Intestinal current measurement for diagnostic classification of patients with questionable cystic fibrosis: validation and reference data

In questionable cystic fibrosis (CF), mild or monosymptomatic phenotypes frequently cause diagnostic difficulties despite detailed algorithms. CF transmembrane conductance regulator (CFTR)-mediated ion transport can be studied ex vivo in rectal biopsies by intestinal current measurement (ICM).

CX3CR1 defines functionally distinct intestinal mononuclear phagocyte subsets which maintain their respective functions during homeostatic and inflammatory conditions

Intestinal mononuclear phagocytes (iMNP) are critically involved in mucosal immunity and tissue homeostasis. Two major non-overlapping populations of iMNP have been identified in mice. CD103(+) iMNP represent a migratory population capable of inducing tolerogenic responses, whereas CX3CR1(+) iMNP are resident cells with disease-promoting potential. CX3CR1(+) iMNP can further be subdivided based on differential expression of CX3CR1. Using CX3CR1(GFP/+) ×RAG2(-/-) mice, we demonstrate that CX3CR1(hi) and CX3CR1(lo) iMNP clearly differ with respect to their morphological and functional properties. Compared with CX3CR1(hi) iMNP, CX3CR1(lo) iMNP are polarised towards pro-inflammatory responses already under homeostatic conditions. During a CD4(+) T-cell-induced colitis, CX3CR1(lo) cells accumulate in the inflamed mucosa and upregulate the expression of pro-inflammatory cytokines and triggering receptor expressed on myeloid cells-1 (TREM-1). In contrast, CX3CR1(hi) iMNP retain their non-inflammatory profile even during intestinal inflammation. These findings identify two functionally distinct iMNP subsets based on differential expression of CX3CR1 and indicate an unanticipated stability of iMNP.

Serotonin-producing enterochromaffin cell tumors of the pancreas: clinicopathologic study of 15 cases and comparison with intestinal enterochromaffin cell tumors

Serotonin-producing tumors of the pancreas are rare endocrine neoplasms composed of enterochromaffin (EC) cells that have been mainly described in the literature as case reports. This study analyzes the clinicopathologic features of a series of pancreatic EC cell neoplasms and their similarities to and differences from intestinal EC cell tumors.

Hypotension during fluid-restricted abdominal surgery: effects of norepinephrine treatment on regional and microcirculatory blood flow in the intestinal tract

Vasopressors, such as norepinephrine, are frequently used to treat perioperative hypotension. Increasing perfusion pressure with norepinephrine may increase blood flow in regions at risk. However, the resulting vasoconstriction could deteriorate microcirculatory blood flow in the intestinal tract and kidneys. This animal study was designed to investigate the effects of treating perioperative hypotension with norepinephrine during laparotomy with low fluid volume replacement.

The continuum of intestinal CD4+ T cell adaptations in host-microbial mutualism

How a mutualistic relationship between the intestinal microbiota and intestinal T cell compartments is established is important, as a breakdown of intestinal T cell homeostasis may cause inflammatory bowel diseases. A number of studies have shown that different bacterial species modulate the intestinal CD4+ T cell compartment in different ways. We performed mechanistic in vivo studies that demonstrated the crucial requirement for regulatory T cells (Treg) and interleukin-10 (IL-10) in the induction of intestinal T cell homeostasis even following colonization with a completely benign microbiota. In the absence of a functional Treg response or IL-10 receptor signaling, the same bacteria that induced a Treg response in wild-type animals now induced T helper type 17 responses, without intestinal inflammation. Therefore, Treg, IL-10 and Th17 are crucial regulatory mechanisms in the intestine not only for controlling inflammation, but also to establish a continuum of CD4+ T cell homeostasis upon commensal colonization.

