploited, e.g., by Fc engineering of therapeutic antibodies.

Aging Induces an Nlrp3 Inflammasome-Dependent Expansion of Adipose B Cells That Impairs Metabolic Homeostasis

During aging, visceral adiposity is often associated with alterations in adipose tissue (AT) leukocytes, inflammation, and metabolic dysfunction. However, the contribution of AT B cells in immunometabolism during aging is unexplored. Here, we show that aging is associated with an expansion of a unique population of resident non-senescent aged adipose B cells (AABs) found in fat-associated lymphoid clusters (FALCs). AABs are transcriptionally distinct from splenic age-associated B cells (ABCs) and show greater expansion in female mice. Functionally, whole-body B cell depletion restores proper lipolysis and core body temperature maintenance during cold stress. Mechanistically, the age-induced FALC formation, AAB, and splenic ABC expansion is dependent on the Nlrp3 inflammasome. Furthermore, AABs express IL-1R, and inhibition of IL-1 signaling reduces their proliferation and increases lipolysis in aging. These data reveal that inhibiting Nlrp3-dependent B cell accumulation can be targeted to reverse metabolic impairment in aging AT.

Depletion of B cells rejuvenates the peripheral B-cell compartment but is insufficient to restore immune competence in aging

Aging is associated with increasing prevalence and severity of infections caused by a decline in bone marrow (BM) lymphopoiesis and reduced B‐cell repertoire diversity. The current study proposes a strategy to enhance immune responsiveness in aged mice and humans, through rejuvenation of the B lineage upon B‐cell depletion. We used hCD20Tg mice to deplete peripheral B cells in old and young mice, analyzing B‐cell subsets, repertoire and cellular functions in vitro, and immune responsiveness in vivo. Additionally, elderly patients, previously treated with rituximab healthy elderly and young individuals, were vaccinated against hepatitis B (HBV) after undergoing a detailed analysis for B‐cell compartments. B‐cell depletion in old mice resulted in rejuvenated B‐cell population that was derived from de novo synthesis in the bone marrow. The rejuvenated B cells exhibited a "young"‐like repertoire and cellular responsiveness to immune stimuli in vitro. Yet, mice treated with B‐cell depletion did not mount enhanced antibody responses to immunization in vivo, nor did they survive longer than control mice in "dirty" environment. Consistent with these results, peripheral B cells from elderly depleted patients showed a "young"‐like repertoire, population dynamics, and cellular responsiveness to stimulus. Nevertheless, the response rate to HBV vaccination was similar between elderly depleted and nondepleted subjects, although antibody titers were higher in depleted patients. This study proposes a proof of principle to rejuvenate the peripheral B‐cell compartment in aging, through B‐cell depletion. Further studies are warranted in order to apply this approach for enhancing humoral immune responsiveness among the elderly population.

B cell depletion or absence does not impede anti-tumor activity of PD-1 inhibitors

Background

PD-1 inhibitors are approved for multiple malignancies and function by stimulating T cells. However, the role of B cells in the anti-tumor activity of these drugs is unknown, as is their activity in patients who have received B cell depleting drugs or with immunoglobulin deficiencies.

Methods

We studied B cell content in 40 melanomas from patients treated with pembrolizumab or nivolumab and assessed the association with response to therapy. Murine MC38 colon cancer and YUMMER1.7 melanoma models were used to determine whether concomitant anti-CD20 antibody injections diminish the anti-tumor effects of anti-PD-1. Results were validated in muMT mice, which lack B cells.

Results

B cells were sparse in most melanomas and B cell content was not associated with response to anti-PD-1 or overall survival. Employing MC38 and YUMMER1.7 models, we demonstrated that anti-CD20 antibodies reduce tumor-infiltrating B cells yet had no effect on tumor growth, response to PD-1 inhibition, or survival. In muMT mice, T-cell dependent tumor rejection and anti-PD-1 responses were no different than in wildtype C57BL/6 J mice.

Conclusions

The degree of tumor infiltrating B cell content is not associated with response to anti-PD-1 inhibitors in melanoma. PD-1 inhibitors cause tumor shrinkage in murine cancer models even when B cells are absent or are depleted. PD-1 inhibitors are likely to be active in patients with impaired B cell function, such as patients undergoing B cell depletion with drugs including rituximab for conditions such as B cell malignancies or autoimmune disorders.

Electronic supplementary material

The online version of this article (10.1186/s40425-019-0613-1) contains supplementary material, which is available to authorized users.

