CD20+ B cell depletion in systemic autoimmune diseases: common mechanism of inhibition or disease-specific effect on humoral immunity?

Evaluation of pediatric rheumatologists' approach to rituximab use: a questionnaire study

Rituximab (RTX) is a chimeric monoclonal antibody that targets the CD20 antigen on B cells and is used in various autoimmune disorders. In this study, we aimed to measure the awareness of pediatric rheumatologists about the use of RTX through a survey. Between February and March 2023, a 42-question survey was sent via email to pediatric rheumatology specialists in Turkey. The participants were questioned for which diagnoses and system involvement they preferred to use RTX, which routine tests they performed, vaccination policy, and adverse events that occurred during or after infusion. Forty-one pediatric rheumatologists answered the survey. They prescribed RTX most frequently for systemic lupus erythematosus (87.8%) and ANCA-associated vasculitis (9.8%). Prior to the administration of RTX, 95% of clinicians checked renal and liver function tests, as well as immunoglobulin levels. The most frequently tested hepatitis markers before treatment were HBsAg and anti-HBs antibody (97.6%), while 85.4% of rheumatologists checked for anti-HCV. Clinicians (31.4%) reported that they postpone RTX infusion 2 weeks following an inactivated vaccine. Sixty-one percent of rheumatologists reported starting RTX treatment 1 month after live vaccines, while 26.8% waited 6 months. The most frequent adverse events were an allergic reaction during RTX infusion (65.9%), hypogammaglobulinemia (46.3%), and rash (36.6%). In the event of hypogammaglobulinemia after RTX treatment, physicians reported that they frequently (58.5%) continued RTX after intravenous immunoglobulin administration.

CONCLUSIONS

RTX has become a common treatment option in pediatric rheumatology in recent years. Treatment management may vary between clinician such as vaccination and routine tests.

WHAT IS KNOWN

• During the course of rituximab therapy, clinicians should be attentive to specific considerations in pre-treatment, during administration, and in post-treatment patient monitoring.

WHAT IS NEW

• There are differences in practice among clinicians in the management of RTX therapy. These practice disparities have the potential to impact the optimal course of treatment. • This study highlights that standardized guidelines are needed for RTX treatment in pediatric rheumatology, particularly for vaccination policies and routine tests.

Rituximab Resistance in Glomerular Diseases: A GlomCon Mini Review

Resistance to rituximab B-cell depletion therapy is a clinically pertinent adverse sequela that can have significant implications for the treatment of immune-mediated glomerular diseases. The true incidence of rituximab resistance remains unknown; however, it is an increasingly recognized treatment complication. Resistance typically presents with suboptimal treatment response, rapid B-cell reconstitution, and a relapsing disease course. Although the diverse mechanisms resulting in rituximab resistance are ongoing topics of research, both primary and secondary mechanisms have been identified as key catalysts. The emergence of human antichimeric antibodies (HACAs) is a major cause of secondary resistance to rituximab therapy and typically appears following repeated drug exposure. Frequently, HACAs develop in the setting of underlying autoimmune disease and contribute to poor B-cell depletion, reduced rituximab therapeutic efficacy, and enhanced drug clearance. The clinical challenge of rituximab resistance necessitates heightened awareness among clinicians. Screening for HACAs should be considered in individuals with poor clinical response to rituximab, more rapid B-cell reconstitution, and relapsing disease. Detection of HACAs may guide treatment alterations, including addition of further immunosuppressive therapy and transitioning to a humanized B-cell depleting monoclonal antibody.

