B-cell oligoclonal expansions in renal tissue of patients with immune-mediated glomerular disease

The immune regulatory role of lymphangiogenesis in kidney disease

The renal lymphatic system is critical for maintaining kidney homeostasis and regulating the immune response inside the kidney. In various kidney pathological situations, the renal lymphatic network experiences lymphangiogenesis, which is defined as the creation of new lymphatic vessels. Kidney lymphangiogenesis controls immunological response inside the kidney by controlling lymphatic flow, immune cell trafficking, and immune cell regulation. Ongoing study reveals lymphangiogenesis's different architecture and functions in numerous tissues and organs. New research suggests that lymphangiogenesis in kidney disorders may regulate the renal immune response in various ways. The flexibility of lymphatic endothelial cells (LECs) improves the kidney's immunological regulatory function of lymphangiogenesis. Furthermore, current research has shown disparate findings regarding its impact on distinct renal diseases, resulting in contradictory outcomes even within the same kidney condition. The fundamental causes of the various effects of lymphangiogenesis on renal disorders remain unknown. In this thorough review, we explore the dual impacts of renal lymphangiogenesis on several kidney pathologies, with a particular emphasis on existing empirical data and new developments in understanding its immunological regulatory function in kidney disease. An improved understanding of the immunological regulatory function of lymphangiogenesis in kidney diseases might help design novel medicines targeting lymphatics to treat kidney pathologies.

B cell dysregulation and depletion therapy in primary membranous nephropathy: Prospects and potential challenges

B cells are crucial to the humoral immune response, originating in the bone marrow and maturing in the spleen and lymph nodes. They primarily function to protect against a wide range of infections through the secretion of antibodies. The role of B cells in primary membranous nephropathy (PMN) has gained significant attention, especially following the discovery of various autoantibodies that target podocyte antigens and the observed positive outcomes from B cell depletion therapy. Increasing evidence points to the presence of abnormal B cell subsets and functions in MN. B cells have varied roles during the different stages of disease onset, progression, and relapse. Initially, B cells facilitate self-antigen presentation, activate effector T cells, and initiate cellular immunity. Subsequently, the disruption of both central and peripheral immune tolerance results in the emergence of autoreactive B cells, with strong germinal center responses as a major source of MN autoantibodies. Additionally, critical B cell subsets, including Bregs, memory B cells, and plasma cells, play roles in the immune dysregulation observed in MN, assisting in predicting disease recurrence and guiding management strategies for MN. This review offers a detailed overview of research advancements on B cells and elucidates their pathological roles in MN.

The abnormal signaling of the B cell receptor and co-receptors of lupus B cells

It is easily understood that studying the physiology and pathophysiology of the BCRtriggered cascade is of importance, particularly in such diseases as systemic lupus erythematosus (SLE) that are considered by many as a "B cell disease". Even though B cells are not considered as the only players in lupus pathogenesis, and other immune and non-immune cells are certainly involved, it is the success of recent B cell-targeting treatment strategies that ascribe a critical role to the lupus B cell.

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.

B Cells in Primary Membranous Nephropathy: Escape from Immune Tolerance and Implications for Patient Management

Membranous nephropathy (MN) is an important cause of nephrotic syndrome and chronic kidney disease (CKD) in adults. The pathogenic significance of B cells in MN is increasingly recognized, especially following the discovery of various autoantibodies that target specific podocytic antigens and the promising treatment responses seen with B cell depleting therapies. The presence of autoreactive B cells and autoantibodies that bind to antigens on podocyte surfaces are characteristic features of MN, and are the result of breaches in central and peripheral tolerance of B lymphocytes. These perturbations in B cell tolerance include altered B lymphocyte subsets, dysregulation of genes that govern immunoglobulin production, aberrant somatic hypermutation and co-stimulatory signalling, abnormal expression of B cell-related cytokines, and increased B cell infiltrates and organized tertiary lymphoid structures within the kidneys. An understanding of the role of B cell tolerance and homeostasis may have important implications for patient management in MN, as conventional immunosuppressive treatments and novel B cell-targeted therapies show distinct effects on proliferation, differentiation and reconstitution in different B cell subsets. Circulating B lymphocytes and related cytokines may serve as potential biomarkers for treatment selection, monitoring of therapeutic response and prediction of disease relapse. These recent advances in the understanding of B cell tolerance in MN have provided greater insight into its immunopathogenesis and potential novel strategies for disease monitoring and treatment.

Seven novel podocyte autoantibodies were identified to diagnosis a new disease subgroup-autoimmune Podocytopathies

Children with idiopathic nephrotic syndrome (INS) usually have podocyte injury, and recent studies suggest a B cell dysfunction in INS. Therefore, this study attempts to screen and identify the podocyte autoantibodies in patients. Two-dimensional electrophoresis and mass spectrometry were used to screen and identify the pathogenic podocyte autoantibodies in children with INS. The positive rate, expression pattern, and clinical correlation of these podocyte autoantibodies in children with INS were determined by clinical study. At least 66% of INS children have podocyte autoantibodies. Seven podocyte autoantibodies closely related to INS were screened and identified for the first time in this study. These podocyte autoantibodies are positively correlated with proteinuria, and its titer will decrease rapidly after effective treatment. In this study, a group of new disease subgroup-"autoimmune podocytes" were identified by podocyte autoantibodies.

Membranous nephropathy

Membranous nephropathy (MN) is a glomerular disease that can occur at all ages. In adults, it is the most frequent cause of nephrotic syndrome. In ~80% of patients, there is no underlying cause of MN (primary MN) and the remaining cases are associated with medications or other diseases such as systemic lupus erythematosus, hepatitis virus infection or malignancies. MN is an autoimmune disease characterized by a thickening of the glomerular capillary walls due to immune complex deposition. Identification of the phospholipase A2 receptor (PLA2R) as the major antigen in adults in 2009 induced a paradigm shift in disease diagnosis and monitoring and several other antigens have since been characterized. Disease outcome is difficult to predict and around one-third of patients will undergo spontaneous remission. In those at high risk of progression, immunosuppressive therapy with cyclophosphamide plus corticosteroids has substantially reduced the need for kidney replacement therapy. Owing to carcinogenic risk, other treatments (calcineurin inhibitors and CD20-targeted B cell depletion therapy (rituximab)) have been developed. However, disease relapses are frequent when calcineurin inhibitors are stopped and the remission rate with rituximab is lower than with cyclophosphamide, particularly in patients with high PLA2R antibody titres. Other new drugs are already available and antigen-specific immunotherapies are being developed.

Helper T Cells in Idiopathic Membranous Nephropathy

Idiopathic membranous nephropathy (IMN) is an autoimmune disease in which the immune system produces an antibody response to its own antigens due to impaired immune tolerance. Although antibodies are derived from plasma cells differentiated by B cells, the T-B cells also contribute a lot to the immune system. In particular, the subsets of helper T (Th) cells, including the dominant subsets such as Th2, Th17, and follicular helper T (Tfh) cells and the inferior subsets such as regulatory T (Treg) cells, shape the immune imbalance of IMN and promote the incidence and development of autoimmune responses. After reviewing the physiological knowledge of various subpopulations of Th cells and combining the existing studies on Th cells in IMN, the role model of Th cells in IMN was explained in this review. Finally, the existing clinical treatment regimens for IMN were reviewed, and the importance of the therapy for Th cells was highlighted.