The Rho guanine dissociation inhibitor α inhibits skeletal muscle Rac1 activity and insulin action.

The molecular events governing skeletal muscle glucose uptake have pharmacological potential for managing insulin resistance in conditions such as obesity, diabetes, and cancer. With no current pharmacological treatments to target skeletal muscle insulin sensitivity, there is an unmet need to identify the molecular mechanisms that control insulin sensitivity in skeletal muscle. Here, the Rho guanine dissociation inhibitor α (RhoGDIα) is identified as a point of control in the regulation of insulin sensitivity. In skeletal muscle cells, RhoGDIα interacted with, and thereby inhibited, the Rho GTPase Rac1. In response to insulin, RhoGDIα was phosphorylated at S101 and Rac1 dissociated from RhoGDIα to facilitate skeletal muscle GLUT4 translocation. Accordingly, siRNA-mediated RhoGDIα depletion increased Rac1 activity and elevated GLUT4 translocation. Consistent with RhoGDIα's inhibitory effect, rAAV-mediated RhoGDIα overexpression in mouse muscle decreased insulin-stimulated glucose uptake and was detrimental to whole-body glucose tolerance. Aligning with RhoGDIα's negative role in insulin sensitivity, RhoGDIα protein content was elevated in skeletal muscle from insulin-resistant patients with type 2 diabetes. These data identify RhoGDIα as a clinically relevant controller of skeletal muscle insulin sensitivity and whole-body glucose homeostasis, mechanistically by modulating Rac1 activity.

Efficacy and Safety of Topical Silymarin Versus Low Fluence 1064-nm Q Switched Nd:YAG Laser in the Treatment of Melasma: A Comparative Randomized Trial.

BACKGROUND AND OBJECTIVES: The management of melasma is challenging and requires multiple uses of available therapeutic options. To compare the short-term efficacy and safety of topical silymarin and low fluence 1064-nm Q-switched ND:YAG laser for treatment of melasma with dermoscopic follow-up. STUDY DESIGN/MATERIALS AND METHODS: Fifty female patients with melasma were included in this study. They were randomly divided into two groups. Group A: 25 patients were treated with six sessions of low fluence Q switched ND:YAG 1064-nm laser, and group B: 25 patients were treated with topical silymarin cream 1.4% with a 3-month treatment duration. Patients were evaluated clinically by the modified melasma area and severity index (mMASI) score. Dermoscopic examinations were performed before and after the treatment sessions. RESULTS: The severity of melasma, as evaluated dermoscopically and clinically by mMASI score, was significantly reduced after treatment in all patients with no recorded side effects. There was no statistically significant difference between both studied groups regarding the change in mMASI score and dermoscopic assessment of the patients after the treatment sessions. CONCLUSION: Both low fluence Q switched ND:YAG 1064-nm laser and topical silymarin cream appear to be safe and effective modalities in the treatment of melasma. © 2021 Wiley Periodicals LLC.

Combined microneedling with topical vitamin D3 or bimatoprost versus microneedling alone in the treatment of alopecia areata: A comparative randomized trial.

INTRODUCTION: Alopecia areata (AA) is a challenging disease with variable treatment outcomes. Hair follicles express vitamin D receptors. Therefore, vitamin D3 may be promising for AA treatment through immunomodulatory mechanisms. The efficacy of bimatoprost in scalp AA treatment was reported by few studies. OBJECTIVE: To evaluate the efficacy and safety of microneedling (MN) with topical vitamin D3 versus MN with bimatoprost in comparison with MN alone in the treatment of localized AA. PATIENTS AND METHODS: Seventy-five patients with localized AA were divided into three groups. The first group: 25 patients were treated with MN alone. The second group: 25 patients treated with MN combined with topical vitamin D3. The third group: 25 patients treated with MN combined with bimatoprost solution. The response was evaluated clinically and dermoscopically. RESULTS: At the end of the study, all groups showed a statistically significant decrease in the SALT score compared to the baseline. The clinical response (regrowth scale): vitamin D and bimatoprost groups showed a statistically significant higher regrowth scale compared to MN alone group (p-value = 0.000). After treatment, hair regrowth was significantly higher in MN combined with bimatoprost than in MN combined with topical vitamin D3. However, after 3 months of follow-up, there was no statistically significant difference between both groups. Side effects were mild and transient in all groups. CONCLUSION: Topical vitamin D3 and bimatoprost combined with MN are safe and effective therapeutic options for localized AA.

Assessment of serum levels of anti-gliadin (IgA and IgG) antibodies in patients with lichen planus: A pilot study.

