Immunopathological effect of Cryptococcus adeliensis in treated rats with chitosan nanoparticles and antibiotics

This study aimed to investigate the effect of immune stimulation by sonicated fungal antigens of Cryptococcus adeliensis using chitosan nanoparticles in rats treated with high doses of antibiotics. For this purpose, sixty rats of both sexes were divided randomly into six groups (10 animals, both males and females, in each group), as following: (G1) immunized with 0.5ml whole sonicated fungal Ag (0.83mg/ml protein concentration) /SC, 2 dose / 2 weeks interval. 2nd group (G2) immunized with 0.5ml whole fungal Ag as G1 and treated daily with high doses of antibiotic for six weeks (gentamicin 0.5mg/mL). 3rd group (G3) immunized I\P, with whole fungal Ag mixed with chitosan nanoparticles (1:1) 0.5 ml, 2 dose / 2 weeks intervals and treated with antibiotic as 2nd group, and (G4) was served as control positive group and (G5) was treated with antibiotic as 2nd group, and sixth group (G6) was served as negative control inoculated with normal saline 0.3ml. At 27 and 30 days post-immunization, skin test was done in 1st, 2nd, 3rd, and 5th groups and blood samples were collected to measure the serum level of antibody titers, after those animals of G1, G2, G3, G4, and G5 were inoculated SC, with 0.3ml, containing 1x108 of the fungal cell, and the sixth group was injected with 0.3ml normal saline I/P. At 4 weeks post-infection. All animals were sacrificed and pieces of tissues were removed from the liver, lung, kidney, and brain for histopathological examination. The result revealed a high mean of skin thickness and high serum antibody titers in immunized animals but in 2nd group, the antibiotic treatment led to depressing values of skin test (ns) and serum of antibody titers (ns). Chitosan nanoparticles can improve values of skin test (***) and serum of antibody titers (***) in the 3rd group. The histopathological result showed severe pathological lesions in examined organs of the positive control group and severe lesions in these organs in animals treated with antibiotics post-infection. In addition, the current result showed mild to moderate lesions in examined organs of immunized animals with moderate lesions in immunized animal’s treatment with antibiotics post-infection. The immunized animals with mixed fungal antigens and chitosan nanoparticles and treatment with antibiotics express mild to no clear lesions in examined organs post-infection. As a conclusion, the prolonged high doses of antibiotics lead to depressing immune response in immunized animal,s while immunized animals with fungal antigens mixed with chitosan nanoparticles can improve the immune response.