Hypoxia Inducible Factor (HIF) Hydroxylases as Regulators of Intestinal Epithelial Barrier Function

The transcription factor HIF-1α in NKp46+ ILCs limits chronic intestinal inflammation and fibrosis

Innate lymphoid cells (ILCs) are critical for intestinal adaptation to microenvironmental challenges, and the gut mucosa is characterized by low oxygen. Adaptation to low oxygen is mediated by hypoxia-inducible transcription factors (HIFs), and the HIF-1α subunit shapes an ILC phenotype upon acute colitis that contributes to intestinal damage. However, the impact of HIF signaling in NKp46+ ILCs in the context of repetitive mucosal damage and chronic inflammation, as it typically occurs during inflammatory bowel disease, is unknown. In chronic colitis, mice lacking the HIF-1α isoform in NKp46+ ILCs show a decrease in NKp46+ ILC1s but a concomitant rise in neutrophils and Ly6Chigh macrophages. Single-nucleus RNA sequencing suggests enhanced interaction of mesenchymal cells with other cell compartments in the colon of HIF-1α KO mice and a loss of mucus-producing enterocytes and intestinal stem cells. This was, furthermore, associated with increased bone morphogenetic pathway-integrin signaling, expansion of fibroblast subsets, and intestinal fibrosis. In summary, this suggests that HIF-1α-mediated ILC1 activation, although detrimental upon acute colitis, protects against excessive inflammation and fibrosis during chronic intestinal damage.

Hypoxic Functional Regulation Pathways in the GI Tract: Focus on the HIF-1α and Microbiota's Crosstalk

Hypoxia is an essential gastrointestinal (GI) tract phenomenon that influences both physiologic and pathologic states. Hypoxia-inducible factors (HIFs), the primary drivers of cell adaptation to low-oxygen environments, have been identified as critical regulators of gut homeostasis: directly, through the induction of different proteins linked to intestinal barrier stabilization (ie, adherent proteins, tight junctions, mucins, integrins, intestinal trefoil factor, and adenosine); and indirectly, through the regulation of several immune cell types and the modulation of autophagy and inflammatory processes. Furthermore, hypoxia and HIF-related sensing pathways influence the delicate relationship existing between bacteria and mammalian host cells. In turn, gut commensals establish and maintain the physiologic hypoxia of the GI tract and HIF-α expression. Based on this premise, the goals of this review are to (1) highlight hypoxic molecular pathways in the GI tract, both in physiologic and pathophysiologic settings, such as inflammatory bowel disease; and (2) discuss a potential strategy for ameliorating gut-related disorders, by targeting HIF signaling, which can alleviate inflammatory processes, restore autophagy correct mechanisms, and benefit the host-microbiota equilibrium.

The role of the gut microbiome in disorders of gut-brain interaction

Disorders of Gut-Brain Interaction (DGBI) are widely prevalent and commonly encountered in gastroenterology practice. While several peripheral and central mechanisms have been implicated in the pathogenesis of DGBI, a recent body of work suggests an important role for the gut microbiome. In this review, we highlight how gut microbiota and their metabolites affect physiologic changes underlying symptoms in DGBI, with a particular focus on their mechanistic influence on GI transit, visceral sensitivity, intestinal barrier function and secretion, and CNS processing. This review emphasizes the complexity of local and distant effects of microbial metabolites on physiological function, influenced by factors such as metabolite concentration, duration of metabolite exposure, receptor location, host genetics, and underlying disease state. Large-scale in vitro work has elucidated interactions between host receptors and the microbial metabolome but there is a need for future research to integrate such preclinical findings with clinical studies. The development of novel, targeted therapeutic strategies for DGBI hinges on a deeper understanding of these metabolite-host interactions, offering exciting possibilities for the future of treatment of DGBI.

The importance of providing dietary fiber in medical and surgical critical care

The early provision of soluble/insoluble fiber to the patient who is critically ill has been controversial in the past. Especially in the setting of hemodynamic instability, dysmotility, or impaired gastrointestinal transit, fear of inspissation of formula with precipitation of nonocclusive mesenteric ischemia (NOMI)/nonocclusive bowel necrosis (NOBN) limited its utilization by medical and surgical intensivists. The incidence of NOMI/NOBN has been estimated at 0.2%-0.3% for all intensive care unit (ICU) patients receiving enteral nutrition (EN), and the occurrence of inspissated formula is even less. The science supporting a benefit from providing fiber has recently increased exponentially. The fermentation of soluble fibers leading to the production of short chain fatty acids supports gut barrier function, modulates immune responses, and promotes refaunation of commensal organisms. The "butyrate effect" refers to local (gastrointestinal tract) and systemic anti-inflammatory responses mediated by the M2 polarization of macrophages, inhibition of histone deacetylase, and stimulation of ubiquitous G protein receptors. Both soluble and insoluble fiber have been shown to promote intestinal motility, reduce feeding intolerance, and shorten hospital length of stay. The benefit of providing dietary fiber early upon admission to the ICU outweighs its minimal associated risk. The point at which the intensivist determines that is safe to initiate EN, both soluble and insoluble fiber should be included in the enteral formulation.

An investigation into the HIF-dependent intestinal barrier protective mechanism of Qingchang Wenzhong decoction in ulcerative colitis management

ETHNOPHARMACOLOGICAL RELEVANCE

Ulcerative colitis (UC) is a chronic, non-specific inflammatory disease affecting the colon and rectum with an etiology that remains elusive. Traditional Chinese medicine (TCM) has been widely used on long-term UC treatment to better maintain the efficacy than traditional aminosalicylic acid or glucocorticosteroids and to ease financial burden of patients. Qingchang Wenzhong Decoction (QCWZD) is a modern TCM decoction with established clinical efficacy but the mechanism of its protection on intestinal barrier function remains unclear.

AIM OF THE STUDY

Current findings highlight that the activation of the hypoxia inducible factor (HIF) pathway can facilitate the repair of intestinal epithelium barrier. This study is to investigate the protective effects of QCWZD and its HIF-targeted ingredients on hypoxia-dependent intestinal barrier.

METHODS

The mice model of UC was induced by dextran sulfate sodium (DSS). Disease activity index (DAI) and histopathology scores and colon length were used to measure the severity of colitis. The DAO activity in serum and protein expression of tight junction (TJ) proteins were detected to explore the function of intestinal barrier. The protein levels of HIF-1α and its downstream gene heme oxygenase-1 (HO-1) were measured as well. HIF-targeted active ingredients in QCWZD were selected by network pharmacology and molecular docking. Protective effects of six constituents on HIF-related anti-oxidative and barrier protective pathway were evaluated by lipopolysaccharide (LPS)-induced HT29 and RAW264.7 cells, through the measurement of the production of ROS and mRNA level of pro-inflammatory cytokines. HIF-1α knockdown was carried out to explore the correlation of protection effects with HIF-related pathway of the active ingredients.

RESULTS

QCWZD effectively alleviated colitis induced by DSS and demonstrated a protective effect on intestinal barrier function by upregulating HIF-related pathways. Six specific ingredients in QCWZD, targeting HIF, successfully reduced the production of cellular ROS and proinflammatory cytokines in LPS-induced cells. It is noteworthy that the barrier protection provided by these molecules is intricately linked with the HIF-related pathway.

CONCLUSIONS

This study elucidates the HIF-related molecular mechanism of QCWZD in protecting the function of the epithelial barrier. Six compounds targeting the activation of the HIF-dependent pathway were demonstrated to unveil a novel therapeutic approach for managing UC.

Crosstalk between hypoxia-inducible factor-1α and short-chain fatty acids in inflammatory bowel disease: key clues toward unraveling the mystery

The human intestinal tract constitutes a complex ecosystem, made up of countless gut microbiota, metabolites, and immune cells, with hypoxia being a fundamental environmental characteristic of this ecology. Under normal physiological conditions, a delicate balance exists among these complex "residents", with disruptions potentially leading to inflammatory bowel disease (IBD). The core pathology of IBD features a disrupted intestinal epithelial barrier, alongside evident immune and microecological disturbances. Central to these interconnected networks is hypoxia-inducible factor-1α (HIF-1α), which is a key regulator in gut cells for adapting to hypoxic conditions and maintaining gut homeostasis. Short-chain fatty acids (SCFAs), as pivotal gut metabolites, serve as vital mediators between the host and microbiota, and significantly influence intestinal ecosystem. Recent years have seen a surge in research on the roles and therapeutic potential of HIF-1α and SCFAs in IBD independently, yet reviews on HIF-1α-mediated SCFAs regulation of IBD under hypoxic conditions are scarce. This article summarizes evidence of the interplay and regulatory relationship between SCFAs and HIF-1α in IBD, pivotal for elucidating the disease's pathogenesis and offering promising therapeutic strategies.

Astragalus polysaccharide promotes the regeneration of intestinal stem cells through HIF-1 signalling pathway

Ionizing radiation (IR)-induced intestinal injury is usually accompanied by high lethality. Intestinal stem cells (ISCs) are critical and responsible for the regeneration of the damaged intestine. Astragalus polysaccharide (APS), one of the main active ingredients of Astragalus membranaceus (AM), has a variety of biological functions. This study was aimed to investigate the potential effects of APS on IR-induced intestine injury via promoting the regeneration of ISCs. We have established models of IR-induced intestinal injury and our results showed that APS played great radioprotective effects on the intestine. APS improved the survival rate of irradiated mice, reversed the radiation damage of intestinal tissue, increased the survival rate of intestinal crypts, the number of ISCs and the expression of intestinal tight junction-related proteins after IR. Moreover, APS promoted the cell viability while inhibited the apoptosis of MODE-K. Through organoid experiments, we found that APS promoted the regeneration of ISCs. Remarkably, the results of network pharmacology, RNA sequencing and RT-PCR assays showed that APS significantly upregulated the HIF-1 signalling pathway, and HIF-1 inhibitor destroyed the radioprotection of APS. Our findings suggested that APS promotes the regeneration of ISCs through HIF-1 signalling pathway, and it may be an effective radioprotective agent for IR-induced intestinal injury.

