The Absence of NLRP3-inflammasome Modulates Hepatic Fibrosis Progression, Lipid Metabolism, and Inflammation in KO NLRP3 Mice during Aging

Promoting longevity in aged liver through NLRP3 inflammasome inhibition using tauroursodeoxycholic acid (TUDCA) and SCD probiotics

This investigation explores the combined influence of SCD Probiotics and tauroursodeoxycholic acid (TUDCA) on liver health in elderly male Sprague-Dawley rats. Through the administration of intravenous TUDCA (300 mg/kg) and oral SCD Probiotics (3 mL at 1 × 10^8 CFU) daily for one week, this study evaluates the biomolecular composition, histopathological alterations, and inflammasome activity in the liver. Analytical methods encompassed ATR-FTIR spectroscopy integrated with machine learning for the assessment of biomolecular structures, RT-qPCR for quantifying inflammasome markers (NLRP3, ASC, Caspase-1, IL18, IL1β), and histological examinations to assess liver pathology. The findings reveal that TUDCA prominently enhanced lipid metabolism by reducing cholesterol esters, while SCD Probiotics modulated both lipid and protein profiles, notably affecting fatty acid chain lengths and protein configurations. Histological analysis showed significant reductions in cellular degeneration, lymphatic infiltration, and hepatic fibrosis. Furthermore, the study noted a decrease in the immunoreactivity for NLRP3 and ASC, suggesting suppressed inflammasome activity. While SCD Probiotics reduced the expression of certain inflammasome-related genes, they also paradoxically increased AST and LDH levels. Conversely, an exclusive elevation in albumin levels was observed in the group treated with SCD Probiotics, implying a protective role against liver damage. These results underscore the therapeutic potential of TUDCA and SCD Probiotics for managing age-associated liver disorders, illustrating their individual and synergistic effects on liver health and pathology. This study provides insights into the complex interactions of these agents, advocating for customized therapeutic approaches to combat liver fibrosis, enhance liver functionality, and decrease inflammation in aging populations.

Different bacteria species lipopolysaccharide co-exposure with NASH diet exacerbate NASH and liver fibrosis progress in mice

BACKGROUND AND AIM

Given the obesity epidemic, nonalcoholic fatty liver disease has become a public health concern; however, the progression mechanism remains obscure. Therefore, experimental nonalcoholic fatty liver disease/steatohepatitis (NASH) animal models that reflect human disease are necessary. In this study, we simulated the effects of gut microbiota imbalance on NASH and liver fibrosis.

METHODS

Different bacterial sources of lipopolysaccharide, including Escherichia coli (GEC) and Salmonella abortus equi (GSE), were combined with a Gubra Amylin NASH (GAN) diet to induce NASH and liver fibrosis.

RESULTS

Serum levels of alanine aminotransferase, hydroxyproline, CD68-positive cells, α-smooth muscle actin, and glial fibrillary acidic protein as well as TNF-α, COL1A1, TGF-β, and NLRP3 expressions in the livers of the GSE group were markedly increased compared to those in the GAN group. The GAN diet with lipopolysaccharide (LPS) treatment resulted in a marked difference in microbiota α-diversity. The GSE group had higher numbers ofincreased Erysipelotrichaceae, Akkermansiaceae, and Bacteroidaceae families than the other groups.

CONCLUSIONS

Based on these results, the GAN diet combined with LPS treatment successfully induced the progression of liver disease to NASH and fibrosis. With consistent histologically proven fibrosis, this obese NASH mouse model has relatively good clinical translatability and is highly applicable for preclinical drug testing for NASH.

