Nano-Encapsulated Antioxidant: Retinoic Acid as a Natural Mucosal Adjuvant for Intranasal Immunization against Chronic Experimental Toxoplasmosis.

The tight relationship between immunity and retinoid levels provides evidence on the critical role of retinoic acid (RA) in regulating immune activity, especially the mucosal one. Mucosal immune response is the key for determination of the outcome of infection, particularly against intracellular mucosal pathogens such as Toxoplasma gondii, where it plays a crucial role as a sentinel against parasite invasion. Herein, the immunomodulatory adjuvant role of RA was evaluated for prophylactic vaccination against chronic Toxoplasma infection. A quantity of 15 µg of RA pre-encapsulated with lipid-based nanoparticles (SLNs) was intranasally used in three doses, two weeks apart, as an adjuvant to the Toxoplasma lysate antigen (TLA). Afterward, mice were infected with 20 cysts of T. gondii (ME49 strain) and were sacrificed at the 4th week post-infection. Parasitological, immunological, biochemical, and histopathological studies were applied as vaccine efficacy measures. The protective role of the tested vaccine was noted using the statistically marked reduction in brain cyst count, accompanied by remarkable levels of protective IFN-γ and antibodies, with amelioration of infection-induced oxidative stress and brain pathology. Ultimately, this experiment outlined the prospective role of a novel, natural, nano-encapsulated and mucosal vaccine adjuvant RA-SLNs as a propitious candidate against chronic toxoplasmosis.

Nano-Encapsulated Melatonin: A Promising Mucosal Adjuvant in Intranasal Immunization against Chronic Experimental T. gondii Infection.

Melatonin (MLT) is now emerging as one of the universally accepted immunostimulators with broad applications in medicine. It is a biological manipulator of the immune system, including mucosal ones. MLT was encapsulated in solid lipid nanoparticles (SLNs), then 100 mg/kg/dose of MLT-SLNs was used as an adjuvant of Toxoplasma lysate antigen (TLA). Experimental mice were intra-nasally inoculated with three doses of different regimens every two weeks, then challenged with 20 cysts of T. gondii Me49 strain, where they were sacrificed four weeks post-infection. Protective vaccine efficacy was evident via the significant brain cyst count reduction of 58.6%, together with remarkably high levels of humoral systemic and mucosal anti-Toxoplasma antibodies (Ig G, Ig A), supported by a reduced tachyzoites invasion of Vero cells in vitro upon incubation with sera obtained from these vaccinated mice. A cellular immune response was evident through the induction of significant levels of interferon-gamma (IFN γ), associated with morphological deteriorations of cysts harvested from the brains of vaccinated mice. Furthermore, the amelioration of infection-induced oxidative stress (OS) and histopathological changes were evident in mice immunized with TLA/MLT-SLNs. In conclusion, the present study highlighted the promising role of intranasal MLT-SLNs as a novel mucosal adjuvant candidate against chronic toxoplasmosis.

The efficacy of antihelminthic compound; Clorsulon against experimental Schistosoma mansoni infection.

The efficacy of Clorsulon (CLS) against experimental schistosomiasis mansoni, using Praziquantel (PZQ) as a therapeutic control was evaluated. Swiss Albino mice were divided into infected non-treated control, PZQ-treated group given a single dose of 500 mg/kg four weeks post infection (PI), and infected mice treated with single, double, and triple doses of 5 mg/kg CLS per dose, one week apart starting from the 4th week PI. All animals were perfused for adults count. Parts of livers and intestines were examined for granulomata number and sizes. Pathological changes in hepatic parenchyma by H&E and Masson trichrome stains were also examined. Results revealed that a single treatment with PZQ caused a significant percentage reduction (%R) of worm load (92.68%), mean egg count in liver and intestine (91.20 & 94.01% respectively), and mean size of liver granulomata was reduced (92.06%). Regarding CLS, the worm burden was reduced proportionally with number of doses given; 87.80, 96.34 & 97.56% in single, double and triple exposures successively. Egg count in liver was decreased by 85.90, 97.01 & 96.23% respectively in treated mice. Number of intestinal granulomata was decreased by 85.28, 94.24 & 95.49% in a similar way. Size of hepatic granulomata was decreased by 89.02, 94.51 & 95.05% by 1, 2 & 3 doses consecutively. All parameters reflected non significant difference between 2 & 3 dose of CLS. The results were critically discussed.

Influence of the antioxidant drug (Antox) on experimental giardiasis and microsporidiosis.

The effect of antioxidant (Antox) on Giardia lamblia and Microsporidium sp. in rats and mice respectively was studied. Parasitologic effect was assessed by the mean parasitic count in infected animals' stool treated and non-treated, and infection intensity in stained section. Biochemical by measuring activities of lactate dehydrogenase (LDH), superoxide dismutase (SOD), malondialdehyde (MDA), myeloperoxidase (MPO) levels and cytokine induced neutrophil chemoattractant-1 (CINC-1) in intestinal homogenates in these animals as shown by cell injury, lipid peroxidation and neutrophil infiltrations. The present results showed that Antox significantly exacerbated G. lamblia and Microsporidium sp. This was manifested by a significant increase in number of G. lamblia cysts and trophozoites in stool and intestinal sections of treated infected rats. Also, microsporidian spores were significantly higher in stool of treated infected mice and infection intensity increased in the intestinal sections. The biochemical study showed a significantly higher degree of cell injury, lipid peroxidation and intestinal neutrophils accumulation in non-treated infected animals whether with G. lamblia or microsporidia. The changes reduced after treatment in giardiasis but none in microsporidiosis. The results were tabulated photographed, and critically discussed.

Effect of Schistosoma mansoni infection on physiological gastrointestinal transit and contractility.

