Clinical Significance of High-Mobility Group Box 1 Protein (HMGB1) and Nod-Like Receptor Protein 3 (NLRP3) in Patients with Ulcerative Colitis

HMGB1 Modulates Macrophage Metabolism and Polarization in Ulcerative Colitis by Inhibiting Cpt1a Expression

BACKGROUND

Macrophage polarization is involved in the development of ulcerative colitis (UC). This study investigated the mechanism by which high mobility group box-1 protein (HMGB1) regulates macrophage polarization through metabolic reprogramming, thereby contributing to the pathogenesis of UC.

METHODS

Dextran sulfate sodium (DSS) was used to induce colitis in mice. RAW264.7 cells were polarized to M1 or M2 macrophages in vitro by stimulating with lipopolysaccharide (LPS)/interferon-γ (IFN-γ) or Interleukin-4 (IL-4), respectively. Macrophage infiltration and distribution within colon tissue were assessed by immunohistochemistry and flow cytometry. Glycolysis, fatty acid oxidation (FAO), and inflammatory factors were evaluated using relevant reagent kits. Chromatin Immunoprecipitation (ChIP) and luciferase reporter experiments were performed to study the regulation of Carnitine palmitoyltransferase 1A (Cpt1a) promoter transcriptional activity by HMGB1.

RESULTS

The mouse UC model showed upregulated HMGB1 and increased macrophage infiltration. Overexpression of HMGB1 promoted M1 macrophage polarization, increased glycolysis, and reduced FAO, whereas knockdown of HMGB1 promoted M2 macrophage polarization, reduced glycolysis, and increased FAO. HMGB1 negatively regulated Cpt1a expression by inhibiting transcription of the Cpt1a promoter. Knockdown of Cpt1a reversed the effects of small interfering RNA targeting HMGB1 (si-HMGB1) on macrophage metabolism and polarization. Administration of adeno-associated virus (AAV)-shHMGB1 in vivo caused a reduction in UC symptoms and inflammation.

CONCLUSIONS

HMGB1 modulates macrophage metabolism in UC by inhibiting Cpt1a expression, leading to increased M1 polarization. This provides a theoretical basis for the clinical application of HMGB1 inhibitors in the treatment of UC.

Saccharomyces cerevisiae SC-2201 Attenuates AOM/DSS-Induced Colorectal Cancer by Modulating the Gut Microbiome and Blocking Proinflammatory Mediators

Colorectal cancer is the third most common cancer in the world today, and studies have shown that the ratio of Candida to Saccharomyces cerevisiae increased, and the abundance of S. cerevisiae in the intestines of patients with colorectal cancer decreased, which suggests that there is an imbalance in the proportion of fungi in the intestines of patients with colorectal cancer. The objective of this study was to screen S. cerevisiae isolate from traditional Chinese fermentation starters and assess its ability to ameliorate dysbiosis and to alleviate the carcinogenic process of azoxymethane/dextran sodium sulfate-induced colorectal cancer in mice model. S. cerevisiae strain SC-2201 was isolated and exhibited probiotic properties, including the ability to survive in an acidic pH environment and in the presence of bile salts in the gastrointestinal tract, as well as antioxidant activities. Oral administration of S. cerevisiae SC-2201 not only alleviated weight loss but also reduced colonic shortening and histological damage in azoxymethane/dextran sodium sulfate-induced colorectal cancer in mice. Furthermore, the administration of S. cerevisiae SC-2201 suppressed the expression of proinflammatory mediators, such as interleukin-1β, interleukin-6, cyclooxygenase-2, vascular endothelial growth factor, nucleotide-binding domain, leucine-rich repeat, and pyrin domain-containing protein 3. Specifically, the analysis of gut bacteriome showed a significant decrease in Bacteroidota and Campylobacterota levels, as well as an increase in Proteobacteria level in the colorectal cancer group, which was alleviated by supplementation with S. cerevisiae SC-2201. The analysis of the mycobiome revealed a significant increase in the levels of Basidiomycota, Apiosordaria, Naganishia, and Taphrina genera in the colorectal cancer group, which were alleviated after supplementation with S. cerevisiae SC-2201. However, the levels of Xenoramularia, Entoloma, and Keissleriella were significantly increased after administration with S. cerevisiae SC-2201. Overall, the findings of this study demonstrate that S. cerevisiae SC-2201 possesses potential probiotic properties and can effectively attenuate the development of colorectal cancer, highlighting its cancer-preventive potential. This is the first report of a S. cerevisiae strain isolated from traditional Chinese fermentation starters which showed good probiotic properties, and mitigated azoxymethane/dextran sodium sulfate-induced colorectal cancer by modulating the gut microbiome and blocking proinflammatory mediators in mice.