Moringa oleifera leaf polysaccharide regulates fecal microbiota and colonic transcriptome in calves

This study investigated the effects of Moringa oleifera polysaccharide on growth performance indicators, serum biochemical indicators, immune organ indicators, colonic morphology, colonic microbiomics and colonic transcriptomics in newborn calves. 21 newborn calves were randomly divided into three groups of 7 calves per treatment group: control group (no Moringa oleifera polysaccharide addition); low-dose group (Moringa oleifera polysaccharide 0.5 g/kg); and high-dose group (Moringa oleifera polysaccharide 1 g/kg). This trial used gavage to feed MOP to calves. The test lasted 8 weeks. Calves were humanely electroshocked on the last day of the trial and slaughtered afterwards. Thymus, spleen, blood and colonic contents were collected for further testing. The results of this trial showed that MOP significantly increased the body weight of newborn calves and reduced the rate of calf diarrhea, thus promoting calf growth. Fecal scores showed a linear decrease with the addition of MOP. In terms of serum biochemistry, feeding MOP significantly increased serum ALB levels in a linear fashion. In terms of serum antioxidants, feeding MOP linearly increased CAT and T-AOC levels and decreased MDA concentrations, and in terms of serum immunity, feeding MOP linearly increased IgA, IgG, and IgM levels. At the same time, MOP regulated the abundance of Firmicutes and Bacteroidetes in the intestinal tract of calves, which reduced the occurrence of diarrhea. In addition, moringa polysaccharide could regulate genes related to inflammatory signaling pathways such as MAPK signaling pathway, TGF-beta signaling pathway, PI3K-Akt signaling pathway and TNF signaling pathway in calves' intestine to reduce the occurrence of intestinal inflammation. In conclusion, MOP can be used as a novel ruminant additive for the prevention of enteritis in calves.

Sodium Butyrate Protects Against Intestinal Oxidative Damage and Neuroinflammation in the Prefrontal Cortex of Ulcerative Colitis Mice Model

Inflammatory bowel diseases (IBD) cause increased inflammatory signalling and oxidative damage. IBDs are correlated with an increased incidence of brain-related disorders suggesting that the gut-brain-axis exerts a pivotal role in IBD. Butyrate is one of the main microbial metabolites in the colon, and it can cross the blood-brain barrier, directly affecting the brain. We induced ulcerative colitis (UC) in mice utilizing dextran sodium sulfate (DSS) in the drinking water for 7 days. Animals were divided into four groups, receiving water or DSS and treated with saline or 0,066 g/kg of Sodium Butyrate for 7 days. We also used an integrative approach, combining bioinformatics functional network and experimental strategies to understand how butyrate may affect UC. Butyrate was able to attenuate colitis severity and intestinal inflammation. Butyrate protected the colon against oxidative damage in UC and protected the prefrontal cortex from neuroinflammation observed in DSS group. Immunocontent of tight junction proteins Claudin-5 and Occludin were reduced in colon of DSS group mice and butyrate was able to restore to control levels. Occludin and Claudin-5 decrease in DSS group indicate that an intestinal barrier disruption may lead to the increased influx of gut-derived molecules, causing neuroinflammation in the prefrontal cortex, observed by increased IBA-1 marker. The probable protection mechanism of butyrate treatment occurs through NRF2 through Nrf2 and HIF-1α activation and consequent activation of catalase and superoxide dismutase. Our data suggest that systemic inflammation associated with intestinal barrier disruption in UC leads to neuroinflammation in the prefrontal cortex, which was atenuated by butyrate.

Proteomics analysis of lung tissue reveals protein makers for the lung injury of adjuvant arthritis rats

Lung injury is one of the common extra‑articular lesions in rheumatoid arthritis (RA). Due to its insidious onset and no obvious clinical symptoms, it can be easily dismissed in the early stage of diagnosis, which is one of the reasons that leads to a decline of the quality of life and subsequent death of patients with RA. However, its pathogenesis is still unclear and there is a lack of effective therapeutic targets. In the present study, tandem mass tag‑labeled proteomics was used to research the lung tissue proteins in RA model (adjuvant arthritis, AA) rats that had secondary lung injury. The aim of the present study was to identify the differentially expressed proteins related to RA‑lung injury, determine their potential role in the pathogenesis of RA‑lung injury and provide potential targets for clinical treatment. Lung tissue samples were collected from AA‑lung injury and normal rats. The differentially expressed proteins (DEPs) were identified by tandem mass spectrometry. Bioinformatic analysis was used to assess the biological processes and signaling pathways associated with these DEPs. A total of 310 DEPs were found, of which 244 were upregulated and 66 were downregulated. KEGG anlysis showed that 'fatty acid degradation', 'fatty acid metabolism', 'fatty acid elongation', 'complement and coagulation cascades', 'peroxisome proliferator‑activated receptor signaling pathway' and 'hypoxia‑inducible factor signaling pathway' were significantly upregulated in the lung tissues of AA‑lung injury. Immunofluorescence staining confirmed the increased expression of clusterin, serine protease inhibitors and complement 1qc in lung tissue of rats with AA lung injury. In the present study, the results revealed the significance of certain DEPs (for example, C9, C1qc and Clu) in the occurrence and development of RA‑lung injury and provided support through experiments to identify potential biomarkers for the early diagnosis and prevention of RA‑lung injury.

Influenza A virus infection during pregnancy causes immunological changes in gut-associated lymphoid tissues of offspring mice

Maternal influenza A virus (IAV) infection during pregnancy can affect offspring immune programming and development. Offspring born from influenza-infected mothers are at increased risk of neurodevelopmental disorders and have impaired respiratory mucosal immunity against pathogens. The gut-associated lymphoid tissue (GALT) represents a large proportion of the immune system in the body and plays an important role in gastrointestinal (GI) homeostasis. This includes immune modulation to antigens derived from food or microbes, gut microbiota composition, and gut-brain axis signaling. Therefore, in this study, we investigated the effect of maternal IAV infection on mucosal immunity of the GI tract in the offspring. There were no major anatomical changes to the gastrointestinal tract of offspring born to influenza-infected dams. In contrast, maternal IAV did affect the mucosal immunity of offspring, showing regional differences in immune cell profiles within distinct GALT. Neutrophils, monocytes/macrophages, CD4+ and CD8+ T cells infiltration was increased in the cecal patch offspring from IAV-infected dams. In the Peyer's patches, only activated CD4+ T cells were increased in IAV offspring. IL-6 gene expression was also elevated in the cecal patch but not in the Peyer's patches of IAV offspring. These findings suggest that maternal IAV infection perturbs homeostatic mucosal immunity in the offspring gastrointestinal tract. This could have profound ramifications on the gut-brain axis and mucosal immunity in the lungs leading to increased susceptibility to respiratory infections and neurological disorders in the offspring later in life.NEW & NOTEWORTHY Influenza A virus (IAV) infection during pregnancy is associated with changes in gut-associated lymphoid tissue (GALT) in the offspring in a region-dependent manner. Neutrophils and monocytes/macrophages were elevated in the cecal patch of offspring from infected dams. This increase in innate immune cell infiltration was not observed in the Peyer's patches. T cells were also elevated in the cecal patch but not in the Peyer's patches.

Regionalization of the antiviral response in the gastrointestinal tract to provide spatially controlled host/pathogen interactions

As the largest mucosal surface, the gastrointestinal (GI) tract plays a key role in protecting the host against pathogen infections. It is a first line of defense against enteric viruses and must act to control infection while remaining tolerant to the high commensal bacteria load found within the GI tract. The GI tract can be divided into six main sections (stomach, duodenum, jejunum, ileum, colon, and rectum), and enteric pathogens have evolved to infect distinct parts of the GI tract. The intestinal epithelial cells (IECs) lining the GI tract are immune competent and can counteract these infections through their intrinsic immune response. Type I and type III interferons (IFNs) are antiviral cytokines that play a key role in protecting IECs against viruses with the type III IFN being the most important. Recent work has shown that IECs derived from the different sections of the GI tract display a unique expression of pattern recognition receptors used to fight pathogen infections. Additionally, it was also shown that these cells show a section-specific response to enteric viruses. This mini-review will discuss the molecular strategies used by IECs to detect and combat enteric viruses highlighting the differences existing along the entero-caudal axis of the GI tract. We will provide a perspective on how these spatially controlled mechanisms may influence virus tropism and discuss how the intestinal micro-environment may further shape the response of IECs to virus infections.

Restoration of dysregulated intestinal barrier and inflammatory regulation through synergistically ameliorating hypoxia and scavenging reactive oxygen species using ceria nanozymes in ulcerative colitis

BACKGROUND

Reactive oxygen species (ROS) overproduction and excessive hypoxia play pivotal roles in the initiation and progression of ulcerative colitis (UC). Synergistic ROS scavenging and generating O₂ could be a promising strategy for UC treatment.

METHODS

Ceria nanozymes (PEG-CNPs) are fabricated using a modified reverse micelle method. We investigate hypoxia attenuating and ROS scavenging of PEG-CNPs in intestinal epithelial cells and RAW 264.7 macrophages and their effects on pro-inflammatory macrophages activation. Subsequently, we investigate the biodistribution, pharmacokinetic properties and long-term toxicity of PEG-CNPs in mice. PEG-CNPs are administered intravenously to mice with 2,4,6-trinitrobenzenesulfonic acid-induced colitis to test their colonic tissue targeting and assess their anti-inflammatory activity and mucosal healing properties in UC.