Despite the fact that anti-gliadin antibodies (AGA) play a key role in coeliac disease (CD) screening, elevated AGA levels have been reported in several immune-mediated cutaneous conditions even in the absence of gastrointestinal disease clinical manifestations. A gluten-free diet led to improvements in some of these disorders. The link between oral lichen planus (LP) and CD was revealed, but there is currently no information available regarding the association between cutaneous LP and gluten sensitivity. This study aimed to assess the AGA (IgA and IgG) serum levels in LP patients compared to controls and to determine their correlation with LP severity. The study included 20 patients with cutaneous LP and 20 age- and sex-matched controls, both free of CD manifestations. The enzyme-linked immunosorbent assay (ELISA) technique was utilized for the evaluation of AGA (IgA and IgG) serum levels. Hepatitis C virus (HCV) antibodies in LP patients were evaluated qualitatively using a chromatographic immunoassay. In LP patients, AGA (IgA and IgG) serum levels were significantly elevated compared to controls (p = 0.015 and p=0.016, respectively). A significant positive correlation between AGA (IgG) serum levels and the age of patients (p= 0.024), duration of disease (p= 0.02), and LP severity index (p< 0.0001) was found. AGA serum levels were insignificantly different between HCV-positive and HCV-negative LP patients (p= 0.054). In conclusion, the significant elevation of serum AGA levels in LP patients reflects a possible link between LP and occult CD. Serum AGA (IgG) levels can be used as a marker of LP severity..

Adenosine monophosphate-activated protein kinase is elevated in human cachectic muscle and prevents cancer-induced metabolic dysfunction in mice.

BACKGROUND: Metabolic dysfunction and cachexia are associated with poor cancer prognosis. With no pharmacological treatments, it is crucial to define the molecular mechanisms causing cancer-induced metabolic dysfunction and cachexia. Adenosine monophosphate-activated protein kinase (AMPK) connects metabolic and muscle mass regulation. As AMPK could be a potential treatment target, it is important to determine the function for AMPK in cancer-associated metabolic dysfunction and cachexia. We therefore established AMPK's roles in cancer-associated metabolic dysfunction, insulin resistance and cachexia. METHODS: In vastus lateralis muscle biopsies from n = 26 patients with non-small cell lung cancer (NSCLC), AMPK signalling and protein content were examined by immunoblotting. To determine the role of muscle AMPK, male mice overexpressing a dominant-negative AMPKα2 (kinase-dead [KiDe]) specifically in striated muscle were inoculated with Lewis lung carcinoma (LLC) cells (wild type [WT]: n = 27, WT + LLC: n = 34, mAMPK-KiDe: n = 23, mAMPK-KiDe + LLC: n = 38). Moreover, male LLC-tumour-bearing mice were treated with (n = 10)/without (n = 9) 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) to activate AMPK for 13 days. Littermate mice were used as controls. Metabolic phenotyping of mice was performed via indirect calorimetry, body composition analyses, glucose and insulin tolerance tests, tissue-specific 2-[3H]deoxy-d-glucose (2-DG) uptake and immunoblotting. RESULTS: Patients with NSCLC presented increased muscle protein content of AMPK subunits α1, α2, ß2, γ1 and γ3 ranging from +27% to +79% compared with control subjects. In patients with NSCLC, AMPK subunit protein content correlated with weight loss (α1, α2, ß2 and γ1), fat-free mass (α1, ß2 and γ1) and fat mass (α1 and γ1). Tumour-bearing mAMPK-KiDe mice presented increased fat loss and glucose and insulin intolerance. LLC in mAMPK-KiDe mice displayed lower insulin-stimulated 2-DG uptake in skeletal muscle (quadriceps: -35%, soleus: -49%, extensor digitorum longus: -48%) and the heart (-29%) than that in non-tumour-bearing mice. In skeletal muscle, mAMPK-KiDe abrogated the tumour-induced increase in insulin-stimulated TBC1D4thr642 phosphorylation. The protein content of TBC1D4 (+26%), pyruvate dehydrogenase (PDH; +94%), PDH kinases (+45% to +100%) and glycogen synthase (+48%) was increased in skeletal muscle of tumour-bearing mice in an AMPK-dependent manner. Lastly, chronic AICAR treatment elevated hexokinase II protein content and normalized phosphorylation of p70S6Kthr389 (mTORC1 substrate) and ACCser212 (AMPK substrate) and rescued cancer-induced insulin intolerance. CONCLUSIONS: Protein contents of AMPK subunits were upregulated in skeletal muscle of patients with NSCLC. AMPK activation seemed protectively inferred by AMPK-deficient mice developing metabolic dysfunction in response to cancer, including AMPK-dependent regulation of multiple proteins crucial for glucose metabolism. These observations highlight the potential for targeting AMPK to counter cancer-associated metabolic dysfunction and possibly cachexia.

TNIK is a conserved regulator of glucose and lipid metabolism in obesity.

Obesity and type 2 diabetes (T2D) are growing health challenges with unmet treatment needs. Traf2- and NCK-interacting protein kinase (TNIK) is a recently identified obesity- and T2D-associated gene with unknown functions. We show that TNIK governs lipid and glucose homeostasis in Drosophila and mice. Loss of the Drosophila ortholog of TNIK, misshapen, altered the metabolite profiles and impaired de novo lipogenesis in high sugar-fed larvae. Tnik knockout mice exhibited hyperlocomotor activity and were protected against diet-induced fat expansion, insulin resistance, and hepatic steatosis. The improved lipid profile of Tnik knockout mice was accompanied by enhanced skeletal muscle and adipose tissue insulin-stimulated glucose uptake and glucose and lipid handling. Using the T2D Knowledge Portal and the UK Biobank, we observed associations of TNIK variants with blood glucose, HbA1c, body mass index, body fat percentage, and feeding behavior. These results define an untapped paradigm of TNIK-controlled glucose and lipid metabolism.