Dry eye （DE） is a prevalent multifactorial disease of the ocular surface， clinically characterized by tear film homeostasis imbalance accompanied by related ocular surface symptoms. Specifically， the tear film is a thin liquid layer of tears covering the cornea and conjunctiva through blinking， while tear film homeostasis serves as the foundation for maintaining normal ocular surface structure and function. Insufficient tear secretion and excessive tear film evaporation lead to tear hyperosmolarity and the production of inflammatory mediators， disrupting tear film homeostasis and subsequently forming DE. Additionally， cascade reactions are triggered， resulting in a "vicious cycle of DE" that exacerbates the disease severity and prolongs its duration. Therefore， for DE treatment， it is crucial to restore tear film homeostasis and terminate this vicious cycle. Traditional Chinese medicine （TCM）， which differentiates and treats DE based on systemic conditions， often achieves favorable therapeutic outcomes， offering additional treatment options for DE. Studies have demonstrated that TCM can alleviate DE by regulating tear film homeostasis and terminating the vicious cycle. This review systematically summarizes recent basic experimental research in China and abroad on TCM in alleviating DE by regulating tear film homeostasis， aiming to provide a theoretical basis for clinical treatment and an insight for research design.

OBJECTIVE: To investigate the expression of citrullinated epitopes in articular cartilage protein and whether its expression is sufficient to induce anti-citrullinated protein antibody (ACPA) response in mice. METHODS: The experimental group was treated with different concentrations of lipopolysaccharide (LPS), heat-inactivated bacteria ( and ) or specific monoclonal antibody against type Ⅱ collagen to induce citrullination of articular cartilage protein, with PBS as the control. Immunohistochemistry with the monoclonal antibody ACC4 (IgG1) that specifically binds to the citrullinated epitope of cartilage protein was performed for detecting the expression of citrullinated protein, with ACC1 (IgG2a) as a positive control antibody and L243 (IgG2a) and Hy2.15 (IgG1) as the negative isotype control. In the in vivo experiment, SD rats were subjected to injection of different doses of LPS in the right knee (with PBS as the controls in the left knee), and 3 days later frozen sections were prepared for immunohistochemical detection of the expression of citrullinated protein. Models of collagen-induced arthritis (CIA) established in different mouse strains were observed for incidence and severity of CIA. Serum samples collected from these models and the sera from rheumatoid arthritis patients were examined for anti-citrullinated protein antibody, and immunohistochemistry was performed to detect the expression of citrullinated protein in the cartilage of the mouse. RESULTS: The citrullinated CII epitope-specific antibody ACC4 did not bind to articular cartilage tissues with different treatments as compared with the positive control antibody ACC1. The ACC4 antibody and the antibodies from patients with rheumatoid arthritis with high titers of anti-citrullinated protein antibody were capable of binding to the synovial tissue around the articular cartilage of the CIA. Luminex analysis showed that the anti-citrullinated protein antibody was lowly expressed in mouse serum, but the anti-type Ⅱ collagen triple helix structure peptide antibody exhibited strong reactivity. CONCLUSIONS Mild acute inflammatory response is not enough to cause citrullination of articular cartilage protein, and the expression of specific epitope requires a high-intensity inflammatory response. Inflammatory articular cartilage protein can express citrullinated epitopes in type Ⅱ collagen-induced arthritis in mice, but the expression of citrullinated epitopes is not sufficient to induce an immune response to anti-citrullinated antibodies. Stronger stimulation signals are required to induce an immune response for producing anti-citrullinated protein antibodies.
Animals ; Arthritis, Experimental ; Autoantibodies ; Cartilage, Articular ; Citrulline ; Humans ; Inflammation ; Mice ; Rats ; Rats, Sprague-Dawley