RESULTS

PEG-CNPs exhibit multi-enzymatic activity that can scavenge ROS and generate O₂, promote intestinal epithelial cell healing and inhibit pro-inflammatory macrophage activation, and have good biocompatibility. After intravenous administration of PEG-CNPs to colitis mice, they can enrich at the site of colonic inflammation, and reduce hypoxia-induced factor-1α expression in intestinal epithelial cells by scavenging ROS to generate O₂, thus further promoting disrupted intestinal mucosal barrier restoration. Meanwhile, PEG-CNPs can effectively scavenge ROS in impaired colon tissues and relieve colonic macrophage hypoxia to suppress the pro-inflammatory macrophages activation, thereby preventing UC occurrence and development.

CONCLUSION

This study has provided a paradigm to utilize metallic nanozymes, and suggests that further materials engineering investigations could yield a facile method based on the pathological characteristics of UC for clinically managing UC.

Bacterial Lysate from the Multi-Strain Probiotic SLAB51 Triggers Adaptative Responses to Hypoxia in Human Caco-2 Intestinal Epithelial Cells under Normoxic Conditions and Attenuates LPS-Induced Inflammatory Response

Hypoxia-inducible factor-1α (HIF-1α), a central player in maintaining gut-microbiota homeostasis, plays a pivotal role in inducing adaptive mechanisms to hypoxia and is negatively regulated by prolyl hydroxylase 2 (PHD2). HIF-1α is stabilized through PI3K/AKT signaling regardless of oxygen levels. Considering the crucial role of the HIF pathway in intestinal mucosal physiology and its relationships with gut microbiota, this study aimed to evaluate the ability of the lysate from the multi-strain probiotic formulation SLAB51 to affect the HIF pathway in a model of in vitro human intestinal epithelium (intestinal epithelial cells, IECs) and to protect from lipopolysaccharide (LPS) challenge. The exposure of IECs to SLAB51 lysate under normoxic conditions led to a dose-dependent increase in HIF-1α protein levels, which was associated with higher glycolytic metabolism and L-lactate production. Probiotic lysate significantly reduced PHD2 levels and HIF-1α hydroxylation, thus leading to HIF-1α stabilization. The ability of SLAB51 lysate to increase HIF-1α levels was also associated with the activation of the PI3K/AKT pathway and with the inhibition of NF-κB, nitric oxide synthase 2 (NOS2), and IL-1β increase elicited by LPS treatment. Our results suggest that the probiotic treatment, by stabilizing HIF-1α, can protect from an LPS-induced inflammatory response through a mechanism involving PI3K/AKT signaling.

Agaricus subrufescens fermented rye affects the development of intestinal microbiota, local intestinal and innate immunity in suckling-to-nursery pigs

BACKGROUND

Agaricus subrufescens is considered as one of the most important culinary-medicinal mushrooms around the world. It has been widely suggested to be used for the development of functional food ingredients to promote human health ascribed to the various properties (e.g., anti-inflammatory, antioxidant, and immunomodulatory activities). In this context, the interest in A. subrufescens based feed ingredients as alternatives for antibiotics has also been fuelled during an era of reduced/banned antibiotics use. This study aimed to investigate the effects of a fermented feed additive -rye overgrown with mycelium (ROM) of A. subrufescens-on pig intestinal microbiota, mucosal gene expression and local and systemic immunity during early life. Piglets received ROM or a tap water placebo (Ctrl) perorally every other day from day 2 after birth until 2 weeks post-weaning. Eight animals per treatment were euthanized and dissected on days 27, 44 and 70.

RESULTS

The results showed ROM piglets had a lower inter-individual variation of faecal microbiota composition before weaning and a lower relative abundance of proteobacterial genera in jejunum (Undibacterium and Solobacterium) and caecum (Intestinibacter and Succinivibrionaceae_UCG_001) on day 70, as compared to Ctrl piglets. ROM supplementation also influenced gut mucosal gene expression in both ileum and caecum on day 44. In ileum, ROM pigs showed increased expression of TJP1/ZO1 but decreased expression of CLDN3, CLDN5 and MUC2 than Ctrl pigs. Genes involved in TLR signalling (e.g., TICAM2, IRAK4 and LY96) were more expressed but MYD88 and TOLLIP were less expressed in ROM pigs than Ctrl animals. NOS2 and HIF1A involved in redox signalling were either decreased or increased in ROM pigs, respectively. In caecum, differentially expressed genes between two groups were mainly shown as increased expression (e.g., MUC2, PDGFRB, TOLLIP, TNFAIP3 and MYD88) in ROM pigs. Moreover, ROM animals showed higher NK cell activation in blood and enhanced IL-10 production in ex vivo stimulated MLN cells before weaning.

CONCLUSIONS

Collectively, these results suggest that ROM supplementation in early life modulates gut microbiota and (local) immune system development. Consequently, ROM supplementation may contribute to improving health of pigs during the weaning transition period and reducing antibiotics use.

Hypoxia inducible factor prolyl hydroxylases in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic disease that is characterized by intestinal inflammation. Epithelial damage and loss of intestinal barrier function are believed to be the hallmark pathologies of the disease. In IBD, the resident and infiltrating immune cells consume much oxygen, rendering the inflamed intestinal mucosa hypoxic. In hypoxia, the hypoxia-inducible factor (HIF) is induced to cope with the lack of oxygen and protect intestinal barrier. Protein stability of HIF is tightly controlled by prolyl hydroxylases (PHDs). Stabilization of HIF through inhibition of PHDs is appearing as a new strategy of IBD treatment. Studies have shown that PHD-targeting is beneficial to the treatment of IBD. In this Review, we summarize the current understanding of the role of HIF and PHDs in IBD and discuss the therapeutic potential of targeting PHD-HIF pathway for IBD treatment.

Physiological hypoxia improves growth and functional differentiation of human intestinal epithelial organoids

Background

The epithelium in the colonic mucosa is implicated in the pathophysiology of various diseases, including inflammatory bowel diseases and colorectal cancer. Intestinal epithelial organoids from the colon (colonoids) can be used for disease modeling and personalized drug screening. Colonoids are usually cultured at 18-21% oxygen without accounting for the physiological hypoxia in the colonic epithelium (3% to <1% oxygen). We hypothesize that recapitulating the in vivo physiological oxygen environment (i.e., physioxia) will enhance the translational value of colonoids as pre-clinical models. Here we evaluate whether human colonoids can be established and cultured in physioxia and compare growth, differentiation, and immunological responses at 2% and 20% oxygen.

Methods

Growth from single cells to differentiated colonoids was monitored by brightfield images and evaluated with a linear mixed model. Cell composition was identified by immunofluorescence staining of cell markers and single-cell RNA-sequencing (scRNA-seq). Enrichment analysis was used to identify transcriptomic differences within cell populations. Pro-inflammatory stimuli induced chemokines and Neutrophil gelatinase-associated lipocalin (NGAL) release were analyzed by Multiplex profiling and ELISA. Direct response to a lower oxygen level was analyzed by enrichment analysis of bulk RNA sequencing data.

Results

Colonoids established in a 2% oxygen environment acquired a significantly larger cell mass compared to a 20% oxygen environment. No differences in expression of cell markers for cells with proliferation potential (KI67 positive), goblet cells (MUC2 positive), absorptive cells (MUC2 negative, CK20 positive) and enteroendocrine cells (CGA positive) were found between colonoids cultured in 2% and 20% oxygen. However, the scRNA-seq analysis identified differences in the transcriptome within stem-, progenitor- and differentiated cell clusters. Both colonoids grown at 2% and 20% oxygen secreted CXCL2, CXCL5, CXCL10, CXCL12, CX3CL1 and CCL25, and NGAL upon TNF + poly(I:C) treatment, but there appeared to be a tendency towards lower pro-inflammatory response in 2% oxygen. Reducing the oxygen environment from 20% to 2% in differentiated colonoids altered the expression of genes related to differentiation, metabolism, mucus lining, and immune networks.

Conclusions

Our results suggest that colonoids studies can and should be performed in physioxia when the resemblance to in vivo conditions is important.

Hypoxia-Inducible Factor 1-Alpha Stabilizers in the Treatment of Inflammatory Bowel Diseases: Oxygen as a Novel IBD Therapy?

Despite the significant advances in the medical armamentarium for inflammatory bowel diseases [IBD], current treatment options have notable limitations. Durable remission rates remain low, loss of response is common, administration routes are largely parenteral for novel biologics, and medication safety remains a concern. This explains an ongoing unmet need for safe medications with novel mechanisms of action that are administered orally. In line with these criteria, hypoxia-inducible factor [HIF]-1α stabilizers, acting via inhibition of prolyl hydroxylase enzymes, are emerging as an innovative therapeutic strategy. We herein review the mechanism of action and available clinical data for HIF-1α stabilizers and their potential place in the future IBD treatment algorithm.

