High Irisin levels in nondiabetic HIV-infected males are associated with insulin resistance, nonalcoholic fatty liver disease, and subclinical atherosclerosis

Circulating irisin levels in patients with MAFLD: an updated systematic review and meta-analysis

Objective

Current research suggests that irisin is closely linked to the pathogenesis and progression of metabolic dysfunction-associated fatty liver disease (MAFLD). This systematic review and meta-analysis updates our previous meta-analysis and further explores the relevance between circulating irisin levels and MAFLD.

Methods

Nine databases (PubMed, EMBASE, Cochrane Library, CNKI, Wanfang, Weipu, CBM, Clinicaltrials.gov and gray literature) were retrieved as of 1st August, 2024. The standardized mean difference (SMD) and 95% confidence interval (CI) represent pooled effect size. We used the Newcastle-Ottawa Scale to evaluate the quality of articles and the certainty of evidence assessed by GRADE system. All statistical analyses were performed using RevMan 5.3 and Stata 12(Stata Corporation, yi TX).

Results

Fifteen case-control studies were included. Circulating irisin levels in the MAFLD group were markedly lower than those in the healthy group (SMD=-1.04 [-1.93, -0.14]). Subgroup analyses by race, age, severity and T2DM revealed that circulating irisin levels were lower in the MAFLD group compared to those in the healthy controls in the Asian population (SMD=-1.38 [-2.44, -0.31], P<0.05) and in those above 50 years old (SMD=-2.23 [-3.64, -0.81], P<0.05) and higher in the mild MAFLD groups than those in moderate to severe MAFLD groups (SMD = 11.68 [9.05, 14.31], P<0.05). And the circulating irisin levels in MAFLD patients with T2DM were significantly lower than those in healthy group (SMD = -2.90 [-4.49, -1.30]). ELISA kits from different companies also presented different relationships.

Conclusions

There were significantly lower circulating irisin levels in the MAFLD group than in the healthy control group. Although these results differed from our previous results, there is no denying that circulating irisin levels are closely associated with the advancement of MAFLD.

Assessment of Metabolic, Inflammatory, and Immunological Disorders Using a New Panel of Plasma Parameters in People Living with HIV Undergoing Antiretroviral Therapy-A Retrospective Study

Background/Objectives: People living with HIV (PLWH) treated with combined antiretroviral therapy (cART) show a greater predisposition to metabolic and inflammatory disturbances compared to the general population. This study aimed to assess the effect of five years of cART use on the level of selected parameters related to carbohydrate and lipid metabolism and inflammation in PLWH compared to the uninfected. Methods: The levels of sirtuins (-1, -3, -6); irisin (IRS); myostatin (MSTN); peptide YY (PYY); glucagon-like peptide-1 (GLP-1); dipeptidyl peptidase IV (DPP-4); fetuin-A (FETU-A); pentraxin 3 (PTX3); chemokine stromal cell-derived factor 1 (SDF-1); regulated on activation, normal T cell expressed and presumably secreted (RANTES); and interleukins (-4, -7, -15) in the plasma of PLWH and a control group were evaluated by immunoassay methods. The results obtained after five years of antiretroviral therapy were compared with the levels obtained before and one year after cART. Results: Analysis of the parameters after five years of cART showed significantly higher levels in PLWH compared to the control group for SIRT-6, IRS, and IL-4 and significantly lower levels for RANTES and IL-7. There were significantly higher levels of SIRT-6, PYY, GLP-1, and PTX3 obtained after five years of cART compared to the results before therapy and after one year of cART. Conclusions: The results indicated changes occur in the expression of selected parameters during cART use in PLWH. Further research on the clinical usefulness of selected parameters and obtaining new information on the development of HIV-related comorbidities needs to be conducted.

Regional variation in NAFLD prevalence and risk factors among people living with HIV in Europe: a meta-analysis

Background and Aim

Europe faces an elevated risk of nonalcoholic fatty liver disease (NAFLD) among people living with HIV (PLWH), contributing to the region's highest global burden of NAFLD. However, the prevalence of NAFLD across various European countries and regions remains unclear. This study aims to investigate the prevalence and risk factors associated with NAFLD among PLWH across European countries.

