Systemic lupus erythematosus (SLE) is a chronic systemic inflammatory autoimmune disease characterized by a breakdown of tolerance to self. The autoantibodies generated in SLE are directed against nuclear components, with which they form immune complexes (ICs). ICs play key roles in organ and tissue damage, as well as in the activation of the innate and adaptive immune system during the disease course. Therefore, it is of prime importance to understand the mechanisms responsible for the development of B cells producing these pathogenic autoantibodies. There is compelling evidence that T follicular helper (Tfh) cells play a fundamental role in this process. In this review, we will summarize the current knowledge regarding the involvement of Tfh cells in SLE pathogenesis, and discuss potential strategies to target Tfh cells and/or molecules as a therapeutic modality of SLE.Keywords: Autoantibody r B cell r Systemic lupus erythematosus (SLE) r Tfh cell
IntroductionSystemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by a loss of tolerance toward nuclear components, leading to autoantibody production, immune complex formation and organ and tissue damage. Described more than 150 years ago primarily as a skin disorder affecting women in the "prime of life", it was soon recognized that the disease could adopt a systemic course and carry a serious prognosis, "its termination being frequently fatal to life" [1]. In the final years of the 19th century and over the 20th century, many of the recognizable features, as well as the clinical heterogeneity of the disease, were described [2]. Human lupus in fact presents with a spectrum of clinical manifestations ranging from solely skin involvement (cutaneous lupus erythematosus) to a systemic disease (SLE), the latter characterized by a relapsing and remitting course with flares of high morbidity (reviewed in [2]). As initially described, the disease Correspondence: Dr. Hideki Ueno e-mail: hidekiu@baylorhealth.edu affects predominantly young women, with a female-to-male ratio of 9:1, albeit the reasons for this skewed sexual ratio remain poorly understood. The range of target organs is broad, and includes skin, joints, kidney, lung and the central nervous system. Lupus nephritis affects 40-70% of SLE patients with a various incidence dependent on ethnicity, age, group and gender, and constitutes a critical driver of morbidity and mortality (reviewed in [3]). In the 1950s, only 50% of patients with SLE survived 5 years; now, thanks to earlier diagnosis and better treatment, the majority of patients survive more than 10 years. Over time, infections and cardiovascular complications represent the leading causes of fatal outcomes (reviewed in [4]). A better understanding of human SLE pathogenesis is needed because few effective treatments are currently available, and only one drug has been approved for lupus in the past 50 years.Generation of autoantibodies is a hallmark of autoimmune diseases including SLE. Autoantibodies target a broad range of self-ant...