Polysaccharides influence human health via microbiota-dependent and -independent pathways

Polysaccharides are the most diverse molecules and can be extracted from abundant edible materials. Increasing research has been conducted to clarify the structure and composition of polysaccharides obtained from different materials and their effects on human health. Humans can only directly assimilate very limited polysaccharides, most of which are conveyed to the distal gut and fermented by intestinal microbiota. Therefore, the main mechanism underlying the bioactive effects of polysaccharides on human health involves the interaction between polysaccharides and microbiota. Recently, interest in the role of polysaccharides in gut health, obesity, and related disorders has increased due to the wide range of valuable biological activities of polysaccharides. The known roles include mechanisms that are microbiota-dependent and involve microbiota-derived metabolites and mechanisms that are microbiota-independent. In this review, we discuss the role of polysaccharides in gut health and metabolic diseases and the underlying mechanisms. The findings in this review provide information on functional polysaccharides in edible materials and facilitate dietary recommendations for people with health issues. To uncover the effects of polysaccharides on human health, more clinical trials should be conducted to confirm the therapeutic effects on gut and metabolic disease. Greater attention should be directed toward polysaccharide extraction from by-products or metabolites derived from food processing that are unsuitable for direct consumption, rather than extracting them from edible materials. In this review, we advanced the understanding of the structure and composition of polysaccharides, the mutualistic role of gut microbes, the metabolites from microbiota-fermenting polysaccharides, and the subsequent outcomes in human health and disease. The findings provide insight into the proper application of polysaccharides in improving human health.

Comparison of risk of peritoneal dialysis-associated peritonitis between roxadustat and recombinant human erythropoietin in peritoneal dialysis patients: a retrospective comparative cohort study

Background

Roxadustat and recombinant human erythropoietin (rhuEPO) have been approved for the treatment of renal anemia in patients undergoing dialysis. The comparison of risk of peritoneal dialysis (PD)-associated peritonitis between roxadustat and rhuEPO in PD patients remains uncertain. We aimed to compare the risk of PD-associated peritonitis between roxadustat and rhuEPO and examine possible modifiers for the comparison in PD patients.

Methods

A total of 437 PD patients with renal anemia (defined as hemoglobin ≤10.0 g/dL) from 4 centers were selected. Participants were scheduled for follow-up every 1-3 months at each center. We compared differences in baseline characteristics by medication group and 1:1 matching group based on propensity scores. PD-associated peritonitis was defined according to the International Society for Peritoneal Dialysis guidelines. Univariable and multivariable Cox proportional hazard analyses were performed to compare the risk of PD-associated peritonitis between roxadustat and rhuEPO in PD patients. Propensity score matching method was used to examine the robustness of results.

Results

A total of 437 participants, including 291 in roxadustat group and 146 in rhuEPO group, were included in the current study, respectively. During a median follow-up of 13.0 (25th-75th, 10.0-15.0) months, PD-associated peritonitis occurred in 68 patients, including 26 of 291 (0.10 episodes per patient-year) patients in the roxadustat group and 42 of 146 (0.27 episodes per patient-year) patients in the rhuEPO group. Overall, compared to patients in the rhuEPO group, the roxadustat group (hazard ratio, 0.345; 95% confidence interval: 0.202-0.589) was associated with a lower risk of PD-associated peritonitis with adjustment of use of roxadustat medication, age, sex, hypertension status, diabetes status, dialysis vintage, serum potassium, hemoglobin, and albumin. Furthermore, the results were consistent with the propensity score analysis. None of the variables, including age, sex, body mass index, PD vintage, presence of residual renal function, hemoglobin, albumin, serum potassium, and C-reactive protein levels, significantly modified the associations.

Conclusions

Our study demonstrated that compared with rhuEPO, roxadustat may reduce the risk of PD-associated peritonitis in PD patients, highlighting the importance of roxadustat for the prevention of PD-associated peritonitis in PD patients.

Emerging computational paradigms to address the complex role of gut microbial metabolism in cardiovascular diseases

The human gut microbiota and its associated perturbations are implicated in a variety of cardiovascular diseases (CVDs). There is evidence that the structure and metabolic composition of the gut microbiome and some of its metabolites have mechanistic associations with several CVDs. Nevertheless, there is a need to unravel metabolic behavior and underlying mechanisms of microbiome-host interactions. This need is even more highlighted when considering that microbiome-secreted metabolites contributing to CVDs are the subject of intensive research to develop new prevention and therapeutic techniques. In addition to the application of high-throughput data used in microbiome-related studies, advanced computational tools enable us to integrate omics into different mathematical models, including constraint-based models, dynamic models, agent-based models, and machine learning tools, to build a holistic picture of metabolic pathological mechanisms. In this article, we aim to review and introduce state-of-the-art mathematical models and computational approaches addressing the link between the microbiome and CVDs.

Essential role for epithelial HIF-mediated xenophagy in control of Salmonella infection and dissemination

The intestinal mucosa exists in a state of “physiologic hypoxia,” where oxygen tensions are markedly lower than those in other tissues. Intestinal epithelial cells (IECs) have evolved to maintain homeostasis in this austere environment through oxygen-sensitive transcription factors, including hypoxia-inducible factors (HIFs). Using an unbiased chromatin immunoprecipitation (ChIP) screen for HIF-1 targets, we identify autophagy as a major pathway induced by hypoxia in IECs. One important function of autophagy is to defend against intracellular pathogens, termed “xenophagy.” Analysis reveals that HIF is a central regulator of autophagy and that in vitro infection of IECs with Salmonella Typhimurium results in induction of HIF transcriptional activity that tracks with the clearance of intracellular Salmonella. Work in vivo demonstrates that IEC-specific deletion of HIF compromises xenophagy and exacerbates bacterial dissemination. These results reveal that the interaction between hypoxia, HIF, and xenophagy is an essential innate immune component for the control of intracellular pathogens.

Dowdell et al. show that hypoxia, through stabilization of HIF-1α, activates autophagy in intestinal epithelial cells (IECs). Further, the model invasive bacterium Salmonella Typhimurium stabilizes HIF in IECs to trigger anti-bacterial autophagy (xenophagy). This mechanism demonstrates an essential mucosal innate immune response for control of invasive pathogens.

Hypoxia-inducible factor as a bridge between healthy barrier function, wound healing, and fibrosis

The healthy mammalian intestine is lined by a single layer of epithelial cells. These cells provide a selectively permeable barrier to luminal contents and normally do so in an efficient and effective manner. Barrier function in the healthy mucosa is provided via several mechanisms including epithelial junctional complexes, mucus production, as well as mucosal-derived antimicrobial proteins. As tissue metabolism is central to the maintenance of homeostasis in the mucosa, intestinal [Formula: see text] levels are uniquely low due to counter-current blood flow and the presence of the microbiota, resulting in the stabilization of the transcription factor hypoxia-inducible factor (HIF). Ongoing studies have revealed that HIF molds normal intestinal metabolism and is central to the coordination of barrier regulation during both homeostasis and active disease. During acute inflammation, HIF is central to controlling the rapid restitution of the epithelium consistent with normal wound healing responses. In contrast, HIF may also contribute to the fibrostenotic response associated with chronic, nonresolving inflammation. As such, HIF may function as a double-edged sword in the overall course of the inflammatory response. Here, we review recent literature on the contribution of HIF to mucosal barrier function, wound healing, and fibrosis.

High performance inkjet printed embedded electrochemical sensors for monitoring hypoxia in a gut bilayer microfluidic chip

Sensing devices have shown tremendous potential for monitoring state-of-the-art organ chip devices. However, challenges like miniaturization while maintaining higher performance, longer operating times for continuous monitoring, and fabrication complexities limit their use. Herein simple, low-cost, and solution-processible inkjet dispenser printing of embedded electrochemical sensors for dissolved oxygen (DO) and reactive oxygen species (ROS) is proposed for monitoring developmental (initially normoxia) and induced hypoxia in a custom-developed gut bilayer microfluidic chip platform for 6 days. The DO sensors showed a high sensitivity of 31.1 nA L mg^-1 with a limit of detection (LOD) of 0.67 mg L^-1 within the 0-9 mg L^-1 range, whereas the ROS sensor had a higher sensitivity of 1.44 nA μm^-1 with a limit of detection of 1.7 μm within the 0-300 μm range. The dynamics of the barrier tight junctions are quantified with the help of an in-house developed trans-epithelial-endothelial electrical impedance (TEEI) sensor. Immunofluorescence staining was used to evaluate the expressions of HIF-1α and tight junction protein (TJP) ZO-1. This platform can also be used to enhance bioavailability assays, drug transport studies under an oxygen-controlled environment, and even other barrier organ models, as well as for various applications like toxicity testing, disease modeling and drug screening.

The role of the mitochondrial protein VDAC1 in inflammatory bowel disease: a potential therapeutic target

Recent studies have implicated mitochondrial dysfunction as a trigger of inflammatory bowel diseases, including Crohn's disease (CD) and ulcerative colitis (UC). We have investigated the role of the mitochondria gate-keeper protein, the voltage-dependent-anion channel 1 (VDAC1), in gastrointestinal inflammation and tested the effects of the newly developed VDAC1-interacting molecules, VBIT-4 and VBIT-12, on UC induced by dextran sulfate sodium (DSS) or trinitrobenzene sulphonic acid (TNBS) in mice. VDAC1, which controls metabolism, lipids transport, apoptosis, and inflammasome activation, is overexpressed in the colon of CD and UC patients and DSS-treated mice. VBIT-12 treatment of cultured colon cells inhibited the DSS-induced VDAC1 overexpression, oligomerization, and apoptosis. In the DSS-treated mice, VBIT-12 suppressed weight loss, diarrhea, rectal bleeding, pro-inflammatory cytokine production, crypt and epithelial cell damage, and focal inflammation. VBIT-12 also inhibited the infiltration of inflammatory cells, apoptosis, mtDNA release, and activation of caspase-1 and NRLP3 inflammasome to reduce the inflammatory response. The levels of the ATP-gated P2X7-Ca2+/K+ channel and ER-IP3R-Ca2+ channel, and of the mitochondrial anti-viral protein (MAVS), mediating NLRP3 inflammasome assembly and activation, were highly increased in DSS-treated mice, but not when VBIT-12 treated. We conclude that UC may be promoted by VDAC1-overexpression and may therefore be amenable to treatment with novel VDAC1-interacting molecules. This VDAC1-based strategy exploits a completely new target for UC treatment and opens a new avenue for treating other inflammatory/autoimmune diseases.