Crosstalk between B lymphocytes, microbiota and the intestinal epithelium governs immunity versus metabolism in the gut

Using a systems biology approach, we discovered and dissected a three-way interaction between the immune system, the intestinal epithelium and the microbiota. We found that, in the absence of B cells, or of IgA, and in the presence of the microbiota, the intestinal epithelium launches its own protective mechanisms, upregulating interferon-inducible immune response pathways and simultaneously repressing Gata4-related metabolic functions. This shift in intestinal function leads to lipid malabsorption and decreased deposition of body fat. Network analysis revealed the presence of two interconnected epithelial-cell gene networks, one governing lipid metabolism and another regulating immunity, that were inversely expressed. Gene expression patterns in gut biopsies from individuals with common variable immunodeficiency or with HIV infection and intestinal malabsorption were very similar to those of the B cell-deficient mice, providing a possible explanation for a longstanding enigmatic association between immunodeficiency and defective lipid absorption in humans.

Intestinal bacterial colonization induces mutualistic regulatory T cell responses

Mammals harbor a dense commensal microbiota in the colon. Regulatory T (Treg) cells are known to limit microbe-triggered intestinal inflammation and the CD4+ T cell compartment is shaped by the presence of particular microbes or bacterial compounds. It is, however, difficult to distinguish whether these effects reflect true mutualistic immune adaptation to intestinal colonization or rather idiosyncratic immune responses. To investigate truly mutualistic CD4+ T cell adaptation, we used the altered Schaedler flora (ASF). Intestinal colonization resulted in activation and de novo generation of colonic Treg cells. Failure to activate Treg cells resulted in the induction of T helper 17 (Th17) and Th1 cell responses, which was reversed by wild-type Treg cells. Efficient Treg cell induction was also required to maintain intestinal homeostasis upon dextran sulfate sodium-mediated damage in the colon. Thus, microbiota colonization-induced Treg cell responses are a fundamental intrinsic mechanism to induce and maintain host-intestinal microbial T cell mutualism.

Depletion of murine intestinal microbiota: effects on gut mucosa and epithelial gene expression

Background Inappropriate cross talk between mammals and their gut microbiota may trigger intestinal inflammation and drive extra-intestinal immune-mediated diseases. Epithelial cells constitute the interface between gut microbiota and host tissue, and may regulate host responses to commensal enteric bacteria. Gnotobiotic animals represent a powerful approach to study bacterial-host interaction but are not readily accessible to the wide scientific community. We aimed at refining a protocol that in a robust manner would deplete the cultivable intestinal microbiota of conventionally raised mice and that would prove to have significant biologic validity. Methodology/Principal Findings Previously published protocols for depleting mice of their intestinal microbiota by administering broad-spectrum antibiotics in drinking water were difficult to reproduce. We show that twice daily delivery of antibiotics by gavage depleted mice of their cultivable fecal microbiota and reduced the fecal bacterial DNA load by 400 fold while ensuring the animals' health. Mice subjected to the protocol for 17 days displayed enlarged ceca, reduced Peyer's patches and small spleens. Antibiotic treatment significantly reduced the expression of antimicrobial factors to a level similar to that of germ-free mice and altered the expression of 517 genes in total in the colonic epithelium. Genes involved in cell cycle were significantly altered concomitant with reduced epithelial proliferative activity in situ assessed by Ki-67 expression, suggesting that commensal microbiota drives cellular proliferation in colonic epithelium. Conclusion We present a robust protocol for depleting conventionally raised mice of their cultivatable intestinal microbiota with antibiotics by gavage and show that the biological effect of this depletion phenocopies physiological characteristics of germ-free mice.

The function of secretory IgA in the context of the intestinal continuum of adaptive immune responses in host-microbial mutualism

The large production of immunoglobulin (Ig)A is energetically costly. The fact that evolution retained this apparent luxury of intestinal class switch recombination to IgA within the human population strongly indicates that there must be a critical specific function of IgA for survival of the species. The function of IgA has been investigated in a series of different models that will be discussed here. While IgA has clear protective functions against toxins or in the context of intestinal viral infections, the function of IgA specific for non-pathogenic commensal bacteria remains unclear. In the context of the current literature we present a hypothesis where secretory IgA integrates as an additional layer of immune function into the continuum of intestinal CD4 T cell responses, to achieve a mutualistic relationship between the intestinal commensal microbiota and the host.

