Niclosamide Modulates the Cellular and Humoral Immune Response in Balb/c Mice

Background: Niclosamide, a STAT3 inhibitor, is widely under investigation due to its anti-cancer properties. STAT3 also exhibits an exciting role in the immune responses. Objective: This study aimed to evaluate the impact of niclosamide on immune response of mice. Methods: Niclosamide was administered to balb/c mice. To evaluate cell-mediated immune response, a contact-hypersensitivity (CHS) test, cyclophosphamide-induced neutropenic assay, and carbon clearance test were performed, whereas a humoral immune response was evaluated by hemagglutination assay (HA) and mice lethality test. The concentration of TGF-β1 was determined by enzyme-linked immunosorbent assay (ELISA) on murine peritoneal macrophages. Results: In the CHS test, niclosamide caused a decrease in skin thickness, significantly exhibiting a decrease in inflammation. A highly significant decrease in overall leukocyte count (lymphocytes and neutrophils) was observed before and after cyclophosphamide injection as compared with the control group. However, only a highly significant decrease in the neutrophil percentage was observed. Niclosamide has decreased the phagocytic process immensely compared with the control. In the HA titer, niclosamide was found to reduce the antibodies' titer compared with the negative control group. In the mice lethality test, the treatment groups have shown an increase in the percentage of mortality. TGF-β1 elevated in peritoneal macrophages when treated with niclosamide, in a dose-dependent manner. Conclusion: Niclosamide exerts potent immunomodulatory effects by significantly suppressing cell-mediated and humoral immune responses and increasing the levels of TGF-β1 in mice. Niclosamide might be added as an adjuvant to immunosuppressive drugs for the treatment of autoimmune diseases.