HIF-1α Stabilization in Flagellin-Stimulated Human Bronchial Cells Impairs Barrier Function

The respiratory epithelium provides a first line of defense against pathogens. Hypoxia-inducible factor (HIF)1α is a transcription factor which is stabilized in hypoxic conditions through the inhibition of prolyl-hydroxylase (PHD)2, the enzyme that marks HIF1α for degradation. Here, we studied the impact of HIF1α stabilization on the response of primary human bronchial epithelial (HBE) cells to the bacterial component, flagellin. The treatment of flagellin-stimulated HBE cells with the PHD2 inhibitor IOX2 resulted in strongly increased HIF1α expression. IOX2 enhanced the flagellin-induced expression of the genes encoding the enzymes involved in glycolysis, which was associated with the intracellular accumulation of pyruvate. An untargeted pathway analysis of RNA sequencing data demonstrated the strong inhibitory effects of IOX2 toward key innate immune pathways related to cytokine and mitogen-activated kinase signaling cascades in flagellin-stimulated HBE cells. Likewise, the cell-cell junction organization pathway was amongst the top pathways downregulated by IOX2 in flagellin-stimulated HBE cells, which included the genes encoding claudins and cadherins. This IOX2 effect was corroborated by an impaired barrier function, as measured by dextran permeability. These results provide a first insight into the effects associated with HIF1α stabilization in the respiratory epithelium, suggesting that HIF1α impacts properties that are key to maintaining homeostasis upon stimulation with a relevant bacterial agonist.

Microenvironmental Metabolites in the Intestine: Messengers between Health and Disease

The intestinal mucosa is a highly absorptive organ and simultaneously constitutes the physical barrier between the host and a complex outer ecosystem. Intestinal epithelial cells (IECs) represent a special node that receives signals from the host and the environment and translates them into corresponding responses. Specific molecular communication systems such as metabolites are known to transmit information across the intestinal boundary. The gut microbiota or food-derived metabolites are extrinsic factors that influence the homeostasis of the intestinal epithelium, while mitochondrial and host-derived cellular metabolites determine the identity, fitness, and regenerative capacity of IECs. Little is known, however, about the role of intrinsic and extrinsic metabolites of IECs in the initiation and progression of pathological processes such as inflammatory bowel disease and colorectal cancer as well as about their impact on intestinal immunity. In this review, we will highlight the most recent contributions on the modulatory effects of intestinal metabolites in gut pathophysiology, with a particular focus on metabolites in promoting intestinal inflammation or colorectal tumorigenesis. In addition, we will provide a perspective on the role of newly identified oncometabolites from the commensal and opportunistic microbiota in shaping response and resistance to antitumor therapy.

New Therapeutic Approach for Intestinal Fibrosis Through Inhibition of pH-Sensing Receptor GPR4

BACKGROUND

Patients suffering from inflammatory bowel diseases (IBDs) express increased mucosal levels of pH-sensing receptors compared with non-IBD controls. Acidification leads to angiogenesis and extracellular matrix remodeling. We aimed to determine the expression of pH-sensing G protein-coupled receptor 4 (GPR4) in fibrotic lesions in Crohn's disease (CD) patients. We further evaluated the effect of deficiency in Gpr4 or its pharmacologic inhibition.

METHODS

Paired samples from fibrotic and nonfibrotic terminal ileum were obtained from CD patients undergoing ileocaecal resection. The effects of Gpr4 deficiency were assessed in the spontaneous Il-10-/- and the chronic dextran sodium sulfate (DSS) murine colitis model. The effects of Gpr4 deficiency and a GPR4 antagonist (39c) were assessed in the heterotopic intestinal transplantation model.

RESULTS

In human terminal ileum, increased expression of fibrosis markers was accompanied by an increase in GPR4 expression. A positive correlation between the expression of procollagens and GPR4 was observed. In murine disease models, Gpr4 deficiency was associated with a decrease in angiogenesis and fibrogenesis evidenced by decreased vessel length and expression of Edn, Vegfα, and procollagens. The heterotopic animal model for intestinal fibrosis, transplanted with terminal ileum from Gpr4-/- mice, revealed a decrease in mRNA expression of fibrosis markers and a decrease in collagen content and layer thickness compared with grafts from wild type mice. The GPR4 antagonist decreased collagen deposition. The GPR4 expression was also observed in human and murine intestinal fibroblasts. The GPR4 inhibition reduced markers of fibroblast activation stimulated by low pH, notably Acta2 and cTgf.

CONCLUSIONS

Expression of GPR4 positively correlates with the expression of profibrotic genes and collagen. Deficiency of Gpr4 is associated with a decrease in angiogenesis and fibrogenesis. The GPR4 antagonist decreases collagen deposition. Targeting GPR4 with specific inhibitors may constitute a new treatment option for IBD-associated fibrosis.

Stabilization but no functional influence of HIF-1α expression in the intestinal epithelium during Salmonella Typhimurium infection

The hypoxia-inducible transcription factor 1 (HIF-1) has been shown to enhance microbial killing and to ameliorate the course of bacterial infections. While the impact of HIF-1 on inflammatory diseases of the gut has been studied intensively, its function in bacterial infections of the gastrointestinal tract remains largely elusive. With the help of a publicly available gene expression data set, we could infer significant activation of HIF-1 after oral infection of mice with Salmonella Typhimurium. Immunohistochemistry and western blot analysis confirmed marked HIF-1α protein stabilization, especially in the intestinal epithelium. This prompted us to analyze conditional Hif1a-deficient mice to examine cell type-specific functions of HIF-1 in this model. Our results demonstrate enhanced non-canonical induction of HIF-1 activity upon Salmonella infection in the intestinal epithelium as well as in macrophages. Surprisingly, Hif1a deletion in intestinal epithelial cells did not impact on inflammatory gene expression, bacterial spread or disease outcome. In contrast, Hif1a deletion in myeloid cells enhanced intestinal Cxcl2 expression and reduced the cecal Salmonella load. In vitro, HIF-1α-deficient macrophages showed an overall impaired transcription of mRNA encoding pro-inflammatory factors, however, intracellular survival of Salmonella was not impacted by HIF-1α deficiency.

S3QELs protect against diet-induced intestinal barrier dysfunction

The underlying causes of aging remain elusive, but may include decreased intestinal homeostasis followed by disruption of the intestinal barrier, which can be mimicked by nutrient‐rich diets. S3QELs are small‐molecule suppressors of site III_Qo electron leak; they suppress superoxide generation at complex III of the mitochondrial electron transport chain without inhibiting oxidative phosphorylation. Here we show that feeding different S3QELs to Drosophila on a high‐nutrient diet protects against greater intestinal permeability, greater enterocyte apoptotic cell number, and shorter median lifespan. Hif‐1α knockdown in enterocytes also protects, and blunts any further protection by S3QELs. Feeding S3QELs to mice on a high‐fat diet also protects against the diet‐induced increase in intestinal permeability. Our results demonstrate by inference of S3QEL use that superoxide produced by complex III in enterocytes contributes to diet‐induced intestinal barrier disruption in both flies and mice.

Long-Term Environmental Hypoxia Exposure and Haematopoietic Prolyl Hydroxylase-1 Deletion Do Not Impact Experimental Crohn's Like Ileitis

Simple Summary

Hypoxia-induced signalling represents an important contributor to inflammatory bowel disease (IBD) pathophysiology. However, available data solely focus on colonic inflammation while the primary disease location in Crohn’s disease patients is the terminal ileum. Therefore, we explored the effects of environmental hypoxia and immune cell-specific deletion of oxygen sensor prolyl hydroxylase (PHD) 1 in a Crohn’s like ileitis mouse model. Five-week-old TNF^∆ARE/+ mice and wildtype (WT) littermates were housed in normoxia (21% O₂) or hypoxia (8% O₂) for 10 weeks. Although environmental hypoxia increased both systemic as ileal markers of hypoxia, the body weight evolution in both WT and TNF^∆ARE/+ mice was not affected. Interestingly, hypoxia did increase circulatory monocytes, ileal mononuclear phagocytes and proinflammatory cytokine expression in WT mice. However, no histological or inflammatory gene expression differences in the ileum could be identified between TNF^∆ARE/+ mice housed in hypoxia versus normoxia nor between TNF^∆ARE/+ and WT mice with additional loss of immune cell-specific Phd1 expression. This is the first study showing that long-term environmental hypoxia or haematopoietic Phd1-deletion does not impact experimental ileitis. Therefore, it strongly questions whether targeting hypoxia-induced signalling via currently available PHD inhibitors would exert an immune suppressive effect in IBD patients with ileal inflammation.

