IL-6 Trans-Signaling Is Increased in Diabetes, Impacted by Glucolipotoxicity, and Associated With Liver Stiffness and Fibrosis in Fatty Liver Disease

Proteomic insights into metabolic dysfunction-associated steatotic disease: Identifying therapeutic targets and assessing on-target side effects

AIMS

The prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD) is rising sharply, yet treatment options remain inadequate. To uncover new therapeutic targets for MASLD, we conducted a comprehensive proteome-wide Mendelian randomization (MR) and phenome-wide association study (PheWAS).

MATERIALS AND METHODS

Discovery MR utilized protein quantitative trait loci (pQTL) data on 4907 plasma protein levels from 35,559 individuals, alongside genome-wide association study (GWAS) on MASLD from the Million Veteran Program (68,725 cases / 95,482 controls). Validation comprised five pairwise combinations of these discovery datasets with three additional datasets: pQTL data for 2923 proteins from the UK Biobank, and liver biopsy-confirmed MASLD GWAS (1483 cases/17,781 controls) and MRI-liver fat GWAS (31,377 subjects) (excluding discovery pair). Candidate proteins underwent druggability assessment and on-target side effect evaluation via PheWAS.

KEY FINDINGS

We identified 26 proteins associated with MASLD after Bonferroni correction (P < 1.16 × 10-5), with 19 of them showing no significant reverse association. Interleukin-6 (IL-6), alpha-1-antitrypsin (α1-antitrypsin), 5-hydroxytryptamine receptor 7 (5-HT7R), ephrin-B1 (EFNB1), and protein MENT (CA056) were replicated. Notably, IL-6 (OR = 2.02; 95 % CI 1.54-2.64), 5-HT7R (OR = 2.73; 95 % CI 1.96-3.80), and EFNB1 (OR = 1.82; 95 % CI 1.59-2.08) were positively associated with MASLD risk, whereas α1-antitrypsin (OR = 0.84; 95 % CI 0.78-0.90) and CA056 (OR = 0.90; 95 % CI 0.86-0.94) appeared protective. Among these, IL-6, 5-HT7R, and α1-antitrypsin were druggable. PheWAS identified potential cardiovascular side effects for 5-HT7R and α1-antitrypsin.

SIGNIFICANCE

The integrative study identified several plasma proteins associated with MASLD. IL-6, α1-antitrypsin, 5-HT7R, EFNB1 and CA056 deserve further investigation as potential drug targets for MASLD.

The role of macrophages in hypertrophic scarring: molecular to therapeutic insights

Hypertrophic Scar (HS) is a common fibrotic disease of the skin, usually caused by injury to the deep dermis due to trauma, burns, or surgical injury. The main feature of HS is the thickening and hardening of the skin, often accompanied by itching and pain, which seriously affects the patient's quality of life. Macrophages are involved in all stages of HS genesis through phenotypic changes. M1-type macrophages primarily function in the early inflammatory phase by secreting pro-inflammatory factors, while M2-type macrophages actively contribute to tissue repair and fibrosis. Despite advances in understanding HS pathogenesis, the precise mechanisms linking macrophage phenotypic changes to fibrosis remain incompletely elucidated. This review addresses these gaps by discussing the pathological mechanisms of HS formation, the phenotypic changes of macrophages at different stages of HS formation, and the pathways through which macrophages influence HS progression. Furthermore, emerging technologies for HS treatment and novel therapeutic strategies targeting macrophages are highlighted, offering potential avenues for improved prevention and treatment of HS.

Regulation of the immune microenvironment by SUMO in diabetes mellitus

Post-translational modifications such as SUMOylation are crucial for the functionality and signal transduction of a diverse array of proteins. Analogous to ubiquitination, SUMOylation has garnered significant attention from researchers and has been implicated in the pathogenesis of various human diseases in recent years, such as cancer, neurological lesions, cardiovascular diseases, diabetes mellitus, and so on. The pathogenesis of diabetes, particularly type 1 and type 2 diabetes, has been closely associated with immune dysfunction, which constitutes the primary focus of this review. This review will elucidate the process of SUMOylation and its impact on diabetes mellitus development and associated complications, focusing on its regulatory effects on the immune microenvironment. This article summarizes various signaling pathways at both cellular and molecular levels that are implicated in these processes. Furthermore, it proposes potential new targets for drug development aimed at the prevention and treatment of diabetes mellitus based on insights gained from the SUMOylation process.

Assessment of skeletal muscle alterations and circulating myokines in metabolic dysfunction-associated steatotic liver disease: A cross-sectional study

BACKGROUND

Skeletal muscle alterations (SMAs) are being increasingly recognized in patients with metabolic dysfunction-associated steatotic liver disease (MASLD) and appear to be associated with deleterious outcomes in these patients. However, their actual prevalence and pathophysiology remain to be elucidated.

AIM

To determine the prevalence of SMAs and to assess the significance of circulating myokines as biomarkers in patients with MASLD.

