Novel therapeutic concepts for inflammatory bowel disease-from bench to bedside

Macrophagic HDAC3 inhibition ameliorates Dextran Sulfate Sodium induced inflammatory bowel disease through GBP5-NLRP3 pathway

Inflammatory bowel disease (IBD) is a chronic inflammatory intestinal disease, characterized by dysregulated immune response. HDAC3 is reported to be an epigenetic brake in inflammation, playing critical roles in macrophages. However, its role in IBD is unclear. In our study, we found HDAC3 was upregulated in CX3CR1-positive cells in the mucosa from IBD mice. Conditional knockout (cKO) of Hdac3 in CX3CR1 positive cells attenuated the disease severity of Dextran Sulfate Sodium (DSS)-induced colitis. In addition, inhibition of HDAC3 with RGFP966 could also alleviate the DSS-induced tissue injury and inflammation in IBD. The RNA sequencing results revealed that Hdac3 cKO restrained DSS-induced upregulation of genes in the pathways of cytokine-cytokine receptor interaction, complement and coagulation cascades, chemokine signaling, and extracellular matrix receptor interaction. We also identified that Guanylate-Binding Protein 5 (GBP5) was transcriptionally regulated by HDAC3 in monocytes by RNA sequencing. Inhibition of HDAC3 resulted in decreased transcriptional activity of interferon-gamma-induced expression of GBP5 in CX3CR1-positive cells, such as macrophages and microglia. Overexpression of HDAC3 upregulated the transcriptional activity of GBP5 reporter. Lastly, conditional knockout of Hdac3 in macrophages (Hdac3 mKO) attenuated the disease severity of DSS-induced colitis. In conclusion, inhibition of HDAC3 in macrophages could ameliorate the disease severity and inflammatory response in colitis by regulating GBP5-NLRP3 axis, identifying a new therapeutic avenue for the treatment of colitis.

HIF1A-dependent induction of alveolar epithelial PFKFB3 dampens acute lung injury

Acute lung injury (ALI) is a severe form of lung inflammation causing acute respiratory distress syndrome in patients. ALI pathogenesis is closely linked to uncontrolled alveolar inflammation. We hypothesize that specific enzymes of the glycolytic pathway could function as key regulators of alveolar inflammation. Therefore, we screened isolated alveolar epithelia from mice exposed to ALI induced by injurious ventilation to assess their metabolic responses. These studies pointed us toward a selective role for isoform 3 of the 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFKFB3). Pharmacologic inhibition or genetic deletion of Pfkfb3 in alveolar epithelia (Pfkfb3loxP/loxP SPC-ER-Cre+ mice) was associated with profound increases in ALI during injurious mechanical ventilation or acid instillation. Studies in genetic models linked Pfkfb3 expression and function to Hif1a. Not only did intratracheal pyruvate instillation reconstitute Pfkfb3loxP/loxP or Hif1aloxP/loxP SPC-ER-Cre+ mice, but pyruvate was also effective in ALI treatment of wild-type mice. Finally, proof-of-principle studies in human lung biopsies demonstrated increased PFKFB3 staining in injured lungs and colocalized PFKFB3 to alveolar epithelia. These studies reveal a specific role for PFKFB3 in counterbalancing alveolar inflammation and lay the groundwork for novel metabolic therapeutic approaches during ALI.

Co-regulation of circadian clock genes and microRNAs in bone metabolism

Mammalian bone is constantly metabolized from the embryonic stage, and the maintenance of bone health depends on the dynamic balance between bone resorption and bone formation, mediated by osteoclasts and osteoblasts. It is widely recognized that circadian clock genes can regulate bone metabolism. In recent years, the regulation of bone metabolism by non-coding RNAs has become a hotspot of research. MicroRNAs can participate in bone catabolism and anabolism by targeting key factors related to bone metabolism, including circadian clock genes. However, research in this field has been conducted only in recent years and the mechanisms involved are not yet well established. Recent studies have focused on how to target circadian clock genes to treat some diseases, such as autoimmune diseases, but few have focused on the co-regulation of circadian clock genes and microRNAs in bone metabolic diseases. Therefore, in this paper we review the progress of research on the co-regulation of bone metabolism by circadian clock genes and microRNAs, aiming to provide new ideas for the prevention and treatment of bone metabolic diseases such as osteoporosis.

