Induction Of Apoptosis In Epithelial Cells Research Articles

Analysis of the Amino Acid Sequence Variation of the 67-72p Protein and the Structural Pili Proteins of Corynebacterium diphtheriae for their Suitability as Potential Vaccine Antigens.

The aim of this study was to identify the potential vaccine antigens in Corynebacterium diphtheriae strains by in silico analysis of the amino acid variation in the 67–72p surface protein that is involved in the colonization and induction of epithelial cell apoptosis in the early stages of infection. The analysis of pili structural proteins involved in bacterial adherence to host cells and related to various types of infections was also performed. A polymerase chain reaction (PCR) was carried out to amplify the genes encoding the 67–72p protein and three pili structural proteins (SpaC, SpaI, SapD) and the products obtained were sequenced. The nucleotide sequences of the particular genes were translated into amino acid sequences, which were then matched among all the tested strains using bioinformatics tools. In the last step, the affinity of the tested proteins to major histocompatibility complex (MHC) classes I and II, and linear B-cell epitopes was analyzed. The variations in the nucleotide sequence of the 67–72p protein and pili structural proteins among C. diphtheriae strains isolated from various infections were noted. A transposition of the insertion sequence within the gene encoding the SpaC pili structural proteins was also detected. In addition, the bioinformatics analyses enabled the identification of epitopes for B-cells and T-cells in the conserved regions of the proteins, thus, demonstrating that these proteins could be used as antigens in the potential vaccine development. The results identified the most conserved regions in all tested proteins that are exposed on the surface of C. diphtheriae cells.

Monocyte and M1 Macrophage-induced Barrier Defect Contributes to Chronic Intestinal Inflammation in IBD.

Macrophages are key players in inflammatory bowel diseases (IBD). This study aimed to determine site-specific effects of defined macrophage subtypes on the integrity of the intestinal epithelial barrier. Macrophage subtypes in situ in intestinal specimens of patients with IBD were visualized by immunohistochemistry. In vitro polarization of human peripheral CD14 cells yielded M1 or M2 macrophages. The influence of primary monocytes or macrophage subtypes on epithelial barrier integrity was analyzed by transepithelial resistance measurements, Western blot analysis, confocal laser scanning microscopy, and cytometric bead array in a coculture model of primary human macrophages and layers of intestinal epithelial cell lines. The lamina propria of the inflamed intestine in patients with IBD, predominantly in Crohn's disease, is massively infiltrated by CD68 cells also positive for inducible nitric oxide synthase and tumor necrosis factor (TNF) α. The presence of M1 macrophage shifted the balance in the local macrophage compartment towards a proinflammatory state. In the coculture model, monocytes and M1 macrophages reduced transepithelial resistance as a marker for epithelial barrier integrity. The mechanisms for paracellular leakage included intracellular relocalization of tight junction proteins like claudin-2 and epithelial cell apoptosis. Determined by specific cytokine blockade, M1 macrophages exerted their deleterious effect mainly through TNF-α, whereas monocyte-mediated damage was driven by the inflammasome effector cytokines, interleukin-1β and interleukin-18. Lamina propria monocytes and M1 macrophages invading intestinal tissues directly contribute to disrupting the epithelial barrier through deregulation of tight junction proteins and induction of epithelial cell apoptosis, thus driving intestinal inflammation in IBD.

Caspases-3, -8, and -9 are required for induction of epithelial cell apoptosis by enteropathogenic E. coli but are dispensable for increased paracellular permeability

Enteropathogenic Escherichia coli (EPEC) is an important cause of diarrhea, particularly among infants in developing countries. An increase in intestinal permeability due to EPEC infection has been suggested as a factor in the development of diarrhea. Abnormally high levels of programmed cell death (apoptosis) of intestinal epithelial cells can lead to increased intestinal permeability. The effects of EPEC on cell apoptosis remain incompletely understood. This study characterized the mechanisms of EPEC-induced epithelial apoptosis and examined whether this effect contributes to heightened permeability in an in vitro model of infection. We report that EPEC-induced apoptosis in T84 intestinal epithelial cells via a mechanism involving caspases-3, -6, -8, and -9, the cleavage of PARP, and oligonucleosome formation. In addition, EPEC time-dependently increased paracellular permeability as assessed by transepithelial resistance and the apical-to-basolateral movement of 3000 MW dextran. Furthermore, EPEC infection led to the cleavage and mislocalization of tight junctional ZO-1 and occludin. However, pharmacological inhibition of caspases did not prevent the EPEC-induced disruptions in epithelial barrier structure and function. Taken together, these results suggest that a caspase-dependent upregulation in epithelial cell apoptosis during EPEC infection occurs independent of impaired intestinal barrier function.