Repurposing of rituximab biosimilars to treat B cell mediated autoimmune diseases

Rituximab, the first monoclonal antibody approved for the treatment of lymphoma, eventually became one of the most popular and versatile drugs ever in terms of clinical application and revenue. Since its patent expiration, and consequently, the loss of exclusivity of the original biologic, its repurposing as an off-label drug has increased dramatically, propelled by the development and commercialization of its many biosimilars. Currently, rituximab is prescribed worldwide to treat a vast range of autoimmune diseases mediated by B cells. Here, we present a comprehensive overview of rituximab repurposing in 115 autoimmune diseases across 17 medical specialties, sourced from over 1530 publications. Our work highlights the extent of its off-label use and clinical benefits, underlining the success of rituximab repurposing for both common and orphan immune-related diseases. We discuss the scientific mechanism associated with its clinical efficacy and provide additional indications for which rituximab could be investigated. Our study presents rituximab as a flagship example of drug repurposing owing to its central role in targeting cluster of differentiate 20 positive (CD20) B cells in 115 autoimmune diseases.

Immune pathogenesis of idiopathic granulomatous mastitis: from etiology toward therapeutic approaches

Idiopathic granulomatous mastitis (IGM) is a noncancerous, chronic inflammatory disorder of breast with unknown causes, posing significant challenges to the quality of life due to its high refractoriness and local aggressiveness. The typical symptoms of this disease involve skin redness, a firm and tender breast mass and mastalgia; others may include swelling, fistula, abscess (often without fever), nipple retraction, and peau d'orange appearance. IGM often mimics breast abscesses or malignancies, particularly inflammatory breast cancer, and is characterized by absent standardized treatment options, inconsistent patient response and unknown mechanism. Definite diagnosis of this disease relies on core needle biopsy and histopathological examination. The prevailing etiological theory suggests that IGM is an autoimmune disease, as some patients respond well to steroid treatment. Additionally, the presence of concurrent erythema nodosum or other autoimmune conditions supports the autoimmune nature of the disease. Based on current knowledge, this review aims to elucidate the autoimmune-favored features of IGM and explore its potential etiologies. Furthermore, we discuss the immune-mediated pathogenesis of IGM using existing research and propose immunotherapeutic strategies for managing this condition.

Modern advances in heart transplantation

Heart transplantation (HTx) is the only definitive therapy for patients with end stage heart disease. With the increasing global prevalence of heart failure, the demand for HTx has continued to grow and outpace supply. In this paper, we will review advances in the field of HTx along the clinical journey of a HTx recipient. Starting with the sensitized patient, we discuss current methods to define sensitization, and assays to help identify clinically relevant anti-HLA antibodies. Desensitization strategies targeting all levels of the adaptive immune system are discussed with emphasis on novel techniques such as anti-CD 38 blockade and use of the Immunoglobulin G-Degrading Enzyme of Streptococcus Pyogenes. We next discuss donor procurement and the resurgence of donation after circulatory death as a viable strategy to significantly and safely increase the donor pool. Post-transplant, we evaluate non-invasive surveillance techniques including gene expression profiling and donor-derived cell-free DNA. Last, we discuss the ground-breaking developments in the field of xenotransplantation.

A review on gout: Looking back and looking ahead

Gout is a metabolic disease caused by the deposition of monosodium urate (MSU) crystals inside joints, which leads to inflammation and tissue damage. Increased concentration of serum urate is an essential step in the development of gout. Serum urate is regulated by urate transporters in the kidney and intestine, especially GLUT9 (SLC2A9), URAT1 (SLC22A12) and ABCG. Activation of NLRP3 inflammasome bodies and subsequent release of IL-1β by monosodium urate crystals induce the crescendo of acute gouty arthritis, while neutrophil extracellular traps (NETs) are considered to drive the self-resolving of gout within a few days. If untreated, acute gout may eventually develop into chronic tophaceous gout characterized by tophi, chronic gouty synovitis, and structural joint damage, leading the crushing burden of treatment. Although the research on the pathological mechanism of gout has been gradually deepened in recent years, many clinical manifestations of gout are still unable to be fully elucidated. Here, we reviewed the molecular pathological mechanism behind various clinical manifestations of gout, with a view to making contributions to further understanding and treatment.

