Interleukin-6 (IL-6) is a cytokine that plays a crucial role in inflammation and B cell maturation. It is primarily produced and secreted into the serum at sites of acute and chronic inflammation, inducing inflammatory responses through the interleukin-6 receptor alpha (IL-6Rα). Upon binding to IL-6Rα, IL-6 interacts with two GP130 molecules to form a hexameric complex in a 2:2:2 configuration. This receptor complex formation recruits tyrosine kinases from the Janus kinase family (JAK1, JAK2, and TYK2), which phosphorylate tyrosine sites within the intracellular domain of GP130, leading to the activation of signaling cascades. IL-6 has a broad impact on both immune and non-immune cells. In CD4+ T helper (Th) cells, IL-6 drives the differentiation of activated naïve Th cells into IL-17 and IL-22 expressing Th17 and Th22 cells, which are crucial for anti-bacterial and anti-fungal defense. Conversely, IL-6 inhibits the differentiation of CD4+ T regulatory cells, which play a key role in restraining inflammatory responses. In hepatocytes, IL-6 induces the expression of inflammation-induced acute phase proteins, including C-reactive protein (CRP) ^[1]. IL-6 is a pleiotropic cytokine associated with various diseases, including diabetes and systemic juvenile idiopathic arthritis. IL-6 signatures, partially based on the activity of STAT1 and STAT3, are indicators of prognosis or therapeutic response in patients with autoimmune diseases or cancer. Its role as a target in cancer immunotherapy and autoimmune diseases has attracted widespread attention ^[2-4].

The B6-hIL6 mouse is an Il6 gene humanized model, in which the endogenous Il6 gene sequence in mice is replaced in situ with the human IL6 gene sequence. This model can be used in researching autoimmune diseases, inflammation-related diseases, cancer, and infectious diseases. It is also useful for the development, screening, and evaluation of IL6-targeted drugs.