Fluor

Microbial & Biochemical Technology
Research Article Research Article

Cavallo et al., J Microbial Biochem Technol 2012, 4:2 http://dx.doi.org/10.4172/1948-5948.1000068

Open Access Open Access

MAP Kinases are Required for Apoptosis of HCT-8 Epithelial Cells Induced by the Parasite Giardia intestinalis
Pasqua Cavallo1, Antonia Cianciulli1, Rosa Calvello2, Teresa Dragone1 and MariaAntonietta Panaro1*
1 2

Department of Scienze Mediche di Base, University of Bari, P.zza G. Cesare, 11, I-70124 Bari, Italy Department Farmaco-Biologico, University of Bari, University of Bari, P.zza G. Cesare, 11, I-70124 Bari, Italy

Abstract
Giardia intestinalis is a protozoan that causes a generally self-limited clinical illness typically characterized by diarrhea, abdominal cramps, bloating,weight loss and malabsorption. The pathogenesis of giardiasis is multifactorial and probably different in various animal models, but the mechanisms responsible for the disease are still poorly understood. We previously reported that G. intestinalis is able to induce apoptosis in the human HCT-8 epithelial cell line through the activation of both the intrinsic and extrinsic apoptotic pathways. Inthe present study we demonstrate that activation of the mitogen-activated protein kinases (MAPKs) plays an important role in the regulation of HCT-8 cell apoptosis induced by G. intestinalis. MAPK activation seems to correlate with regulation of the apoptotic process because specific MAPK inhibitors significantly reduced the expression of the active form of caspase-3 in infected cells. Apoptoticchanges were also dramatically inhibited by pre-treatment of the cells with JNK or p38 specific inhibitors, but not ERK 1/2 inhibitor. Taken together, these results suggest a critical role for MAPK activation in G. intestinalis-induced apoptosis in the human HCT-8 cell line.

Keywords: MAPK; Apoptosis; Giardia; HCT-8; Protozoa
Introduction
Giardia intestinalis (also known as G. lamblia and G.duodenalis) is a deeply divergent protist that causes intestinal infection worldwide. Infection can cause a generally self-limited clinical illness (i.e. giardiasis) typically characterized by diarrhea, abdominal cramps, bloating, weight loss and malabsorption, though asymptomatic infection frequently occurs [1-3]. Several reports have associated giardiasis with the development of chronic entericdisorders, allergies and reactive arthritis [4-7]. The parasite exists in two forms: infectious cysts and diseasecausing trophozoites. In the gut lumen, trophozoites differentiate into cysts, which are passed in the host’s feces. Cysts have a filamentous wall that is resistant to harsh environmental conditions, facilitating the spread of giardiasis. For this reason, G. intestinalis poses aconsiderable problem, especially in the developing world where hygiene conditions are inadequate for blocking its transmission by the fecal-oral route. Giardia species are ubiquitously distributed and have been detected in nearly all classes of vertebrates, including domestic animals and wildlife [8]. Recent advances in molecular epidemiology have led to the identification of specialized genetic groups(i.e., assemblages) that are relatively species-specific. Assemblages A and B of G. intestinalis primarily infect humans and primates, assemblages C and D infect dogs, assemblage F infects cats, assemblage E infects hoofstock and assemblage G infects rodents [9]. Although G. intestinalis infects both humans and animals, the role of zoonotic transmission to humans and the importance of animalcontamination of food and water are being re-examined. The pathogenesis of giardiasis is multifactorial and the mechanisms responsible for the disease are poorly understood [10]. We previously reported that G. intestinalis is able to induce apoptosis in the human HCT-8 epithelial cell line. In particular, we observed activation of both the intrinsic and extrinsic apoptotic pathways, down-regulation of...