Diabetic nephropathy (DN) has become the leading cause of end stage renal disease (ESRD) in developed countries, in which over 90% of the diabetes burden is type 2 in origin. Despite the ever advancing knowledge in the pathogenetic mechanisms of DN, a specific treatment is still lacking and management using contemporary approaches or exploiting newly described therapeutic targets are largely unrewarding. BMP-7 has been reported to confer renal protective effects in acute and chronic kidney disease models, but its potential utility in type 2 diabetic nephropathy remains unknown. In this work, therefore, I hypothesized that BMP-7 confers renal protection that will be explore in vitro in AGE-induced tubular epithelial cells, and in vivo in a murine type 2 DN model. Primary human proximal tubular epithelial cells (PTECs) were growth-arrested and exposed to glycated human serum albumin (AGEs) with or without BMP-7. Inhibitors of different signaling pathways were used to dissect the involvement of each pathway. Nine-week-old db/db mice and their db/m littermates underwent uninephrectomy (Unx) or sham operation, and received BMP-7 (300 μg/kg body weight) or vehicle treatment intraperitoneally every other day for 8 weeks before sacrifice. In cultured human PTECs, exposure to AGEs induced overexpression of ICMA-1, MCP-1, IL-8 and IL-6, involving activation of at least p44/42 and p38 MAPK signaling. BMP-7 dose-dependently attenuated AGE-induced up-regulation of ICMA-1, MCP-1, IL-8 and IL-6 at both mRNA and protein levels. Moreover, BMP-7 suppressed AGE-induced p38 and p44/42 MAPK phosphorylation and reactive oxygen species production in PTECs. Compared with vehicle control, Unx db/db mice treated with BMP-7 for 8 weeks had significantly lower urinary albumin-to-creatinine ratio (3549±816.2 μg/mg vs. 8612±2037 μg/mg, p=0.036), serum BUN (33.26±1.09 mg/dL vs. 37.49±0.89 mg/dL, p=0.006), and renal cortical expression of ICMA-1 and MCP-1 at both gene and protein levels. PAS staining of kidney tissue showed less severe tubular damage and interstitial inflammatory cell infiltration in the BMP-7-treated group. In conclusion, this series of experiments demonstrated that BMP-7 attenuates tubular pro-inflammatory responses in diabetic kidney disease by suppressing oxidative stress and multiple signaling pro-inflammatory pathways including p38 and p44/42 MAPK. These observations are largely translated in animals with diabetic kidney inflammation. The potential application of BMP-7 as a therapeutic molecule in diabetic nephropathy warrants further investigation and development. / published_or_final_version / Medicine / Doctoral / Doctor of Philosophy

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Class of 2010 Abstract / OBJECTIVES:The main purpose of this study was to review recent and good quality studies of the antimicrobial therapy of for moderate to severe (“limb threatening”) DFI. The analysis of these studies was to conclude with one or two “standard” approach to the routine management of this clinical entity. METHODS: This literature review study consisted of an evaluation of clinical trials that compare two or more active systemic antimicrobial regimens for the treatment of moderate to severe (i.e., “limb-threatening”) diabetic foot infections in human patients. Literature sources were identified primarily from OVID MEDLINE, but also included additional tertiary sources. The primary criteria for the clinical studies were: prospective, controlled, randomized and investigator blinded. Studies had to be published after the year 2003, and be available in full-text in English. RESULTS: Ultimately, only four studies were found that met the criteria for consideration. Trials differed in numerous features. All four studies were sponsored by the manufacturer of one of the comparator drugs. Three of the four were non-inferiority design. Evidence is lacking that any of the suggested regimens are superior. CONCLUSIONS: Instead of meeting our original goal of concluding that one or two regimens could be the “standard” management of DFI, we were limited to commentary on the quality and applicability of the current literature on this clinical entity. Numerous suggestions for improvement in the clinical information provided by DFI studies were offered. We eagerly anticipate the publication of the updated IDSA guideline document on DFI.

Rationale and hypothesis: Diabetic sensory neuropathy involves a distal dying-back of nerve fibers. Neuronal mitochondrial function is impaired in diabetes and Sirtuin 2 (SIRT2) is a sensor of redox state that regulates cellular bioenergetics. The role of SIRT2 in regulating the phenotype of adult sensory neurons derived from both control and diabetic rats or wild type and SIRT2 knockout (KO) mice was studied. It was hypothesized that sensory neurons under a hyperglycemic state would have a lowered NAD+/NADH ratio thus deactivating the SIRT2 pathway. It was further hypothesized that the down regulation of SIRT2 would diminish the activity of the AMP-activated protein kinase (AMPK) pathway resulting in mitochondrial dysfunction. This defect would contribute to distal dying-back of axons observed in diabetes. Methodology: Type 1 diabetes was induced in rodents by streptozotocin (STZ). Adult sensory neurons derived from control or STZ-diabetic rats or control and SIRT2 knockout (KO) mice were cultured in defined media with varying doses of neurotrophic factors and D-glucose. Protein levels were determined by quantitative Western blotting and neurite outgrowth quantified by immunocytochemistry. Plasmid transfection was initiated for overexpression of SIRT2 constructs and Seahorse XF24 analyzer was utilized to measure mitochondrial function of cultured neurons. Results: Overexpression of SIRT2 elevated total neurite outgrowth in cultures derived from control and STZ-diabetic rats. Cultures derived from SIRT2 KO mice exhibited diminished neurite outgrowth. The AMPK pathway was inhibited under high glucose treatment through activation of the polyol pathway. Pharmacological inhibition of the polyol pathway improved mitochondrial bioenergetics and neurite outgrowth in sensory neurons. Augmented expression of electron transport proteins and increased mitochondrial mass was associated with enhanced bioenergetic function. Conclusion: SIRT2 is a key component driving mitochondrial function and axon regeneration through the activation of AMPK pathway. In diabetes this pathway is suppressed via elevated polyol pathway activity. / October 2016

Diabetic foot ulcers (DFUs) are a common and severe adverse event associated with diabetes, as 25% of diabetic patients will experience DFUs. The lack of effective DFU therapies results in 20% of diabetic patients requiring amputation. We first developed an algorithm to account for polydispersity when calculating nanoparticle concentration, which will reduce variability between batches and treatments. We also developed a novel 2-layer biomaterial, which combines anti-microbial properties of CLKRS peptide coated silver nanoparticles (CLKRS- AgNPs) with a pro-regenerative collagen matrix embedded with microscopic skin tissue columns (MSTC), to promote DFU wound healing. The collagen hydrogel formulation was optimized, and the physical properties, biocompatibility, and wound healing properties were assessed. Our results indicate that the CLKRS-AgNPs prevent bacterial growth and the collagen matrix provides a regenerative environment. Last, we developed and tested antimicrobial fabrics which can also be applied to chronic wounds, such as DFUs, to prevent and treat infections.