The adipocytokine resistin stimulates the production of proinflammatory cytokines TNF-α and IL-6 in pancreatic acinar cells via NF-κB activation

Predictive value of adipokines for the severity of acute pancreatitis: a meta-analysis

BACKGROUND

Severe acute pancreatitis (SAP) is a dangerous condition with a high mortality rate. Many studies have found an association between adipokines and the development of SAP, but the results are controversial. Therefore, we performed a meta-analysis of the association of inflammatory adipokines with SAP.

METHODS

We screened PubMed, EMBASE, Web of Science and Cochrane Library for articles on adipokines and SAP published before July 20, 2023. The quality of the literature was assessed using QUADAS criteria. Standardized mean differences (SMD) with 95% confidence intervals (CI) were calculated to assess the combined effect. Subgroup analysis, sensitivity analysis and publication bias tests were also performed on the information obtained.

RESULT

Fifteen eligible studies included 1332 patients with acute pancreatitis (AP). Pooled analysis showed that patients with SAP had significantly higher serum levels of resistin (SMD = 0.78, 95% CI:0.37 to 1.19, z = 3.75, P = 0.000). The difference in leptin and adiponectin levels between SAP and mild acute pancreatitis (MAP) patients were not significant (SMD = 0.30, 95% CI: -0.08 to 0.68, z = 1.53, P = 0.127 and SMD = 0.11, 95% CI: -0.17 to 0.40, z = 0.80, P = 0.425, respectively). In patients with SAP, visfatin levels were not significantly different from that in patients with MAP (SMD = 1.20, 95% CI: -0.48 to 2.88, z = 1.40, P = 0.162).

CONCLUSION

Elevated levels of resistin are associated with the development of SAP. Resistin may serve as biomarker for SAP and has promise as therapeutic target.

Regulatory mechanisms of macrophage polarization in adipose tissue

In adipose tissue, macrophages are the most abundant immune cells with high heterogeneity and plasticity. Depending on environmental cues and molecular mediators, adipose tissue macrophages (ATMs) can be polarized into pro- or anti-inflammatory cells. In the state of obesity, ATMs switch from the M2 polarized state to the M1 state, which contributes to chronic inflammation, thereby promoting the pathogenic progression of obesity and other metabolic diseases. Recent studies show that multiple ATM subpopulations cluster separately from the M1 or M2 polarized state. Various factors are related to ATM polarization, including cytokines, hormones, metabolites and transcription factors. Here, we discuss our current understanding of the potential regulatory mechanisms underlying ATM polarization induced by autocrine and paracrine factors. A better understanding of how ATMs polarize may provide new therapeutic strategies for obesity-related diseases.

Astaxanthin Inhibits Interleukin-6 Expression in Cerulein/Resistin-Stimulated Pancreatic Acinar Cells

Acute pancreatitis is a common clinical condition with increasing the proinflammatory mediators, including interleukin-6 (IL-6). Obesity is a negative prognostic factor in acute pancreatitis. Obese patients with acute pancreatitis have a higher systemic inflammatory response rate. Levels of serum resistin, an adipocytokine secreted by fat tissues, increase with obesity. Cerulein, a cholecystokinin analog, induces calcium (Ca²⁺) overload, oxidative stress, and IL-6 expression in pancreatic acinar cells, which are hallmarks of acute pancreatitis. A recent study showed that resistin aggravates the expression of inflammatory cytokines in cerulein-stimulated pancreatic acinar cells. We aimed to investigate whether resistin amplifies cerulein-induced IL-6 expression and whether astaxanthin (ASX), an antioxidant carotenoid with anti-inflammatory properties, inhibits ceruelin/resistin-induced IL-6 expression in pancreatic acinar AR42J cells. We found that resistin enhanced intracellular Ca²⁺ levels, NADPH oxidase activity, intracellular reactive oxygen species (ROS) production, NF-κB activity, and IL-6 expression in cerulein-stimulated AR42J cells, which were inhibited by ASX in a dose-dependent manner. The calcium chelator BAPTA-AM inhibited cerulein/resistin-induced NADPH oxidase activation and ROS production. Antioxidant N-acetyl cysteine (NAC) and ML171, a specific NADPH oxidase 1 inhibitor, suppressed cerulein/resistin-induced ROS production, NF-κB activation, and IL-6 expression. In conclusion, ASX inhibits IL-6 expression, by reducing Ca²⁺ overload, NADPH oxidase-mediated ROS production, and NF-κB activity in cerulein/resistin-stimulated pancreatic acinar cells. Consumption of ASX-rich foods could be beneficial for preventing or delaying the incidence of obesity-associated acute pancreatitis.

