Project description:Diabetes Mellitus (DM) is a chronic, severe disease rapidly increasing in incidence and prevalence and is associated with numerous complications. Patients with DM are at high risk of developing diabetic foot ulcers (DFU) that often lead to lower limb amputations, long term disability, and a shortened lifespan. Despite this, the effects of DM on human foot skin biology are largely unknown. Thus, the focus of this study was to determine whether DM changes foot skin biology predisposing it for healing impairment and development of DFU. Foot skin samples were collected from 20 patients receiving corrective foot surgery and, using a combination of multiple molecular and cellular approaches we performed comparative analyses of non-ulcerated non-neuropathic diabetic foot skin (DFS) and healthy non-diabetic foot skin (NFS). MicroRNA (miR) profiling of laser captured epidermis and primary dermal fibroblasts from both DFS and NFS samples identified 5 miRs de-regulated in the epidermis of DFS though none reached statistical significance. MiR-31-5p and miR-31-3p were most profoundly induced. Although none were significantly regulated in diabetic fibroblasts, miR-29c-3p showed a trend of up-regulation, which was confirmed by qPCR in a prospective set of 20 skin samples. Gene expression profiling of full thickness biopsies identified 36 de-regulated genes in DFS (>2 fold-change, unadjusted p-value ≤ 0.05). Of this group, three out of seven tested genes were confirmed by qPCR: SERPINB3 was up-regulated whereas OR2A4 and LGR5 were down-regulated in DFS. However no morphological differences in histology, collagen deposition, and number of blood vessels or lymphocytes were found. No difference in proliferative capacity was observed by quantification of Ki67 positive cells in epidermis. These findings suggest DM causes only subtle changes to foot skin. Since morphology, mRNA and miR levels were not affected in a major way, additional factors, such as neuropathy, vascular complications, or duration of DM, may further compromise tissue’s healing ability leading to development of DFUs.

Project description:Diabetes mellitus [DM], with its burden of premature morbidity and mortality, represents one of the major threats to human health in the 21st century (Zimmet 2001). Accelerated atherosclerosis affecting arteries that supply the heart, brain and lower extremities is responsible for an increased risk of acute ischemic events. DM is also associated with microvascular disease, which is a leading cause of blindness, renal failure and debilitating neuropathies. Endothelial dysfunction, increased vascular permeability and microvascular cell loss by apoptosis are all hallmarks of diabetic microangiopathy. Diabetic patients not only incur cardiovascular complications more frequently, but also experience worse outcomes due to attenuation of vascular repair mechanisms. This impairment includes quantitative and qualitative abnormalities of bone marrow [BM]-derived progenitor cells (Emanueli 2002&2004; Loomans 2004; Krankel 2005; Fadini 2006). The mechanisms underlying BM dysfunction remain however enigmatic, especially when considering the privileged location that protects stem cells [SC] and progenitor cells [PC] of the marrow from external insults (Kopp 2008 and Kiel 2008). BM endothelial cells [EC] are instead an obvious target of DM, because they are directly exposed to blood glucose and incapable to regulate glucose influx. Strangely enough, little is known about the impact of diabetes on BM microvasculature. We hypothesize that damage induced by DM might start at the microvascular level, in a similar fashion to microangiopathy, which occurs in kidney, retina, heart and brain. We also propose that enduring microvascular cell loss might result in marrow hypo-perfusion and destabilization of SC homeostasis. In order to test this hypothesis, we studied streptozotocin-induced (STZ) type-1 DM and age-matched non-DM mice (n=6 to 10 per group in each experiment). Histological examination of femurs, collected from STZ-mice at 28-30 weeks from induction of DM or controls, showed remarkable differences in bone density and marrow composition. Bone marrow cells from healthy and diabetic animals were next selected for endothelial progenitors and cultured for 10 days under endothelial cell growth conditions. Next RNA was isolated and analysed by Illumina Sentrix Beadarrays.

Dataset Information

Coordinated assembly of NHE3, IRBIT, NHERF1, and ezrin ameliorates fluid malabsorption in diabetes

Publications

Restoration of Na+/H+ exchanger NHE3-containing macrocomplexes ameliorates diabetes-associated fluid loss.

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