20(S)- Protopanaxadiol saponins isolated from Panax notoginseng target the binding of HMGB1 to TLR4 against inflammation in experimental ulcerative colitis

Ulcerative colitis (UC) has emerged as a global healthcare issue due to high prevalence and unsatisfying therapeutic measures. 20(S)- Protopanaxadiol saponins (PDS) from Panax notoginseng with anti-inflammatory properties is a potential anti-colitis agent. Herein, we explored the effects and mechanisms of PDS administration on experimental murine UC. Dextran sulfate sodium-induced murine UC model was employed to investigate anti-colitis effects of PDS, and associated mechanisms were further verified in HMGB1-exposed THP-1 macrophages. Results indicated that PDS administration exerted ameliorative effects against experimental UC. Moreover, PDS administration remarkably downregulated mRNA expressions and productions of related pro-inflammatory mediators, and reversed elevated expressions of proteins related to NLRP3 inflammasome after colitis induction. Furthermore, administration with PDS also suppressed the expression and translocation of HMGB1, interrupting the downstream TLR4/NF-κB pathway. In vitro, ginsenoside CK and 20(S)-protopanaxadiol, the metabolites of PDS, exhibited greater potential in anti-inflammation, and intervened with the TLR4-binding domain of HMGB1 predictably. Expectedly, ginsenoside CK and 20(S)-protopanaxadiol administrations inhibited the activation of TLR4/NF-κB/NLRP3 inflammasome pathway in HMGB1-exposed THP-1 macrophages. Summarily, PDS administration attenuated inflammatory injury in experimental colitis by blocking the binding of HMGB1 to TLR4, majorly attributed to the antagonistic efficacies of ginsenoside CK and 20(S)-protopanaxadiol.

Natural flavones from edible and medicinal plants exhibit enormous potential to treat ulcerative colitis

Ulcerative colitis (UC) is a chronic aspecific gut inflammatory disorder that primarily involves the recta and colons. It mostly presents as a long course of repeated attacks. This disease, characterized by intermittent diarrhoea, fecal blood, stomachache, and tenesmus, severely decreases the living quality of sick persons. UC is difficult to heal, has a high recurrence rate, and is tightly related to the incidence of colon cancer. Although there are a number of drugs available for the suppression of colitis, the conventional therapy possesses certain limitations and severe adverse reactions. Thus, it is extremely required for safe and effective medicines for colitis, and naturally derived flavones exhibited huge prospects. This study focused on the advancement of naturally derived flavones from edible and pharmaceutical plants for treating colitis. The underlying mechanisms of natural-derived flavones in treating UC were closely linked to the regulation of enteric barrier function, immune-inflammatory responses, oxidative stress, gut microflora, and SCFAs production. The prominent effects and safety of natural-derived flavones make them promising candidate drugs for colitis treatment.

Progress on Regulation of NLRP3 Inflammasome by Chinese Medicine in Treatment of Ulcerative Colitis

Ulcerative colitis (UC) is a chronic, non-specific intestinal disease that not only affects the quality of life of patients and their families but also increases the risk of colorectal cancer. The nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing protein 3 (NLRP3) inflammasome is an important component of inflammatory response system, and its activation induces an inflammatory cascade response that is involved in the development and progression of UC by releasing inflammatory cytokines, damaging intestinal epithelial cells, and disrupting the intestinal mucosal barrier. Chinese medicine (CM) plays a vital role in the prevention and treatment of UC and is able to regulate NLRP3 inflammasome. Many experimental studies on the regulation of NLRP3 inflammasome mediated by CM have been carried out, demonstrating that CM formulae with main effects of clearing heat, detoxifying toxicity, drying dampness, and activating blood circulation. Flavonoids and phenylpropanoids can effectively regulate NLRP3 inflammasome. Other active components of CM can interfere with the process of NLRP3 inflammasome assembly and activation, leading to a reduction in inflammation and UC symptoms. However, the reports are relatively scattered and lack systematic reviews. This paper reviews the latest findings regarding the NLRP3 inflammasome activation-related pathways associated with UC and the potential of CM in treating UC through modulation of NLRP3 inflammasome. The purpose of this review is to explore the possible pathological mechanisms of UC and suggest new directions for development of therapeutic tools.

