Objective: Diabetic foot ulcers (DFUs) are devastating complications of diabetes, responsible for a high number of amputations worldwide. Due to its impact on chronic inflammation, psychological distress may negatively impact the healing process. Thus, this study evaluated the influence of psychological distress on physiological indicators of healing prognosis and the potential of stress-reducing therapies for DFU healing. Approach: Patients with chronic DFU were recruited and assessed at enrollment and two months later. According to psychological scores at enrollment, participants were allocated into groups without (group 1) or with (group 3) psychological distress. Participants who reported clinical distress were then randomly allocated into a control (no stress-reducing intervention – group 4) or experimental (with stress-reducing interventions – group 5) group. Subsequently, indicators of healing prognosis were measured. Results: Groups 1 and 3 presented no differences in the Perfusion, Extent, Depth, Infection and Sensation (PEDIS) score, glycated hemoglobin (HbA1c) or inflammatory and angiogenic markers. However, the immune cell ratio was increased by more than 2-fold in group 3, compared to group 1. Importantly, the expression of circulating microRNAs was significantly increased in group 3 [miR-21-5p, miR-155-5p, miR-146a-5p, and miR-221-3p (p<0.05)], compared to group 1. Two months later, group 5 displayed a significant improvement in the Perceived Stress Scale (PSS) and Hospital Anxiety and Depression Scale (HADS) scores (p<0.01), and the immune cell ratio was decreased by more than 2.5-fold. Innovation: This study helped to identify which variables and psychological interventions are more successful in promoting DFU healing. Conclusion: Psychological distress influenced clinical and physiological parameters, leading to compromised DFU healing and consequently underlining the potential of adjuvant stress-reducing approaches.

Dysfunction in key cellular organelles has been linked to diabetic complications. This study intended to investigate the alterations in the unfolded protein response (UPR), autophagy, and mitochondrial function, which are part of the endoplasmic reticulum (ER) stress response, in wound healing (WH) under diabetes conditions. WH mouse models were used to evaluate the UPR, autophagy, mitochondrial fusion, fission, and biogenesis as well as mitophagy in the skin of control and diabetic mice at baseline and 10 days after wounding. The autophagic flux in response to high-glucose conditions was also evaluated in keratinocyte and fibroblast cell cultures. WH was impaired in the diabetic mouse model, and we found that the UPR and autophagy pathways were activated in skin wounds of control mice and in the non-wounded skin of diabetic mice. Moreover, high-glucose conditions induced autophagy in the keratinocyte and fibroblast cell cultures. However, mitophagy did not change in the skin of diabetic mice or the wounded skin. In addition, mitochondrial fusion was activated in control but not in the skin wounds of diabetic mice, while mitochondrial biogenesis is downregulated in the skin of diabetic mice. In conclusion, the activation of the UPR, autophagy, and mitochondrial remodeling are crucial for a proper WH. These results suggest that the increase in ER stress and autophagy in the skin of diabetic mice at baseline significantly escalated to pathological levels after wounding, contributing to impaired WH in diabetes.

Introduction: Thoracic perivascular adipose tissue (tPVAT) has a phenotype resembling brown AT. Dysfunctional tPVAT appears to be linked to vascular dysfunction. Methods: We evaluated uncoupling protein (UCP)-1 expression by western blot, oxidative stress by measuring lipid peroxidation and the antioxidant capacity by high-performance liquid chromatography and spectrophotometry, and mitochondrial respiration by high-resolution respirometry (HRR) in tPVAT, compared to inguinal white AT (iWAT), obtained from non-diabetic (NDM) and streptozocin-induced diabetic (STZ-DM) mice. Mitochondrial respiration was assessed by HRR using protocol 1: Complex I and II oxidative phosphorylation (OXPHOS) and protocol 2: Fatty acid oxidation (FAO) OXPHOS. OXPHOS capacity in tPVAT was also evaluated after UCP-1 inhibition by guanosine 5'-diphosphate (GDP). Results: UCP-1 expression was higher in tPVAT when compared with iWAT in both NDM and STZ-DM mice. The malondialdehyde concentration was elevated in tPVAT from STZ-DM compared to NDM mice. Glutathione peroxidase and reductase activities, as well as reduced glutathione levels, were not different between tPVAT from NDM and STZ-DM mice but were lower compared to iWAT of STZ-DM mice. OXPHOS capacity of tPVAT was significantly decreased under UCP-1 inhibition by GDP in protocol 1. While there were no differences in the OXPHOS capacity between NDM and STZ-DM mice in protocol 1, it was increased in STZ-DM compared to NDM mice in protocol 2. Moreover, complex II- and FAO- linked respiration were elevated in STZ-DM mice under UCP-1 inhibition. Conclusions: Pharmacological therapies could be targeted to modulate UCP-1 activity with a significant impact in the uncoupling of mitochondrial bioenergetics in tPVAT.