T and B lymphocyte dynamics after genetically-modified pig-to-baboon kidney xenotransplantation with an anti-CD40mAb-based immunosuppressive regimen

BACKGROUND

The aim was to monitor recovery of T/B lymphocytes in baboons after depletion by anti-thymocyte globulin (ATG) and anti-CD20mAb (Rituximab), followed by pig kidney transplantation and maintenance therapy with an anti-CD40mAb-based regimen.

METHODS

In baboons (n = 14), induction was with ATG and anti-CD20mAb, and maintenance with (i) anti-CD40mAb, (ii) rapamycin, and (iii) methylprednisolone. Follow-up was for 6 months, or until rejection or other complication developed. Baboon blood was collected at intervals to measure T/B cells and subsets by flow cytometry. In a separate study in baboons receiving the same immunosuppressive regimen (n = 10), the populations of T/B lymphocytes in PBMCs, lymph nodes, and spleen were examined.

RESULTS

After induction therapy, the total lymphocyte count and the absolute numbers of CD3⁺, CD4⁺, and CD8⁺T cells fell by >80%, and no CD22⁺B cells remained (all p < 0.001). T cell numbers began to recover early, but no CD22⁺B cells were present in the blood for 2 months. Recovery of both T and B cells remained at <30% of baseline (p < 0.001), even if rejection developed. At 6 months, effector memory CD8⁺T cells had increased more than other T cell subsets, but a greater percentage of B cells were naïve. In contrast to blood and spleen, T and B cells were not depleted in lymph nodes.

CONCLUSIONS

ATG and anti-CD20mAb effectively decreased T and B lymphocytes in the blood and, in the presence of anti-CD40mAb maintenance therapy, recovery of these cells was inhibited. The recovery of effector memory CD8⁺T cells may be detrimental to long-term graft survival.

Intravenous immunoglobulin as a therapeutic option for patients with worsening COVID-19 under rituximab

Severe cases of the new COVID-19 are being reported in immunosuppressed patients. The risk seems to depend on the type of immunosuppressive agents used and it is particularly important in patients under the long-lasting effect of rituximab. Information regarding the best therapeutic approach to these patients is scarce and further studies are needed. We present a case of a young woman with rheumatoid arthritis treated with rituximab (last administration 4 months before her admission). She presented with a deteriorating and prolonged SARS-CoV-2 infection, with persistent fever, significant elevation of inflammatory markers and radiological progression. Glucocorticoids and antibiotic therapy were initiated, with no response. Intravenous immunoglobulin was then used with a rapid and exuberant response, anticipating a promising role of this therapy in immunosuppressed patients with COVID-19 under the effect of rituximab.

High rates of severe disease and death due to SARS-CoV-2 infection in rheumatic disease patients treated with rituximab: a descriptive study

The objective of this study is to describe the characteristics and outcomes of rheumatic and musculoskeletal disease (RMD) patients who were treated with rituximab and had suspected or confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In this descriptive study, RMD patients who were treated with rituximab in the last 12 months at the Rheumatology Department of our hospital were screened for SARS-CoV-2 infection via telephone interview and a comprehensive review of clinical health records (01/02/2020–26/05/2020). Those with probable or confirmed SARS-CoV-2 infection were included. In total, 76 patients were screened. Of these, 13 (17.1%) had suspected or confirmed SARS-CoV-2 infection. With regard to these 13 patients, the median age at coronavirus disease (COVID-19) diagnosis was 68 years (range 28–76 years) and 8 (61.5%) were female. Five patients had rheumatoid arthritis, three had systemic vasculitis, two had Sjögren syndrome, and two had systemic lupus erythematosus. Additionally, seven patients (53.8%) had pulmonary involvement secondary to RMD. Eight patients (61.5%) developed severe disease leading to hospitalization, and seven developed bilateral pneumonia and respiratory insufficiency. Of the eight hospitalized patients, five (62.5%) fulfilled the acute respiratory distress syndrome criteria and three developed a critical disease and died. Our cohort had a high rate of severe disease requiring hospitalization (61.5%), with bilateral pneumonia and hyperinflammation leading to a high mortality rate (23.1%). Treatment with rituximab should be considered a possible risk factor for unfavorable outcomes in COVID-19 patients with RMD. However, further study is required to confirm this association.