Effects of Interval Jump Rope Exercise Combined with Dark Chocolate Supplementation on Inflammatory Adipokine, Cytokine Concentrations, and Body Composition in Obese Adolescent Boys

We examined the effects of six weeks of dark chocolate supplementation combined with interval jump rope exercise (JRE) on inflammatory cytokines, adipokines, and body composition in obese adolescent boys. Forty-eight obese adolescent boys (age  = 15.4  ±  1.1 years and body mass index  =  32.2  ±  2.4 kg/m²) were randomly assigned into one of four groups: JRE + white chocolate (JW; n = 13), JRE + dark chocolate supplementation (JD; n = 13), dark chocolate supplementation (DS; n = 12), or control (C; n = 12). Participants in JW and JD groups performed JRE for three times per week for six weeks. Participants in the DS and JD groups consumed 30 g of dark chocolate containing 83% of cocoa. Body composition, pro-inflammatory cytokines ((hs-CRP, TNF-α, IL-6), adipokines (leptin, resistin, RBP-4, chemerin, MCP-1), and anti-inflammatory adipokines (irisin, adiponectin)) were evaluated prior to and after the intervention trials. All three intervention trials significantly (p < 0.05) decreased body mass, waist-hip ratio, fat mass, hs-CRP, TNF-α, IL-6, leptin, resistin, RBP-4, and MCP-1, and increased irisin and adiponectin concentrations. The improvements in these parameters were greater in the JD group, and additionally, chemerin concentrations decreased only in the JD group. JD enhanced adiponectin concentrations and decreased IL-6 concentrations compared to C. Moreover, JD significantly reduced chemerin concentrations, an effect not observed in any of the other interventions. We demonstrated that dark chocolate supplementation potentiated JRE-induced decreases in body mass, WHR, FM, hs-CRP, TNF-α, IL-6, leptin, resistin, RBP-4, and MCP-1, chemerin as well as increases irisin and adiponectin concentrations in obese adolescent boys. Therefore, JRE combined with dark chocolate supplementation could be a beneficial in reducing obesity-induced inflammation in adolescent boys.

Resistin Activates p65 Pathway and Reduces Glycogen Content through Keratin 8

Resistin is associated with metabolic syndrome and inflammatory conditions. Many studies have suggested that resistin inhibits the accumulation of glycogen; however, the exact mechanisms of resistin-induced decrease in glycogen content remain unclear. Keratin 8 is a typical epithelial intermediate filament protein, but numerous studies suggest a vital role of K8 in glucose metabolism. However, it is still not known whether K8 participates in the mediation of resistin-induced reduction of cellular glycogen accumulation. In this study, we found that resistin upregulated expression of the p65 subunit of NF-κB, which led to the promotion of K8 transcriptional expression; in turn, the expression of K8 inhibited glycogen accumulation in HepG2 cells.

Cytokines and inflammation in adipogenesis: an updated review

The biological relevance of cytokines is known for more than 20 years. Evidence suggests that adipogenesis is one of the biological events involved in the regulation of cytokines, and pro-inflammatory cytokines (e.g., TNFα and IL-1β) inhibit adipogenesis through various pathways. This inhibitory effect can constrain the hyperplastic expandability of adipose tissues. Meanwhile, chronic low-grade inflammation is commonly observed in obese populations. In some individuals, the impaired ability of adipose tissues to recruit new adipocytes to adipose depots during overnutrition results in adipocyte hypertrophy, ectopic lipid accumulation, and insulin resistance. Intervention studies showed that pro-inflammatory cytokine antagonists improve metabolism in patients with metabolic syndrome. This review focuses on the cytokines currently known to regulate adipogenesis under physiological and pathophysiological circumstances. Recent studies on how inhibited adipogenesis leads to metabolic disorders were summarized. Although the interplay of cytokines and lipid metabolism is yet incompletely understood, cytokines represent a class of potential therapeutic targets in the treatment of metabolic disorders.

Inflammatory Effects of Subacute Exposure of Roundup in Rat Liver and Adipose Tissue

Roundup is a popular herbicide containing glyphosate as an active ingredient. The formulation of Roundup is speculated to have critical toxic effects, one among which is chronic inflammation. The present study analyzed adverse inflammatory effects in the liver and adipose tissue of rats after a subacute exposure of Roundup. Adult male rats were exposed to various doses of Roundup (0, 5, 10, 25, 50, 100 and 250 mg/kg bodyweight [bw] glyphosate) orally, everyday for 14 days. On day 15, liver and adipose tissues from dosed rats were analyzed for inflammation markers. C-reactive protein in liver, cytokines IL-1β, TNF-α, IL-6, and inflammatory response marker, and prostaglandin–endoperoxide synthase were upregulated in liver and adipose of rats exposed to higher (100 and 250 mg/kg bw/d) doses of Roundup. Cumulatively, our data suggest development of inflammation in lipid and hepatic organs upon exposure to Roundup. Furthermore, liver histological studies showed formation of vacuoles, fibroid tissue, and glycogen depletion in the groups treated with doses of higher Roundup. These observations suggest progression of fatty liver disease in Roundup-treated adult rats. In summary, our data suggest progression of multiorgan inflammation, liver scarring, and dysfunction post short-term exposure of Roundup in adult male rats.