METHODS

Skeletal muscle strength and muscle mass were measured in a cross-sectional study in a cohort of 62 patients fulfilling MASLD criteria, recruited from the outpatient clinics of a tertiary level hospital. The degree of fibrosis and liver steatosis was studied using abdominal ultrasound and transitional elastography. Anthropometric and metabolic characteristics as well as serum levels of different myokines were also determined in the MASLD cohort. Statistical analysis was performed comparing results according to liver fibrosis and steatosis.

RESULTS

No significant differences were found in both skeletal muscle strength and skeletal muscle mass in patients with MASLD between different stages of liver fibrosis. Interestingly, serum levels of fibroblast growth factor-21 (FGF21) were significantly higher in patients with MASLD with advanced hepatic fibrosis (F3-F4) than in those with lower fibrosis stages (F0-F2) (197.49 ± 198.27 pg/mL vs 95.62 ± 83.67 pg/mL; P = 0.049). In addition, patients with MASLD with severe hepatosteatosis (S3) exhibited significantly higher serum levels of irisin (1116.87 ± 1161.86 pg/mL) than those with lower grades (S1-S2) (385.21 ± 375.98 pg/mL; P = 0.001).

CONCLUSION

SMAs were uncommon in the patients with MASLD studied. Higher serum levels of irisin and FGF21 were detected in patients with advanced liver steatosis and fibrosis, respectively, with potential implications as biomarkers.

Relationship of Interleukin 6 with Hepatic Steatosis and Liver Fibrosis in Rheumatoid Arthritis at a Rheumatology Care Center in Cartagena, Colombia

BACKGROUND/OBJECTIVES

This study aimed to investigate the association of IL-6 with steatotic liver disease (SLD) and liver fibrosis (LF) in rheumatoid arthritis (RA) patients at a rheumatology center in Cartagena de Indias, Colombia.

METHODS

This was a cross-sectional study that included RA and non-RA cases. The level of cellular expression of interleukin 6 (IL-6) was evaluated by flow cytometry in peripheral blood leukocytes, and the presence of SLD and LF was detected by elastosonography. The main outcome was to establish the association between the levels of cellular expression of IL-6 and the development of SLD and LF.

RESULTS

This study included 47 cases of RA and 34 cases on-RA, with a mean age of 54 and 55 years, respectively. The frequency of SLD was 55.3% in RA and 38.2% in non-RA. The frequency of LF was 12.8% in RA and 14.7% in non-RA, with no statistical difference. The levels of cellular expression of IL-6 were significantly higher in RA compared to non-RA. Cellular expression of IL-6 was associated with the presence of SLD (54% vs. 30.3%; p = 0.002). This association was not maintained in RA cases (49.5% vs. 47.6%; p = 0.571). No association was found between cellular expression of IL-6 and LF in the total population (43.8% vs. 42.7%; p = 0.813) nor in RA cases (59.41% vs. 48.3%; p = 0.526).

CONCLUSIONS

IL-6 levels were related to SLD in the evaluated sample, and RA was not a risk factor for SLD or LF. The prognostic role of IL-6 for SLD in patients with RA requires further studies.

IL-6 and diabetic kidney disease

Diabetic kidney disease (DKD) is a severe microvascular complication of diabetes associated with high mortality and disability rates. Inflammation has emerged as a key pathological mechanism in DKD, prompting interest in novel therapeutic approaches targeting inflammatory pathways. Interleukin-6 (IL-6), a well-established inflammatory cytokine known for mediating various inflammatory responses, has attracted great attention in the DKD field. Although multiple in vivo and in vitro studies highlight the potential of targeting IL-6 in DKD treatment, its exact roles in the disease remains unclear. This review presents the roles of IL-6 in the pathogenesis of DKD, including immunoinflammation, metabolism, hemodynamics, and ferroptosis. In addition, we summarize the current status of IL-6 inhibitors in DKD-related clinical trials and discuss the potential of targeting IL-6 for treating DKD in the clinic.

Conditional deletion of CEACAM1 in hepatic stellate cells causes their activation

OBJECTIVES

Hepatic CEACAM1 expression declines with advanced hepatic fibrosis stage in patients with metabolic dysfunction-associated steatohepatitis (MASH). Global and hepatocyte-specific deletions of Ceacam1 impair insulin clearance to cause hepatic insulin resistance and steatosis. They also cause hepatic inflammation and fibrosis, a condition characterized by excessive collagen production from activated hepatic stellate cells (HSCs). Given the positive effect of PPARγ on CEACAM1 transcription and on HSCs quiescence, the current studies investigated whether CEACAM1 loss from HSCs causes their activation.

METHODS

We examined whether lentiviral shRNA-mediated CEACAM1 donwregulation (KD-LX2) activates cultured human LX2 stellate cells. We also generated LratCre + Cc1fl/fl mutants with conditional Ceacam1 deletion in HSCs and characterized their MASH phenotype. Media transfer experiments were employed to examine whether media from mutant human and murine HSCs activate their wild-type counterparts.