Qingre Xingyu recipe exerts inhibiting effects on ulcerative colitis development by inhibiting TNFα/NLRP3/Caspase-1/IL-1β pathway and macrophage M1 polarization

As a chronic inflammatory bowel disease, ulcerative colitis (UC) imposes a significant burden on public healthcare worldwide due to its increasing morbidity. Chinese medicines are regarded as potent therapeutic agents for UC treatment with minimal side effects. In the present study, we sought to determine the novel role of a traditional medicine Qingre Xingyu (QRXY) recipe in the development of UC and aimed to contribute to the currently available knowledge about UC by exploring the downstream mechanism of QRXY recipe in UC. Mouse models of UC were established by injections with dextran sulphate sodium (DSS), where the expression of tumor necrosis factor-alpha (TNFα), NLR family pyrin domain containing 3 (NLRP3), and interleukin-1β (IL-1β) was determined followed by an analysis of their interactions. The DSS-treated NLRP3 knockout (^-/-) Caco-2 cell model was successfully constructed. The in vitro and in vivo effects of the QRXY recipe on UC were investigated with the determination of disease activity index (DAI), histopathological scores, transepithelial electrical resistance, FITC-dextran, as well as cell proliferation and apoptosis. In vivo and in vitro experiments indicated that the QRXY recipe reduced the degree of intestinal mucosal injury of UC mice and functional damage of DSS-induced Caco-2 cells by inhibition of the TNFα/NLRP3/caspase-1/IL-1β pathway and M1 polarization of macrophages, and TNFα overexpression or NLRP3 knockdown could counterweigh the therapeutic effects of QRXY recipe. To conclude, our study elicited that QRXY inhibited the expression of TNFα and inactivated the NLRP3/Caspase-1/IL-1β pathway, thereby alleviating intestinal mucosal injury and relieving UC in mice.

Gallic acid ameliorates dextran sulfate sodium-induced ulcerative colitis in mice via inhibiting NLRP3 inflammasome

Background: Ulcerative colitis (UC) is a chronic recurrent inflammatory bowel disease (IBD). The conventional drugs for UC may induce severe side effects. Herbal medicine is considered as a complementary and alternative choice for UC. Purpose: This study aims to estimate the effect of natural polyphenol gallic acid (GA) on the NLRP3 inflammasome with dextran sulfate sodium (DSS)-induced colitis in mice. Study design: The body weights and symptoms of BALB/c mice were recorded. Histological evaluation, ELISA, q-PCR, immunohistochemistry, and western blotting were carried out to observe the morphology, cytokine contents, mRNA expressions, and protein expressions, respectively. Lipopolysaccharide (LPS)-induced RAW264.7 macrophage was used to probe GA's effect on relative protein expression. Results: GA attenuated weight loss (p < 0.05), relieved symptoms, and ameliorated colonic morphological injury (p < 0.05) in mice with colitis induced by DSS. GA also lowered the contents of TNF-α, IL-1β, IL-18, IL-33, and IFN-γ in the serum and colon of mice, which were elevated by DSS, downregulated protein, and mRNA expressions of the NLRP3 pathway in the colon tissue. Furthermore, GA downregulated the expressions of NLRP3 (p < 0.05), iNOS (p < 0.01), COX2 (p < 0.01), and P-p65 (p < 0.05), and suppressed NO release (p < 0.001) in LPS-induced RAW264.7 cells. Conclusion: GA ameliorated DSS-induced UC in mice via inhibiting the NLRP3 inflammasome. These findings furnish evidence for the anti-inflammatory effect of herbal medicines containing GA on UC.