B cell depletion and pregnancy: Review and applications for MS treatment

Multiple sclerosis (MS) is a chronic autoimmune condition primarily affecting young adults. As there are numerous uncertainties faced by young women of childbearing age who are living with this chronic condition and the gender ratio is increasingly skewed towards women, it has become critical to define a clear approach to questions of disease management prior to and during pregnancy. With the approval of B cell depletion therapy for treatment of relapsing remitting and primary progressive MS, we explore the available data on using this type of therapy in the setting of pregnancy. We also provide recommendations regarding use of B-cell depleting therapies for patients who are considering or attempting conception.

Non-Antibody-Secreting Functions of B Cells and Their Contribution to Autoimmune Disease

B cells play multiple important roles in the pathophysiology of autoimmune disease. Beyond producing pathogenic autoantibodies, B cells can act as antigen-presenting cells and producers of cytokines, including both proinflammatory and anti-inflammatory cytokines. Here we review our current understanding of the non-antibody-secreting roles that B cells may play during development of autoimmunity, as learned primarily from reductionist preclinical models. Attention is also given to concepts emerging from clinical studies using B cell depletion therapy, which shed light on the roles of these mechanisms in human autoimmune disease.

Idiopathic nephrotic syndrome and rituximab: may we predict circulating B lymphocytes recovery?

BACKGROUND

Rituximab (RTX) has been shown to be an efficient treatment for steroid-dependent nephrotic syndrome (SDNS). A long B cell depletion period seems to improve the duration of remission. This study reports the duration of B cell depletion after each RTX infusion in patients with nephrotic syndrome.

METHODS

We retrospectively report the data of 22 patients with a diagnosis of a SDNS or steroid-resistant nephrotic syndrome (SRNS) and a treatment with RTX in a single center. B cell depletion duration was compared to the first B cell depletion duration and to the previous B cell depletion duration in each patient.

RESULTS

Twenty-two patients (5 girls) were included. Seventy-six periods of B cell depletions were compared to the first B cell depletion duration and to the preceding B cell depletion duration in the same patient. Total duration of B cell depletion was 26 (6-66) months. Individual post-RTX infusion B cell depletion duration was 5.1 (1.6-14) months. Median B cell depletion duration following the first RTX cure for children who had received 1 to 2 infusions at first cure was not statistically different of those who had received 3 to 4 infusions (p = 0.18). Comparing the B cell depletion induced by previous RTX courses and the following B cell depletion, 89.5% of patients had a similar duration within an open interval from 2 months.

CONCLUSION

Once the individual time interval until B cell recovery is determined, monitoring could be individualized by targeting the expected date of B cell recovery or by performing pre-emptive RTX injections.

Novel Diagnostic and Therapeutic Strategies in Juvenile Autoimmune Hepatitis

Juvenile autoimmune hepatitis (JAIH) is a rare, chronic, inflammatory disease of the liver characterized by a complex interaction between genetic, immunological, and environmental factors leading to loss of immunotolerance to hepatic antigens. It affects both children and adolescents, most commonly females, and its clinical manifestations are quite variable. JAIH is progressive in nature and if left untreated may lead to cirrhosis and terminal liver failure. Although JAIH was first described almost 50 years ago, there have been few significant advances in the clinical management of these patients, both in terms of available diagnostic tools and therapeutic options. Aminotransferase activity, class G immunoglobulins and autoantibodies are the biomarkers used to diagnose AIH and monitor treatment response alongside clinical and histological findings. Despite their utility and cost-effectiveness, these biomarkers are neither an accurate expression of AIH pathogenic mechanism nor a precise measure of treatment response. Current standard of care is mainly based on the administration of steroids and azathioprine. This combination of drugs has been proven effective in inducing remission of disease in the majority of patients dramatically improving their survival; however, it not only fails to restore tolerance to hepatic autoantigens, but it also does not halt disease progression in some patients, it is often needed life-long and finally, it has deleterious side-effects. The ideal therapy should be enough selective to contrast immune-mediated live damage while preserving or potentiating the ability to develop permanent tolerance vs. pathogenic autoantigens. By reviewing the state of the art literature, this article highlights novel diagnostic and therapeutic strategies for managing pediatric AIH with a special focus on new strategies of immunotherapy. These promising tools could improve the diagnostic algorithm, more accurately predict disease prognosis, and provide targeted, individualized treatment.

