Preinduction of heat shock protein 70 protects mice against post-infection irritable bowel syndrome via NF-κB and NOS/NO signaling pathways

MicroRNA-16 inhibits the TLR4/NF-κB pathway and maintains tight junction integrity in irritable bowel syndrome with diarrhea

Irritable bowel syndrome with diarrhea (IBS-D) is a chronic and relapsing inflammatory disorder in which pathogenesis has been shown to be in part the result of miRNA-mediated signaling. Here, we investigated the alleviatory role of miR-16 in IBS-D. First, we established an IBS-D mouse model using colonic instillation of acetic acid and developed an IBS-D cell model using lipopolysaccharide exposure. The experimental data demonstrated that miR-16 was underexpressed in the serum of IBS-D patients, as well as in the colorectal tissues of IBS-D mouse models and lipopolysaccharide-exposed intestinal epithelial cells. Next, miR-16 and TLR4 were overexpressed or inhibited to characterize their roles in the viability and apoptosis of intestinal epithelial cells, inflammation, and epithelial tight junction. We found that miR-16 overexpression increased the viability of intestinal epithelial cells, maintained tight junction integrity, and inhibited cell apoptosis and inflammation. We showed that miR-16 targeted TLR4 and inhibited the TLR4/NF-κB signaling pathway. Additionally, inhibition of NF-κB suppressed the long noncoding RNA XIST, thereby promoting enterocyte viability, inhibiting apoptosis and cytokine production, and maintaining tight junction integrity. In vivo experiments further verified the alleviatory effect of miR-16 on IBS-D symptoms in mice. Taken together, we conclude that miR-16 downregulates XIST through the TLR4/NF-κB pathway, thereby relieving IBS-D. This study suggests that miR-16 may represent a potential target for therapeutic intervention against IBS-D.

Upregulated adenosine 2A receptor accelerates post-infectious irritable bowel syndrome by promoting CD4+ T cells’ T helper 17 polarization

BACKGROUND

Post-infectious irritable bowel syndrome (PI-IBS) is generally regarded as a functional disease. Several recent studies have reported the involvement of low-grade inflammation and immunological dysfunction in PI-IBS. T helper 17 (Th17) polarization occurs in IBS. Adenosine and its receptors participate in intestinal inflammation and immune regulation.

AIM

To investigate the role of Th17 polarization of CD4+ T cells regulated by adenosine 2A receptor (A2AR) in PI-IBS.

METHODS

A PI-IBS model was established by infecting mice with Trichinella spiralis. The intestinal A2AR and CD4+ T lymphocytes were detected by immunohistochemistry, and the inflammatory cytokines were detected by enzyme-linked immunoassay. CD4+ T lymphocytes present in the animal’s spleen were separated and cultured with or without A2AR agonist and antagonist. Western blotting and real-time quantitative polymerase chain reaction were performed to determine the effect of A2AR on the cells and intestinal tissue. Cytokine production was determined. The protein and mRNA levels of A2AR associated signaling pathway molecules were also evaluated. Furthermore, A2AR agonist and antagonist were injected into the mouse model and the clinical features were observed.

RESULTS

The PI-IBS mouse model showed increased expression of ATP and A2AR (P < 0.05), and inhibition of A2AR improved the clinical features in PI-IBS, including the abdominal withdrawal reflex and colon transportation test (P < 0.05). The number of intestinal CD4+ T cells and interleukin-17 (IL-17) protein levels increased during PI-IBS, which was reversed by administration of the A2AR antagonist (P < 0.05). CD4+ T cells expressed A2AR and produced IL-17 in vitro, which was regulated by the A2AR agonist and antagonist. The A2AR antagonist increased the production of IL-17 by CD4+ T cells via the Janus kinase-signal transducer and activator of transcription-receptor-related orphan receptor γ signaling pathway.

CONCLUSION

The results of the present study suggested that the upregulation of A2AR increases PI-IBS by promoting the Th17 polarization of CD4+ T cells.

Otilonium Bromide treatment prevents nitrergic functional and morphological changes caused by chronic stress in the distal colon of a rat IBS model

Irritable bowel syndrome (IBS) is a highly prevalent gastrointestinal disorder characterized by periods of remission and exacerbation. Among the risk factors to develop IBS, psychosocial stress is widely acknowledged. The water avoidance stress repeatedly applied (rWAS) is considered effective to study IBS etio-pathogenesis. Otilonium bromide (OB), a drug with multiple mechanisms of action, is largely used to treat IBS patients. Orally administered, it concentrates in the large bowel and significantly ameliorates the IBS symptomatology. Presently, we tested whether rWAS rats developed neuro-muscular abnormalities in the distal colon and whether OB treatment prevented them. The investigation was focussed on the nitrergic neurotransmission by combining functional and morphological methodologies. The results confirm rWAS as reliable animal model to investigate the cellular mechanisms responsible for IBS: exposure to one-hour psychosocial stress for 10 days depressed muscle contractility and increased iNOS expression in myenteric neurons. OB treatment counteracted these effects. We hypothesize that these effects are due to the corticotropin-releasing factor (CRF) release, the main mediator of the psychosocial stress, followed by a CRF1receptor activation. OB, that was shown to prevent CRF1r activation, reasonably interrupted the cascade events that bring to the mechanical and immunohistochemical changes affecting rWAS rat colon.

