Recent insights of obesity-induced gut and adipose tissue dysbiosis in type 2 diabetes

An imbalance in microbial homeostasis, referred to as dysbiosis, is critically associated with the progression of obesity-induced metabolic disorders including type 2 diabetes (T2D). Alteration in gut microbial diversity and the abundance of pathogenic bacteria disrupt metabolic homeostasis and potentiate chronic inflammation, due to intestinal leakage or release of a diverse range of microbial metabolites. The obesity-associated shifts in gut microbial diversity worsen the triglyceride and cholesterol level that regulates adipogenesis, lipolysis, and fatty acid oxidation. Moreover, an intricate interaction of the gut-brain axis coupled with the altered microbiome profile and microbiome-derived metabolites disrupt bidirectional communication for instigating insulin resistance. Furthermore, a distinct microbial community within visceral adipose tissue is associated with its dysfunction in obese T2D individuals. The specific bacterial signature was found in the mesenteric adipose tissue of T2D patients. Recently, it has been shown that in Crohn’s disease, the gut-derived bacterium Clostridium innocuum translocated to the mesenteric adipose tissue and modulates its function by inducing M2 macrophage polarization, increasing adipogenesis, and promoting microbial surveillance. Considering these facts, modulation of microbiota in the gut and adipose tissue could serve as one of the contemporary approaches to manage T2D by using prebiotics, probiotics, or faecal microbial transplantation. Altogether, this review consolidates the current knowledge on gut and adipose tissue dysbiosis and its role in the development and progression of obesity-induced T2D. It emphasizes the significance of the gut microbiota and its metabolites as well as the alteration of adipose tissue microbiome profile for promoting adipose tissue dysfunction, and identifying novel therapeutic strategies, providing valuable insights and directions for future research and potential clinical interventions

Acaciaside-B-enriched fraction of Acacia auriculiformis is a prospective spermicide with no mutagenic property

As a part of our continued venture to develop a safe and effective spermicide, we have identified a triterpene glycoside (Acaciaside-B (Ac-B))-enriched fraction (Ac-B-en) isolated from the seeds of Acacia auriculiformis and evaluated its spermicidal potential in vitro. Sperm motility was completely inhibited within 20 s at a minimum effective concentration (MEC) of 120 mg/ml. Tests for sperm viability by dual fluoroprobe staining showed the effect to be spermicidal with an EC50 of 35.20 mg/ml. A series of investigations including tests for hypo-osmotic swelling, membrane lipid peroxidation, and electron microscopy document that the spermicidal effect of the fraction involves loss of sperm plasma membrane integrity and dissolution of the acrosomal vesicle – the two most important structural components that play diverse roles in physiological functions of sperm including fertilization. The fraction at 10!MEC exerted no detrimental effects on in vitro growth of Lactobacillus acidophilus, which is considered the major constituent of vaginal microflora that maintains vaginal health. Ames tests performed with different strains of Salmonella typhimurium including TA 97a, 98, 100, and 102, which detect mutagens causing bp substitution or frameshifting at G-C or A-T bp, demonstrate no mutagenic potential of the fraction. Significant spermicidal potential with no possible mutagenic effect and adverse impacts on lactobacilli growth attests to the credential of Ac-B-en as a prospective future spermicide for the development of a safe and effective vaginal contraceptive formulation

Fetuin-A acts as an endogenous ligand of TLR4 to promote lipid-induced insulin resistance

Toll-like receptor 4 (TLR4) has a key role in innate immunity by activating an inflammatory signaling pathway. Free fatty acids (FFAs) stimulate adipose tissue inflammation through the TLR4 pathway, resulting in insulin resistance 1, 2, 3, 4, 5, 6, 7. However, current evidence suggests that FFAs do not directly bind to TLR4 8, 9, but an endogenous ligand for TLR4 remains to be identified. Here we show that fetuin-A (FetA) could be this endogenous ligand and that it has a crucial role in regulating insulin sensitivity via Tlr4 signaling in mice. FetA (officially known as Ahsg) knockdown in mice with insulin resistance caused by a high-fat diet (HFD) resulted in downregulation of Tlr4-mediated inflammatory signaling in adipose tissue, whereas selective administration of FetA induced inflammatory signaling and insulin resistance. FFA-induced proinflammatory cytokine expression in adipocytes occurred only in the presence of both FetA and Tlr4; removing either of them prevented FFA-induced insulin resistance. We further found that FetA, through its terminal galactoside moiety, directly binds the residues of Leu100–Gly123 and Thr493–Thr516 in Tlr4. FFAs did not produce insulin resistance in adipocytes with mutated Tlr4 or galactoside-cleaved FetA. Taken together, our results suggest that FetA fulfills the requirement of an endogenous ligand for TLR4 through which lipids induce insulin resistance. This may position FetA as a new therapeutic target for managing insulin resistance and type 2 diabetes

Cutaneous Epithelial to Mesenchymal Transition Activator ZEB1 Regulates Wound Angiogenesis and Closure in a Glycemic Status–Dependent Manner

