The College of Pharmacy discussed the MSc thesis entitled “Evaluation of the Therapeutic Effects of Iraqi Callistemon viminalis Extract on Collagen-Induced Rheumatoid Arthritis in Rats” by the student Luay Mohammed Khudhair and the supervisor, Professor Dr. Shihab Hattab Mutlag, at the Pharmacology and Toxicology Department.
The study aimed to evaluate the anti-inflammatory and anti-arthritic potential of Callistemon viminalis extract in a collagen-induced arthritis rat model. The study also sought to compare its efficacy with methotrexate and to assess its influence on inflammatory biomarkers (TNF-α, IL-1β, IL-6, CRP, and RF) and joint histopathology.
The study included inducing arthritis in 30 male Wistar rats. Among these, 25 rats that successively developed arthritis, the animal models were randomly divided into five experimental groups (n=5 per group). The groups were categorized as follows: a negative control group, an arthritis control group, a methotrexate (MTX)-treated group that received 2.5 mg/kg/week, and two groups treated daily with ethanolic Callistemon viminalis extract at doses of 50 mg/kg/day and 100 mg/kg/day, respectively, for a duration of 28 days. Weekly evaluations were conducted to monitor body weight, paw thickness, and arthritic index. Serum biomarkers including TNF-α, IL-6, IL-1β, C-reactive protein (CRP), and rheumatoid factor (RF) were measured to assess systemic inflammation. NF-κB expression in synovial tissue was quantified using real-time PCR. Furthermore, histopathological analysis of knee joint tissues was performed to assess structural changes.
The results showed that treatment with Callistemon viminalis extract at doses of (50 and 100 mg/kg) significantly reduced paw swelling and arthritis index scores (p<0.05) and stabilized body weight compared to arthritis control rats, indicating reduced systemic inflammation. Furthermore, treated groups showed significantly lower serum levels of TNF-α, IL-1β, IL-6, rheumatoid factor, and C-reactive protein (p<0.05), reflecting potent anti-inflammatory and immunomodulatory properties of the extract. NF-κB expression in synovial tissue was significantly downregulated. Histopathological analysis further supported these outcomes, revealing substantial improvements in joint integrity, characterized by decreased inflammation, reduced synovial hyperplasia, and diminished cartilage damage.
The study recommended further investigation into the therapeutic potential of Callistemon viminalis extract, emphasizing the need to explore the effects of higher doses, assess its long-term safety profile, and elucidate the underlying molecular mechanisms responsible for its anti-inflammatory and immunomodulatory properties. Additionally, the potential synergistic effects of Callistemon viminalis when used in combination with conventional pharmacological agents warrant comprehensive evaluation.