Plasma Resistin Levels in Patients with Acute Aortic Dissection: A Propensity Score-Matched Observational Case-Control Study

Background

The aim of this observational case-control study was to compare the levels of plasma resistin between patients with acute aortic dissection and matched controls, and to use propensity score matching (PSM) to reduce case selection bias and clinical confounders.

Material/Methods

With the use of PSM, this study included 43 pairs of patients with acute aortic dissection (type-A and type-B dissection) and matched controls. Plasma resistin levels and other laboratory parameters were compared between the two groups, including white blood cell (WBC) count, glucose, high sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and D-dimer. The correlations between resistin and other laboratory parameters were evaluated in patients with acute aortic dissection.

Results

Following PSM adjustment for clinical variables, including age, sex, body mass index, smoking, alcohol drinking, hypertension, diabetes mellitus, coronary heart disease and stroke, plasma resistin levels were significantly increased in patients with acute aortic dissection when compared with controls (35.2±13.8 vs. 18.4±9.1 ng/ml) (p<0.001). WBC counts, and levels of glucose, hs-CRP, IL-6, TNF-α and D-dimer were also significantly increased in the patients with aortic dissection compared with the control group. After adjustment for these variables, the association between plasma resistin levels and acute aortic dissection remained significant (OR, 1.114; 95% CI, 1.036–1.224) (p<0.001). Plasma resistin levels was positively correlated with WBC count (r=0.368, p=0.015), hs-CRP (r=0.359, p=0.022), IL-6 (r=0.306, p=0.046) and TNF-α levels (r=0.315, p=0.040) in patients with acute aortic dissection.

Conclusions

Acute aortic dissection is associated with elevated levels of plasma resistin and other pro-inflammatory cytokines. Plasma resistin levels is positively associated with other pro-inflammatory cytokines in acute aortic dissection.

The role of adipokines in skeletal muscle inflammation and insulin sensitivity

Background

There is currently an unmet clinical need to develop better pharmacological treatments to improve glucose handling in Type II Diabetes patients with obesity. To this end, determining the effect of obesity-associated adipokines on skeletal muscle insulin sensitivity has emerged as an important area of drug discovery research. This review draws together the data on the functional role of adipokines on skeletal muscle insulin signalling, highlights several understudied novel adipokines and provides a perspective on the direction of future research.

Main body

The adipokines leptin, resistin, visfatin and adiponectin have all been shown to affect skeletal muscle insulin sensitivity by impacting on the activity of components within insulin signalling pathways, affecting GLUT4 translocation and modulating insulin-mediated skeletal muscle glucose uptake. Furthermore, proteomic analysis of the adipose tissue secretome has recently identified several novel adipokines including vaspin, chemerin and pref-1 that are associated with obesity and insulin resistance in humans and functionally impact on insulin signalling pathways. However, predominantly, these functional findings are the result of studies in rodents, with in vitro studies utilising either rat L6 or murine C2C12 myoblasts and/or myotubes. Despite the methodology to isolate and culture human myoblasts and to differentiate them into myotubes being established, the use of human muscle in vitro models for the functional validation of adipokines on skeletal muscle insulin sensitivity is limited.

Conclusion

Understanding the mechanism of action and function of adipokines in mediating insulin sensitivity in skeletal muscle may lead to the development of novel therapeutics for patients with type 2 diabetes. However, to date, studies conducted in human skeletal muscle cells and tissues are limited. Such human in vitro studies should be prioritised in order to reduce the risk of candidate drugs failing in the clinic due to the assumption that rodent skeletal muscle target validation studies will to translate to human.

From Placenta to Polycystic Ovarian Syndrome: The Role of Adipokines

Adipokines are cytokines produced mainly by adipose tissue, besides many other tissues such as placenta, ovaries, peripheral-blood mononuclear cells, liver, muscle, kidney, heart, and bone marrow. Adipokines play a significant role in the metabolic syndrome and in cardiovascular diseases, have implications in regulating insulin sensitivity and inflammation, and have significant effects on growth and reproductive function. The objective of this review was to analyze the functions known today of adiponectin, leptin, resistin, and visfatin from placenta throughout childhood and adolescence. It is well known now that their serum concentrations during pregnancy and lactation have long-term effects beyond the fetus and newborn. With regard to puberty, adipokines are involved in the regulation of the relationship between nutritional status and normal physiology or disorders of puberty and altered gonadal function, as, for example, premature pubarche and polycystic ovarian syndrome (PCOS). Cytokines are involved in the maturation of oocytes and in the regular progression of puberty and pregnancy.

