1,721,010 research outputs found
Impact of food additives on gut homeostasis
No full textIn physiological conditions, the gut is heavily infiltrated with various subsets of inflammatory cells, whose activity is tightly controlled by counter-regulatory mechanisms. Defects in such mechanisms can favour the development of chronic intestinal disorders, such as Crohn's disease (CD) and ulcerative colitis (UC), the principal forms of inflammatory bowel diseases (IBD) in humans, as well as systemic disorders. Over the last years, the frequency of intestinal and systemic immune-inflammatory disorders has increased in previously low incidence areas, likely due to the Westernization of lifestyles, including dietary habits. The Western diet is characterized by high consumption of proteins, saturated fats and sweets, as well as by a broad use of food additives (e.g., emulsifiers, bulking agents), which are used to preserve and enhance food quality. Accumulating evidence suggests that food additives can perturb gut homeostasis, thereby contributing to promote tissue-damaging inflammatory responses. For instance, mice given the emulsifiers carboxymethylcellulose and polysorbate 80 develop dysbiosis with overgrowth of mucus-degrading bacteria. Such an effect triggers colitis in animals deficient in either interleukin-10, a cytokine exerting anti-inflammatory and regulatory functions, or Toll-like receptor 5, a receptor recognizing the bacterial flagellin. Similarly, the polysaccharide maltodextrin induces endoplasmic reticulum stress in intestinal goblet cells, thereby impairing mucus release and increasing host susceptibility to colitis. In this review, we report and discuss the current knowledge about the impact of food additives on gut homeostasis and their potential contribution to the development of inflammatory disorders
Implication of Intestinal Barrier Dysfunction in Gut Dysbiosis and Diseases
Full text linkThe intestinal mucosal barrier, also referred to as intestinal barrier, is widely recognized as a critical player in gut homeostasis maintenance as it ensures the complex crosstalk between gut microbes (both commensals and pathogens) and the host immune system. Highly specialized epithelial cells constantly cope with several protective and harmful agents to maintain the multiple physiological functions of the barrier as well as its integrity. However, both genetic defects and environmental factors can break such equilibrium, thus promoting gut dysbiosis, dysregulated immune-inflammatory responses, and even the development of chronic pathological conditions. Here, we review and discuss the molecular and cellular pathways underlying intestinal barrier structural and functional homeostasis, focusing on potential alterations that may undermine this fine balance
Increased Foxp3(+) Regulatory T Cells in Poly(ADP-Ribose) Polymerase-1 Deficiency
No full textGrowing evidence is unveiling a role for poly(ADP-ribose) polymerase (PARP)-1 in the regulation of inflammatory/immune responses. In the current study, we investigated the effects of PARP-1 deficiency on regulatory T cell differentiation. Increased numbers of regulatory CD4(+)CD25(+)/Foxp3(+) T cells were found in thymus, spleen, and lymph nodes of PARP-1 knockout (KO) mice compared with wild-type (WT) controls. The increased frequency of regulatory T cells in the periphery resulted in impaired CD4 cell proliferation and IL-2 production, which could be restored by CD25(+) cell depletion. Phenotype and inhibitory functions of PARP-1 KO regulatory T cells were similar to WT cells, indicating that PARP-1 affects regulatory T cell differentiation rather than function. Purified naive CD4 cells from PARP-1 KO mice stimulated in vitro expressed forkhead box p3 mRNA at higher levels and generated a greater number of Foxp3(+) cells (inducible regulatory T [iTreg] cells) than the WT counterpart. This finding was due to a higher rate of naive CD4 cell to Foxp3(+) iTreg cell conversion rather than to higher resistance to apoptosis induction. Interestingly, PARP-1 deficiency did not affect retinoid-related orphan receptor-gamma t mRNA expression and differentiation of purified naive CD4 cells to Th17 cells. PARP-1 KO iTreg cells showed features similar to WT regulatory T cells, suggesting that modulation of PARP-1 during the immune response might be used to induce greater numbers of functional regulatory T cells. In conclusion, our findings represent the first evidence that PARP-1 can affect regulatory T cell differentiation and open new perspectives on potential targets for modulating immune responses. The Journal of Immunology, 2010, 184: 3470-3477
Opposite roles of poly-(ADP-ribose)-polymerase-1 in Th2 and regulatory T cell differentiation
No full textSmad7 and its potential as therapeutic target in inflammatory bowel diseases
No full textBackground: The etiology of Crohn's disease (CD) and ulcerative colitis (UC), the two major forms of inflammatory bowel disease (IBD) in humans, is still unknown, but evidence suggests that genetic and environmental factors interact to promote an excessive immune response that leads to tissue damage. Defects in the counter-regulatory mechanisms are also supposed to make a major contribution to the amplification and maintenance of the IBD-related inflammatory response. One such a mechanism involves TGF-β1, a cytokine synthesized by both immune and non-immune cells in the gut, which is essential in the maintenance of immune homeostasis. In both CD and UC, active inflammation occurs in areas characterized by enhanced production of TGF-β1 and reduced ability of this cytokine to activate Smad-associated signaling and suppress inflammatory pathways. The defective TGF-β1 activity is due to elevated levels of Smad7, an intracellular protein that inhibits TGF-β1-associated Smad signaling. Methods: Data from original studies and reviews were selected through an accurate research of the literature using the terms "IBD", "colitis", "Crohn's disease", "Smad7", "TGF-β1", "antisense oligonucleotide" and "Mongersen". Results: Twenty-fours studies describing the most accredited hypothesis about IBD pathogenesis and the role of Smad7 in the negative control of TGF-β1 were discussed in the review. Additionally, we reported data from original work illustrating the generation and the in vitro and in vivo effect of a specific Smad7 antisense oligonucleotide on intestinal inflammatory signals. We also discussed the results of phase 1 and phase 2 studies assessing the safety profile and clinical efficacy of Mongersen, an oral Smad7 antisense oligonucleotide containing drug, in patients with active CD. Conclusions: Data indicate that, in IBD, high Smad7 contributes to sustain detrimental immune responses and knockdown of this molecule can help attenuate the ongoing mucosal inflammation in patients with such disorders
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Effects of PARP-1 deficiency on Th1 and Th2 cell differentiation
No full textT cell differentiation to effector Th cells such as Th1 and Th2 requires the integration of multiple synergic and antagonist signals. Poly(ADP-ribosy)lation is a posttranslational modification of proteins catalyzed by Poly(ADP-ribose) polymerases (PARPs). Recently, many reports showed that PARP-1, the prototypical member of the PARP family, plays a role in immune/inflammatory responses. Consistently, its enzymatic inhibition confers protection in several models of immune-mediated diseases, mainly through an inhibitory effect on NF- B (and NFAT) activation. PARP-1 regulates cell functions in many types of immune cells, including dendritic cells, macrophages, and T and B lymphocytes. Our results show that PARP-1KO cells displayed a reduced ability to differentiate in Th2 cells. Under both nonskewing and Th2-polarizing conditions, naïve CD4 cells from PARP-1KO mice generated a reduced frequency of IL-4+ cells, produced less IL-5, and expressed GATA-3 at lower levels compared with cells from wild type mice. Conversely, PARP-1 deficiency did not substantially affect differentiation to Th1 cells. Indeed, the frequency of IFN- γ + cells as well as IFN- γ production, in nonskewing and Th1-polarizing conditions, was not affected by PARP-1 gene ablation. These findings demonstrate that PARP-1 plays a relevant role in Th2 cell differentiation and it might be a target to be exploited for the modulation of Th2-dependent immune-mediated diseases. © 2013 M. Sambucci et al
- …