Methods

A systematic search was conducted across four databases: PubMed, Embase, Web of Science, and Cochrane Library. Data on the prevalence of NAFLD, nonalcoholic steatohepatitis (NASH), and fibrosis, as well as the associated risk factors, were collected among PLWH in Europe.

Results

Thirty-six studies from 13 European nations were included. The prevalence of NAFLD, NASH, and fibrosis were 42% (95%CI 37-48), 35% (95%CI 21-50) and 13% (95%CI 10-15), respectively. Male gender, BMI, waist circumference, Diabetes, hypertension, metabolic syndrome, dyslipidemia, triglycerides, HDL, LDL, ALT, AST, and years on antiretroviral therapy (ART) were found to be risk factors for NAFLD. High BMI and triglycerides were associated with NASH. Patients with high BMI and triglycerides are at increased risk of significant liver fibrosis.

Conclusion

The high prevalence of NAFLD, NASH, and fibrosis among PLWH in Europe highlights the need for early screening, intervention, and increased research focus on adolescents living with HIV. Furthermore, the significant variations observed between countries and regions underscore the influence of related risk factors.

Down regulation of the inverse relationship between parathyroid hormone and irisin in male vitamin D-sufficient HIV patients

PURPOSE

Infection with the human immunodeficiency virus (HIV) predisposes to endocrine disorders, manifesting as a metabolic phenotype that affects the entire adipose-musculoskeletal unit (AMS). The present cross-sectional study aimed to investigate differences in irisin and adiponectin concentrations between people living with HIV and healthy controls, as well as to explore potential correlations between the levels of the aforementioned adipokines and markers of calcium homeostasis.

METHODS

46 HIV-infected individuals and 39 healthy controls (all men) were included in the study. Anthropometric data, adipokine levels, 25-hydroxyvitamin D [(25(OH)D)] and parathyroid hormone (PTH) concentrations were evaluated in the two groups. Correlations for the relationship between adiponectin, irisin, and PTH levels were examined. The results were adjusted for several confounders, including 25(OH)D levels, anthropometry, physical activity, bone mineral density, testosterone levels, and exposure to ultraviolet B radiation.

RESULTS

Mean adiponectin concentrations were significantly lower in the HIV group compared to the control group: 5868 ± 3668 vs 9068 ± 4277 ng/mL, p = 0.011. The same was applicable to irisin concentrations: 8.31 ± 8.17 (HIV) vs 29.27 ± 27.23 (controls) ng/mL, p = 0.013. A statistically significant and negative correlation was observed between irisin and PTH in the control group (r =  - 0.591; p = 0.033). In contrast, no significant correlation was observed between PTH and irisin in the HIV group (p = 0.898).

CONCLUSION

Our results are the first to suggest a possible down regulation of the inverse relationship between PTH and irisin in HIV patients and to highlight that AMS dyshomeostasis could be involved in the development of skeletal and adipose HIV-related morbidities.

Potential role of irisin in digestive system diseases

Digestive system diseases (DSD) are very complex conditions that severely threaten human health. Therefore, there is an urgent need to develop new pharmacological treatment strategies. Irisin, a myokine discovered in 2012, is produced by fibronectin type III domain-containing protein 5 (FNDC5), which is a transmembrane protein. Irisin is involved in promoting the browning of white adipose tissue, the regulation of energy metabolism, and the improvement of insulin resistance. Irisin is also an essential mediator of the inflammatory response, oxidative stress, and cell apoptosis. Recent studies have proved that irisin concentration is altered in DSD and exerts pivotal effects on the initiation, progression, and prognosis of these diseases through various mechanisms. Therefore, studying the expression and function of irisin may have great significance for the diagnosis and treatment of DSD. Here, we focus on irisin and explore the multiple molecular pathways targeted by irisin therapy. This review indicates that irisin can serve as a diagnostic marker or potential therapeutic agent for DSD. DATA AVAILABILITY: Not applicable.