B cell phenotypes in baboons with pig artery patch grafts receiving conventional immunosuppressive therapy

BACKGROUND

In the pig-to-baboon artery patch model with no immunosuppressive therapy, a graft from an α1,3-galactosyltransferase gene-knockout (GTKO) pig elicits a significant anti-nonGal IgG response, indicating sensitization to the graft. A costimulation blockade-based regimen, e.g., anti-CD154mAb or anti-CD40mAb, prevents sensitization. However, neither of these agents is currently FDA-approved. The aim of the present study was to determine the efficacy of FDA-approved agents on the T and B cell responses.

METHODS

Artery patch xenotransplantation in baboons was carried out using GTKO/CD46 pigs with (n = 2) or without (n = 1) the mutant transgene for CIITA-knockdown. Immunosuppressive therapy consisted of induction with ATG and anti-CD20mAb, and maintenance with different combinations of CTLA4-Ig, tacrolimus, and rapamycin. In addition, all 3 baboons received daily corticosteroids, the IL-6R blocker, tocilizumab, at regular intervals, and the TNF-α blocker, etanercept, for the first 2 weeks. Recipient blood was monitored for anti-nonGal antibody levels by flow cytometry (using GTKO/CD46 pig aortic endothelial cells), and mixed lymphocyte reaction (MLR). CD22+B cell profiles (naïve [IgD+/CD27-], non-switched memory [IgD+/CD27+], and switched memory [IgD-/CD27+] B cell subsets) were measured by flow cytometry. At 6 months, the baboons were euthanized and the grafts were examined histologically.

RESULTS

No elicited anti-pig antibodies developed in any baboon. The frequency of naïve memory B cells increased significantly (from 34% to 90%, p = 0.0015), but there was a significant decrease in switched memory B cells (from 17% to 0.5%, p = 0.015). MLR showed no increase in the proliferative T cell response in those baboons that had received CTLA4-Ig (n = 2). Histological examination showed few or no features of rejection in any graft.

CONCLUSIONS

The data suggest that immunosuppressive therapy with only FDA-approved agents may be adequate to prevent an adaptive immune response to a genetically-engineered pig graft, particularly if CTLA4-Ig is included in the regimen, in part because the development of donor-specific memory B cells is inhibited.

Rapidly increasing off-label use of rituximab in multiple sclerosis in Sweden - Outlier or predecessor?

OBJECTIVES

Off-label use of rituximab to treat MS patients in Sweden is high, and the need for long-term safety data may not be met. Our objectives were to assess the rate of rituximab prescription in patients with multiple sclerosis in Sweden and, in addition, to evaluate the safety of rituximab in a single centre for patients with multiple sclerosis.

MATERIAL AND METHODS

Review of the Swedish MS register was performed to study the number of MS patients treated with rituximab during the last 6 years. Investigation also included a retrospective review of medical files in search for possible side effects/adverse events in all adult patients with MS treated with rituximab at Uppsala University Hospital.

RESULTS

Presently, in Sweden the rate of rituximab prescriptions in relation to other annually started of disease- modifying drugs in MS is 53.5%.

CONCLUSIONS

The share of MS patients in Sweden who are treated with rituximab is very high, and also rapidly increasing. Taken into account the off-label use, cases with adverse medical conditions that could possibly be related to rituximab use should be reported thoroughly.