Acteoside alleviates dextran sulphate sodium‑induced ulcerative colitis via regulation of the HO‑1/HMGB1 signaling pathway

Ulcerative colitis (UC) is a significant burden on human health, and the elucidation of the mechanism by which it develops has potential for the prevention and treatment of UC. It has been reported that acteoside (ACT) exhibits strong anti‑inflammatory activity. In the present study, it was hypothesized that ACT may exert a protective effect against UC. The effects of ACT on inflammation, oxidative stress and apoptosis were evaluated using dextran sulphate sodium (DSS)‑treated mice and DSS‑treated human colorectal adenocarcinoma Caco‑2 cells, which have an epithelial morphology. The results demonstrated that the ACT‑treated mice with DSS‑induced UC exhibited significantly reduced colon inflammation, as demonstrated by a reversal in body weight loss, colon shortening, disease activity index score, inflammation, oxidative stress and colonic barrier dysfunction. Further in vivo experiments demonstrated that ACT inhibited DSS‑induced apoptosis in colon tissues, as demonstrated by the results of the TUNEL assay and the altered protein expression levels of Bax, cleaved caspase‑3 and Bcl‑2. Furthermore, DSS significantly stimulated the protein expression levels of high mobility group box 1 protein (HMGB1), which serves a central role in the initiation and progression of UC, an effect which was markedly inhibited by ACT. Finally, DSS significantly decreased the protein expression levels of heme oxygenase‑1 (HO‑1) in colon tissues and the effect of ACT on GSH, apoptotic proteins and HMGB1 was markedly attenuated in the presence of the HO‑1 inhibitor tin protoporphyrin. In conclusion, ACT ameliorated colon inflammation through HMGB1 inhibition in a HO‑1‑dependent manner.

Pyroptosis and Its Role in Autoimmune Disease: A Potential Therapeutic Target

Autoimmune diseases are a group of heterogeneous diseases with diverse clinical manifestations that can be divided into systemic and organ-specific. The common etiology of autoimmune diseases is the destruction of immune tolerance and the production of autoantibodies, which attack specific tissues and/or organs in the body. The pathogenesis of autoimmune diseases is complicated, and genetic, environmental, infectious, and even psychological factors work together to cause aberrant innate and adaptive immune responses. Although the exact mechanisms are unclear, recently, excessive exacerbation of pyroptosis, as a bond between innate and adaptive immunity, has been proven to play a crucial role in the development of autoimmune disease. Pyroptosis is characterized by pore formation on cell membranes, as well as cell rupture and the excretion of intracellular contents and pro-inflammatory cytokines, such as IL-1β and IL-18. This overactive inflammatory programmed cell death disrupts immune system homeostasis and promotes autoimmunity. This review examines the molecular structure of classical inflammasomes, including NLRP3, AIM2, and P2X7-NLRP3, as the switches of pyroptosis, and their molecular regulation mechanisms. The sophisticated pyroptosis pathways, including the canonical caspase-1-mediated pathway, the noncanonical caspase-4/5/11-mediated pathway, the emerging caspase-3-mediated pathway, and the caspase-independent pathway, are also described. We highlight the recent advances in pyroptosis in autoimmune diseases, such as systemic lupus erythematosus, rheumatoid arthritis, inflammatory bowel disease, Sjögren's syndrome and dermatomyositis, and attempt to identify its potential advantages as a therapeutic target or prognostic marker in these diseases.

Quantitation of Trastuzumab and an Antibody to SARS-CoV-2 in Minutes Using Affinity Membranes in 96-Well Plates

Quantitation of therapeutic monoclonal antibodies (mAbs) in human serum could ensure that patients have adequate levels of mAbs for effective treatment. This research describes the use of affinity, glass-fiber membranes in a 96-well-plate format for rapid (<5 min) quantitation of the therapeutic mAb trastuzumab and a mAb against the SARS-CoV-2 spike protein. Adsorption of a poly(acrylic acid)-containing film in membrane pores and activation of the -COOH groups in the film enable covalent-linking of affinity peptides or proteins to the membrane. Passage of mAb-containing serum through the affinity membrane results in mAb capture within 1 min. Subsequent rinsing, binding of a secondary antibody conjugated to a fluorophore, and a second rinse yield mAb-concentration-dependent fluorescence intensities in the wells. Calibration curves established from analyses on different days have low variability and allow determination of mAb levels in separately prepared samples with an average error <10%, although errors in single-replicate measurements may reach 40%. The assays can occur in diluted serum with physiologically relevant mAb concentrations, as well as in undiluted serum. Thus, the combination of 96-well plates containing affinity membranes, a microplate reader, and a simple vacuum manifold affords convenient mAb quantitation in <5 min.