The potential role of FNDC5/irisin in various liver diseases: awakening the sleeping beauties

Fibronectin type III domain-containing protein 5 (FNDC5) is a transmembrane protein and the precursor of irisin, which serves as a systemic exerkine/myokine with multiple origins. Since its discovery in 2012, this hormone-like polypeptide has rapidly evolved to a component significantly involved in a gamut of metabolic dysregulations and various liver diseases. After a decade of extensive investigation on FNDC5/irisin, we are still surrounded by lots of open questions regarding its diagnostic and therapeutic values. In this review, we first concentrated on the structure-function relationship of FNDC5/irisin. Next, we comprehensively summarised the current knowledge and research findings regarding pathogenic roles/therapeutic applications of FNDC5/irisin in the context of non-alcoholic fatty liver disease, fibrosis, liver injury due to multiple detrimental insults, hepatic malignancy and intrahepatic cholestasis of pregnancy. Moreover, the prominent molecules involved in the underlying mechanisms and signalling pathways were highlighted. As a result, emerging evidence reveals FNDC5/irisin may act as a proxy for diagnosing liver disease pathology, a sensitive biomarker for assessing damage severity, a predisposing factor for surveilling illness progression and a treatment option with protective/preventive impact, all of which are highly dependent on disease grading and contextually pathological features.

Irisin Suppresses Nicotine-Mediated Atherosclerosis by Attenuating Endothelial Cell Migration, Proliferation, Cell Cycle Arrest, and Cell Senescence

Atherosclerotic disease has become the major cause of death worldwide. Smoking, as a widespread independent risk factor, further strengthens the health burden of atherosclerosis. Irisin is a cytokine that increases after physical activity and shows an atheroprotective effect, while its specific mechanism in the process of atherosclerosis is little known. The reversal effect of irisin on intimal thickening induced by smoking-mediated atherosclerosis was identified in Apoe^–/– mice through the integrin αVβ5 receptor. Endothelial cells treated with nicotine and irisin were further subjected to RNA-seq for further illustrating the potential mechanism of irisin in atherosclerosis, as well as the wound healing assays, CCK-8 assays, β-gal staining and cell cycle determination to confirm phenotypic alterations. Endothelial differential expressed gene enrichment showed focal adhesion for migration and proliferation, as well as the P53 signaling pathway for cell senescence and cell cycle control. Irisin exerts antagonistic effects on nicotine-mediated migration and proliferation via the integrin αVβ5/PI3K pathway. In addition, irisin inhibits nicotine-mediated endothelial senescence and cell cycle arrest in G0/G1 phase via P53/P21 pathway. This study further illustrates the molecular mechanism of irisin in atherosclerosis and stresses its potential as an anti-atherosclerotic therapy.

Effect of Combined Antiretroviral Therapy on the Levels of Selected Parameters Reflecting Metabolic and Inflammatory Disturbances in HIV-Infected Patients

Subjects infected with human immunodeficiency virus (HIV) treated with combined antiretroviral therapy (cART) show a greater predisposition to metabolic disturbances compared to the general population. The aim of the study was to assess the effect of cART on the level of selected parameters related to carbohydrate and lipid metabolism, cardiovascular diseases and inflammation in the plasma of HIV-infected patients against the uninfected. The levels of irisin (IRS), myostatin (MSTN), peptide YY (PYY), glucagon-like peptide-1 (GLP-1), dipeptidyl peptidase IV (DPP-4), fetuin A (FETU-A), pentraxin 3 (PTX 3), chemokine stromal cell-derived factor 1 (SDF-1), and regulated on activation normal T cell expressed and secreted (RANTES) in the plasma of HIV-infected patients and the control group were measured by immunoassay methods. HIV-infected patients were analyzed in terms of CD4+ T cells and CD8+ T cell count, HIV RNA viral load, and the type of therapeutic regimen containing either protease inhibitors (PIs) or integrase transfer inhibitors (INSTIs). The analysis of HIV-infected patients before and after cART against the control group showed statistically significant differences for the following parameters: IRS (p = 0.02), MSTN (p = 0.03), PYY (p = 0.03), GLP-1 (p = 0.03), PTX3 (p = 0.03), and RANTES (p = 0.02), but no significant differences were found for DPP-4, FETU-A, and SDF-1. Comparing the two applied therapeutic regimens, higher levels of all tested parameters were shown in HIV-infected patients treated with INSTIs compared to HIV-infected patients treated with PIs, but the differences were not statistically significant. The obtained results indicated significant changes in the expression of selected parameters in the course of HIV infection and cART. There is need for further research on the clinical usefulness of the selected parameters and for new information on the pathogenesis of HIV-related comorbidities to be provided. The obtained data may allow for better monitoring of the course of HIV infection and optimization of therapy in order to prevent the development of comorbidities as a result of long-term use of cART.

