Search

Placental malaria is a common clinical complication during pregnancy and is associated with abortion, premature delivery, intrauterine growth retardation and low birth weight. The present study was designed to delineate the underlying mechanism of placental pathology during malarial infection with special reference to oxidative stress and apoptosis. Experimentally, pregnant BALB/c mice were infected with Plasmodium berghei infected red blood cells on gestation day 10. The presence of malarial infection in placenta was confirmed by histopathological studies. It was observation that infected placenta had plugged placental sinusoids with parasitized red blood cells and malarial pigments. Interestingly, we found significant increase in the level of malondialdehyde, the index of oxidative stress and decreased activity of catalase, the antioxidant in infected placenta. Furthermore, in infected placenta the oxidative stress mediated apoptosis was determined by DNA fragmentation assay, ethidium bromide/acridine orange staining and caspase activity. It was observed that oxidative stress begin after second day of malarial infection. Interestingly, it was observed that there was down regulation of anti-apoptotic protein Bcl-2 and up regulation of pro-apoptotic protein Bax in infected placenta, suggesting the involvement of mitochondrial pathway of apoptosis which was further confirmed by activation of caspase 9. However, no change in the expression of Fas gene and caspase 8 activity, indicated the absence of death receptor pathway. Thus, it can be concluded that the placental pathology during malarial infection is mediated by mitochondrial pathway of apoptosis occurring due to augmented lipid peroxidation which may in turn jeopardise the materno-fetal relationship. [ABSTRACT FROM AUTHOR]

Background: Amoebiasis is a major public health problem in tropical and subtropical countries. Currently, metronidazole is the gold choice medication for the treatment of this disease. However, reports have indicated towards the possibility of development of metronidazole-resistance in Entamoeba strains in near future. In view of the emergence of this possibility, in addition to the associated side effects and mutagenic ability of the currently available anti-amoebic drugs, there is a need to explore newer therapeutics against this disease. In this context, the present study evaluated the amoebicidal potential of cryptdin-2 against E. histolytica. Methods/Principal Findings: In the present study, cryptdin-2 exhibited potent in-vitro amoebicidal activity against E. histolytica in a concentration dependent manner at a minimum amoebicidal concentration (MAC) of 4 mg/L. Scanning electron microscopy as well as phase contrast microscopic investigations of cryptdin-2 treated trophozoites revealed that the peptide was able to induce significant morphological alterations in terms of membrane wrinkling, leakage of the cytoplasmic contents and damaged plasma membrane suggesting a possible membrane dependent amoebicidal activity. N-phenyl napthylamine (NPN) uptake assay in presence of sulethal, lethal as well as twice the lethal concentrations further confirmed the membrane-dependent mode of action of cryptdin-2 and suggested that the peptide could permeabilize the plasma membrane of E. histolytica. It was also found that cryptdin-2 interfered with DNA, RNA as well as protein synthesis of E. histolytica exerting the highest effect against DNA synthesis. Thus, the macromolecular synthesis studies correlated well with the observations of membrane permeabilization studies. Significance/Conclusions: The amoebicidal efficacy of cryptdin-2 suggests that it may be exploited as a promising option to combat amoebiasis or, at least, may act as an adjunct to metronidazole and/or other available anti-amoebic drugs. Author Summary: Intestinal amoebiasis, caused by Enatmoeba histolytica continues to be a major public health problem in tropical and subtropical countries and is considered to be the third principal parasitic disease responsible for mortality in the world. In addition to the mutagenic ability and known toxicity of conventional anti-amoebic drugs, there are reports indicating the emergence of treatment failures to these drugs. Therefore, there has been a considerable interest in exploring the potential of various antimicrobial peptides having higher efficacy and lower toxicity to combat such parasitic infections. Herein, we present the amoebicidal efficacy of cryptdin-2, a Paneth cell alpha-defensin against E. histolytica. Cryptdin-2 was found to decrease the number of trophozoites of E. histolytica in a concentration dependent manner. By and large, cryptdin-2 could retain its amoebicidal activity in the presence of cations, bile salts and at various pH values. Microscopic analysis and N-phenyl napthylamine (NPN) uptake assay revealed membrane dependent amoebicidal action of the peptide. It was also demonstrated that cryptdin-2 has the potential to target the intracellular macromolecular synthesis machinery of Entamoeba. Based on these results, cryptdin-2 seems to be a promising agent for the development of novel therapeutics against amoebiasis or at least may act as an adjunct to conventional antibiotics against E. histolytica. [ABSTRACT FROM AUTHOR]