Human intestinal epithelial cells respond to β‐glucans via Dectin‐1 and Syk

Intestinal epithelial cells (IECs) are the first to encounter luminal antigens and may be involved in intestinal immune responses. Fungi are important components of the intestinal microflora. The potential role of fungi, and in particular their cell wall component β‐glucan, in modulating human intestinal epithelial responses is still unclear. Here we examined whether human IECs are capable of recognizing and responding to β‐glucans, and the potential mechanisms of their activation. We show that human IECs freshly isolated from surgical specimens, and the human IEC lines HT‐29 and SW480, express the β‐glucan receptor Dectin‐1. The β‐glucan‐consisting glycans curdlan and zymosan stimulated IL‐8 and CCL2 secretion by IEC lines. This was significantly inhibited by a Dectin‐1 blockade using its soluble antagonist laminarin. Spleen tyrosine kinase (Syk), a signaling mediator of Dectin‐1 activation, is expressed in human IECs. β‐glucans and Candida albicans induced Syk phosphorylation, and Syk inhibition significantly decreased β‐glucan‐induced chemokine secretion from IECs. Thus, IECs may respond to β‐glucans by the secretion of pro‐inflammatory chemokines in a Dectin‐1‐ and Syk‐dependent pathway, via receptors and a signaling pathway described to date only for myeloid cells. These findings highlight the importance of fungi–IEC interactions in intestinal inflammation.     

Mutation cluster region,association between germline and somatic mutations and genotype-phenotype correlation in upper gastrointestinal familial adenomatous polyposis

Studies of adenomatous polyposis coli (APC) mutations in familial adenomatous polyposis (FAP) have focused on large bowel disease. It has been found that: 1) germline APC mutations around codon 1300 are associated with severe colorectal polyposis; 2) somatic APC mutations in colorectal tumors tend to cluster approximately between codons 1250 and 1450; and 3) patients with germline mutations close to codon 1300 tend to acquire somatic mutations (second hits) in their colorectal polyps by allelic loss, whereas the tumors of other FAP patients have truncating second hits. Using new and published data, we have investigated how germline and somatic APC mutations influence the pathogenesis of upper gastrointestinal polyps in FAP. We have compared the results with those from colorectal disease. We found that somatic mutations in upper gastrointestinal polyps cluster approximately between codons 1400 and 1580. Patients with germline APC mutations after codon 1400 tend to show allelic loss in their upper gastrointestinal polyps; the tumors of other patients have truncating somatic mutations after codon 1400. Finally, patients with germline mutations after codon 1400 tend to have more severe duodenal polyposis (odds ratio, 5.72; 95% confidence interval, 1.13 to 28.89; P = 0.035). Thus, in both upper gastrointestinal and colorectal tumors, a specific region of the APC gene is associated with severe disease, clustering of somatic mutations, and loss of the wild-type allele. However, the region concerned is different in upper gastrointestinal and colorectal disease. The data suggest that loss of all APC SAMP repeats is probably necessary for duodenal and gastric tumorigenesis in FAP, as it is in colonic tumors. Compared with colonic tumors, however, retention of a greater number of beta-catenin binding/degradation repeats is optimal for tumorigenesis in upper gastrointestinal FAP.     

Erythropoietin and its antagonist regulate hypoxic fictive breathing in newborn mice

Clinical use of erythropoietin in adult and newborn patients has revealed its involvement in neuroprotection, neurogenesis, and angiogenesis. More recently, we showed in adult mouse, that brain erythropoietin interacts with the major brainstem centers associated with respiration to enhance the ventilatory response to acute and chronic conditions of physiological hypoxia (e.g., as occurring at high altitude). However, whether brain erythropoietin is involved in breathing regulation in newborns remains unknown. In this study, en bloc brainstem-spinal cord preparations were obtained from mice at postnatal day 4. After various periods (30, 60, or 90 min) of incubation with 0, 25, or 250 U of erythropoietin, preparations were superfused with artificial cerebrospinal fluid bubbled with normoxic or hypoxic gas mixtures. The electrophysiological fictive breathing produced by axons at the C4 ventral root was next recorded. Our results show that erythropoietin attenuates the hypoxia-mediated decrease of the central respiratory activity and improves post-hypoxic recovery. Additional analysis revealed that the soluble erythropoietin receptor (the endogenous erythropoietin antagonist) dramatically decreases neural hypoxic respiratory activity, confirming the specific erythropoietin effect on respiratory drive. These results imply that erythropoietin exerts main modulation and maintenance of respiratory motor output during hypoxic and post-hypoxic challenges in 4-days old mice.     