Corn Peptides Alleviate Nonalcoholic Fatty Liver Fibrosis in Mice by Inhibiting NLRP3 Inflammasome Activation and Regulating Gut Microbiota

This study aimed to investigate the effects of corn gluten-derived soluble epoxide hydrolase (sEH) inhibitory peptides on nonalcoholic fatty liver fibrosis induced by a high-fat diet and carbon tetrachloride in mice. Mice treated with corn peptides at doses of 500 or 1000 mg/kg/d for 4 weeks exhibited reduced sEH activity in serum and liver, enhanced lipid metabolism, and decreased lipid accumulation and oxidative stress. Corn peptides effectively downregulated the mRNA levels of Pro-IL-1β, Pro-IL-18, NOD-like receptor protein 3 (NLRP3), ASC, Pro-caspase-1, Caspase-1, and GSDMD in the liver. This hepatoprotective effect of corn peptides by inhibiting NLRP3 inflammasome activation was further validated in H2O2-induced HepG2 cells. Moreover, corn peptides restored the composition of the gut microbiota and promoted short-chain fatty acid production. This study provides evidence that corn-derived sEH inhibitory peptides have hepatoprotective activity against nonalcoholic fatty liver fibrosis by suppressing NLRP3 inflammasome activation and modulating gut microbiota.

Trimethylamine N-oxide: a meta-organismal axis linking the gut and fibrosis

BACKGROUND

Tissue fibrosis is a common pathway to failure in many organ systems and is the cellular and molecular driver of myriad chronic diseases that are incompletely understood and lack effective treatment. Recent studies suggest that gut microbe-dependent metabolites might be involved in the initiation and progression of fibrosis in multiple organ systems.

MAIN BODY OF THE MANUSCRIPT

In a meta-organismal pathway that begins in the gut, gut microbiota convert dietary precursors such as choline, phosphatidylcholine, and L-carnitine into trimethylamine (TMA), which is absorbed and subsequently converted to trimethylamine N-oxide (TMAO) via the host enzyme flavin-containing monooxygenase 3 (FMO3) in the liver. Chronic exposure to elevated TMAO appears to be associated with vascular injury and enhanced fibrosis propensity in diverse conditions, including chronic kidney disease, heart failure, metabolic dysfunction-associated steatotic liver disease, and systemic sclerosis.

CONCLUSION

Despite the high prevalence of fibrosis, little is known to date about the role of gut dysbiosis and of microbe-dependent metabolites in its pathogenesis. This review summarizes recent important advances in the understanding of the complex metabolism and functional role of TMAO in pathologic fibrosis and highlights unanswered questions.

Honey vesicle-like nanoparticles protect aged liver from non-alcoholic steatohepatitis

Non-alcoholic steatohepatitis (NASH), an advanced form of non-alcoholic fatty liver disease (NAFLD), has emerged as the leading cause of liver failure and related death. Currently, no medication is specifically approved to treat NAFLD or NASH. Here we report that oral administration of honey vesicle-like nanoparticles (H-VLNs) to naturally aged mice protects the liver from NASH development. H-VLNs are dominantly taken up by Kupffer cells in the liver and suppress hepatic chronic inflammation and further development of fibrosis and nodule formation in aged mice. Besides their reported anti-inflammasome function, H-VLNs are found to inhibit the transcriptional activities of C-JUN and nuclear factor-kappa B (NF-κB). MicroRNAs miR5119 and miR5108 and phenolic compound luteolin in H-VLNs are identified in suppressing both the C-JUN and NF-κB pathways. Collectively, oral intake of H-VLNs represents a promising new user-friendly modality to prevent the development of NASH.

The role and mechanism of pyroptosis and potential therapeutic targets in non-alcoholic fatty liver disease (NAFLD)

Non-alcoholic fatty liver disease (NAFLD) is a clinical pathological syndrome characterized by the excessive accumulation of fat within liver cells, which can progress to end-stage liver disease in severe cases, posing a threat to life. Pyroptosis is a distinct, pro-inflammatory form of cell death, differing from traditional apoptosis. In recent years, there has been growing research interest in the association between pyroptosis and NAFLD, encompassing the mechanisms and functions of pyroptosis in the progression of NAFLD, as well as potential therapeutic targets. Controlled pyroptosis can activate immune cells, eliciting host immune responses to shield the body from harm. However, undue activation of pyroptosis may worsen inflammatory responses, induce cellular or tissue damage, disrupt immune responses, and potentially impact liver function. This review elucidates the involvement of pyroptosis and key molecular players, including NOD-like receptor thermal protein domain associated protein 3(NLRP3) inflammasome, gasdermin D (GSDMD), and the caspase family, in the pathogenesis and progression of NAFLD. It emphasizes the promising prospects of targeting pyroptosis as a therapeutic approach for NAFLD and offers valuable insights into future directions in the field of NAFLD treatment.