Serum levels of NLRC4 and MCP-2/CCL8 in patients with active Crohn's disease

Crohn's disease (CD) is characterized by malfunction of immune-regulatory mechanisms with disturbed intestinal mucosal homeostasis and increased activation of mucosal immune cells, leading to abnormal secretion of numerous pro- and anti-inflammatory mediators. MCP2/CCL8 is produced by intestinal epithelial cells and macrophages, and is a critical regulator of mucosal inflammation. NLRC4 is expressed in phagocytes and intestinal epithelial cells and is involved in intestinal homeostasis and host defense. However, no study to date has assessed the circulating levels of NLRC4 and MCP2/CCL8 in patients with CD. The study was aimed to investigate the serum levels of MCP2/CCL8 and NLRC4 in patients with active CD. Sixty-nine patients with active CD and 60 healthy participants were included in the study. Serum levels of NLRC4 and MCP2/CCL8 were determined using an enzyme-linked immunosorbent assay. The median serum NLRC4 levels were lower in the patient group than in the controls (71.02 (range, 46.59-85.51) pg/mL vs. 99.43 (range 83.52-137.79) pg/mL) (P < 0.001). The median serum levels of MCP2/CCL8 were decreased in patients with CD (28.68 (range, 20.16-46.0) pg/mL) compared with the controls (59.96 (range, 40.22-105.59) pg/mL) (P < 0.001). Cut-off points of NLRC4 (<81 pg/mL) and MCP2/CCL8 (<40 pg/mL) showed high sensitivity and specificity for identifying active CD. In conclusion, this is the first study to examine circulating levels of MCP2/CCL8 and NLRC4 in patients with active CD. Our results suggest that serum NLRC4 and MCP2/CCL8 levels may be involved in the pathogenesis of CD and may have a protective effect on intestinal homeostasis and inflammation. Serum levels of MCP2/CCL8 and NLRC4 could be used as a diagnostic tool and therapeutic target for CD.

NLRP3 Inflammasome: Checkpoint Connecting Innate and Adaptive Immunity in Autoimmune Diseases

Autoimmune diseases are a broad spectrum of human diseases that are characterized by the breakdown of immune tolerance and the production of autoantibodies. Recently, dysfunction of innate and adaptive immunity is considered to be a key step in the initiation and maintenance of autoimmune diseases. NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome is a multimeric protein complex, which can detect exogenous pathogen irritants and endogenous danger signals. The main function of NLRP3 inflammasome is to promote secretion of interleukin (IL)-1β and IL-18, and pyroptosis mediated by caspase-1. Served as a checkpoint in innate and adaptive immunity, aberrant activation and regulation of NLRP3 inflammasome plays an important role in the pathogenesis of autoimmune diseases. This paper reviewed the roles of NLRP3 inflammasome in autoimmune diseases, which shows NLRP3 inflammasome may be a potential target for autoimmune diseases deserved further study.

Serum HMGB1 level is correlated with serum I-FABP level in neonatal patients with necrotizing enterocolitis

Background

This study aims to investigate clinical significance of HMGB1 in neonatal patients with necrotizing enterocolitis (NEC).

Methods

This observational study enrolled a total of 106 stage II-III NEC neonatal patients, who were admitted in our hospital from March 2014 to March 2019. In addition, 99 suspected NEC patients and 200 healthy controls were included. The serum levels of HMGB1, I-FABP, and inflammatory factors CRP, IL-1β, IL-6 and TNF-α were determined by enzyme-linked immunosorbent assay (ELISA). Then, the demographic data and clinical characteristics of all patients were collected. Statistical analysis was conducted to determine the correlation between HMGB1 and the clinical characteristics.

Results

No significant difference was found in the basic characteristics of NEC patients and healthy controls, except for birth weight and gestational age. The expression levels of HMGB1, I-FABP, and inflammatory factors IL-1β, IL-6 and TNF-α were significantly higher in NEC patients, when compared to healthy controls. The serum levels of HMGB1, I-FABP, IL-1β and IL-6 markedly increased in stage II-III NEC patients, when compared to stage I NEC patients. The Pearson’s analysis revealed a positive correlation between HMGB1 and I-FABP, HMGB1 and IL-1β, and HMGB1 and IL-6. The ROC curve revealed that both HMGB1 and I-FABP can potentially be used as diagnostic factors for NEC. The logistic multivariate regression revealed that I-FABP, IL-1β and IL-6 are independent risk factors for mortality in neonatal NEC patients.

