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Abstract Summary Cryptosporidiosis which is caused by the protozoan parasites of the genus Cryptosporidium is a major health problem for humans and livestock. Cryptosporidium infection can cause severe consequences in immune deficient hosts. No effective drug therapy has been approved till now. Thus, it is increasingly necessary for evaluating new potential drugs against Cryptosporidium in immunocompromised patients. In the present study, the efficacy of miltefosine, a phospholipid drug which has been introduced as antileishmanial effective agent and water extract of Phoenix dactylifera fruits were evaluated in mice infected with Cryptosporidium. The study was conducted on seventy laboratory CD1mice with a weight range of 20-25 gm. The animals were provided by the Schistosome biological supply program (SBSP) at Theodor Bilharz Research Institute (TBRI) and were divided into three main groups. Control group (A) comprising 10 animals (uninfected and untreated) .Group (B) immunocompetent infected group comprising 30 mice which were infected by oral-gastric gavage. Each mouse was inoculated with 200µl of PBS containing 10P 3 Psporulated C. parvum oocysts. Group (C) immunosuppressed Summary 182 infected group comprising 30 mice received (Dexamethasone) drug in a dose of 20 mg/kg/day intramuscularly for 20 days three times per week, then each mouse was inoculated with 200µl of PBS containing 10P 2 P sporulated C. parvum oocysts. Both groups (B and C) were subdivided into three equal infected subgroups. Subgroup (B1) immunocompetent infected while subgroup (B2) infected and treated with miltefosine and subgroup B3 infected and treated with water extract of P. dactylifera fruits. Moreover, subgroup (C1) immunosuppressed infected while subgroup (C2) immunosuppressed infected and treated with miltefosine and subgroup (C3) immunosuppressed infected and treated with water extract of P. dactylifera fruits. Faecal analysis was performed and the number of Cryptosporidium oocysts/gm of faeces was counted for parasitological study ten days and three weeks after treatment. Molecular study and histopathological examination of intestinal, liver sections and spleen were held. Phagocytic index and several serological studies including interferon (IFN)-γ and interleukin (IL)-4, (IL)-10 and (IL) - 17 were assessed in mice serum. Molecular study by nested PCR (targeting COWP gene) was carried out to determine Cryptosporidium genotypes and revealed Cryptosporidium parvum. Summary 183 The percentage of reduction in the number of C. parvum oocysts after 10 days of treatment with miltefosine, in both immunocompetent infected and immunosuppressed infected groups was non -significant (p>0.05). While the percentage of reduction in the number of C. parvum oocysts after ten days of treatment with P. dactylifera was highly statistically significant (p<0.001).The percentage of reduction in the number of C. parvum oocysts after three weeks of treatment with miltefosine and P. dactylifera extract in both immunocompetent and immunosuppressed were highly statistically significant (p<0.001). Several degrees of inflammatory changes were seen in all infected groups. Major histological changes were observed in intestine of immunosuppressed infected group associated with complete, severe villous atrophy changes. Low-grade dysplasia was investigated. Also in this study, the use of Modified Ziehl -Neelsen staining technique in tissue was attempt for the first time. Sections of small intestine, C. parvum oocysts, were visualized in the intestinal glandular epithelium as oval and round shaped. Treated mice with miltefosine showed improvement of the lining epithelium of the intestine, while complete healing of intestinal mucosa was seen after treatment by aqueous extract of P. dactylifera fruits. Summary 184 Liver sections of immunosuppressed infected mice revealed some moderate pathological changes such as inflammatory cellular infiltrations and hepatocytic vacuolations. Treatment by miltefosine and aqueous extract of P. dactylifera fruits revealed remarkable healing of liver tissue. Spleen sections of mice from immunosuppressed infected group revealed disorganization of the splenic tissue including atrophic white pulp and distended red pulp with sheets of megakaryocytes representing the extra medullary hematopoiesis. Three weeks after treatment by miltefosine and aqueous extract of P. dactylifera fruits revealed normal architecture of spleen tissue. By the end of the experiment ultrastructural examination of the small intestine reported remarkable destruction of the intestinal cell projection by C. parvum infection with degeneration of intestinal submucosa. With miltefosine treatment partial healing of the destructed intestinal cell projections was observed. Meanwhile, P. dactylifera treatment showed complete repair of the intestinal cell projections as well as healing of the mucosa and the submucosa. Primary and secondary immune responses were noticed before and after treatment. Three weeks after administration of miltefosine the means of phagocytic cells decreased in infected Summary 185 treated with miltefosine drug while slightly increased in immunosuppressed infected treated with miltefosine. Three weeks treatment with aqueous extract of P. dactylifera fruits significant differences (p < 0.05) were seen between all groups infected and treated. Serum circulating cytokines (IFN-γ, IL-4, IL-10 and IL-17) were increased during the infection and treatment period in mice groups when compared to the control normal group. Only IFN-γ and IL-17 levels increased in infected and immunosuppressed infected groups after treatment with miltefosine. In treated mice by P. dactylifera all cytokines level decreased reaching nearly to control normal mice levels. |