Profiles associated with significant hepatic fibrosis consisting of alanine aminotransferase >30 U/L, exercise habits, and metabolic dysfunction-associated steatotic liver disease

AIM

In patients with steatotic liver disease (SLD), significant hepatic fibrosis is a prognostic factor with various etiologies, including inflammation and metabolic dysfunction. This study aimed to investigate independent factors and profiles associated with significant hepatic fibrosis, including alanine aminotransferase (ALT) levels >30 U/L and metabolic dysfunction-associated SLD (MASLD), in health check-up examinees.

METHODS

This single-center, retrospective, observational cohort study enrolled 1378 consecutive health checkup examinees from April 2018 to September 2022. Shear wave elastography (SWE) was performed during a routine ultrasound examination, and patients with liver stiffness ≥6.60 kPa were defined as having significant hepatic fibrosis. Patients were classified into nonsignificant hepatic fibrosis (n = 1220) or a significant hepatic fibrosis (n = 158) group according to this definition.

RESULTS

In multivariate analysis, the independent factor for significant hepatic fibrosis was aging (≥65 years; OR 9.637, 95% CI 6.704-13.852, p < 0.0001). According to decision tree analysis, the initial classifier was aging (≥65 years). After aging, an ALT level >30 U/L was the second relevant factor for significant hepatic fibrosis, regardless of age. An undirected graphical model showed that an ALT level of >30 U/L was directly associated with significant hepatic fibrosis. In patients aged ≥65 years with an ALT level >30 U/L, significant hepatic fibrosis was observed in 52% of the patients. Meanwhile, in patients aged ≥65 years with an ALT level ≤30 U/L, MASLD was the third classifier, with significant hepatic fibrosis observed in 38% of patients.

CONCLUSIONS

ALT levels >30 U/L and MASLD may be involved in the pathogenesis of significant hepatic fibrosis in patients aged ≥65 years.

Role of pattern recognition receptors in the development of MASLD and potential therapeutic applications

Metabolic dysfunction-associated steatotic liver disease (MASLD) has become one of the most prevalent liver diseases worldwide, and its occurrence is strongly associated with obesity, insulin resistance (IR), genetics, and metabolic stress. Ranging from simple fatty liver to metabolic dysfunction-associated steatohepatitis (MASH), even to severe complications such as liver fibrosis and advanced cirrhosis or hepatocellular carcinoma, the underlying mechanisms of MASLD progression are complex and involve multiple cellular mediators and related signaling pathways. Pattern recognition receptors (PRRs) from the innate immune system, including Toll-like receptors (TLRs), C-type lectin receptors (CLRs), NOD-like receptors (NLRs), RIG-like receptors (RLRs), and DNA receptors, have been demonstrated to potentially contribute to the pathogenesis for MASLD. Their signaling pathways can induce inflammation, mediate oxidative stress, and affect the gut microbiota balance, ultimately resulting in hepatic steatosis, inflammatory injury and fibrosis. Here we review the available literature regarding the involvement of PRR-associated signals in the pathogenic and clinical features of MASLD, in vitro and in animal models of MASLD. We also discuss the emerging targets from PRRs for drug developments that involved agent therapies intended to arrest or reverse disease progression, thus enabling the refinement of therapeutic targets that can accelerate drug development.

