Advances in the treatment of IgA nephropathy with biological agents.

Immunoglobulin A nephropathy (IgAN) is the most common primary glomerular disease, and the "four-hit" theory represents its currently accepted pathogenic mechanism. Mucosal immunity triggered by infections in the respiratory tract, intestines, or other areas leads to antigen presentation, T cell stimulation, B cell maturation, and the production of IgA-producing plasma cells. The proteins B-lymphocyte stimulator (BLyS) and a proliferation-inducing ligand (APRIL) are involved in this process, and alternative complement and lectin pathway activation are also part of the pathogenic mechanism. Kidney Disease Improving Global Outcomes guidelines indicate that a specific effective treatment for IgAN is lacking, with renin-angiotensin-aldosterone system inhibitors being the primary therapy. Recent research shows that biological agents can significantly reduce proteinuria, stabilize the estimated glomerular filtration rate, and reverse some pathological changes, such as endocapillary proliferation and crescent formation. There are four main categories of biological agents used to treat IgA nephropathy, specifically anti-CD20 monoclonal antibodies, anti-BLyS or APRIL monoclonal antibodies, monoclonal antibodies targeting both BLyS and APRIL (telitacicept and atacicept), and monoclonal antibodies inhibiting complement system activation (narsoplimab and eculizumab). However, further research on the dosages, treatment duration, long-term efficacy, and safety of these biological agents is required.