Irisin levels in the serum and cerebrospinal fluid of patients with multiple sclerosis and the expression and distribution of irisin in experimental autoimmune encephalomyelitis

Irisin is a novel hormone-like myokine that plays an important role in central nervous system (CNS) diseases, such as cerebral ischaemia and Alzheimer's disease. However, irisin is rarely investigated in multiple sclerosis (MS), a typical inflammatory demyelinating disease of the CNS, and in experimental autoimmune encephalomyelitis (EAE), a typical model of MS. We determined the levels of irisin in the serum and cerebrospinal fluid in patients with MS. The expression and histological distribution of irisin were determined in EAE. Serum irisin levels in patients with MS and in EAE mice were increased, and the levels of FNDC5/irisin mRNA were decreased in the spinal cord and brain regardless of the onset, peak or chronic phase of EAE. Immunofluorescence staining showed co-localization of irisin and neurones. The levels of irisin fluctuated with disease progression in MS and EAE. Irisin may be involved in the pathological process of MS/EAE.

Irisin alleviates obesity-related spermatogenesis dysfunction via the regulation of the AMPKα signalling pathway

BACKGROUND

Infertility is a common complication in obese men. Oxidative stress and testicular apoptosis play critical roles in obesity-induced spermatogenesis dysfunction. It has been reported that irisin, an exercise-induced myokine, may attenuate oxidative damage and testicular apoptosis in several diseases; however, its role in obesity-induced spermatogenesis dysfunction remains unclear. The purpose of this study was to investigate the role and underlying mechanism of irisin in obesity-induced dysfunction of spermatogenesis.

METHODS

Male mice were fed a high-fat diet (HFD) for 24 weeks to establish a model of obesity-induced spermatogenesis dysfunction. To explore the effects of irisin, mice were subcutaneously infused with recombinant irisin for 8 weeks beginning at 16 weeks after starting a HFD. To confirm the role of AMP-activated protein kinase α (AMPKα), AMPKα-deficient mice were used.

RESULTS

The data showed decreased serum irisin levels in obese patients, which was negatively correlated with sperm count and progressive motility. Irisin was downregulated in the plasma and testes of obese mice. Supplementation with irisin protected against HFD-induced spermatogenesis dysfunction and increased testosterone levels in mice. HFD-induced oxidative stress, endoplasmic reticulum (ER) stress and testicular apoptosis were largely attenuated by irisin treatment. Mechanistically, we identified that irisin activated the AMPKα signalling pathway. With AMPKα depletion, we found that the protective effects of irisin on spermatogenesis dysfunction were abolished in vivo and in vitro.

CONCLUSIONS

In conclusion, we found that irisin alleviated obesity-related spermatogenesis dysfunction via activation of the AMPKα signalling pathway. Based on these findings, we hypothesized that irisin is a potential therapeutic agent against obesity-related spermatogenesis dysfunction.