Abstract

Environmental hypoxia and hypoxia-induced signalling in the gut influence inflammatory bowel disease pathogenesis, however data is limited to colitis. Hence, we investigated the effect of environmental hypoxia and immune cell-specific deletion of oxygen sensor prolyl hydroxylase (PHD) 1 in a Crohn’s like ileitis mouse model. Therefore, 5-week-old C57/BL6 TNF^∆ARE/+ mice and wildtype (WT) littermates were housed in normoxia (21% O₂) or hypoxia (8% O₂) for 10 weeks. Systemic inflammation was assessed by haematology. Distal ileal hypoxia was evaluated by pimonidazole staining. The ileitis degree was scored on histology, characterized via qPCR and validated in haematopoietic Phd1-deficient TNF^∆ARE/+ mice. Our results demonstrated that hypoxia did not impact body weight evolution in WT and TNF^∆ARE/+ mice. Hypoxia increased red blood cell count, haemoglobin, haematocrit and increased pimonidazole intensity in the ileum. Interestingly, hypoxia evoked an increase in circulatory monocytes, ileal mononuclear phagocytes and proinflammatory cytokine expression in WT mice. Despite these alterations, no histological or ileal gene expression differences could be identified between TNF^∆ARE/+ mice housed in hypoxia versus normoxia nor between haematopoietic Phd1-deficient TNF^∆ARE/+ and their WT counterparts. Therefore, we demonstrated for the first time that long-term environmental hypoxia or haematopoietic Phd1-deletion does not impact experimental ileitis development.

Metabolic networks in mutant KRAS-driven tumours: tissue specificities and the microenvironment

Oncogenic mutations in KRAS drive common metabolic programmes that facilitate tumour survival, growth and immune evasion in colorectal carcinoma, non-small-cell lung cancer and pancreatic ductal adenocarcinoma. However, the impacts of mutant KRAS signalling on malignant cell programmes and tumour properties are also dictated by tumour suppressor losses and physiological features specific to the cell and tissue of origin. Here we review convergent and disparate metabolic networks regulated by oncogenic mutant KRAS in colon, lung and pancreas tumours, with an emphasis on co-occurring mutations and the role of the tumour microenvironment. Furthermore, we explore how these networks can be exploited for therapeutic gain.

Imitating Hypoxia and Tumor Microenvironment with Immune Evasion by Employing Three Dimensional in vitro Cellular Models: Impressive Tool in Drug Discovery

The heterogeneous tumor microenvironment is exceptionally perplexing and not wholly comprehended. Different multifaceted alignments lead to the generation of oxygen destitute situations within the tumor niche that modulate numerous intrinsic tumor microenvironments. Disentangling these communications is vital for scheming practical therapeutic approaches that can successfully decrease tumor allied chemotherapy resistance by utilizing the innate capability of the immune system. Several research groups have concerned with a protruding role for oxygen metabolism along with hypoxia in the immunity of healthy tissue. Hypoxia in addition to hypoxia-inducible factors (HIFs) in the tumor microenvironment plays an important part in tumor progression and endurance. Although numerous hypoxia-focused therapies have shown promising outcomes both in vitro and in vivo these outcomes have not effectively translated into clinical preliminaries. Distinctive cell culture techniques have utilized as an in vitro model for tumor niche along with tumor microenvironment and proficient in more precisely recreating tumor genomic profiles as well as envisaging therapeutic response. To study the dynamics of tumor immune evasion, three-dimensional (3D) cell cultures are more physiologically important to the hypoxic tumor microenvironment. Recent research has revealed new information and insights into our fundamental understanding of immune systems, as well as novel results that have been established as potential therapeutic targets. There are a lot of patented 3D cell culture techniques which will be highlighted in this review. At present notable 3D cell culture procedures in the hypoxic tumor microenvironment, discourse open doors to accommodate both drug repurposing, advancement, and divulgence of new medications and will deliberate the 3D cell culture methods into standard prescription disclosure especially in the field of cancer biology which will be discussing here.

Network pharmacology dissection of multiscale mechanisms for jiaoqi powder in treating ulcerative colitis

ETHNOPHARMACOLOGICAL RELEVANCE

The incidence of ulcerative colitis (UC) is increasing worldwide, making it a serious public health challenge. Currently, there are no accepted curative treatments for UC. As such, the exploration of new therapeutic strategies for UC treatment is of considerable clinical importance. Jiaoqi powder (JQP) is a classic Chinese medicinal formula commonly used as a complementary and alternative medicine for treating gastrointestinal bleeding. JQP is thus a potential alternative medicine for UC treatment. However, the protective mechanism underlying the action of JQP has not been elucidated, thereby, necessitating further studies to decipher the mechanisms involved in the complex interplay among its components.

AIM OF THE STUDY

To explore the protective effect of JQP against UC and to further investigate its mechanism in silico and in vivo using a systems pharmacology approach.

MATERIALS AND METHODS

A systems pharmacology approach was used to predict the active components of JQP. Putative targets and the potential mechanism of JQP on UC were obtained through target fishing, network construction, and enrichment analyses. An animal-based model of dextran sodium sulfate (DSS)-induced colitis in C57BL/6 mice was further used to validate the treatment mechanisms of JQP. The underlying pharmacological mechanisms of JQP in UC were determined using polymerase chain reaction tests, histological staining, immunohistochemistry, enzyme-linked immunoassays, and flow cytometry analysis.

RESULTS

In this study, 17 effective components and 941 potential targets of JQP were identified. Similarly, 2104 UC-related targets were also identified. Construction of PPI networks led to the identification of 184 putative therapeutic targets of JQP. Sixty-nine core targets among these 184 were further screened based on their DC values. Gene ontology (GO) functional and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses revealed that the core targets were primarily enriched in immune response and inflammatory signalling pathways. Subsequent animal-based in vivo experiments revealed that JQP ameliorated symptoms and histological changes in DSS colitis by significantly impairing DSS's ability to induce high expression levels of NF-κB/p65, IL-1β, IL-6, and TNF-α. JQP also reduced the levels of COX-2, CCL2, CXCL2, HIF-1α, MMP3 and MMP9 and regulated the Th17/Treg cell balance in DSS-induced mice.

CONCLUSIONS

This study demonstrated that JQP could treat UC by improving the mucosal inflammatory response, repairing the intestinal barrier, and modulating the Th17/Treg immune balance. The results of this study provide new insights into UC treatment and further elucidate the theoretical and practical implications of the pharmaceutical development of TCMs.

Hypoxia Reduces the Transcription of Fibrotic Markers in the Intestinal Mucosa

Introduction

Intestinal fibrosis, characterized by excessive deposition of extracellular matrix proteins, is a common and severe clinical complication of inflammatory bowel disease (IBD). However, the mechanisms underlying fibrosis remain elusive, and currently, there are limited effective pharmacologic treatments that target the development of fibrosis. Hypoxia is one of the key microenvironmental factors influencing intestinal inflammation and has been linked to fibrosis.

Objective

In the present study, we sought to elucidate the impact of hypoxia on fibrotic gene expression in the intestinal mucosa.

Methods

Human volunteers, IBD patients, and dextran sulphate sodium-treated mice were exposed to hypoxia, and colonic biopsies were collected. The human intestinal epithelial cell line Caco-2, human THP-1 macrophages, and primary human gut fibroblasts were subjected to hypoxia, and changes in fibrotic gene expression were assessed.

Results

Human volunteers subjected to hypoxia presented reduced transcriptional levels of fibrotic and epithelial-mesenchymal transition markers in the intestinal mucosa. IBD patients showed a trend towards a decrease in tissue inhibitor of metalloproteinase 1 protein expression. In mice, hypoxic conditions reduced the colonic expression of several collagens and matrix metalloproteinases. Hypoxic Caco-2 cells, THP-1 cells, and primary gut fibroblasts showed a significant downregulation in the expression of fibrotic and tissue remodelling factors.

Conclusions

Stabilization of hypoxia-inducible factors might represent a novel therapeutic approach for the treatment of IBD-associated fibrosis.

Hypoxia increases the expression of stem cell markers in human osteosarcoma cells

Osteosarcoma (OS) is the most common primary malignant tumor of bone. It is a common phenomenon that osteosarcoma cells have a hypoxic microenvironment. Hypoxia can dedifferentiate cells of several malignant tumor types into stem cell-like phenotypes. However, the role of hypoxia in stemness induction and the expression of cancer stem cell (CSC) markers in human osteosarcoma cells has not been reported. The present study examined the effects of hypoxia on stem-like cells in the human osteosarcoma MNNG/HOS cells. Under the incubation with 1% oxygen, the expression of CSCs markers (Oct-4, Nanog and CD133) in MNNG/HOS cells were increased. Moreover, MNNG/HOS cells cultured under hypoxic conditions were more likely to proliferate into spheres and resulted in larger xenograft tumor. Hypoxia also increased the mRNA and protein levels of hypoxia-inducible factor (HIF)-1α. Then rapamycin was used, which has been shown to lower HIF-1α protein level, to inhibit the hypoxic response. Rapamycin suppressed the expression of HIF-1α protein and CSCs markers (Oct4, Nanog and CD133) in MNNG/HOS cells. In addition, pretreatment with rapamycin reduced the efficiency of MNNG/HOS cells in forming spheres and xenograft tumors. The results demonstrated that hypoxia (1% oxygen) can dedifferentiate some of the MNNG/HOS cells into stem cell-like phenotypes, and that the mTOR signaling pathway participates in this process via regulating the expression of HIF-1α protein.

The Landscape of Interactions between Hypoxia-Inducible Factors and Reactive Oxygen Species in the Gastrointestinal Tract

The gastrointestinal tract (GT) is the major organ involved in digestion, absorption, and immunity, which is prone to oxidative destruction by high levels of reactive oxygen species (ROS) from luminal oxidants, such as food, drugs, and pathogens. Excessive ROS will lead to oxidative stresses and disrupt essential biomolecules, which also act as cellular signaling molecules in response to growth factors, hormones, and oxygen tension changes. Hypoxia-inducible factors (HIFs) are critical regulators mediating responses to cellular oxygen tension changes, which are also involved in energy metabolism, immunity, renewal, and microbial homeostasis in the GT. This review discusses interactions between HIF (mainly HIF-1α) and ROS and relevant diseases in the GT combined with our lab's work. It might help to develop new therapies for gastrointestinal diseases associated with ROS and HIF-1α.