The role of inflammasomes in human diseases and their potential as therapeutic targets

Inflammasomes are large protein complexes that play a major role in sensing inflammatory signals and triggering the innate immune response. Each inflammasome complex has three major components: an upstream sensor molecule that is connected to a downstream effector protein such as caspase-1 through the adapter protein ASC. Inflammasome formation typically occurs in response to infectious agents or cellular damage. The active inflammasome then triggers caspase-1 activation, followed by the secretion of pro-inflammatory cytokines and pyroptotic cell death. Aberrant inflammasome activation and activity contribute to the development of diabetes, cancer, and several cardiovascular and neurodegenerative disorders. As a result, recent research has increasingly focused on investigating the mechanisms that regulate inflammasome assembly and activation, as well as the potential of targeting inflammasomes to treat various diseases. Multiple clinical trials are currently underway to evaluate the therapeutic potential of several distinct inflammasome-targeting therapies. Therefore, understanding how different inflammasomes contribute to disease pathology may have significant implications for developing novel therapeutic strategies. In this article, we provide a summary of the biological and pathological roles of inflammasomes in health and disease. We also highlight key evidence that suggests targeting inflammasomes could be a novel strategy for developing new disease-modifying therapies that may be effective in several conditions.

Nlrp3 Deficiency Alleviates Lipopolysaccharide-Induced Acute Kidney Injury via Suppressing Renal Inflammation and Ferroptosis in Mice

The nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome is a vital component of many inflammatory responses. Here, we intended to investigate the involvement of NLRP3 in lipopolysaccharide (LPS)-induced sepsis-associated acute kidney injury (S-AKI) and explore its mechanisms. For the first time, we validated elevated NLRP3 expression in the renal tissues of S-AKI patients by immunohistochemistry analysis. Through LPS injection in both wild-type and Nlrp3-/- mice, a S-AKI model was developed. It was found that LPS-induced kidney injury, including an abnormal morphology in a histological examination, abnormal renal function in a laboratory examination, and an increase in the expression of AKI biomarkers, was dramatically reversed in Nlrp3-deficient mice. Nlrp3 deletion alleviated renal inflammation, as evidenced by the suppression of the expression of pro-inflammatory cytokines and chemokines. A combinative analysis of RNA sequencing and the FerrDb V2 database showed that Nlrp3 knockout regulated multiple metabolism pathways and ferroptosis in LPS-induced S-AKI. Further qPCR coupled with Prussian blue staining demonstrated that Nlrp3 knockout inhibited murine renal ferroptosis, indicating a novel mechanism involving S-AKI pathogenesis by NLRP3. Altogether, the aforementioned findings suggest that Nlrp3 deficiency alleviates LPS-induced S-AKI by reducing renal inflammation and ferroptosis. Our data highlight that NLRP3 is a potential therapeutic target for S-AKI.

Inhibiting NLRP3 signaling in aging podocytes improves their life- and health-span

The decrease in the podocyte's lifespan and health-span that typify healthy kidney aging cause a decrease in their normal structure, physiology and function. The ability to halt and even reverse these changes becomes clinically relevant when disease is superimposed on an aged kidney. RNA-sequencing of podocytes from middle-aged mice showed an inflammatory phenotype with increases in the NLRP3 inflammasome, signaling for IL2/Stat5, IL6 and TNF, interferon gamma response, allograft rejection and complement, consistent with inflammaging. Furthermore, injury-induced NLRP3 signaling in podocytes was further augmented in aged mice compared to young ones. The NLRP3 inflammasome (NLRP3, Caspase-1, IL1β IL-18) was also increased in podocytes of middle-aged humans. Higher transcript expression for NLRP3 in human glomeruli was accompanied by reduced podocyte density and increased global glomerulosclerosis and glomerular volume. Pharmacological inhibition of NLRP3 with MCC950, or gene deletion, reduced podocyte senescence and the genes typifying aging in middle-aged mice, which was accompanied by an improved podocyte lifespan and health-span. Moreover, modeling the injury-dependent increase in NLRP3 signaling in human kidney organoids confirmed the anti-senescence effect of MC9950. Finally, NLRP3 also impacted liver aging. Together, these results suggest a critical role for the NLRP3 inflammasome in podocyte and liver aging.

