Lipopolysaccharide induces a downregulation of adiponectin receptors in-vitro and in-vivo

Quercetin declines LPS induced inflammation and augments adiponectin expression in 3T3-L1 differentiated adipocytes SIRT-1 dependently

BACKGROUND

Inflammation is an important factor contributing to obesity-induced metabolic disorders. Different investigations confirm that local inflammation in adipose issues is the primary reason for such disorder, resulting in low-grade systemic inflammation. Anti-inflammatory, antioxidant, and epigenetic modification are among the varied properties of Quercetin (QCT) as a natural flavonoid.

OBJECTIVE

The precise molecular mechanism followed by QCT to alleviate inflammation has been unclear. This study explores whether the anti-inflammatory effects of QCT in 3T3-L1 differentiated adipocytes may rely on SIRT-1.

METHODS

The authors isolated 3T3-L1 pre-adipocyte cells and exposed them to varying concentrations of QCT, lipopolysaccharide (LPS), and a selective inhibitor of silent mating type information regulation 2 homolog 1 (SIRT-1) called EX-527. After determining the optimal dosages of QCT, LPS, and EX-527, they assessed the mRNA expression levels of IL-18, IL-1, IL-6, TNF-α, SIRT-1, and adiponectin using quantitative reverse transcription-polymerase chain reaction (qRT-PCR).

RESULTS

The study showed considerable cytotoxic effects of LPS (200 ng/mL) + QCT (100 µM) + EX-527 (10 µM) on 3T3-L1 differentiated adipocytes after 48 h of incubation. QCT significantly upregulated the expression levels of adiponectin and SIRT-1 (p < 0.0001). However, introducing SIRT-1 inhibitor (p < 0.0001) reversed the impact of QCT on adiponectin expression. Additionally, QCT reduced SIRT-1-dependent pro-inflammatory cytokines in 3T3-L1 differentiated adipocytes (p < 0.0001).

CONCLUSION

This study revealed that QCT treatment reduced crucial pro-inflammatory cytokines levels and increased adiponectin levels following LPS treatment. This finding implies that SIRT-1 may be a crucial factor for the anti-inflammatory activity of QCT.

Are gut dysbiosis, barrier disruption, and endotoxemia related to adipose tissue dysfunction in metabolic disorders? Overview of the mechanisms involved

Recently, compelling evidence points to dysbiosis and disruption of the epithelial intestinal barrier as major players in the pathophysiology of metabolic disorders, such as obesity. Upon the intestinal barrier disruption, components from bacterial metabolism and bacteria itself can reach peripheral tissues through circulation. This has been associated with the low-grade inflammation that characterizes obesity and other metabolic diseases. While circulating bacterial DNA has been postulated as a common feature of obesity and even type 2 diabetes, almost no focus has been given to the existence and effects of bacteria in peripheral tissues, namely the adipose tissue. As a symbiont population, it is expected that gut microbiota modulate the immunometabolism of the host, thus influencing energy balance mechanisms and inflammation. Gut inflammatory signals cause direct deleterious inflammatory responses in adipose tissue and may also affect key gut neuroendocrine mechanisms governing nutrient sensing and energy balance, like incretins and ghrelin, which play a role in the gut-brain-adipose tissue axis. Thus, it is of major importance to disclose how gut microbiota and derived signals modulate neuroendocrine and inflammatory pathways, which contribute to the dysfunction of adipose tissue and to the metabolic sequelae of obesity and related disorders. This review summarizes the current knowledge regarding these topics and identifies new perspectives in this field of research, highlighting new pathways toward the reduction of the inflammatory burden of metabolic diseases.

Adiponectin antagonises LPS-regulated secretion of inflammatory factors in airway epithelial cells, and its expression is regulated by many factors