Niosomal versus nano-crystalline ivermectin against different stages of Trichinella spiralis infection in mice

Ivermectin (IVM) is one of the competitive treatments used for trichinellosis. However, several studies linked its efficacy with early diagnosis and administration to tackle the intestinal phase with limited activity being recorded against encysted larvae. The aim of this study was to employ niosomes for enhancing effectiveness of oral IVM against different stages of Trichinella spiralis (T. spiralis) infection with reference to nano-crystalline IVM. Mice were randomized into four groups: group Ι, 15 uninfected controls; group ΙΙ, 30 infected untreated controls; group ΙΙΙ, 30 infected nano-crystalline IVM treated, and group ΙV, 30 infected niosomal IVM treated. All groups were equally subdivided into 3 subgroups; (a) treated on the 1^st day post infection (dpi), (b) treated on the 10^th dpi, and (c) treated on the 30^th dpi. Assessment was done by counting adult worms and larvae plus histopathological examination of jejunum and diaphragm. Biochemical assessment of oxidant/antioxidant status, angiogenic, and inflammatory biomarkers in intestinal and muscle tissues was also performed. Both niosomes and nano-crystals resulted in significant reduction in adult and larval counts compared to the infected untreated control with superior activity of niosomal IVM. The superiority of niosomes was expressed further by reduction of inflammation in both jejunal and muscle homogenates. Biochemical parameters showed highly significant differences in all treated mice compared to infected untreated control at different stages with highly significant effect of niosomal IVM. In conclusion, niosomal IVM efficacy exceeded the nano-crystalline IVM in treatment of different phases of trichinellosis.

Effect of high-dose vitamin D supplementation on antibody titers to heat shock protein 27 in adolescent girls

Background Although vitamin D deficiency is associated with several inflammatory conditions, there have been few studies on the effects of vitamin D supplementation on markers of oxidative stress (OS) and inflammation. The aim of the current study was to evaluate the effects of high-dose vitamin D supplementation on heat shock protein 27 antibody (anti-Hsp27) titers in adolescent girls. Methods Five hundred and fifty adolescent girls received vitamin D3 at a dose of 50,000 IU/week for 9 weeks. Demographic, clinical and biochemical markers including serum fasting blood glucose (FBG), lipid profile and anti-Hsp27 titers as well as hematological parameters including white blood cell (WBC) count and red blood cell (RBC) distribution width (RDW) were determined in all the subjects at baseline and at the end of the study. Results Serum vitamin D significantly increased from 6.4 (4.2-9.6) ng/mL to 35.6 (25.8-47.5) ng/mL (p < 0.001) following the intervention. Furthermore, serum anti-Hsp27 titers were significantly lower after the 9-week vitamin D administration period (0.22 [0.12-0.33] optical density [OD] vs. 0.19 [0.11-0.31] OD; p = 0.002). A significant correlation was found between serum anti-Hsp27 and RDW (r = 0.13, p = 0.037). The reduction in RDW values after intervention was particularly evident in subjects with the greatest increase in serum vitamin D levels. Conclusions High-dose vitamin D supplementation was found to reduce antibody titers to Hsp27. Further randomized placebo-controlled trials are warranted to determine the long-term effect of vitamin D administration on the inflammatory process especially that associated with chronic disease.

HSP70 protects rats and hippocampal neurons from central nervous system oxygen toxicity by suppression of NO production and NF-κB activation