Fibronectin type III domain-containing 5 in cardiovascular and metabolic diseases: a promising biomarker and therapeutic target

Cardiovascular and metabolic diseases are the leading causes of death and disability worldwide and impose a tremendous socioeconomic burden on individuals as well as the healthcare system. Fibronectin type III domain-containing 5 (FNDC5) is a widely distributed transmembrane glycoprotein that can be proteolytically cleaved and secreted as irisin to regulate glycolipid metabolism and cardiovascular homeostasis. In this review, we present the current knowledge on the predictive and therapeutic role of FNDC5 in a variety of cardiovascular and metabolic diseases, such as hypertension, atherosclerosis, ischemic heart disease, arrhythmia, metabolic cardiomyopathy, cardiac remodeling, heart failure, diabetes mellitus, and obesity.

The Controversial Role of Irisin in Clinical Management of Coronary Heart Disease

Irisin, a PGC1α-dependent myokine, was once believed to have beneficial effects induced by exercise. Since its first discovery of adipose browning in 2012, multiple studies have been trying to explore the metabolic functions of irisin, such as glucose and lipid metabolism. However, recently many studies with irisin concentration measuring were doubt for methodological problems, which may account for the continuous inconsistencies. New tools like recombinant irisin and gene-knockout mice are required to reconfirm the questioned functions of irisin. In this paper, we make a critical introduction to the latest researches concerning the relationship between irisin and coronary heart disease, which includes atherosclerosis, stable angina pectoris and acute coronary syndromes. These studies provided various controversial evidence of short and long-term monitoring and therapeutic effect from molecular cellular mechanisms, in vivo experiments and epidemiological investigation. But with ambiguities, irisin still has a long way to go to identify its functions in the clinical management.

Physiopathology of Lifestyle Interventions in Non-Alcoholic Fatty Liver Disease (NAFLD)

Non-alcoholic fatty liver disease (NAFLD) is a major health problem, and its prevalence has increased in recent years. Diet and exercise interventions are the first-line treatment options, with weight loss via a hypocaloric diet being the most important therapeutic target in NAFLD. However, most NAFLD patients are not able to achieve such weight loss. Therefore, the requisite is the investigation of other effective therapeutic approaches. This review summarizes research on understanding complex pathophysiology underlying dietary approaches and exercise interventions with the potential to prevent and treat NAFLD.

Non-alcoholic fatty liver disease in patients infected with human immunodeficiency virus: a systematic review

OBJECTIVE

To evaluate the prevalence of nonalcoholic fatty liver disease (NAFLD) in patients with HIV/AIDS.

METHODS

The systematic review included articles indexed in MEDLINE (by PubMed), Web of Science, IBECS, and LILACS. Studies eligible included the year of publication, diagnose criteria of NAFLD and HIV, and were published in English, Portuguese, or Spanish from 2006 to 2018. The exclusion criteria were studies with HIV-infection patients and other liver diseases. Two reviewers were involved in the study and applied the same methodology, according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses).

RESULTS

One hundred and sixteen papers were selected, including full articles, editorial letters, and reviews. Twenty-seven articles were excluded because they did meet the inclusion criteria. A total of 89 articles were read, and 13 were considered eligible for this review. Four case series used imaging methods to identify NAFLD, and nine included histology. The prevalence of NAFLD in HIV-patients ranged from 30%-100% and, in nonalcoholic steatohepatitis (NASH), from 20% to 89%. A positive association between dyslipidemia, insulin resistance, and body mass index was observed. There was no agreement between the studies that evaluated the relationship between antiretroviral drugs and NAFLD.

CONCLUSION

This systematic review showed a high prevalence of NAFLD in HIV-patients, which was associated with metabolic risk factors. The possible association between antiretroviral therapy and NAFLD needs further studies.

