Nickan Research Institute Immunopathologia Persa 2423-8015 12 2 2026 07 01 The immunomodulatory effect of ivermectin on rat vasculitis model e42741 e42741 10.34172/ipp.2026.42741 EN Teeba Sarem Sadeq https://orcid.org/0009-0003-9307-3005 Nadia H Mohammed https://orcid.org/0000-0001-9234-3198 Inam Sameh Arif https://orcid.org/0000-0002-9194-1919 Journal Article 10.34172/ipp.2026.42741 2024 08 28 2024 11 28 Introduction: Vasculitis is the inflammation of the blood vessel walls and tissues, affecting single organs or multiple systems and is often a hidden factor in numerous disorders. Different pathogens induce innate and adaptive immune system cells to release pro-inflammatory cytokines. These processes lead to the production of proteolytic enzymes, oxidative stress, vascular homeostasis disruption, and destruction of endothelial cells. Objectives: This study aims to investigate the immunomodulatory effects of ivermectin on the rat vasculitis model. Materials and Methods: This experimental animal study included 33 male Wistar albino rats which were divided into five groups. The disease was induced in all groups except group I (control); rats of this group received the dissolving vehicles only. Group II (vasculitis induction group) received ovalbumin and lipopolysaccharide (LPS). Group III, group IV and group V (ivermectin groups) were pretreated with 0.5 mg/kg, 1 mg/kg and 1.5 mg/kg of ivermectin, respectively, for seven days, followed by vasculitis induction using ovalbumin and LPS. Results: This study showed a significant reduction (P<0.001) in serum interleukin-6 (IL-6), C-reactive protein (CRP) and myeloperoxidase (MPO) anti-neutrophil cytoplasmic antibody (ANCA) levels in rats who received ivermectin compared to the disease group. Immunohistochemistry staining of Toll-like receptor 4 (TLR4) showed a decrease in the expression of this receptor in ivermectin groups. Conclusion: Ivermectin modulates inflammatory reactions by inhibiting inflammatory marker expression. Therefore, ivermectin can be effective in protecting against the disease.