Pannexin1 channels in the liver: an open enemy

Pannexin1 proteins form communication channels at the cell plasma membrane surface, which allow the transfer of small molecules and ions between the intracellular compartment and extracellular environment. In this way, pannexin1 channels play an important role in various cellular processes and diseases. Indeed, a plethora of human pathologies is associated with the activation of pannexin1 channels. The present paper reviews and summarizes the structure, life cycle, regulation and (patho)physiological roles of pannexin1 channels, with a particular focus on the relevance of pannexin1 channels in liver diseases.

Genetic deletion or pharmacologic inhibition of the Nlrp3 inflammasome did not ameliorate experimental NASH

It has been postulated that inflammasomes, in particular the NLRP3 (NLR family pyrin domain containing 3) inflammasome, mediate the necroinflammation and fibrosis that characterize nonalcoholic steatohepatitis (NASH) by engaging innate immune responses. We aimed to investigate the impact of genetic deletion or pharmacologic inhibition of the NLRP3 inflammasome on experimental steatohepatitis. Global Nlrp3 KO (expected to inhibit the NLRP3 inflammasome) or Casp1 KO (expected to inhibit all inflammasomes) mice were compared to wild type controls after 6 months on a high-fat, high-cholesterol (HFHC, 1% cholesterol) diet known to induce fibrosing steatohepatitis. Additionally, wildtype mice on a HFHC diet (0.75% or 0.5% cholesterol) for 6 months were either treated or not treated with an oral, pharmacologic inhibitor of Nlrp3 (MCC950) that was delivered in the drinking water (0.3 mg/ml). We found that genetic deletion or pharmacologic inhibition of the NLRP3 inflammasome did not ameliorate any of the histological components of fibrosing NASH in HFHC-fed mice. Collectively, these results do not support NLRP3 inhibition as a potential target for human NASH.

Roles of lipid metabolism and its regulatory mechanism in idiopathic pulmonary fibrosis: A review

Idiopathic pulmonary fibrosis is a progressive lung disease of unknown etiology characterized by distorted distal lung architecture, inflammation, and fibrosis. Several lung cell types, including alveolar epithelial cells and fibroblasts, have been implicated in the development and progression of fibrosis. However, the pathogenesis of idiopathic pulmonary fibrosis is still incompletely understood. The latest research has found that dysregulation of lipid metabolism plays an important role in idiopathic pulmonary fibrosis. The changes in the synthesis and activity of fatty acids, cholesterol and other lipids seriously affect the regenerative function of alveolar epithelial cells and promote the transformation of fibroblasts into myofibroblasts. Mitochondrial function is the key to regulating the metabolic needs of a variety of cells, including alveolar epithelial cells. Sirtuins located in mitochondria are essential to maintain mitochondrial function and cellular metabolic homeostasis. Sirtuins can maintain normal lipid metabolism by regulating respiratory enzyme activity, resisting oxidative stress, and protecting mitochondrial function. In this review, we aimed to discuss the difference between normal and idiopathic pulmonary fibrosis lungs in terms of lipid metabolism. Additionally, we highlight recent breakthroughs on the effect of abnormal lipid metabolism on idiopathic pulmonary fibrosis, including the effects of sirtuins. Idiopathic pulmonary fibrosis has its high mortality and limited therapeutic options; therefore, we believe that this review will help to develop a new therapeutic direction from the aspect of lipid metabolism in idiopathic pulmonary fibrosis.

Thymol Alleviates LPS-Induced Liver Inflammation and Apoptosis by Inhibiting NLRP3 Inflammasome Activation and the AMPK-mTOR-Autophagy Pathway