Roxadustat Attenuates the Disruption of Epithelial Tight Junction in Caco2 Cells and a Rat Model of CKD Through MicroRNA-223

Introduction

Increasing evidence supports the idea that the disruption of epithelial tight junction proteins (TJPs) caused by accumulation of uremia toxins, such as homocysteine (Hcy), is one of the most important mechanisms underlying the damage of intestinal barrier function (IBF) in chronic kidney disease (CKD). Since the decrease of hypoxia inducible factor-1α (HIF-1α) is reported to be involved in Hcy-induced cell injury, and the upregulation of microRNA-223 (miR-223) plays a vital protective role in the impairment of IBF in the experimental colitis, we investigated the effect of HIF-1α stabilizer roxadustat on the disruption of TJPs induced by Hcy and CKD and the underlying mechanism.

Methods

Chronic kidney disease was induced in rats via 5/6 nephrectomy. In a series of experiments, the rats were treated orally with roxadustat of different doses. The expression of tight junction proteins, HIF-1α, and miR-223 was analyzed in different groups by western blotting analysis, RT-qPCR techniques and immunofluorescence. A series of experiments with cultured Caco2 cells was performed.

Results

The results showed that the expression of TJPs (occludin, claudin-1, and ZO-1) decreased significantly, accompanied by the reduction of HIF-1α and miR-223 in Hcy-treated Caco2 cells and colonic mucosa of uremic rats. The reduction of HIF-1α and miR-223 was reversed by roxadustat and the decrease of TJPs expression was attenuated in both Caco2 cells induced by Hcy and colon tissue of CKD rats. Furthermore, transfection with miR-223 mimics increased the expression of TJPs, while transfection with miR-223 inhibitor decreased their expression in Caco2 cells. MiR-223 inhibitor applied before roxadustat treatment partly diminished the effect of roxadustat on TJPs expression in Caco2 cells.

Conclusion

These results indicated that roxadustat attenuated the disruption of epithelial TJPs induced by Hcy in Caco2 cells and the damage of colonic epithelium in CKD rats through the upregulation of miR-223 induced by HIF-1α. A novel insight into the IBF dysfunction in CKD was provided, and it suggests a potential therapeutic use of roxadustat for the IBF dysfunction besides anemia in CKD.

Correlation of Hypoxia-inducible facto-1α and C-reactive protein with disease evaluation in patients with ulcerative colitis

OBJECTIVE

To investigate the expression levels of hypoxia-inducible factor-1α (HIF-1α) and C-reactive protein (CRP) in patients with ulcerative colitis and correlations of HIF-1α and CRP levels with disease severity.

METHODS

A total of 82 patients with confirmed ulcerative colitis were enrolled in this study and according to the disease severity grading, these patients were assigned into three groups: mild group (n=25), moderate group (n=31) and severe group (n=26). And other 30 patients without ulcerative colitis as demonstrated by colonoscopy examination were enrolled in control group in the same period. HIF-1α and CRP levels were detected by ELISA and Real-time PCR and compared among different groups. Pearson's correlation analysis was performed to evaluate the correlations of HIF-1α and CRP levels with disease severity. Logistic regression analysis was used to explore risk factors of disease severity in patients with ulcerative colitis.

