Do heat shock proteins play any role in gut inflammation?

Intake of Lactobacillus delbrueckii (pExu:hsp65) Prevents the Inflammation and the Disorganization of the Intestinal Mucosa in a Mouse Model of Mucositis

5-Fluorouracil (5-FU) is an antineoplastic drug that causes, as a side effect, intestinal mucositis, acute inflammation in the small bowel. The Heat Shock Protein (Hsp) are highly expressed in inflammatory conditions, developing an important role in immune modulation. Thus, they are potential candidates for the treatment of inflammatory diseases. In the mucositis mouse model, the present study aimed to evaluate the beneficial effect of oral administration of milk fermented by Lactobacillus delbrueckii CIDCA 133 (pExu:hsp65), a recombinant strain. This approach showed increased levels of sIgA in the intestinal fluid, reducing inflammatory infiltrate and intestinal permeability. Additionally, the histological score was improved. Protection was associated with a reduction in the gene expression of pro-inflammatory cytokines such as Tnf, Il6, Il12, and Il1b, and an increase in Il10, Muc2, and claudin 1 (Cldn1) and 2 (Cldn2) gene expression in ileum tissue. These findings are corroborated with the increased number of goblet cells, the electronic microscopy images, and the reduction of intestinal permeability. The administration of milk fermented by this recombinant probiotic strain was also able to reverse the high levels of gene expression of Tlrs caused by the 5-FU. Thus, the rCIDCA 133:Hsp65 strain was revealed to be a promising preventive strategy for small bowel inflammation.

Dietary supplementation of biofloc influences growth performance, physiological stress, antioxidant status and immune response of juvenile sea cucumber Apostichopus japonicus (Selenka)

Bioflocs are rich in various probiotics and bioactive compounds, which play an important role in improving growth and health status of aquatic organisms. A 60-day experiment was conducted to investigate the effects of dietary supplementation of biofloc on growth performance, digestive enzyme activity, physiological stress, antioxidant status, expression of immune-related genes and disease resistance of sea cucumber Apostichopus japonicus. Juvenile sea cucumbers were fed five experimental diets containing graded levels of biofloc from 0% to 20% (referred as B0, B5, B10, B15 and B20, respectively). The results showed that the sea cucumbers at dietary supplementation levels of 10%-15% biofloc had significantly higher specific growth rate (SGR) compared to control group (diet B0). Digestive enzyme activity increased with the increasing of dietary biofloc level, while no significant difference was found between diets B15 and B20. Dietary supplementation of biofloc also had significant influences on physiological stress parameters except for lactate. There was no significant discrepancy in total coelomocytes counts (TCC) in coelomic fluid of sea cucumber between the treatments. Phagocytosis and respiratory burst of cellular immune at 15% and 20% biofloc levels were significantly higher than those of control group. Significant increases in superoxide dismutase (SOD), total nitric oxide synthase (T-NOS), lysozyme (LSZ), acid phosphatase (ACP) and alkaline phosphatase (AKP) activities of sea cucumber were found at highest dietary supplementation level of 20% biofloc. The expression patterns of immune-related genes (i.e., Hsp90, Hsp70, p105, Rel, NOS and LSZ) in tissues of sea cucumber were analyzed between the experimental diets, and a general trend of up-regulation was observed at higher biofloc levels. Furthermore, dietary 10%-20% biofloc significantly reduced cumulative mortality of sea cucumber after being challenged with Vibrio splendidus. In conclusion, dietary supplementation of biofloc could improve growth performance of A. japonicus, by increasing digestive enzyme activity, releasing physiological stress, enhancing immune response and disease resistance of sea cucumber. The suitable supplemental level of approximately 15% biofloc was recommended in the present study.