Tumor necrosis factor-α -308 G>A and interleukin-6 -174 G>C promoter polymorphisms and pemphigus

The objective of this study was to analyze the possible involvement of the tumor necrosis factor (TNF)-α -308 G>A and interleukin-6 (IL-6) -174 G>C polymorphisms in the susceptibility and/or disease profile of pemphigus in Egyptian patients. Detection of TNF-α -308 G>A by amplification refractory mutation system and IL-6 -174 G>C by restriction fragment length polymorphism was performed for 70 patients and 203 controls. No significant differences were observed in the distribution of TNF-α -308 in pemphigus patients and controls. However, GA+AA genotypes were more frequent in pemphigus vulgaris (PV) patients only versus controls (p(c) = 0.046). The frequency of the C allele and CC/GC genotypes of IL-6 -174 was significantly higher in pemphigus patients and those with the 2 major clinical forms (PV and pemphigus foliaceus [PF]) compared with controls (p < 0.05). Comparison of the distribution of TNF-α -308 and IL-6 -174 variants in relation to clinical type of pemphigus (PV versus PF), activity score, recurrence, and demographic data of patients revealed no significant associations. The IL-6 -174 CC genotype represents a marker of increased susceptibility to pemphigus in Egyptian patients and GG genotype can be considered a low-risk genotype; TNF-α -308 A-containing genotypes contribute to the susceptibility to PV only.     

Focal and segmental glomerulosclerosis in murine models: a histological and ultrastructural characterization with immunohistochemistry correlation of glomerular CD44 and WT1 expression

Aim: Focal segmental glomerulosclerosis (FSGS) is a common progressive chronic renal disease. Podocyte injury and loss are the postulated pivotal events that trigger FSGS. In this study, the authors aim to examine the evolution of FSGS in murine models histologically, ultrastructurally and immunohistochemically with special emphasis on podocytes and parietal epithelial cells (PECs). Material and methods: FSGS resembling primary FSGS in humans was initiated in Wistar rats using intravenous Adriamycin injections. Blood and urine analysis were performed at 0, 8, and 12 weeks. Both the control kidneys and the test kidneys were harvested at 8 and 12 weeks, examined histologically and ultrastructurally and the findings correlated with the glomerular expression of immunostains specific for podocytes (WT-1) and for activated PECs (CD44). Results: FSGS developed in both 8 and 12 weeks test groups showing progressive proteinuria, podocytopathy and segmental glomerular scarring. There was a decrease in the glomerular expression of WT-1 with a concurrent increase in the glomerular expression of CD44, indicating podocyte loss with synchronous increase in activated PECs. The evolving FSGS correlated negatively with podocytes and positively with activated PECs. Conclusion: Our study shows that with podocyte injury there is podocyte effacement and loss, proteinuria, glomerular segmental adhesion and scarring, all culminating in FSGS. In addition, there is activation, hyperplasia and hypertrophy of PECs. This demonstrates that both podocyte loss and PEC activation promote FSGS. Our findings are consistent with recent investigations. More studies are required to further understand the role of these cells in the evolution of FSGS and subsequently introduce new targeted treatment modalities.     

Gastroesophageal reflux in mechanically ventilated pediatric patients and its relation to ventilator-associated pneumonia

Introduction  

The objective was to determine the frequency of gastroesophageal reflux (GER) in mechanically ventilated pediatric patients and its role as a risk factor for ventilator-associated pneumonia (VAP), which may be enhanced among those patients.     

Inflammatory bowel disease in the pregnant woman

This article discusses fertility and inflammatory bowel disease, the influence of inflammatory bowel disease on pregnancy, the influence of pregnancy on inflammatory bowel disease, the safety of breast-feeding while taking medication for active disease, and abdominal pain in the pregnant woman with inflammatory bowel disease.