Interaction of filarial proteins on growth regulation of normal lung epithelial cells in vitro

Antiviral Evaluation of Herbal Drugs

The viral infection and resistance to the existing antiviral drugs are alarming, which is a serious public health concern. Medicinal plants are valuable resources for treatment of viral infections and can be used for the management of infections like herpes simplex virus (HSV), human immunodeficiency virus (HIV), influenza, etc. The antiviral screening of plant extracts should be highly selective, specific, and sensitive for bioactivity guided isolation of the active compounds from the plant extracts. The antiviral screening system should be validated for accuracy, reproducibility, simplicity, and cost effectiveness. This chapter highlights on various aspects for screening and evaluation of antiviral natural components including factors affecting antiviral in vivo studies, host cells, organisms, and culture media followed by different virus-specific assays for antiviral screening of natural products.

Epithelial cells release proinflammatory cytokines and undergo c-Myc-induced apoptosis on exposure to filarial parasitic sheath protein-Bcl2 mediates rescue by activating c-H-Ras

Circulating filarial proteins elicit strong immunologic reactions in humans leading to the chronic manifestations in human lymphatic filariasis such as lymphatic occlusion, fibrosis, edema, and in some cases, tropical pulmonary eosinophilia. Our earlier studies, in vitro, conclusively prove that filarial parasitic sheath proteins induce apoptosis in HEp2 cells, an epithelial cell line, by a pathway inhibitable by bcl2. The present findings provide evidence that c-myc activation triggers apoptosis in HEp2 cells and that it is also responsible for the burst of abortive proliferation at 6 d of treatment of HEp2 bcl2 cells that overexpress bcl2, with filarial parasitic sheath protein, demonstrating the interplay between the two genes c-myc and bcl2, wherein bcl2 acts by restoring the prosurvival signal to c-myc and keeping its apoptotic tendency in check. This study also indicates that bcl2 upregulates c-H-ras, engaging ras to bring about the suppression of apoptosis through protein tyrosine kinase elevation, thus promoting the survival of the HEp2 bcl2 cells. In addition to the activation of these "signal switches," we also observe that these cells release cytokines like IL-6 and IL-8 through the upregulation of c-fos, when exposed to filarial parasitic sheath protein, reflecting on the immunomodulatory capacity of the epithelium to elicit a host immune response by setting up a chemotactic gradient, attracting inflammatory cells to the site of infection.

Extralymphatic disease due to bancroftian filariasis

Infection with Wuchereria bancrofti, Brugia malayi, or B. timori not only affects the structure and function of lymphatic vessels but is also associated with extralymphatic pathology and disease. Because it is now possible to detect living adult worms by ultrasonography, much emphasis is placed on lymphatic pathology. However, the finding of renal damage in asymptomatic microfilaremic carriers has led to increased recognition of the importance of extralymphatic clinical manifestation in bancroftian filariasis. The authors present a number of clinical syndromes that may be manifestations of extralymphatic filarial disease and discuss possible mechanisms that cause these conditions. The main purpose of this paper is to raise the awareness of students and physicians of the prevalence and the importance of extralymphatic disease in bancroftian filariasis so that it is diagnosed and treated properly and also to alert for the need of additional research in this area.

Hepatic tissue culture model for study of host-parasite interactions in alveolar echinococcosis

An in vitro model for growth and differentiation of the metacestode tissue of the tapeworm Echinococcus multilocularis is described. This model simulates the organotropism of the parasite toward the liver of the intermediate host. In the presence of collagen-embedded primary hepatocytes from rats and humans, which can be kept in culture for 2 to 3 months, the parasitic vesicles grew by exogenous budding and multiplied about 12-fold within 3 weeks. In contrast, without the hepatocytes, the metacestodes rapidly degenerated. Development of protoscolices was seen only in the presence of rat hepatocytes but not in coculture of the metacestodes with hepatocytes of human origin, thus reflecting the in vivo situation during infection of rodents and in alveolar echinococcosis in humans. The experiments indicated that growth of the metacestodes and development of protoscolices depended on soluble low-molecular-weight factors released by the hepatocytes. The in vitro-grown metacestodes did not differ morphologically from the larvae found in infected intermediate hosts, and their infectivity was completely maintained. This report describes the first in vitro model of alveolar echinococcosis and will be the basis for future studies on host-parasite interactions of this important zoonosis.