Hsp65-Producing Lactococcus lactis Prevents Inflammatory Intestinal Disease in Mice by IL-10- and TLR2-Dependent Pathways

Heat shock proteins (Hsps) are highly expressed at all sites of inflammation. As they are ubiquitous and immunodominant antigens, these molecules represent good candidates for the therapeutic use of oral tolerance in autoimmune and chronic inflammatory diseases. Evidences from human and animal studies indicate that inflammatory bowel disease (IBD) results from uncontrolled inflammatory responses to intestinal microbiota. Hsps are immunodominant proteins expressed by several immune cells and by commensal bacteria. Using an IBD mouse model, we showed that oral pretreatment with genetically modified Lactococcus lactis that produces and releases Mycobacterium Hsp65, completely prevented DSS-induced colitis in C57BL/6 mice. Protection was associated with reduced pro-inflammatory cytokines, such as IFN-γ, IL-6, and TNF-α; increased IL-10 production in colonic tissue; and expansion of CD4⁺Foxp3⁺ and CD4⁺LAP⁺ regulatory T cells in spleen and mesenteric lymph nodes. This effect was dependent on IL-10 and toll-like receptor 2. Thus, this approach may open alternative options for long-term management of IBD.

Comparative transcriptome analysis of papilla and skin in the sea cucumber, Apostichopus japonicus

Papilla and skin are two important organs of the sea cucumber. Both tissues have ectodermic origin, but they are morphologically and functionally very different. In the present study, we performed comparative transcriptome analysis of the papilla and skin from the sea cucumber (Apostichopus japonicus) in order to identify and characterize gene expression profiles by using RNA-Seq technology. We generated 30.6 and 36.4 million clean reads from the papilla and skin and de novo assembled in 156,501 transcripts. The Gene Ontology (GO) analysis indicated that cell part, metabolic process and catalytic activity were the most abundant GO category in cell component, biological process and molecular funcation, respectively. Comparative transcriptome analysis between the papilla and skin allowed the identification of 1,059 differentially expressed genes, of which 739 genes were expressed at higher levels in papilla, while 320 were expressed at higher levels in skin. In addition, 236 differentially expressed unigenes were not annotated with any database, 160 of which were apparently expressed at higher levels in papilla, 76 were expressed at higher levels in skin. We identified a total of 288 papilla-specific genes, 171 skin-specific genes and 600 co-expressed genes. Also, 40 genes in papilla-specific were not annotated with any database, 2 in skin-specific. Development-related genes were also enriched, such as fibroblast growth factor, transforming growth factor-β, collagen-α2 and Integrin-α2, which may be related to the formation of the papilla and skin in sea cucumber. Further pathway analysis identified ten KEGG pathways that were differently enriched between the papilla and skin. The findings on expression profiles between two key organs of the sea cucumber should be valuable to reveal molecular mechanisms involved in the development of organs that are related but with morphological differences in the sea cucumber.

Fish oil attenuates liver injury caused by LPS in weaned pigs associated with inhibition of TLR4 and nucleotide-binding oligomerization domain protein signaling pathways

This study evaluated whether fish oil exerted a hepatoprotective effect in a LPS-induced liver injury model via regulation of TLR4 and nucleotide-binding oligomerization domain protein (NOD) signaling pathways. Twenty-four piglets were used in a 2 × 2 factorial design, and the main factors included diet (5% corn oil or 5% fish oil) and immunological challenge (LPS or saline). Fish oil resulted in enrichment of eicosapentaenoic acid, docosahexaenoic acid and total (n-3) polyunsaturated fatty acids in liver. Less severe liver injury was observed in pigs fed fish oil, as evidenced by improved serum biochemical parameters and less severe histological liver damage. In addition, higher expression of liver tight junction proteins, and lower hepatocyte proliferation and higher hepatocyte apoptosis were observed in pigs fed fish oil. The improved liver integrity in pigs fed fish oil was concurrent with reduced hepatic mRNA expression of TLR4, myeloid differentiation factor 88, IL-1 receptor-associated kinase 1 and TNF- α receptor-associated factor 6, and NOD1, NOD2 and receptor-interacting serine/threonine-protein kinase 2, as well as reduced hepatic protein expression of NF-κB p65, leading to reduced hepatic pro-inflammatory mediators. These results indicate that fish oil improves liver integrity partially via inhibition of TLR4 and NOD signaling pathways under an inflammatory condition.