Immunosuppression in Experimental Chagas Disease Is Mediated by an Alteration of Bone Marrow Stromal Cell Function During the Acute Phase of Infection

After infection with Trypanosoma cruzi, the etiologic agent of Chagas disease, immunosuppression, and apoptosis of mature lymphocytes contribute to the establishment of the parasite in the host and thereby to persistence and pathology in the chronic stage of infection. In a systemic mouse model of experimental Chagas disease, we have demonstrated a strong depletion of mature B cells in the spleen during the first 2 weeks of infection. Remarkably, the decrease in this cell population commenced already in the bone marrow from infected mice and was a concomitant of an increased apoptosis in pro- and pre-B cell populations. Pro- and pre-B cells in the bone marrow showed a significant reduction accompanied by a functional disturbance of bone marrow-derived stromal cells resulting in diminished levels of IL-7, an essential factor for the development of B cell precursors. Ex vivo, stromal cells isolated from the bone marrow of infected mice had a strikingly impaired capacity to maintain the development of pro- and pre-B cells obtained from uninfected animals. Together, the reduction of an active humoral immune response during acute Chagas disease suggests to be an initial immune evasion mechanism of the parasite to establish persistent infection. Therefore, prevention of B cell depletion by rescuing the stromal cells during this early phase, could give rise to new therapeutic approaches.

Infection Dynamics of Hepatitis E Virus in Wild-Type and Immunoglobulin Heavy Chain Knockout JH -/- Gnotobiotic Piglets

Hepatitis E virus (HEV), the causative agent of hepatitis E, is an important but incompletely understood pathogen causing high mortality during pregnancy and leading to chronic hepatitis in immunocompromised individuals. The underlying mechanisms leading to hepatic damage remain unknown; however, the humoral immune response is implicated. In this study, immunoglobulin (Ig) heavy chain J_H ^-/- knockout gnotobiotic pigs were generated using CRISPR/Cas9 technology to deplete the B-lymphocyte population, resulting in an inability to generate a humoral immune response to genotype 3 HEV infection. Compared to wild-type gnotobiotic piglets, the frequencies of B lymphocytes in the Ig heavy chain J_H ^-/- knockouts were significantly lower, despite similar levels of other innate and adaptive T-lymphocyte cell populations. The dynamic of acute HEV infection was subsequently determined in heavy chain J_H ^-/- knockout and wild-type gnotobiotic pigs. The data showed that wild-type piglets had higher viral RNA loads in feces and sera compared to the J_H ^-/- knockout pigs, suggesting that the Ig heavy chain J_H ^-/- knockout in pigs actually decreased the level of HEV replication. Both HEV-infected wild-type and J_H ^-/- knockout gnotobiotic piglets developed more pronounced lymphoplasmacytic hepatitis and hepatocellular necrosis lesions than other studies with conventional pigs. The HEV-infected J_H ^-/- knockout pigs also had significantly enlarged livers both grossly and as a ratio of liver/body weight compared to phosphate-buffered saline-inoculated groups. This novel gnotobiotic pig model will aid in future studies into HEV pathogenicity, an aspect which has thus far been difficult to reproduce in the available animal model systems.IMPORTANCE According to the World Health Organization, approximately 20 million HEV infections occur annually, resulting in 3.3 million cases of hepatitis E and >44,000 deaths. The lack of an efficient animal model that can mimic the full-spectrum of infection outcomes hinders our ability to delineate the mechanism of HEV pathogenesis. Here, we successfully generated immunoglobulin heavy chain J_H ^-/- knockout gnotobiotic pigs using CRISPR/Cas9 technology, established a novel J_H ^-/- knockout and wild-type gnotobiotic pig model for HEV, and systematically determined the dynamic of acute HEV infection in gnotobiotic pigs. It was demonstrated that knockout of the Ig heavy chain in pigs decreased the level of HEV replication. Infected wild-type and J_H ^-/- knockout gnotobiotic piglets developed more pronounced HEV-specific lesions than other studies using conventional pigs, and the infected J_H ^-/- knockout pigs had significantly enlarged livers. The availability of this novel model will facilitate future studies of HEV pathogenicity.

B cell depletion reduces T cell activation in pancreatic islets in a murine autoimmune diabetes model

AIMS/HYPOTHESIS

Type 1 diabetes is a T cell-mediated autoimmune disease characterised by the destruction of beta cells in the islets of Langerhans, resulting in deficient insulin production. B cell depletion therapy has proved successful in preventing diabetes and restoring euglycaemia in animal models of diabetes, as well as in preserving beta cell function in clinical trials in the short term. We aimed to report a full characterisation of B cell kinetics post B cell depletion, with a focus on pancreatic islets.

METHODS

Transgenic NOD mice with a human CD20 transgene expressed on B cells were injected with an anti-CD20 depleting antibody. B cells were analysed using multivariable flow cytometry.