Thymol is a natural antibacterial agent found in the essential oil extracted from thyme, which has been proven to be beneficial in food and medicine. Meanwhile, the NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome and autophagy have been reported to play key roles in the progression of liver injury. However, the effects of thymol on the NLRP3 inflammasome and autophagy in protecting the liver remain unclear. The present study used a mouse model with liver injury induced by lipopolysaccharides (LPS) to investigate the regulatory mechanisms of thymol. We found that thymol alleviated LPS-induced liver structural damage, as judged by reduced inflammatory cell infiltration and improved structure. In addition, elevated levels of the liver damage indicators (alanine transaminase (ALT), aspartate transaminase (AST), and total bilirubin (TBIL)) dropped after thymol administration. The mRNA and protein expression of inflammatory cytokines (tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-22), apoptosis-related genes (caspase3 and caspase9), and the activity of apoptosis-related genes (caspase3 and caspase9) were increased in LPS-treated livers, whereas the changes were alleviated after thymol administration. Thymol inhibited LPS-induced increment in lactate dehydrogenase (LDH) activity in primary hepatocytes of the mouse. In addition, thymol protected mice from liver injury by inhibiting NLRP3 inflammasome activation induced by LPS. Mechanistically, the present study indicates that thymol has liver protective activity resulting from the modulation of the AMP-activated protein kinase—mammalian target of rapamycin (AMPK–mTOR) to regulate the autophagy pathway, hence curbing inflammation.

The NLRP3 inflammasome in fibrosis and aging: The known unknowns

Aging-related diseases such as cancer, cardiovascular diseases, diabetes, and neurodegenerative diseases are often accompanied by fibrosis. The NLRP3 inflammasome triggers the inflammatory response and subsequently promotes fibrosis through pathogen-associated molecular patterns (PAMPs). In this review, we first introduce the general background and specific mechanism of NLRP3 in fibrosis. Second, we investigate the role of NLRP3 in fibrosis in different organs/tissues. Third, we discuss the relationship between NLRP3 and fibrosis during aging. In summary, this review describes the latest progress on the roles of NLRP3 in fibrosis and aging and reveals the possibility of NLRP3 as an antifibrotic and anti-aging treatment target.

The NLRP3 Inflammasome in Non-Alcoholic Fatty Liver Disease and Steatohepatitis: Therapeutic Targets and Treatment

Non-alcoholic fatty liver disease (NAFLD) is among the most prevalent primary liver diseases worldwide and can develop into various conditions, ranging from simple steatosis, through non-alcoholic steatohepatitis (NASH), to fibrosis, and eventually cirrhosis and hepatocellular carcinoma. Nevertheless, there is no effective treatment for NAFLD due to the complicated etiology. Recently, activation of the NLPR3 inflammasome has been demonstrated to be a contributing factor in the development of NAFLD, particularly as a modulator of progression from initial hepatic steatosis to NASH. NLRP3 inflammasome, as a caspase-1 activation platform, is critical for processing key pro-inflammatory cytokines and pyroptosis. Various stimuli involved in NAFLD can activate the NLRP3 inflammasome, depending on the diverse cellular stresses that they cause. NLRP3 inflammasome-related inhibitors and agents for NAFLD treatment have been tested and demonstrated positive effects in experimental models. Meanwhile, some drugs have been applied in clinical studies, supporting this therapeutic approach. In this review, we discuss the activation, biological functions, and treatment targeting the NLRP3 inflammasome in the context of NAFLD progression. Specifically, we focus on the different types of therapeutic agents that can inhibit the NLRP3 inflammasome and summarize their pharmacological effectiveness for NAFLD treatment.

A Comprehensive Review of Receptor-Type Tyrosine-Protein Phosphatase Gamma (PTPRG) Role in Health and Non-Neoplastic Disease

Protein tyrosine phosphatase receptor gamma (PTPRG) is known to interact with and regulate several tyrosine kinases, exerting a tumor suppressor role in several type of cancers. Its wide expression in human tissues compared to the other component of group 5 of receptor phosphatases, PTPRZ expressed as a chondroitin sulfate proteoglycan in the central nervous system, has raised interest in its role as a possible regulatory switch of cell signaling processes. Indeed, a carbonic anhydrase-like domain (CAH) and a fibronectin type III domain are present in the N-terminal portion and were found to be associated with its role as [HCO3-] sensor in vascular and renal tissues and a possible interaction domain for cell adhesion, respectively. Studies on PTPRG ligands revealed the contactins family (CNTN) as possible interactors. Furthermore, the correlation of PTPRG phosphatase with inflammatory processes in different normal tissues, including cancer, and the increasing amount of its soluble form (sPTPRG) in plasma, suggest a possible role as inflammatory marker. PTPRG has important roles in human diseases; for example, neuropsychiatric and behavioral disorders and various types of cancer such as colon, ovary, lung, breast, central nervous system, and inflammatory disorders. In this review, we sum up our knowledge regarding the latest discoveries in order to appreciate PTPRG function in the various tissues and diseases, along with an interactome map of its relationship with a group of validated molecular interactors.