Fish oil enhances intestinal integrity and inhibits TLR4 and NOD2 signaling pathways in weaned pigs after LPS challenge

Long-chain (n-3) PUFA exert beneficial effects on inflammatory bowel diseases in animal models and clinical trials. In addition, pattern recognition receptors such as toll-like receptors (TLR) and nucleotide-binding oligomerization domain proteins (NOD) play a critical role in intestinal inflammation. We hypothesized that fish oil could alleviate Escherichia coli LPS-induced intestinal injury via modulation of TLR4 and NOD signaling pathways. Twenty-four weaned piglets were used in a 2 × 2 factorial design and the main factors included a dietary treatment (5% corn oil or 5% fish oil) and immunological challenge (LPS or saline). After feeding fish oil or corn oil diets for 21 d, pigs were injected with LPS or saline. At 4 h postinjection, blood samples were collected and pigs were killed. EPA, DHA, and total (n-3) PUFA were enriched in intestinal mucosa through fish supplementation. Fish oil improved intestinal morphology, indicated by greater villus height and villus height:crypt depth ratio, and intestinal barrier function, indicated by decreased plasma diamine oxidase (DAO) activity and increased mucosal DAO activity as well as enhanced protein expression of intestinal tight junction proteins including occludin and claudin-1. Moreover, fish oil decreased intestinal TNFα and PGE(2) concentrations and caspase-3 and heat shock protein 70 protein expression. Finally, fish oil downregulated the mRNA expression of intestinal TLR4 and its downstream signals myeloid differentiation factor 88, IL-1 receptor-associated kinase 1, TNFα receptor-associated factor 6, and NOD2, and its adaptor molecule, receptor-interacting serine/threonine-protein kinase 2. Fish oil decreased the protein expression of intestinal NFκB p65. These results indicate that fish oil supplementation is associated with inhibition of TLR4 and NOD2 signaling pathways and concomitant improvement of intestinal integrity under an inflammatory condition.

Aberrant expression of the polarity complex atypical PKC and non-muscle myosin IIA in active and inactive inflammatory bowel disease

Epithelial barrier function is contingent on appropriate polarization of key protein components. Work in intestinal epithelial cell cultures and animal models of bowel inflammation suggested that atypical PKC (aPKC), the kinase component of the Par3–Par6 polarity complex, is downregulated by pro-inflammatory signaling. Data from other laboratories showed the participation of myosin light chain kinase in intestinal inflammation, but there is paucity of evidence for assembly of its major target, non-muscle myosin II, in inflammatory bowel disease (IBD). In addition, we showed before that non-muscle myosin IIA (nmMyoIIA) is upregulated in intestinal inflammation in mice and TNFα-treated Caco-2 cells. Thus far, it is unknown if a similar phenomena occur in patients with IBD. Moreover, it is unclear whether aPKC downregulation is directly correlated with local mucosal inflammation or occurs in uninvolved areas. Frozen sections from colonoscopy material were stained for immunofluorescence with extensively validated specific antibodies against phosphorylated aPKC turn motif (active form) and nmMyoIIA. Inflammation was scored for the local area from where the material was obtained. We found a significant negative correlation between the expression of active aPKC and local inflammation, and a significant increase in the apical expression of nmMyoIIA in surface colon epithelia in inflamed areas, but not in non-inflamed mucosa even in the same patients. Changes in aPKC and nmMyoIIA expression are likely to participate in the pathogenesis of epithelial barrier function in response to local pro-inflammatory signals. These results provide a rationale for pursuing mechanistic studies on the regulation of these proteins.