Conclusions

Serum HMGB1 levels are upregulated in neonatal NEC patients, and these are correlated with the patient’s prognosis.

Sex-Specific Signature in the Circulating NLRP3 Levels of Saudi Adults with Metabolic Syndrome

Recently, inflammasomes such as NLRP3 as cytosolic pattern-recognition receptors have been implicated in the development of inflammation; however, limited investigations report the circulating levels of this protein. The objective, thus, was to investigative circulating NLRP3 levels in Saudi patients with a low-grade inflammatory disorder called metabolic syndrome (MetS). Two hundred Saudi adults aged 30–65, with or without MetS diagnosed on the basis of National Cholesterol Education Programme Adult Treatment Panel III (NCEP ATP III) criteria, were randomly recruited. Five MetS components were established according to the diagnostic criteria in the study subjects. Circulating levels of NLRP3 and known inflammation markers, such as tumor necrosis factor α (TNF-α), C-reactive protein (CRP) and interleukins (IL-1β and IL-18), were measured in the blood samples taken from the study subjects. Gender-based analysis showed a significant elevated circulating levels of NLRP3 in non-MetS men compared to non-MetS females (p < 0.001). Moreover, an increase in circulating levels of NLRP3 with a number of MetS components (p = 0.038) was observed only in females. A significant positive correlation of NLRP3 levels with age (r = 0.20, p = 0.04), BMI (r = 0.32, p < 0.01) and waist (r = 0.24, p = 0.02) and a significant negative correlation between NLRP3 and HDL-cholesterol (r= −0.21, p = 0.03) were also observed in females. Logistic regression analysis also yielded a sex-specific positive association of NLRP3 with MetS in females, with this association influenced mostly by central obesity and dyslipidemia components of MetS. In conclusion, this study suggests a sexual disparity in the circulating levels of NLRP3, with a trend of increasing circulating NLRP3 levels with increasing MetS components observed only in females, influenced mostly by adiposity and dyslipidemia components of MetS. Longitudinal studies with a larger sample size and investigating sex-specific hormones with NLRP3 would be needed to establish a causal relationship of NLRP3 with MetS.

Evidences of CTLA-4 and PD-1 Blocking Agents-Induced Cardiotoxicity in Cellular and Preclinical Models

Background: Several strategies based on immune checkpoint inhibitors (ICIs) have been developed for cancer therapy, opening to advantages in cancer outcomes. However, several ICI-induced side effects have emerged in these patients, especially a rare but clinically significant cardiotoxicity with high rate of mortality. We studied the cytotoxic and pro-inflammatory properties of Ipilimumab and Nivolumab, the underlying pathways and cytokine storm involved. Methods: Co-cultures of human cardiomyocytes and lymphocytes were exposed to Ipilimumab or Nivolumab; cell viability and expression of leukotrienes, NLRP3, MyD88, and p65/NF-kB were performed. C57 mice were treated with Ipilimumab (15 mg/kg); analysis of fractional shortening, ejection fraction, radial and longitudinal strain were made before and after treatments through 2D-echocardiography. Expression of NLRP3, MyD88, p65/NF-kB, and 12 cytokines were analyzed in murine myocardium. Results: Nivolumab and Ipilimumab exert effective anticancer, but also significant cardiotoxic effects in co-cultures of lymphocytes and tumor or cardiac cells. Both ICIs increased NLRP3, MyD88, and p65/NF-kB expression compared to untreated cells, however, the most pro-inflammatory and cardiotoxic effects were seen after exposure to Ipilimumab. Mice treated with Ipilimumab showed a significant decrease in fractional shortening and radial strain with respect to untreated mice, coupled with a significant increase in myocardial expression of NLRP3, MyD88, and several interleukins. Conclusions: Nivolumab and Ipilimumab exert cytotoxic effects mediated by the NLRP3/IL-1β and MyD88 pathways, leading to pro-inflammatory cytokine storm in heart tissue.