Alleviation effects of grape seed proanthocyanidin extract on inflammation and oxidative stress in a d-galactose-induced aging mouse model by modulating the gut microbiota

Grape seed proanthocyanidin extract delayed the d-galactose-induced aging process in mice through the gut microbiota–liver axis and microbiota–brain axis.

The Fibrotic Effects of TMAO on Human Renal Fibroblasts Is Mediated by NLRP3, Caspase-1 and the PERK/Akt/mTOR Pathway

Trimethylamine N-oxide (TMAO), a product of gut microbiota metabolism, has previously been shown to be implicated in chronic kidney disease. A high TMAO-containing diet has been found to cause tubulointerstitial renal fibrosis in mice. However, today there are no data linking specific molecular pathways with the effect of TMAO on human renal fibrosis. The aim of this study was to investigate the fibrotic effects of TMAO on renal fibroblasts and to elucidate the molecular pathways involved. We found that TMAO promoted renal fibroblast activation and fibroblast proliferation via the PERK/Akt/mTOR pathway, NLRP3, and caspase-1 signaling. We also found that TMAO increased the total collagen production from renal fibroblasts via the PERK/Akt/mTOR pathway. However, TMAO did not induce fibronectin or TGF-β1 release from renal fibroblasts. We have unraveled that the PERK/Akt/mTOR pathway, NLRP3, and caspase-1 mediates TMAO’s fibrotic effect on human renal fibroblasts. Our results can pave the way for future research to further clarify the molecular mechanism behind TMAO’s effects and to identify novel therapeutic targets in the context of chronic kidney disease.

Ginsenoside Rg1 ameliorates aging‑induced liver fibrosis by inhibiting the NOX4/NLRP3 inflammasome in SAMP8 mice

Aging is often accompanied by liver injury and fibrosis, eventually leading to the decline in liver function. However, the mechanism of aging‑induced liver injury and fibrosis is still not fully understood, to the best of our knowledge, and there are currently no effective treatment options available for liver aging. Ginsenoside Rg1 (Rg1) has been reported to exert potent anti‑aging effects due to its potential antioxidant and anti‑inflammatory activity. The present study aimed to investigate the protective effect and underlying mechanism of action of Rg1 in aging‑induced liver injury and fibrosis in senescence‑accelerated mouse prone 8 (SAMP8) mice treated for 9 weeks. The histopathological results showed that the arrangement of hepatocytes was disordered, vacuole‑like degeneration occurred in the majority of cells, and collagen IV and TGF‑β1 expression levels, that were detected via immunohistochemistry, were also significantly upregulated in the SAMP8 group. Rg1 treatment markedly improved aging‑induced liver injury and fibrosis, and significantly downregulated the expression levels of collagen IV and TGF‑β1. In addition, the dihydroethylene staining and western blotting results showed that Rg1 treatment significantly reduced the levels of reactive oxygen species (ROS) and IL‑1β, and downregulated the expression levels of NADPH oxidase 4 (NOX4), p47phox, p22phox, phosphorylated‑NF‑κB, caspase‑1, apoptosis‑associated speck‑like protein containing a C‑terminal caspase recruitment domain and the NLR family pyrin domain containing 3 (NLRP3) inflammasome, which were significantly upregulated in the liver tissues of elderly SAMP8 mice. In conclusion, the findings of the present study suggested that Rg1 may attenuate aging‑induced liver injury and fibrosis by reducing NOX4‑mediated ROS oxidative stress and inhibiting NLRP3 inflammasome activation.