An attenuated Salmonella enterica serovar Typhimurium strain lacking the ZnuABC transporter induces protection in a mouse intestinal model of Salmonella infection

Salmonella enterica serovar Typhimurium has long been recognised as a zoonotic pathogen of economic significance in animals and humans. Attempts to protect humans and livestock may be based on immunization with vaccines aimed to induce a protective response. We recently demonstrated that the oral administration of a Salmonella enterica serovar Typhimurium strain unable to synthesize the zinc transporter ZnuABC is able to protect mice against systemic salmonellosis induced by a virulent homologous challenge. This finding suggested that this mutant strain could represent an interesting candidate vaccine for mucosal delivery. In this study, the protective effect of this Salmonella strain was tested in a streptomycin-pretreated mouse model of salmonellosis that is distinguished by the capability of evoking typhlitis and colitis. The here reported results demonstrate that mice immunized with Salmonella enterica serovar Typhimurium (S. Typhimurium) SA186 survive to the intestinal challenge and, compared to control mice, show a reduced number of virulent bacteria in the gut, with milder signs of inflammation. This study demonstrates that the oral administration a of S. Typhimurium strain lacking ZnuABC is able to elicit an effective immune response which protects mice against intestinal S. Typhimurium infection. These results, collectively, suggest that the streptomycin-pretreated mouse model of S. typhimurium infection can represent a valuable tool to screen S. typhimurium attenuated mutant strains and potentially help to assess their protective efficacy as potential live vaccines.

Intestinal glucose absorption but not endogenous glucose production differs between colostrum- and formula-fed neonatal calves

Glucose supply markedly changes during the transition to extrauterine life. In this study, we investigated diet effects on glucose metabolism in neonatal calves. Calves were fed colostrum (C; n = 7) or milk-based formula (F; n = 7) with similar nutrient content up to d 4 of life. Blood plasma samples were taken daily before feeding and 2 h after feeding on d 4 to measure glucose, lactate, nonesterified fatty acids, protein, urea, insulin, glucagon, and cortisol concentrations. On d 2, additional blood samples were taken to measure glucose first-pass uptake (FPU) and turnover by oral [U-(13)C]-glucose and i.v. [6,6-(2)H(2)]-glucose infusion. On d 3, endogenous glucose production and gluconeogenesis were determined by i.v. [U-(13)C]-glucose and oral deuterated water administration after overnight feed deprivation. Liver tissue was obtained 2 h after feeding on d 4 and glycogen concentration and activities and mRNA abundance of gluconeogenic enzymes were measured. Plasma glucose and protein concentrations and hepatic glycogen concentration were higher (P < 0.05), whereas plasma urea, glucagon, and cortisol (d 2) concentrations as well as hepatic pyruvate carboxylase mRNA level and activity were lower (P < 0.05) in group C than in group F. Orally administered [U-(13)C]-glucose in blood was higher (P < 0.05) but FPU tended to be lower (P < 0.1) in group C than in group F. The improved glucose status in group C resulted from enhanced oral glucose absorption. Metabolic and endocrine changes pointed to elevated amino acid degradation in group F, presumably to provide substrates to meet energy requirements and to compensate for impaired oral glucose uptake.

Intestinal microbes affect phenotypes and functions of invariant natural killer T cells in mice

Invariant natural killer T (iNKT) cells undergo canonical, Vα14-Jα18 rearrangement of the T-cell receptor (TCR) in mice; this form of the TCR recognizes glycolipids presented by CD1d. iNKT cells mediate many different immune reactions. Their constitutive activated and memory phenotype and rapid initiation of effector functions after stimulation indicate previous antigen-specific stimulation. However, little is known about this process. We investigated whether symbiotic microbes can determine the activated phenotype and function of iNKT cells.

A survey on intestinal parasites of livestock guardian dogs and herding dogs in Switzerland

The present study describes the occurrence of intestinal parasite infections in livestock guardian dogs and herding dogs. A total of 71 guardian dogs (more than half of the total number of guardian dogs in Switzerland) and 21 herding dogs were coprologically examined, using a combined sedimentation-flotation method. In 21 (23 %) of the dogs intestinal parasites were detected, and 8 (8.7 %) of these dogs shed either sporocysts of Sarcocystis sp. (n = 6) or taeniid eggs (n = 2). The evaluation of questionnaires providing data on age, origin and deworming schemes of the dogs completed the study.