Many studies have shown that adiponectin is closely related to chronic obstructive pulmonary disease (COPD), but the specific role of adiponectin in COPD is still not well understood. Adiponectin and IL-6 expression in patients with acute exacerbation of COPD (AECOPD) was detected by ELISA. Human bronchial epithelial cells (HBECs) were stimulated with TNF-α, IL-6, apoptotic cells or LPS. Then, the expression of adiponectin was detected by qRT-PCR and western blotting, and pro- and anti-inflammatory factors were detected by ELISA. Adiponectin expression in AECOPD patients increased after treatment. TNF-α and apoptotic cells promoted adiponectin expression in HBECs in a dose-dependent manner, and apoptotic cells significantly promoted adiponectin secretion. IL-6 also promoted adiponectin expression, but it inhibited adiponectin expression at high doses and with long treatment times. LPS inhibited adiponectin expression, but when HBECs were pretreated with anti-TNF-α and then treated with LPS, the expression and secretion of adiponectin increased significantly with increasing anti-TNF-α concentrations. Adiponectin stimulated the secretion of pro-inflammatory factors in HBECs, but this effect was not concentration dependent. Adiponectin promoted the secretion of anti-inflammatory factors in a dose-dependent manner. Although LPS also stimulated HBECs to secrete pro-inflammatory and anti-inflammatory factors, adiponectin inhibited LPS-induced pro-inflammatory factor secretion and enhanced anti-inflammatory factor secretion. Many factors regulate the expression and secretion of adiponectin, and adiponectin regulates the balance of the inflammatory response and inhibits further expansion of inflammation. SIGNIFICANCE OF THE STUDY: Many studies have shown that adiponectin is closely related to chronic obstructive pulmonary disease (COPD), but the specific role of adiponectin in COPD is still not well understood. Adiponectin expression in AECOPD patients increased after treatment. TNF-α, IL-6 and apoptotic cells promoted adiponectin expression in HBECs. Adiponectin stimulated the secretion of pro-inflammatory factors in HBECs, but this effect was not concentration dependent. Adiponectin promoted the secretion of anti-inflammatory factors in a dose-dependent manner. Adiponectin inhibited LPS-induced pro-inflammatory factor secretion and enhanced anti-inflammatory factor secretion. Therefore, many factors regulate the expression and secretion of adiponectin, and adiponectin regulates the balance of the inflammatory response and inhibits further expansion of inflammation.

Serum markers of inflammation and oxidative stress in sarcopenia

BACKGROUND

Sarcopenia is a geriatric syndrome characterized by the presence of low muscle mass and function. Possible mechanisms underlying sarcopenia include oxidative stress and elevation of inflammatory cytokines.

AIMS

The aim of the study was to evaluate the relationship between sarcopenia and biomarkers that may be involved in its pathogenesis and hence early detection.

METHODS

A total of 72 patients (36 sarcopenic and 36 non-sarcopenic) were included in the study. An experienced geriatric team applied comprehensive geriatric assessment to all patients. Anthropometric measures, gait speed and handgrip strength were recorded. Bioelectrical impedance analysis was used to assess skeletal muscle mass. In addition to routine clinical laboratory tests, serum adiponectin, thioredoxin-1 and pentraxin-3 levels were measured. Sarcopenia was defined according to the European Working Group on Sarcopenia in older Adults as the presence of low muscle mass and low muscle function or muscle performance.

RESULTS

Sarcopenic patients were more likely to be functionally dependent and had lower scores on comprehensive geriatric assessment tools. Erythrocyte sedimentation rate (ESR) and C-reactive protein levels were significantly higher in the sarcopenic group. There was no significant difference in serum levels of thioredoxin-1 and pentraxin-3. Sarcopenic patients had lower levels of hemoglobin, albumin, total protein, calcium, triglycerides, uric acid and adiponectin (p < 0.05). Hypertension and body mass index were inversely correlated with sarcopenia whereas ESR was positively correlated.

DISCUSSION AND CONCLUSION

The present study demonstrated an association of sarcopenia with inflammatory markers CRP, ESR and adiponectin. Long-term prospective studies are warranted to confirm the relationship between markers oxidative stress and age related muscle decline.

Lunasin attenuates obesity-related inflammation in RAW264.7 cells and 3T3-L1 adipocytes by inhibiting inflammatory cytokine production

Obesity has become a major threat to public health and is accompanied by chronic low-grade inflammation, which leads to various pathological developments. Lunasin, a natural seed peptide, exhibits several biological activities, such as anti-carcinogenesis, anti-inflammatory, and antioxidant activities. However, the mechanism of action of lunasin in obesity-related inflammation has not been investigated. The aim of this study was to explore whether lunasin could reduce the inflammation induced by obesity-related mediators in RAW264.7 cells and 3T3-L1 adipocytes and whether it could attenuate the crosstalk between the two cell lines. RAW264.7 cells were cultured in leptin-containing medium, adipocyte-conditioned medium (Ad-CM), or co-cultured with 3T3-L1 cells to mimic the physiology of obesity. The data showed that the secretion of pro-inflammatory cytokine interleukin-1β (IL-1β) was inhibited by lunasin after leptin activation of RAW264.7 cells. In addition, lunasin decreased monocyte chemoattractant protein-1 (MCP-1) and IL-1β secretions in the Ad-CM model. Cytokine MCP-1, IL-6, tumor necrosis factor (TNF)-α, and IL-1β secretions were significantly decreased by leptin or Ad-CM plus lipopolysaccharide stimulation. Subsequently, the co-culture of the two cells refined the direct relation between them, resulting in apparently increased MCP-1, and decreased IL-6 levels after lunasin treatment. In 3T3-L1 adipocytes, lunasin also exhibited anti-inflammatory property by inhibiting MCP-1, plasminogen activator inhibitor-1, and leptin productions stimulated by (TNF)-α, lipopolysaccharide, or RAW264.7 cell-conditioned medium. This result revealed that lunasin acts as a potential anti-inflammatory agent not only in macrophages but also in adipocytes, disrupting the crosstalk between these two cells. Therefore, this study suggests the intake of lunasin from diet or as a supplement, for auxiliary prevention or therapy in obesity-related inflammatory applications.