RESULTS

LratCre + Cc1fl/fl mutants displayed hepatic inflammation and fibrosis but without insulin resistance or hepatic steatosis. Their HSCs, like KD-LX2 cells, underwent myofibroblastic transformation and their media activated wild-type HSCs. This was inhibited by nicotinic acid treatment which blunted the release of IL-6 and fatty acids, both of which activate the epidermal growth factor receptor (EGFR) tyrosine kinase. Gefitinib inhibition of EGFR and its downstream NF-κB/IL-6/STAT3 inflammatory and MAPK-proliferation pathways also blunted HSCs activation in the absence of CEACAM1.

CONCLUSIONS

Loss of CEACAM1 in HSCs provoked their myofibroblastic transformation in the absence of insulin resistance and hepatic steatosis. This response is mediated by autocrine HSCs activation of the EGFR pathway that amplifies inflammation and proliferation.

Conditional deletion of CEACAM1 causes hepatic stellate cell activation

Objectives

Hepatic CEACAM1 expression declines with advanced hepatic fibrosis stage in patients with MASH. Global and hepatocyte-specific deletions of Ceacam1 impair insulin clearance to cause hepatic insulin resistance and steatosis. They also cause hepatic inflammation and fibrosis, a condition characterized by excessive collagen production from activated hepatic stellate cells (HSCs). Given the positive effect of PPARγ on CEACAM1 transcriptoin and on HSCs quiescence, the current studies investigated whether CEACAM1 loss from HSCs causes their activation.

Methods

We examined whether lentiviral shRNA-mediated CEACAM1 donwregulation (KD-LX2) activates cultured human LX2 stellate cells. We also generated LratCre+Cc1 fl/fl mutants with conditional Ceacam1 deletion in HSCs and characterized their MASH phenotype. Media transfer experiments were employed to examine whether media from mutant human and murine HSCs activate their wild-type counterparts.

Results

LratCre+Cc1 fl/fl mutants displayed hepatic inflammation and fibrosis but without insulin resistance or hepatic steatosis. Their HSCs, like KD-LX2 cells, underwent myofibroblastic transformation and their media activated wild-type HDCs. This was inhibited by nicotinic acid treatment which stemmed the release of IL-6 and fatty acids, both of which activate the epidermal growth factor receptor (EGFR) tyrosine kinase. Gefitinib inhibition of EGFR and its downstream NF-κB/IL-6/STAT3 inflammatory and MAPK-proliferation pathways also blunted HSCs activation in the absence of CEACAM1.

Conclusions

Loss of CEACAM1 in HSCs provoked their myofibroblastic transformation in the absence of insulin resistance and hepatic steatosis. This response is mediated by autocrine HSCs activation of the EGFR pathway that amplifies inflammation and proliferation.

Interleukins: Pathogenesis in Non-Alcoholic Fatty Liver Disease

Inflammatory cytokines have been implicated as crucial contributors to the onset and progression of non-alcoholic fatty liver disease (NAFLD). The exact mechanisms by which interleukins (ILs) contribute to NAFLD may vary, and ongoing research is aimed at understanding the specific roles of different ILs in the pathogenesis of this condition. In addition, variations in environmental factors and genetics in each individual can influence the onset and/or progression of NAFLD. The lack of clinical studies related to the potential therapeutic properties of IL-1 inhibitors currently does not allow us to conclude their validity as a therapeutic option, although preclinical studies show promising results. Further studies are needed to elucidate their beneficial properties in NAFLD treatment.

Flavonoids and ischemic stroke-induced neuroinflammation: Focus on the glial cells

Ischemic stroke is one of the most cases worldwide, with high rate of morbidity and mortality. In the pathological process of ischemic stroke, neuroinflammation is an essential process that defines the functional prognosis. After stroke onset, microglia, astrocytes and the infiltrating immune cells contribute to a complicated neuroinflammation cascade and play the complicated roles in the pathophysiological variations of ischemic stroke. Both microglia and astrocytes undergo both morphological and functional changes, thereby deeply participate in the neuronal inflammation via releasing pro-inflammatory or anti-inflammatory factors. Flavonoids are plant-specific secondary metabolites and can protect against cerebral ischemia injury via modulating the inflammatory responses. For instances, quercetin can inhibit the expression and release of pro-inflammatory cytokines, such as tumor necrosis factor (TNF)-α, IL-6 and IL-1β, in the cerebral nervous system (CNS). Apigenin and rutin can promote the polarization of microglia to anti-inflammatory genotype and then inhibit neuroinflammation. In this review, we focused on the dual roles of activated microglia and reactive astrocyte in the neuroinflammation following ischemic stroke and discussed the anti-neuroinflammation of some flavonoids. Importantly, we aimed to reveal the new strategies for alleviating the cerebral ischemic stroke.