A novel modulation of structural and functional changes of mouse bone marrow derived dendritic cells (BMDCs) by interleukin-2(IL-2)

IL-2 is a pleiotropic cytokine produced by T cell after antigen activation of T cell and it is so called T cell growth factor. A large number of documents suggest that Il-2 plays pivotal roles in the immune response and now Il-2 is an approved drug being used for various kinds of diseases such as cancer and dermatitis. (1) The aim of present exploration was to look at effect of IL-2 on structural, phenotypic and functional maturation of murine BMDCs. The structural and phenotypic maturation of BMDCs under influence of IL-2 were evaluated by light microscope and flow cytometry (FCM). The functional maturation of BMDCs was confirmed by cytochemistry assay, FITC-dextran, acid phosphatase (ACP) activity, bio-assay and enzyme linked immunosorbent assay (ELISA).We elucidated that IL-2 up-regulated the expression of key surface markers such as: CD80, CD83, CD86, CD40 and MHC II molecules on BMDCs, down-regulated phagocytosis activity, induced more production of IL-12 and TNF-α secreted by BMDCs. Therefore it can be concluded that IL-2 effectively enhance the maturation of BMDCs. Our results provide direct evidence to support IL-2 would be used as a potent adjuvant in preparation of DC-based vaccines, as well as an immune remedy for cancer situation.

Significance of resistin expression in acute pancreatitis

The aim of the present study was to detect the expression of resistin in rats with acute pancreatitis (AP) and investigate its significance in the pathogenesis of AP. In total, 40 Sprague-Dawley rats were randomly divided into four groups (n=10), including the normal control, sham-operated, acute edematous pancreatitis (AEP) and acute necrotizing pancreatitis (ANP) groups. Following the establishment of animal models, the levels of serum resistin, C-reactive protein (CRP), tumor necrosis factor-α (TNF-α) and interleukin (IL)-1β were measured using ELISA. Resistin expression in the pancreatic tissues was detected using an immunohistochemical method. In addition, the mRNA expression of resistin in the pancreatic tissues was analyzed with quantitative polymerase chain reaction. The levels of serum amylase, serum resistin, TNF-α, IL-1β and CRP were all significantly higher in the AEP and ANP groups when compared with the control and sham-operated groups (P<0.01), as were the pancreas/body weight ratios and pathological scores of the pancreas. These increases were more significant in the ANP group than in the AEP group (P<0.05). The mRNA expression levels of resistin in the pancreatic tissues were markedly higher in the AEP and ANP groups when compared with the control and sham-operated groups (P<0.01), particularly in the pancreatic tissues of the ANP group, which exhibited notably higher levels compared with the AEP group. The serum resistin level was found to positively correlate with the serum levels of CRP, TNF-α and IL-1β, and the pathological scores of the pancreatic tissues. In conclusion, the results indicated that resistin may be associated with the occurrence and development of AP; thus, the protein may be a valuable indicator for assessing the severity of AP.

Site-specific changes in cytokine response to septic dose of lipopolysaccharide in ovariectomized female rats

PURPOSE

The immune response is altered according to hormonal and metabolic status. Obesity increases the inflammatory and fever response, whereas loss of gonadal steroid decreases behavioral response to immune stress. However, the immune systems of ovariectomized animals exhibiting obesity and gonadal steroid deficiency, particularly under septic conditions, have not been fully examined. In the present study, we evaluated the ovariectomy-induced changes of central and peripheral immune responses to life-threatening septic stimulus.

METHODS AND RESULTS

Ovariectomized rats showed heavier body weight and lighter uterine weight when compared with gonadally intact rats. Fever response to septic dose of lipopolysaccharide (LPS) in ovariectomized rats was less evident when compared with that in gonadally intact rats. In addition, under LPS-injected septic conditions, hypothalamic gene levels of Interleukin-1β (IL-1β), Interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) and serum protein levels of IL-1β and TNF-α in ovariectomized rats were lower than those in gonadally intact rats. On the other hand, IL-6 levels in visceral fat under septic conditions were higher in ovariectomized rats than in gonadally intact rats.

CONCLUSIONS

These findings indicate that ovariectomy-induced site-specific changes in cytokine response under septic conditions. As hypothalamic, but not peripheral, pro-inflammatory cytokines are directly involved in the fever response, the attenuation of fever response observed in ovariectomized rats may be caused by a reduction in central cytokine responses.