RESULTS

The expression levels of HIF-1α and CRP in ulcerative colitis group were significantly higher than those in control group (all P<0.001). The levels of HIF-1α and CRP in patients with ulcerative colitis increased remarkably with the increase of disease severity. Patients in mild group had the lowest levels of HIF-1α and CRP, while patients in severe group had the highest levels of HIF-1α and CRP. Logistic regression analysis showed that the expression of HIF-1α and CRP were the risk factors for disease severity of ulcerative colitis (all P<0.001). And Pearson correlation analysis showed that HIF-1α and CRP levels were significantly associated with Rachmilewitz score and disease activity index (DAI), respectively (all P<0.001).

CONCLUSION

The levels of HIF-1α and CRP were up-regulated in patients with ulcerative colitis and positively correlated with the progression of ulcerative colitis, indicating that the detection of HIF-1α and CRP expression could be used for predicting the disease severity.

Ulcerative Colitis in Hematological Malignancies: Paraneoplastic Manifestation or Coincidental Bystander?

Evidence of coexistence of diverse hematological malignancies—lymphoma, leukemia, multiple myeloma, and myelodysplastic syndromes—and either ulcerative colitis or Crohn's disease can be found in the literature. However, a more “systemic” effort to reach further and examine the potential of either one as paraneoplastic manifestation has not been performed. Based on these, three cases of ulcerative colitis manifesting before, simultaneously, and after the onset of different hematological malignancies are presented and critically evaluated.

Therapeutic effect of adenosine on experimentally induced acute ulcerative colitis model in rats

Purpose

To examine the therapeutic effect of external adenosine on an acetic acid-induced acute ulcerative colitis model in rats.

Methods

Thirty male mature rats were divided into three groups as control, acute colitis (AC) and AC+adenosine group (AC+AD). AC was induced by rectal administration of 4% acetic acid (AA). 5mg/kg/day adenosine was performed i.p for 4 weeks to AC+AD group. Rectum and colon were excised for microscopic and histopathological histopathologic evaluations, and immunohistochemical analysis of nuclear factor kappa B (NF-kB). Blood samples were collected for biochemical detection of TNF-α, Pentraxin-3 and malondialdehyde (MDA) levels.

Results

AC group had generalized hyperemia and hemorrhage with increased macroscopic and histopathological scores compared with control (P <0.0001) while adenosine treatment decreased these scores significantly (P <0.001), with reduced distribution of disrupted epithelium, leukocyte infiltrates, and focal hemorrhage. AC group showed significantly increased immunoexpression of NF-kB in rectum, plasma and tissue levels of TNF-α, plasma Pentraxin-3 and MDA levels (P <0.0001) while adenosine reduced these levels (P < 0.05).

Conclusion

Adenosine appears to promote healing of colon and rectum exposed to AA-induced AC, suggesting a boosting effect of adenosine on the intestinal immune system to cure ulcerative colitis.

MicroRNA miR-223 as regulator of innate immunity

MicroRNAs were discovered more than 2 decades ago and have profound impact on diverse biological processes. Specific microRNAs have important roles in modulating the innate immune response and their dysregulation has been demonstrated to contribute to inflammatory diseases. MiR-223 in particular, is very highly expressed and tightly regulated in hematopoietic cells. It functions as key modulator for the differentiation and activation of myeloid cells. The central role of miR-223 in myeloid cells, especially neutrophil and macrophage differentiation and activation has been studied extensively. MiR-223 contributes to myeloid differentiation by enhancing granulopoiesis while inhibiting macrophage differentiation. Uncontrolled myeloid activation has detrimental consequences in inflammatory disease. MiR-223 serves as a negative feedback mechanism controlling excessive innate immune responses in the maintenance of myeloid cell homeostasis. This review summarizes several topics covering the function of miR-223 in myeloid differentiation, neutrophil and macrophage functions, as well as in inflammatory diseases including acute respiratory distress syndrome and inflammatory bowel disease. In addition, nonmyeloid functions of miR-223 are also discussed in this review. Therapeutic enhancement of miR-223 to dampen inflammatory targets is also highlighted as potential treatment to control excessive innate immune responses during mucosal inflammation.