Therapeutic and diagnostic targeting of fibrosis in metabolic, proliferative and viral disorders

Fibrosis is a common denominator in many pathologies and crucially affects disease progression, drug delivery efficiency and therapy outcome. We here summarize therapeutic and diagnostic strategies for fibrosis targeting in atherosclerosis and cardiac disease, cancer, diabetes, liver diseases and viral infections. We address various anti-fibrotic targets, ranging from cells and genes to metabolites and proteins, primarily focusing on fibrosis-promoting features that are conserved among the different diseases. We discuss how anti-fibrotic therapies have progressed over the years, and how nanomedicine formulations can potentiate anti-fibrotic treatment efficacy. From a diagnostic point of view, we discuss how medical imaging can be employed to facilitate the diagnosis, staging and treatment monitoring of fibrotic disorders. Altogether, this comprehensive overview serves as a basis for developing individualized and improved treatment strategies for patients suffering from fibrosis-associated pathologies.

Demethylenetetrahydroberberine alleviates nonalcoholic fatty liver disease by inhibiting the NLRP3 inflammasome and oxidative stress in mice

AIMS

Demethylenetetrahydroberberine (DMTHB) is a novel derivative of berberine and demethyleneberberine. This research explored the pharmacological effects and molecular mechanisms of DMTHB on nonalcoholic fatty liver disease (NAFLD).

MATERIALS AND METHODS

C57BL/6 mice were induced by a methionine- and choline- deficient (MCD) diet and L02 cells were induced by palmitic acid to establish NAFLD animal and cell models. qPCR and western blotting were used to detect the expression of genes and proteins associated with pharmacological mechanism. A biotin-labeled DMTHB pulldown assay was used to further clarify the pharmacological targets.

KEY FINDINGS

Our results indicated that DMTHB significantly alleviates NAFLD in mice. Biochemical assays showed that serum alanine aminotransferase, aspartate aminotransferase and hepatic lipids were significantly decreased in MCD-induced NAFLD mice orally administered of DMTHB (50 mg/kg or 150 mg/kg body weight daily) for 30 d. qPCR and ELISA analysis demonstrated that DMTHB reduced the expression of serum proinflammatory cytokines, such as TNF-α, IL-1β and IL-6. Moreover, pull-down assays and compound-centric chemical proteomics illustrated that DMTHB inhibited NOD-like receptor protein 3 (NLRP3) inflammasome signaling. In addition, DMTHB also attenuated oxidative stress and endoplasmic reticulum stress by downregulation CYP2E-1 and ATF-4 expression. Moreover, DMTHB treatment ameliorated the liver fibrosis in MCD-induced NAFLD mice by suppressing the expression of TGF-β1, α-SMA and collagen 1A1.

SIGNIFICANCE

DMTHB targeted the NLRP3 inflammasome to suppress inflammation and inhibited CYP2E1 to reduce oxidative stress and ER stress. Consequently, DMTHB may have therapeutic benefits in the treatment of NAFLD in the clinic.

Intersection of immunometabolism and immunosenescence during aging

Aging is associated with the highest risk for morbidity and mortality to chronic or metabolic diseases, which are present in 50% of the elderly. Improving metabolic and immune function of the elderly would improve quality of life and reduce the risk for all other diseases. Tissue-resident macrophages and the NLRP3 inflammasome are established drivers of inflammaging and metabolic dysfunction. Energy-sensing signaling pathways connect sterile and metabolic inflammation with cellular senescence and tissue dysfunction. We discuss recent advances in the immunometabolism field. Common themes revealed by recent publications include the alterations in metabolic signaling (SIRTUIN, AMPK, or mTOR pathways) in aged immune cells, the impact of senescence on inflammaging and tissue dysfunction, and the age-related changes in metabolic tissues, especially adipose tissue, as an immunological organ. Promising gerotherapeutics are candidates to broadly target nutrient and energy sensing, inflammatory and senescence pathways, and have potential to improve healthspan and treat age-related diseases.