Food Processing, Dysbiosis, Gastrointestinal Inflammatory Diseases, and Antiangiogenic Functional Foods or Beverages

Foods and beverages provide nutrients and alter the gut microbiota, resulting in eubiosis or dysbiosis. Chronic consumption of a diet that is high in saturated or trans fats, meat proteins, reducing sugars, and salt and low in fiber induces dysbiosis. Dysbiosis, loss of redox homeostasis, mast cells, hypoxia, angiogenesis, the kynurenine pathway, transglutaminase 2, and/or the Janus kinase pathway are implicated in the pathogenesis and development of inflammatory bowel disease, celiac disease, and gastrointestinal malignancy. This review discusses the effects of oxidative, carbonyl, or glycative stress-inducing dietary ingredients or food processing-derived compounds on gut microbiota and gastrointestinal epithelial and mast cells as well as on the development of associated angiogenic diseases, including key signaling pathways. The preventive or therapeutic potential and the biochemical pathways of antiangiogenic or proangiogenic foods or beverages are also described. The outcomes of the interactions between disease pathways and components of food are critical for the design of foods and beverages for healthy lives.

Intrauterine Hypoxia Changed the Colonization of the Gut Microbiota in Newborn Rats

Background: Accumulating evidence suggests a connection between the gut microbiota and neonatal diseases. Hypoxia may play an important role in the intestinal lesions in neonates. Objective: This study aims to determine whether the gut microbiota differs between intrauterine hypoxic rats and healthy controls and to identify the factors that influence the changes in the gut microbiota. Methods: We constructed an intrauterine hypoxia model in rats and collected the intestinal contents of intrauterine hypoxic newborn rats and normal newborn rats within 4 h and on the seventh day after birth. They were divided them into the intrauterine hypoxia first-day group (INH1), intrauterine hypoxia seventh-day group (INH7), normal first-day group (NOR1), and normal seventh-day group (NOR7). The contents of the intestines were sequenced with 16S rRNA sequencing, the sequencing results were analyzed for biological information, and the differences in the diversity, richness, and individual taxa among the groups were analyzed. Results: The abundance of the gut microbiota of neonatal rats with intrauterine hypoxia was higher than that of the control group rats. Intrauterine hypoxia altered the structural composition of the gut microbiota in neonatal rats. The INH1 group showed increased species richness, phylogenetic diversity, and β-diversity, and altered relative abundance in several taxa compared to those in the control group. The differences in the microbiota among the four groups were significantly higher than those within the group, and the differences in the abundance and diversity of the INH7 and NOR7 groups decreased after 7 days of suckling. Functional analysis based on the Cluster of Orthologous Groups (COG) suggested that 23 functional COG categories. There was no significant difference in the functional categories between the hypoxia group and the normal group. Conclusion: Intrauterine hypoxia changed the initial colonization of the gut microbiota in neonatal rats. It could increase the species richness and β-diversity of the gut microbiota, and altered relative abundances of several taxa.

Yak milk-derived exosomal microRNAs regulate intestinal epithelial cells on proliferation in hypoxic environment

Intestinal epithelial cells (IEC) act as an important intestinal barrier whose function can be impaired upon induction by hypoxia. Although intestinal barrier injuries are preventable by milk-derived exosomal microRNAs (miRNAs), the underlying mechanism remains poorly understood. This study aimed to characterize the effect of yak and cow milk-derived exosomal miRNA on the barrier function of IEC-6 under hypoxic conditions, and explore the mechanism of yak milk exosomal miRNA to relieve the hypoxia stress. First, by Illumina HiSeq 2500 (Illumina Inc., San Diego, CA) sequencing, the miRNA expression was systematically screened, and differential expression of 130 miRNAs was identified with 51 being upregulated and 79 downregulated in yak and cow milk-derived exosomes. Furthermore, the top 20 miRNAs that had a relatively consistent high expression in yak milk exosome were identified, and bta-miR-34a was found to be an effective regulator for alleviating hypoxic injury of IEC-6. In vitro assay of the role of bta-miR-34a on survival of IEC-6 in hypoxia by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) confirmed its effectiveness to significantly increase IEC-6 survival up to 13% for 12 h, and up to 9.5% for 24 h. Investigation on the regulatory relationship between bta-miRNA-34a and the hypoxia-inducible factor/apoptosis signaling pathway provided insights into the possible mechanisms by which bta-miR-34a activated the hypoxia-inducible factor and apoptosis signaling pathway, thus promoting IEC-6 survival. The results of this study suggest an important relationship between miRNA expression and intestine barrier integrity, which facilitated further understanding of the physiological function of yak and cow milk exosomal miRNAs, as well as mechanisms of hypoxia-driven epithelial homeostasis.

An update on T-2 toxin and its modified forms: metabolism, immunotoxicity mechanism, and human exposure assessment

T-2 toxin is the most toxic trichothecene mycotoxin, and it exerts potent toxic effects, including immunotoxicity, neurotoxicity, and reproductive toxicity. Recently, several novel metabolites, including 3',4'-dihydroxy-T-2 toxin and 4',4'-dihydroxy-T-2 toxin, have been uncovered. The enzymes CYP3A4 and carboxylesterase contribute to T-2 toxin metabolism, with 3'-hydroxy-T-2 toxin and HT-2 toxin as the corresponding primary products. Modified forms of T-2 toxin, including T-2-3-glucoside, exert their immunotoxic effects by signaling through JAK/STAT but not MAPK. T-2-3-glucoside results from hydrolyzation of the corresponding parent mycotoxin and other metabolites by the intestinal microbiota, which leads to enhanced toxicity. Increasing evidence has shown that autophagy, hypoxia-inducible factors, and exosomes are involved in T-2 toxin-induced immunotoxicity. Autophagy promotes the immunosuppression induced by T-2 toxin, and a complex crosstalk between apoptosis and autophagy exists. Very recently, "immune evasion" activity was reported to be associated with this toxin; this activity is initiated inside cells and allows pathogens to escape the host immune response. Moreover, T-2 toxin has the potential to trigger hypoxia in cells, which is related to activation of hypoxia-inducible factor and the release of exosomes, leading to immunotoxicity. Based on the data from a series of human exposure studies, free T-2 toxin, HT-2 toxin, and HT-2-4-glucuronide should be considered human T-2 toxin biomarkers in the urine. The present review focuses on novel findings related to the metabolism, immunotoxicity, and human exposure assessment of T-2 toxin and its modified forms. In particular, the immunotoxicity mechanisms of T-2 toxin and the toxicity mechanism of its modified form, as well as human T-2 toxin biomarkers, are discussed. This work will contribute to an improved understanding of the immunotoxicity mechanism of T-2 toxin and its modified forms.

Anti-inflammatory activities of green tea catechins along the gut-liver axis in nonalcoholic fatty liver disease: lessons learned from preclinical and human studies

Nonalcoholic fatty liver disease (NAFLD), which is the most prevalent hepatic disorder worldwide, affecting 25% of the general population, describes a spectrum of progressive liver conditions ranging from relatively benign liver steatosis and advancing to nonalcoholic steatohepatitis (NASH), fibrosis, and cirrhosis. Hallmark features of NASH are fatty hepatocytes and inflammatory cell infiltrates in association with increased activation of hepatic nuclear factor kappa-B (NFκB) that exacerbates liver injury. Because no pharmacological treatments exist for NAFLD, emphasis has been placed on dietary approaches to manage NASH risk. Anti-inflammatory bioactivities of catechin-rich green tea extract (GTE) have been well-studied, especially in preclinical models that have detailed its effects on inflammatory responses downstream of NFκB activation. This review will therefore discuss the experimental evidence that has advanced an understanding of the mechanisms by which GTE, either directly through its catechins or potentially indirectly through microbiota-derived metabolites, limits NFκB activation and NASH-associated liver injury. Specifically, it will describe the hepatic-level benefits of GTE that attenuate intracellular redox distress and pro-inflammatory signaling from extracellular receptors that otherwise activate NFκB. In addition, it will discuss the anti-inflammatory activities of GTE on gut barrier function as well as prebiotic and antimicrobial effects on gut microbial ecology that help to limit the translocation of gut-derived endotoxins (e.g. lipopolysaccharides) to the liver where they otherwise upregulate NFκB activation by Toll-like receptor-4 signaling. This summary is therefore expected to advance research translation of the hepatic- and intestinal-level benefits of GTE and its catechins to help manage NAFLD-associated morbidity.

Hypoxia and Innate Immunity: Keeping Up with the HIFsters

Recent years have witnessed an emergence of interest in understanding metabolic changes associated with immune responses, termed immunometabolism. As oxygen is central to all aerobic metabolism, hypoxia is now recognized to contribute fundamentally to inflammatory and immune responses. Studies from a number of groups have implicated a prominent role for oxygen metabolism and hypoxia in innate immunity of healthy tissue (physiologic hypoxia) and during active inflammation (inflammatory hypoxia). This inflammatory hypoxia emanates from a combination of recruited inflammatory cells (e.g., neutrophils, eosinophils, and monocytes), high rates of oxidative metabolism, and the activation of multiple oxygen-consuming enzymes during inflammation. These localized shifts toward hypoxia have identified a prominent role for the transcription factor hypoxia-inducible factor (HIF) in the regulation of innate immunity. Such studies have provided new and enlightening insight into our basic understanding of immune mechanisms, and extensions of these findings have identified potential therapeutic targets. In this review, we summarize recent literature around the topic of innate immunity and mucosal hypoxia with a focus on transcriptional responses mediated by HIF.