Immunology of idiopathic nephrotic syndrome

The pathogenesis of idiopathic nephrotic syndrome (INS) is as yet unknown, but several lines of evidence indicate that the immune system may play a crucial pathogenic role in non-genetic INS. The most important of these are, first, the effectiveness of therapy based on immunosuppression and, second, a vast body of data derived both from experimental models and from patient studies that implicate T cells and more recently B cells as major players in INS pathogenesis. However, recent findings also suggest a direct role of podocytes as drivers of the disease process, and the interplay between the glomerulus and the immune system is still being elucidated. In this review we provide an overview of current knowledge on the role of different components of the immune system in determining disease. Advances in our understanding of the pathogenesis of INS may help drive new, more tailored therapeutic approaches.

T regulatory cells and B cells cooperate to form a regulatory loop that maintains gut homeostasis and suppresses dextran sulfate sodium-induced colitis

Regulatory T cells (Tregs) and B cells present in gut-associated lymphoid tissues (GALT) are both implicated in the resolution of colitis. However, how the functions of these cells are coordinated remains elusive. We used the dextran sulfate sodium (DSS)-induced colitis model combined with gene-modified mice to monitor the progression of colitis, and simultaneously examine the number of Tregs and B cells, and the production of IgA antibodies. We found that DSS-treated mice exhibited more severe colitis in the absence of B cells, and that the adoptive transfer of B cells attenuated the disease. Moreover, the transfer of IL-10(-/-) B cells also attenuated colitis, suggesting that B cells inhibited colitis through an interleukin-10 (IL-10)-independent pathway. Furthermore, antibody depletion of Tregs resulted in exacerbated colitis. Intriguingly, the number of GALT Tregs in B cell-deficient mice was significantly decreased during colitis and the adoptive transfer of B cells into these mice restored the Treg numbers, indicating that B cells contribute to Treg homeostasis. We also found that B cells induced the proliferation of Tregs that in turn promoted B-cell differentiation into IgA-producing plasma cells. These results demonstrate that B cells and Tregs interact and cooperate to prevent excessive immune responses that can lead to colitis.

Immune reconstitution inflammatory syndrome associated with biologic therapy

The use of biologics in the treatment of autoimmune disease, cancer, and other immune conditions has revolutionized medical care in these areas. However, there are drawbacks to the use of these medications including increased susceptibility to opportunistic infections. One unforeseen risk once opportunistic infection has occurred with biologic use is the onset of immune reconstitution inflammatory syndrome (IRIS) upon drug withdrawal. Although originally described in human immunodeficiency virus (HIV) patients receiving highly active antiretroviral therapy, it has become clear that IRIS may occur when recovery of immune function follows opportunistic infection in the setting of previous immune compromise/suppression. In this review, we draw attention to this potential pitfall on the use of biologic drugs.

Kinetics of hematogones in bone marrow samples from patients with non-Hodgkin lymphomas treated with rituximab-containing regimens: a flow cytometric study

Treatment with rituximab, either alone or in combination with antiblastic drugs, causes significant depletion of circulating B-lymphocytes and modifications of B cell maturation in the bone marrow. In the present study, we analyzed the kinetics of hematogones in bone marrow samples from 55 patients suffering from non-Hodgkin lymphomas and treated with rituximab-containing regimens. Maturation arrest at the level of stage 2 hematogones, along with complete depletion of naïve, mature B-lymphocytes, was observed as short-term effects (2 months after completion of chemo-immunotherapy). Further bone marrow samples, obtained 12 months after the last rituximab infusion in 21 patients undergoing long-term follow-up and treated with rituximab maintenance therapy, showed complete normalization of B-lymphocyte ontogeny. Hypogammaglobulinemia developed in 26 patients, and was still observed in nine of the 21 patients undergoing long-term follow-up. Our study provides novel data on hematogone kinetics in the setting of patients with non-Hodgkin lymphomas treated with chemo-immunotherapy containing rituximab and with rituximab maintenance. Our observations show that hypogammaglobulinemia can persist in a significant percentage of patients, despite complete recovery of B-lymphocyte ontogeny.