The work aimed to study the effect of Schistosoma mansoni (S. mansoni) on gastrointestinal transit and contractility of the colonic muscles of two subgroups of experimental mice, infected by 50 & 200 cercaria/mouse respevtively, at 8th & 12th week postinfection (PI). In addition, the histopathologic changes in the colon, and the immunological changes of the host were studied at different durations. At 8th weeks PI, in both subgroups, gastrointestinal transit was statistically significant decreased, in concurrent with statistically significant increase in the colonic muscle contractility compared to the controls. The colon was inflamed as shown by mucosal inflammatory infiltrates, with large size and number of schistosomal granulomas. The serum antigen was absent, while the serum antibody was detectable at low titre. At 12th weeks PI, there was a more statistically significant decrease in gastro-intestinal transit, and increase in the colonic muscle contractility. The colon was still inflamed, but the granulomas were reduced in size and in number, with increase in the fibrocytes density. These alterations coincided with absence of serum antigen and increase in the antibody titre. All changes were more pronounced in the 2nd group of mice (200 ceraria/mouse) than the 1st one (50 cercaria/mouse). So, intestinal schistosomiasis is associated with great structural, functional and immunological changes, related to the time course and the infection intensity which may be involved in the pathogenesis and clinical manifestations of the disease.

The adjuvant effects of IL-12 and BCG on autoclaved Leishmania major vaccine in experimental cutaneous leishmaniasis.

Cutaneous leishmaniasis is a universal disease causing skin ulceration and deformity. A reliable vaccine remains to be a possible practical means of control. The amastigotes multiply intracellulary in macrophages provoking a cell-mediated type of immune response. IL-12 is the central cytokine of CMI. It is produced by sensitized macrophages, stimulates both Th1 and NK cells to secrete IFN-gamma which in turn activates the intracellular killing of Leishmania in macrophages via increased oxygen radicals. This work aimed mainly at studying the adjuvant effect of IL-12 on autoclaved L. major (ALM) vaccine, compared to that of BCG in L. major infection. The material included five groups of Swiss albino mice; the test group infected after receiving ALM+IL-12, a non-infected control group, and three other control groups infected after receiving ALM+BCG, IL-12 alone and BCG alone L. major was cultured to provide promastigotes for vaccine and infection. The measured parameters included the lesion size, type and progress; the parasite density and the level of IFN-gamma in serum. The results showed that the best protection against challenge infection was obtained by ALM + IL-12 followed by ALM + BCG. The former is recommended for use as a vaccine with regards to its proved efficacy and known safety.

Influence of photon beam irradiation on Lymnaea natalensis snails infected with Fasciola gigantica.

Lymnaea natalensis is the intermediate host of Fasciola gigantica in Egypt. The effect of photon beam irradiation on the ability of the laboratory reared L. natalensis to support the larval development of F. gigantica has been studied. 120 snails were divided into two groups: The control infected non irradiated group (GI) and the experimental infected irradiated group (GII). The later group was subdivided into two subgroups: GIIa: snails irradiated before infection and GIIb: snails irradiated after infection. Photon beam irradiation had non significant effect on the survival rate between the all groups at the 30th day post infection. The life span, the number of infected snails and the length of the shedding period were significantly decreased in the two irradiated subgroups than the control group. The effect was more obvious on GIIb without significant difference. The number of metacercariae significantly decreased in the 2 irradiated subgroups than the control one. Also, it was significantly decreased in GIIb when compared with GIIa. So, photon beam irradiation has a great role on retarding larval development of F. gigantica inside the snail. This opens the way to a new strategy for fascioliasis control of in Egypt.

The utility of lactoferrin in differentiating parasitic from bacterial infections.

Lactoferrin is an iron binding glycoprotein found in the 2ry granules of PMN. In order to determine the usefulness of such marker for neutrophilic activity in differentiating cases suffering from amoebic and bacillary dysentery, Schistosoma and bacterial UTI infections, we examined stool and urine specimens using anti-lactoferrin antibodies (lactoferrin latex agglutination test: LFLA), compared with different standard gold techniques. Our results demonstrated that cases with either shigllosis or UTI revealed a high lactoferrin titer which was positively correllated with the number of PMN. In addition cases with Entamoeba histolytica or S. haematobium were characterized by relatively lower inflammatory process as expressed by mild lactoferrin titer which was also correlated with the PMN count. In addition, the findings of the present work indicated that LFLA was sensitive and specific when used alone and its sensitivity was augmented after coupling with other simple indirect methods of diagnosis. In conclusion, results described the reliability of using LFLA as a simple, rapid, sensitive method in differentiating, certain parasitic from bacterial diseases.

Congenital trichinellosis in experimentally infected mice.

The present study aimed at allocating the time during pregnancy at which transplacental transmission of Trichinella spiralis (T. spiralis) larvae took place. Swiss albino mice were infected at different durations of pregnancy; five days before mating, on gestation day zero and five days after mating. Furthermore, to study the effect of immunosuppression on transplacental transmission, half of the experimental mice were immunosuppressed using cyclophosphamide drug (Endoxan). The percentage of infected uteri, embryos and placentas and the mean larval count were calculated on day 8 post infection (PI). Moreover, the percentage of infected offspring and the mean larval count in their muscles were estimated on day 30 PI. The results of the present study revealed that, transplacental transmission of T. spiralis could occur in offspring of mice when their mothers are infected before or after pregnancy. This was documented by the presence of larvae in the muscles of offspring. However, the rate of this transmission increased when the mothers are infected at late pregnancy whether they were immunosuppressed or not. The administration of the immunosuppressive drug whether before or after pregnancy increased the rate of infection and the mean larval count in both uteri of mothers and muscles of their offspring. A higher percentage of abortion was demonstrated in females infected before mating in different studied groups.