Major histocompatibility complex and alveolar epithelial apoptosis in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic disease characterized by fibroblast expansion, and tissue remodeling. It is considered a multifactorial disease but the possible involved genes are largely unknown. Interestingly, studies regarding the possible role of major histocompatibility complex (MHC) are scanty and show contradictory results. In this study, we evaluated the polymorphisms of the MHC, locus HLA-B, -DRB1, and -DQB1 in a cohort of 75 IPF patients and 95 controls by using PCR and hybridization with sequence-specific oligonucleotide probes. In addition, we examined the effect of bronchoalveolar lavage (BAL) from IPF patients with different MHC haplotypes on alveolar epithelial growth rate by WST-1 cell viability assay and on epithelial apoptosis by flow cytometry and by cleaved caspase-3 in cell homogenates. Three haplotypes were significantly increased in IPF: (1) HLA-B*15-DRB1*0101-DQB1*0501 (OR=10.72, CI=1.43-459.6; pC=0.011); (2) HLA-B*52-DRB1*1402-DQB1*0301 (OR=4.42, CI=1.21-24.1; pC=0.024); and (3) HLA-B*35-DRB1*0407-DQB1*0302 (OR=4.73, CI=1.53-19.5; pC=0.005). BAL from patients with the later haplotype significantly reduced epithelial growth rate ( approximately 30%) and caused epithelial cell apoptosis assayed by cleaved caspase-3 (351.7+/-16.5 pg/10(6) cells versus 264+/-24 from controls, and 274+/-36.8 and 256.5+/-10.7 from the other haplotypes; P<0.05), and DNA breaks labeling by flow cytometry (23.7+/-6.9% versus 3.1+/-0.7% from controls, and 6.5+/-0.6% and 7.6+/-1.2% from the other two haplotypes; P<0.01). These findings suggest that some MHC polymorphisms confer susceptibility to IPF, which might be related with the induction of epithelial cell apoptosis, a critical process in the development of the disease.

Viruses contribute to the development of Sjögren's syndrome

Viruses contribute to the development of Sjögren's syndrome

Induction of Epithelial Cell Apoptosis in the Uterus by a Mouse Uterine Ischemia-Reperfusion Model: Possible Involvement of Tumor Necrosis Factor-α

Menstruation in primates is preceded by a period of intense vasoconstriction, with resultant ischemia-reperfusion. Although apoptosis is involved in endometrial breakdown, the relationship between ischemia-reperfusion and apoptosis in the female genital tract has not been determined. To investigate the relationship between ischemia-reperfusion and apoptosis in the uterus, we analyzed a uterine ischemia-reperfusion model using BDF1 and C57BL/6 mice. Ischemia was induced by clamping the uterine horn and uterine artery for 5 to 30 min, followed by 6, 12, 24, or 48 h of reperfusion (n = 4 for each group). The number of TUNEL-positive endometrial cells increased with the duration of ischemia and reached a maximum at 24 h of reperfusion, but then tended to decrease at 48 h. Transmission electron micrographs of endometrial cells revealed a typical nuclear condensation, confirming the occurrence of apoptosis. The mRNA expression level of the proinflammatory cytokine tumor necrosis factor-alpha (TNFalpha) in the uterus increased after reperfusion. Ischemia-reperfusion-induced endometrial apoptosis was markedly decreased in TNF-R p55-deficient mice, confirming the essential role of TNFalpha in the induction of apoptosis by ischemia-reperfusion (n = 4). Our results suggest that ischemia-reperfusion and subsequent TNFalpha expression may be critical factors in inducing endometrial cell apoptosis. Our mouse model could be suitable for investigating ischemia-related uterine injury in humans, particularly in menstruation.

T-cell–induced mucosal damage in the intestine

T cells are central to most inflammatory disorders of the intestine, particularly Celiac disease, graft vs. host disease, Crohn disease, and ulcerative colitis. The mechanisms by which T cells contribute to mucosal damage in these disorders have been explored using both in vitro and in vivo models. This review will highlight recent studies directed at understanding the mechanisms by which T cells are involved in the induction of mucosal damage. The recent studies of in vivo T-cell activation using monoclonal anti-CD3 antibody have shown that a number of cytotoxic T-cell pathways are required and involved in the induction of mucosal damage and in particular in the induction of epithelial cell apoptosis. These include the Fas/FasL and perforin pathways. Other mediators of T-cell-induced cytotoxicity, such as TNFalpha and IFNgamma may contribute to mucosal damage but are not required for the induction of mucosal damage in vivo. In addition, several studies have tried to identify the role of regulatory mucosal T cells and the physiologically relevant triggers for T-cell-induced mucosal damage. It is now clear that there are significant redundancies in the mechanisms that lead to immune-mediated mucosal damage and that the mechanisms that operate in vivo may not be predicted by in vitro experiments. These investigations are improving our understanding of the pathogenesis of immune-mediated enteropathies and will hopefully lead to new approaches to the management of these disorders.