Adiponectin treatment attenuates inflammatory response during early sepsis in obese mice

BACKGROUND

Morbid obesity increases the cost of care in critically ill patients. Sepsis is the leading cause of death in noncoronary intensive care units. Circulating cell-endothelial cell interactions in microcirculation are the rate-determining factors in any inflammation; obesity increases these interactions further. Adiponectin deficiency is implicated in increased cardiovascular risk in obese patients. We have shown that adiponectin deficiency increases microvascular dysfunction in early sepsis. In the present study, we investigated the effect of adiponectin replacement on nutritionally obese mice with early sepsis.

METHODS

We used cecal ligation and puncture model of sepsis in mice with diet-induced obesity (DIO) vs control diet (CTRL), with or without adiponectin treatment. We studied leukocyte/platelet adhesion in the cerebral microcirculation in early sepsis. We also studied the effect of adiponectin on free fatty acid (FFA)-fed and lipopolysaccharide-stimulated bone marrow-derived macrophages (BMDM) for mechanistic studies.

RESULTS

Leukocyte and platelet adhesion increased in the cerebral microcirculation of DIO and CTRL mice with early sepsis vs. sham; moreover cell adhesion in DIO-sepsis group was significantly higher than in the CTRL-sepsis group. Adiponectin replacement decreased leukocyte/platelet adhesion in CTRL and DIO mice. In FFA-fed BMDM, adiponectin treatment decreased tumor necrosis factor-alpha mRNA expression and increased sirtuin-1 (SIRT1) mRNA expression. Furthermore, using BMDM from SIRT1 knockout mice, we showed that the adiponectin treatment decreased inflammatory response in FFA-fed BMDM via SIRT1-dependent and -independent pathways.

CONCLUSION

Adiponectin replacement attenuates microvascular inflammation in DIO-sepsis mice. Mechanistically, adiponectin treatment in FFA-fed mouse macrophages attenuates inflammatory response via SIRT1-dependent and -independent pathways.

Myeloid Cell-Specific Lipin-1 Deficiency Stimulates Endocrine Adiponectin-FGF15 Axis and Ameliorates Ethanol-Induced Liver Injury in Mice

Lipin-1 is a phosphatidate phosphohydrolase (PAP) required for the generation of diacylglycerol during glycerolipid synthesis, and exhibits dual functions in the regulation of lipid metabolism. Lipin-1 has been implicated in the pathogenesis of alcoholic liver disease (ALD). In the present study, we assessed lipin-1 function in myeloid cells in ALD using a myeloid cell-specific lipin-1 knockout (mLipin-1KO) mouse model. Utilizing the Gao-binge ethanol feeding protocol, matched mLipin-1KO mice and littermate loxP control (WT) mice were pair-fed with either an ethanol-containing diet or an ethanol-free diet (control). Surprisingly, deletion of lipin-1 in myeloid cells dramatically attenuated liver inflammatory responses and ameliorated liver injury that would normally occur following the ethanol feeding protocol, but slightly exacerbated the ethanol-induced steatosis in mice. Mechanistically, myeloid cell-specific lipin-1 deficiency concomitantly increased the fat-derived adiponectin and ileum-derived fibroblast growth factor (FGF) 15. In concordance with concerted elevation of circulating adiponectin and FGF15, myeloid cell-specific lipin-1 deficiency diminished hepatic nuclear factor kappa B (NF-κB) activity, limited liver inflammatory responses, normalized serum levels of bile acids, and protected mice from liver damage after ethanol challenge. Our novel data demonstrate that myeloid cell-specific deletion of lipin-1 ameliorated inflammation and alcoholic hepatitis in mice via activation of endocrine adiponectin-FGF15 signaling.