Serum Irisin: Pathogenesis and Clinical Research in Cardiovascular Diseases

Recently, muscular function/dysfunction has gained importance in the maintenance of metabolic homeostasis in cardiovascular diseases. Skeletal muscle plays a vital role in coordinating the activity and metabolism of endocrine organs by secreting many myokines, especially irisin. Irisin is a polypeptide hormone consisting of 112 amino acids secreted into the blood from muscle and adipose tissues. Serum irisin levels are associated with cardiometabolic risk factors such as obesity and insulin resistance as defined by homeostatic model assessment. Irisin reduces endothelial damage by inhibiting inflammation and oxidative stress, thus playing a key role in maintaining endothelial cell function. Unsurprisingly, low irisin levels cause endothelial dysfunction and increase the incidence of atherosclerosis. We aimed to summarize the studies on this issue since we have not found any review in the literature on the role of serum irisin levels in the process of atherosclerosis and other cardiovascular events in cardiovascular diseases.

Association of Circulating Irisin Levels with Adiposity and Glucose Metabolic Profiles in a Middle-Aged Chinese Population: A Cross-Sectional Study

OBJECTIVE

The myokine irisin has been proposed to affect obesity and metabolism disorders. However, data about the association of irisin with obesity and glucose metabolic status in humans remains controversial, and limited data are available concerning the Chinese population. This study aimed to evaluate the association between serum irisin concentrations and obesity, as well as glucose metabolic and cardiovascular factors in the middle-aged physical activity-matched Chinese Han race population.

METHODS

A total of 740 participants were included in this cross-sectional study, who were divided into a normal weight (NW) group, overweight/obese (OB) group, normal weight type 2 diabetes (DM-NW) group and overweight/obese diabetes (DM-OB) group, and physical activity was evaluated and matched for the four groups. Circulating irisin levels were analyzed and compared among the groups with different adiposity and glucose status. Linear regression analysis was performed to test the relationship between serum irisin and adiposity indices, glucose metabolic and other cardiovascular risk factors.

RESULTS

Circulating irisin levels were significantly correlated with higher levels of direct and indirect adiposity markers, including BMI, waist circumference and fat mass, and other cardiovascular risk factors, such as plasma triglyceride and low-density lipoprotein cholesterol level (p < 0.01). Diabetes patients had lower irisin levels compared to non-diabetes participants, in either normal weight and obese group, resulting in a correlation of irisin with HbA1c, HOMA-IR and HOMA-IS (p < 0.01). Linear regression analysis demonstrated that irisin serum concentrations were independently associated with sex, BMI, HbA1c, HOMA-IR and HOMA-IS (R² = 0.465).

CONCLUSION

These data indicated that circulating irisin was affected by adiposity and glucose metabolism condition in the middle-aged Chinese population. The increase of irisin under conditions of obesity may indicate its physiological function to improve glucose tolerance which is often impaired in obese subjects, but this compensatory secretion of irisin seems likely to be progressing to a secretion failure once diabetes developed.

Irisin alleviates liver ischemia-reperfusion injury by inhibiting excessive mitochondrial fission, promoting mitochondrial biogenesis and decreasing oxidative stress

Current management of liver ischemia-reperfusion (I/R) injury is mainly based on supportive care and no specific treatment is available. Irisin, a recently identified hormone, plays pivotal roles in energy expenditure and oxidative metabolism; however, it remains unknown whether irisin has any protective effects on hepatic I/R injury. In this study, we found that serum and liver irisin levels were markedly decreased at 24 h after hepatic I/R. Treatment with exogenous irisin improved liver function, reduced liver necrosis and cell apoptosis, and relieved inflammatory response after hepatic I/R. Meanwhile, exogenous irisin markedly inhibited mitochondrial fission related protein dynamin related protein 1 (drp-1) and fission 1 (Fis-1) expression in hepatic I/R. Additionally, treatment with exogenous irisin increased mitochondrial content and increased mitochondrial biogenesis related peroxisome proliferative activated receptor-γ (PPARγ) co-activator 1α (PGC-1α) and mitochondrial transcription factor (TFAM) expression. Furthermore, irisin decreased oxidative stress by upregulating uncoupling proteins (UCP) 2 expression in hepatic I/R. The results reveal that treatment with exogenous irisin alleviated hepatic I/R injury by restraining mitochondrial fission, promoting mitochondrial biogenesis and relieving oxidative stress. Irisin treatment appears to be a novel and promising therapeutic approach for hepatic I/R injury.