Experimental in vivo assessment of immunomodulatory effect of Kalobin (Pelargonium reinforme/sidoides extract) on schistosomiasis mansoni

Background: Schistosomiasis is a major tropical disease with significant morbidity and mortality in several developing countries. Hence, searching for a new immunomodulating supportive aid for the sole drug of choice, praziquantel (PZQ), is an important target. Objective: The aim of the present work is to assess the immunomodulatory effect of Kalobin (Pelargonium reinforme/sidoides extract) on schistosomiasis mansoni in vivo. Material and Methods: Swiss albino mice were infected with S. mansoni cercariae and were divided into two major categories, immunocompetent (IC) and immunosuppressed (IS). Immunosuppression was performed 14 successive days prior to infection. Kalobin and PZQ, either individually or combined, were given orally seven weeks post infection (wpi). Only in IC mice, both drugs were given in a combination of 100 mg/kg seven wpi for five consecutive days as a preliminary trial. Other groups were treated with PZQ (IC2, 50 mg/kg and IC1, 200 mg/kg) or Kalobin (IC3, 200 mg/kg) or combined PZQ-Kalobin treatment (IC4, 50 mg/kg each) for five consecutive days. This regimen was administered to both IC and IS subgroups and compared to the negative uninfected non-treated control subgroup and the two corresponding positive infected non-treated control CIC and CIS subgroups. All mice were sacrificed 9 wpi for assessment of parasitological parameters including total worm burden (TWB), tissue egg load, oogram pattern, and measurement of hepatic granuloma number and size. Immunohistochemical procedure was employed to assess the expression of vascular endothelial growth factor (VEGF) in both hepatocytes and sinusoids. Results: Therapy with combined treatment (IC5, 100 mg/Kg each) proved to be superior to the sole PZQ treatment (IC1, 200 mg/kg and IC2, 50 mg/kg) as shown by its effect on TWB and oogram pattern and greater reduction in intestinal and hepatic egg counts in IS groups. Combined PZQ-Kalobin therapy (IC4, 50 mg/kg each) approached the higher individual PZQ dose (IC1, 200 mg/kg) in reducing the granuloma number. The highest reduction in the expression of VEGF in hepatocytes and sinusoids was recorded in the combined PZQ-Kalobin (IC4 and IS4, 50 mg/kg each) followed by subgroup IC3 (Kalobin 200 mg/kg) then IC1 (PZQ 200 mg/kg). Moreover, as regards the IS subgroups; IS4, PZQ-Kalobin 50 mg/kg combination and IS3, Kalobin 200 mg/kg showed better results than all IC subgroups. Individual Kalobin in (IS3) subgroup showed better response than in IC3 subgroup using the same dose of 200 mg/kg. Conclusion: Our study highlighted the immunopotentiating outcome for Kalobin whether in combination with PZQ or individually on schistosomiasis mansoni in vivo.