RESULTS

There was a 10 week delay in the onset of diabetes when comparing control and experimental groups, although the final difference in the diabetes incidence, following prolonged observation, was not statistically significant (p = 0.07). The co-stimulatory molecules CD80 and CD86 were reduced on stimulation of B cells during B cell depletion and repopulation. IL-10-producing regulatory B cells were not induced in repopulated B cells in the periphery, post anti-CD20 depletion. However, the early depletion of B cells had a marked effect on T cells in the local islet infiltrate. We demonstrated a lack of T cell activation, specifically with reduced CD44 expression and effector function, including IFN-γ production from both CD4⁺ and CD8⁺ T cells. These CD8⁺ T cells remained altered in the pancreatic islets long after B cell depletion and repopulation.

CONCLUSIONS/INTERPRETATION

Our findings suggest that B cell depletion can have an impact on T cell regulation, inducing a durable effect that is present long after repopulation. We suggest that this local effect of reducing autoimmune T cell activity contributes to delay in the onset of autoimmune diabetes.

B Cell Modulation Strategies in Autoimmune Diseases: New Concepts

B cells are major effector cells in autoimmunity through antibody production, T cell help and pro-inflammatory cytokine production. Major advances have been made in human B cell biology knowledge using rituximab and type II new anti-CD20 antibodies, anti-CD19 antibodies, anti-CD22 antibodies, autoantigen specific B cell depleting therapy (chimeric antigen receptor T cells), and B cell receptor signaling inhibition (Bruton’s tyrosine kinase inhibitors). However, in certain circumstances B cell depleting therapy may lead to the worsening of the autoimmune disease which is in accordance with the existence of a regulatory B cell population. Current concepts and future directions for B cell modulating therapies in autoimmune diseases with a special focus on pemphigus are discussed.

Ofatumumab for B cell depletion in patients with systemic lupus erythematosus who are allergic to rituximab

OBJECTIVE

B cell depletion, most commonly with rituximab, is an evolving therapeutic approach in SLE. Infusion reactions after rituximab are common, and may prevent re-treatment in patients who previously demonstrated beneficial response. We have used ofatumumab, a fully humanized anti-CD20 mAb, as an alternative B cell-depleting agent in patients with SLE who are rituximab-intolerant due to severe infusion reactions.

METHODS

A single-centre retrospective case series of 16 patients were treated with ofatumumab for SLE between 2012 and 2015.

RESULTS

Ofatumumab infusion was well tolerated in 14/16 patients, in whom the median age was 34 (range 19-55) and the median duration of SLE 9.2 years (0.6-28.5). The cohort was heavily pre-treated, with 50% having prior CYC exposure, and a median cumulative dose of prior rituximab 4 g (1-6). Twelve patients were treated for LN, one for extra-renal flare and one for remission maintenance. B cell-depletion was achieved in 12/14 patients, with comparable reconstitution kinetics to a previous cohort treated with rituximab at our centre, and was associated with improvements in serological markers of disease activity, including ANA, anti-dsDNA antibody and complement levels. Half of the patients with LN achieved renal remission by 6 months. Progressive disease that was unresponsive to augmented immunosuppression with CYC was seen in five patients. During long-term follow-up (median 28 months), five grade III infections were reported, and there were no malignancies or deaths.

CONCLUSION

In this pre-treated cohort with long-standing SLE, ofatumumab was a well-tolerated, safe and effective alternative to rituximab for B cell-depletion therapy.

Remission Induction Therapy with Rituximab for Microscopic Polyangiitis: A Feasibility Study

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is systemic vascular inflammation. Microscopic polyangiitis (MPA) is a major type of AAV in Japan. MPA often affects the kidneys and lungs, leading to death if untreated. Induction therapy (i.e., initial treatment) for MPA has not been optimized, although methylprednisolone and cyclophosphamide are commonly used. Recently, rituximab (RTX) (a monoclonal antibody against the protein CD20) has also been used to treat refractory AAV. RTX at 375 mg/m²/week for 4 weeks (i.e., the conventional lymphoma dosing schedule) is used, but the optimal dosing schedule is controversial. Indeed, a single-dose of RTX successfully controlled nephrotic syndrome. However, to date, the effectiveness of a single RTX dose in treating MPA has not been fully investigated in Japan. This was a retrospective observational study. Six newly diagnosed patients with MPA were initially treated with methylprednisolone and a single dose of RTX (375 mg/m²). We investigated the patients' clinical features, as well as the efficacy and safety of RTX treatment. All patients attained remission on a tapered prednisolone dose of < 10 mg/day during the first 12 months. One patient relapsed after 12 months whereas another required hospitalization owing to infective spondyloarthritis. Adverse reactions to RTX infusion and late-onset neutropenia were not observed. Therefore, a single-dose treatment with RTX induced remission with few complications, and allowed tapering the prednisolone treatment. We conclude that a single dose of RTX is a promising induction therapy for MPA, reducing the cost associated with multiple doses.