During diving, central nervous system oxygen toxicity may cause drowning or barotrauma, which has dramatically limited the working benefits of hyperbaric oxygen in underwater operations and clinical applications. The aim of this study is to understand the effects and the underlying mechanism of heat shock protein 70 on central nervous system oxygen toxicity and its mechanisms in vivo and in vitro. Rats were given geranylgeranylacetone (800 mg/kg) orally to induce hippocampal expression of heat shock protein 70 and then treated with hyperbaric oxygen. The time course of hippocampal heat shock protein 70 expression after geranylgeranylacetone administration was measured. Seizure latency and first electrical discharge were recorded to evaluate the effects of HSP70 on central nervous system oxygen toxicity. Effects of inhibitors of nitric oxide synthase and nuclear factor-κB on the seizure latencies and changes in nitric oxide, nitric oxide synthase, and nuclear factor-κB levels in the hippocampus tissues were examined. In cell experiments, hippocampal neurons were transfected with a virus vector carrying the heat shock protein 70 gene (H3445) before hyperbaric oxygen treatment. Cell viability, heat shock protein 70 expression, nitric oxide, nitric oxide synthase, and NF-κB levels in neurons were measured. The results showed that heat shock protein 70 expression significantly increased and peaked at 48 h after geranylgeranylacetone was given. Geranylgeranylacetone prolonged the first electrical discharge and seizure latencies, which was reversed by neuronal nitric oxide synthase, inducible nitric oxide synthase and NF-κB inhibitors. Nitric oxide, nitric oxide synthase, and inducible nitric oxide synthase levels in the hippocampus were significantly increased after hyperbaric oxygen exposure, but reversed by geranylgeranylacetone, while heat shock protein 70 inhibitor quercetin could inhibit this effect of geranylgeranylacetone. In the in vitro study, heat shock protein 70-overexpression decreased the nitric oxide, nitric oxide synthase, and inducible nitric oxide synthase levels as well as the cytoplasm/nucleus ratio of nuclear factor-κB and protected neurons from hyperbaric oxygen-induced cell injury. In conclusion, overexpression of heat shock protein 70 in hippocampal neurons may protect rats from central nervous system oxygen toxicity by suppression of neuronal nitric oxide synthase and inducible nitric oxide synthase-mediated nitric oxide production and translocation of nuclear factor-κB to nucleus. Impact statement Because the pathogenesis of central nervous system oxygen toxicity (CNS-OT) remains unclear, there are few interventions available. To develop an efficient strategy against CNS-OT, it is necessary to understand its pathogenesis and in particular, the relevant key factors involved. This study examined the protective effects of heat shock protein 70 (HSP70) on CNS-OT via in vivo and in vitro experiments. Our results indicated that overexpression of HSP70 in hippocampal neurons may protect rats from CNS-OT by suppression of nNOS and iNOS-mediated NO production and the activation of NF-κB. These findings contribute to clarification of the role of HSP70 in CNS-OT and provide us a potential novel target to prevent CNS-OT. Clarification of the involvement of NO, NOS and NF-κB provides new insights into the mechanism of CNS-OT and may help us to develop new approach against it by interfering these molecules.

The role of heat shock protein 70 in oxidant stress and inflammatory injury in quail spleen induced by cold stress

The aim of this study was to investigate the role of heat shock protein 70 (Hsp70) in oxidative stress and inflammatory damage in the spleen of quails which were induced by cold stress. One hundred ninety-two 15-day-old male quails were randomly divided into 12 groups and kept at 12 ± 1 °C to examine acute and chronic cold stress. We first detected the changes in activities of antioxidant enzymes in the spleen tissue under acute and chronic cold stress. The activities of glutathione peroxidase (GSH-Px) fluctuated in acute cold stress groups, while they were significantly decreased (p < 0.05) after chronic cold stress. The activities of superoxide dismutase (SOD), inducible nitric oxide synthase (iNOS), and nitric oxide (NO) content were decreased significantly (p < 0.05) in both of the acute and chronic cold stress groups. Malondialdehyde (MDA) content was significantly increased (p < 0.05) under cold stress except the 0.5 h group of acute cold stress. Besides, histopathological analysis showed that quail's spleen tissue was inflammatory injured seriously in both the acute and chronic cold stress groups. Additionally, the inflammatory factors (cyclooxygenase-2 (COX-2), prostaglandin E synthase (PTGES), iNOS, nuclear factor-kappa B (NF-κB), and tumor necrosis factor-a (TNF-α)) and Hsp70 mRNA levels were increased in both of the acute and chronic cold stress groups compared with the control groups. These results suggest that oxidative stress and inflammatory injury could be induced by cold stress in spleen tissues of quails. Furthermore, the increased expression of Hsp70 may play a role in protecting the spleen against oxidative stress and inflammatory damage caused by cold stress.

Heat shock protein 70 protects mouse against post-infection irritable bowel syndrome via up-regulating intestinal γδ T cell's Th17 response

Background

This study investigated the role of HSP70 in modulating intestinal γδ T cells’ Th17 response in Trichinella spiralis-induced PI-IBS mice model.

Methods

The intestinal HSP70’s expression and mRNA level were measured by Western blot and RT-PCR. The intestinal γδ T cell’s morphological changes were analyzed using immunofluorescence staining and confocal laser scanning microscope. The pro-inflammatory cytokines’ level was detected by ELISA. The isolated and purified γδ T cells were pre-incubated with HSP70 and their functions including proliferation, apoptosis, activation and production of IL-17 were also detected.

Results

Heat treatment augmented intestinal HSP70 expression and alleviated the clinical presentations in PI-IBS mice. Meanwhile, intestinal γδ T cells and local IL-17 level were increased by pre-induction of HSP70. HSP70 promoted the proliferation of PI-IBS mice’s intestinal γδ T cells, inhibited the apoptosis and stimulated these cells to secret IL-17 rather than IFN-γ.

Conclusion

Our results suggest that HSP70 plays a protective role via up-regulating intestinal γδ T cell’s Th17 response in PI-IBS mice.

NaHS inhibits NF-κB signal against inflammation and oxidative stress in post-infectious irritable bowel syndrome

In this study, the alleviating role of hydrogen sulfide (H₂S) was investigated in a Post-Infectious Irritable Bowel Syndrome (PI-IBS) murine model and Caco-2 cells.