Epithelial to mesenchymal transition (EMT) and wound vascularization are two critical interrelated processes that enable cutaneous wound healing. Zinc finger E-box binding homeobox 1 (ZEB1), primarily studied in the context of tumor biology, is a potent EMT activator. ZEB1 is also known to contribute to endothelial cell survival as well as stimulate tumor angiogenesis. The role of ZEB1 in cutaneous wounds was assessed using Zeb1+/− mice, as Zeb1−/− mice are not viable. Quantitative stable isotope labeling by amino acids in cell culture (SILAC) proteomics was used to elucidate the effect of elevated ZEB1, as noted during hyperglycemia. Under different glycemic conditions, ZEB1 binding to E-cadherin promoter was investigated using chromatin immunoprecipitation. Cutaneous wounding resulted in loss of epithelial marker E-cadherin with concomitant gain of ZEB1. The dominant proteins downregulated after ZEB1 overexpression functionally represented adherens junction pathway. Zeb1+/− mice exhibited compromised wound closure complicated by defective EMT and poor wound angiogenesis. Under hyperglycemic conditions, ZEB1 lost its ability to bind E-cadherin promoter. Keratinocyte E-cadherin, thus upregulated, resisted EMT required for wound healing. Diabetic wound healing was improved in ZEB+/− as well as in db/db mice subjected to ZEB1 knockdown. This work recognizes ZEB1 as a key regulator of cutaneous wound healing that is of particular relevance to diabetic wound complication

miR-210-3p promotes obesity-induced adipose tissue inflammation and insulin resistance by targeting SOCS1 mediated NF-κB pathway

Under the condition of chronic obesity, an increased level of free fatty acids along with low oxygen tension in the adipose tissue creates a pathophysiological adipose tissue microenvironment (ATenv) leading to the impairment of adipocyte function and insulin resistance. Here, we found the synergistic effect of hypoxia and lipid (HL) surge in fostering adipose tissue macrophages(ATMs) inflammation and its polarization. ATenv significantly increased miR-210-3p expression in ATMs which promotes NF-kB activation-dependent proinflammatory cytokines expressions along with the downregulation of anti-inflammatory cytokines expression. Interestingly, delivery of miR-210-3p mimic significantly increased the macrophage inflammation in absence of HL co-stimulation; while miR-210-3p inhibitor notably compromised HL-induced macrophage inflammation through increased production of SOCS1 (suppressor of cytokine signalling 1), a negative regulator of NF-kB inflammatory signalling pathway. Mechanistically, miR-210 directly binds to 3′ UTR of SOCS1 mRNA and silenced its expression and thus preventing proteasomal degradation of NF-kB p65. Direct delivery of anti-miR-210-3p LNA in the ATenv markedly rescued mice from obesity-induced adipose tissue inflammation and insulin resistance. Thus, miR-210-3p inhibition in ATMs could serve as a novel therapeutic strategy for managing obesity-induced type 2 diabetes.</p

Vapor of Volatile Oils from <em>Litsea cubeba</em> Seed Induces Apoptosis and Causes Cell Cycle Arrest in Lung Cancer Cells

<div><p>Non-small cell lung carcinoma (NSCLC) is a major killer in cancer related human death. Its therapeutic intervention requires superior efficient molecule(s) as it often becomes resistant to present chemotherapy options. Here we report that vapor of volatile oil compounds obtained from <em>Litsea cubeba</em> seeds killed human NSCLC cells, A549, through the induction of apoptosis and cell cycle arrest. Vapor generated from the combined oils (VCO) deactivated Akt, a key player in cancer cell survival and proliferation. Interestingly VCO dephosphorylated Akt at both Ser⁴⁷³ and Thr³⁰⁸; through the suppression of mTOR and pPDK1 respectively. As a consequence of this, diminished phosphorylation of Bad occurred along with the decreased Bcl-xL expression. This subsequently enhanced Bax levels permitting the release of mitochondrial cytochrome c into the cytosol which concomitantly activated caspase 9 and caspase 3 resulting apoptotic cell death. Impairment of Akt activation by VCO also deactivated Mdm2 that effected overexpression of p53 which in turn upregulated p21 expression. This causes enhanced p21 binding to cyclin D1 that halted G1 to S phase progression. Taken together, VCO produces two prong effects on lung cancer cells, it induces apoptosis and blocked cancer cell proliferation, both occurred due to the deactivation of Akt. In addition, it has another crucial advantage: VCO could be directly delivered to lung cancer tissue through inhalation.</p> </div

VCO induces apoptosis in A549 lung cancer cells.

<p>(<b>A</b>) Annexin-Cy3 (red) and 6-CFDA (green) double staining of apoptotic cells was examined by fluorescence microscopy where VCO treated A549 cells showed both green and red stains and control (untreated) cells stained green only. (<b>B</b>) Percentage of apoptotic A549 cells was measured at different time points (0 h, 12 h, 24 h, 36 h) with VCO treatments. (<b>C</b>) Mitochondrial membrane potential was observed in control and VCO exposed (36 h) A549 lung cancer cells by JC-1 staining assay. (<b>D</b>) Apoptotic DNA fragmentation was observed by VCO treated A-549 cells on 1.5% agarose gel electrophoresis. Data are presented as means ± SEM of three independent experiments. *p<0.05, **p<0.01 versus control (0 h). Bar represents 20 µm.</p

Deactivation of Bad with altered Bcl-xL/Bax ratio on mitochondrial membrane by VCO exposure.

<p>(<b>A</b>) Immunoblot analysis was performed to evaluate the level of pBad Ser¹³⁶ and Bad in A549 cells exposed with VCO for different time periods (0 h, 12 h, 24 h, 36 h). β-actin served as internal control. Bands were quantified by densitometric analysis where pBad level was compared with Bad level. (<b>B</b>) Protein level of Bcl-xL and Bax of these cells were also evaluated by immunoblot analysis. Densitometric analysis showed Bcl-xL was negatively correlated with Bax level when A549 cells were exposed with VCO. Values are means ± SEM of three independent experiments, *p<0.05, **p<0.01 versus control (0 h).</p