Human Milk Oligosaccharides Activate Epidermal Growth Factor Receptor and Protect Against Hypoxia-Induced Injuries in the Mouse Intestinal Epithelium and Caco2 Cells

BACKGROUND

Hypoxia-induced intestinal barrier injuries lead to necrotizing enterocolitis (NEC). Although NEC in preterm neonates is preventable by human milk oligosaccharides (HMOs), the underlying mechanism remains unknown.

OBJECTIVE

To reveal the role and mechanism of HMOs in protecting against hypoxia-induced injuries in intestinal epithelium of neonatal mice and cultured Caco2 cells.

METHODS

NEC was induced by hypoxia and cold stress. Seventy C57BL/C pups (7-d-old) were divided into 5 groups and fed maternal breast milk (BM), formula alone (FF), or the formula added with HMOs at 5 (LHMO), 10 (MHMO), or 20 mg/mL (HHMO) for 3 d. Ileal hypoxia inducible factor 1α (HIF1α) and cleaved Caspase 3 were determined, along with staining for Ki-67 protein to labeled proliferative cells. In vitro, adherent Caco2 cells (undifferentiated, passage 14) were treated with HMOs, galacto-oligosaccharides, fructo-oligosaccharides, or mixed oligosaccharides at 10 mg/mL for 1 d exposed to 1% O2. Cell proliferation and apoptosis, along with phosphorylated epidermal growth factor receptor (P-EGFR) and 38KD MAPK (P-P38), were assayed in differentiated or undifferentiated Caco2 cells.

RESULTS

Compared with the FF-fed mice, those fed MHMO and HHMO had 52% lower (P < 0.05) NEC scores, 60-80% greater (P < 0.05) KI67-positive cell numbers, and 56-71% decreases (P < 0.05) in ileal HIF1α and cleaved Caspase 3 (56-71%). Compared with those untreated, the HMO-treated Caco2 cells displayed 60% greater (P < 0.05) proliferative activity and 19% lower (P < 0.05) apoptotic cells after the hypoxia exposure. The HMO treatment led to 58% or 10-fold increases (P < 0.05) of P-EGFR and 48-89% decreases (P < 0.05) of P-P38 in either differentiated or undifferentiated Caco2 cells compared with the controls.

CONCLUSION

Supplementing HMOs at 10-20 mg/mL into the formula for neonatal mice or media for Caco2 cells conferred protection against the hypoxia-induced injuries. The protection in the Caco2 cells was associated with an activation of EGFR.

Hesperetin ameliorates DSS-induced colitis by maintaining the epithelial barrier via blocking RIPK3/MLKL necroptosis signaling

Hesperetin, a flavonoid from citrus fruits, possess various pharmacological properties, including anti-inflammatory, anti-oxidative, anti-tumor potentials. However, the role and its mechanism in ulcerative colitis (UC) remains unclear. This study aimed to investigate the protective effects and mechanisms of hesperetin on dextran sodium sulfate (DSS) -induced colitis. Our results showed that hesperetin significantly relieved the symptoms of DSS -induced colitis and increased the expressions of zonula occludens-1 (ZO-1), occludin and mucin2 (MUC-2) as well as the decrease of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-18, HMGB1 and IL-6. Of note, results from immunohistochemistry (IHC) and western blotting indicated that hesperetin inhibited the expressions of receptor-interacting protein kinase 3 (RIPK3) and mixed lineage kinase domain-like (MLKL), the two key proteins of necroptosis pathway, and inactivated RIPK3/MLKL necroptosis signalling. Meanwhile, in the cell-coculture system between Caco-2 and RAW264.7 cells, hesperetin treatment significantly ameliorated the decrease of trans epithelial electric resistance (TEER) value while HS-173 (necroptosis inducer) could obviously influence the effect of hesperetin. In addition, hesperetin attenuated the LPS-induced increasing in 4-kDa fluorescein isothiocyanate-dextran (FD4) permeability while HS-173 could weaken the protective effect of hesperetin. Meanwhile, HS-173 reduced the changes in the expressions of phosphorylated RIPK3, phosphorylated MLKL, ZO-1, occludin and MUC-2 as well as TNF-α, IL-1β. These findings demonstrated hesperetin ameliorated DSS-induced colitis by maintaining the epithelial barrier via blocking the intestinal epithelial necroptosis.

Hypoxia-inducible factors in metabolic reprogramming during sepsis

Sepsis is a highly heterogeneous syndrome that is caused by an imbalanced host response to infection. Despite huge investments, sepsis remains a contemporary threat with significant burden on health systems. Vascular dysfunction and elevated oxygen consumption by highly metabolically active immune cells result in tissue hypoxia during inflammation. The transcription factor hypoxia-inducible factor-1a (HIF1α), and its family members, plays an important role in cellular metabolism and adaptation to cellular stress caused by hypoxia. In this review, we discuss the role of HIF in sepsis. We show possible mechanisms by which the inflammatory response activated during sepsis affects the HIF pathway. The activated HIF pathway in turn changes the metabolism of both innate and adaptive immune cells. As HIF expression in leukocytes of septic patients can be directly linked with mortality, we discuss multiple ways of interfering with the HIF signaling pathway.

Prolyl Hydroxylase Inhibition Mitigates Pouchitis

BACKGROUND

Pouchitis is the most common long-term complication after restorative proctocolectomy with ileal pouch-anal anastomosis (IPAA) for ulcerative colitis (UC) or familial adenomatous polyposis (FAP), which can eventually progress to pouch failure, necessitating permanent stoma construction. Hypoxia-inducible transcription factor prolyl hydroxylase-containing enzymes (PHD1, PHD2, and PHD3) are molecular oxygen sensors that control adaptive gene expression through hypoxia-inducible factor (HIF). Emerging evidence supports PHDs as being therapeutic targets in intestinal inflammation. However, pharmacological inhibition of PHDs has not been validated as a treatment strategy in pouchitis.

METHODS

PHD1-3 mRNA and protein expression were analyzed in mucosal pouch and prepouch ileal patient biopsies. After establishment of a preclinical IPAA model in rats, the impact of the pan-PHD small-molecule inhibitor dimethyloxalylglycine (DMOG) on dextran sulfate sodium (DSS)-induced pouchitis was studied. Clinical and molecular parameters were investigated.

RESULTS

PHD1, but not PHD2 or PHD3, was overexpressed in pouchitis in biopsies of patients with IPAA for UC but not FAP. In addition, PHD1 expression correlated with disease activity. DMOG treatment profoundly mitigated DSS-induced pouchitis in a rodent IPAA model. Mechanistically, DMOG restored intestinal epithelial barrier function by induction of tight junction proteins zona occludens-1 and claudin-1 and alleviation of intestinal epithelial cell apoptosis, thus attenuating pouch inflammation.

CONCLUSIONS

Together, these results establish a strong therapeutic rationale for targeting PHD1 with small-molecule inhibitors in pouchitis after IPAA for UC.

CLDN1 induces autophagy to promote proliferation and metastasis of esophageal squamous carcinoma through AMPK/STAT1/ULK1 signaling

Tight junction is a structural constitution in cell-cell adhesion and play an important role in the maintenance of permeability and integrity of normal epithelial cell barrier. The protein encoded by Claudin 1 (CLDN1), a member of the claudin family, is an integral membrane protein and a component of tight junction strands. CLDN1 has been proved to regulate the proliferation and metastasis of multiple tumors, but little is known about its role in esophageal squamous cell carcinoma (ESCC). Here, we found that CLDN1 was aberrantly increased in ESCC tissues and cell lines, and mainly distributed in the nucleus of tumor cells. Furthermore, we confirmed that CLDN1 promoted the proliferation and metastasis of ESCC by triggering autophagy both in vitro and in vivo. Mechanically, we validated that CLDN1-induced autophagy via increasing Unc-51 like autophagy activating kinase 1 (ULK1) expression through AMP-activated protein kinase (AMPK)/signal transducer and activator of transcription 1 (STAT1) signaling pathway in ESCC cells. Taken together, our findings demonstrated that aberrant expression and distribution of CLDN1 promoted the proliferation and metastasis of esophageal squamous carcinoma by triggering autophagy through AMPK/STAT1/ULK1 signaling pathway.

Dual Effects of Chinese Herbal Medicines on Angiogenesis in Cancer and Ischemic Stroke Treatments: Role of HIF-1 Network

Hypoxia-inducible factor-1 (HIF-1)–induced angiogenesis has been involved in numerous pathological conditions, and it may be harmful or beneficial depending on the types of diseases. Exploration on angiogenesis has sparked hopes in providing novel therapeutic approaches on multiple diseases with high mortality rates, such as cancer and ischemic stroke. The HIF-1 pathway is considered to be a major regulator of angiogenesis. HIF-1 seems to be involved in the vascular formation process by synergistic correlations with other proangiogenic factors in cancer and cerebrovascular disease. The regulation of HIF-1–dependent angiogenesis is related to the modulation of HIF-1 bioactivity by regulating HIF-1α transcription or protein translation, HIF-1α DNA binding, HIF-1α and HIF-1α dimerization, and HIF-1 degradation. Traditional Chinese herbal medicines have a long history of clinical use in both cancer and stroke treatments in Asia. Growing evidence has demonstrated potential proangiogenic benefits of Chinese herbal medicines in ischemic stroke, whereas tumor angiogenesis could be inhibited by the active components in Chinese herbal medicines. The objective of this review is to provide comprehensive insight on the effects of Chinese herbal medicines on angiogenesis by regulating HIF-1 pathways in both cancer and ischemic stroke.