Conspectus Diabetic foot ulcers (DFUs) are chronic wounds that develop in 30% of diabetic patients. In DFUs, the normal wound healing process consisting of inflammation, angiogenesis, and extracellular matrix (ECM) remodeling is dysregulated and stalled. Upon injury, neutrophils and monocytes arrive at the wound and secrete matrix metalloproteinase (MMP)-8 and reactive oxygen species (ROS). ROS activates nuclear factor kappa beta (NF-κB), which upregulates MMP-9. Monocytes become macrophages, secreting tumor growth factor (TGF)-β1 and vascular endothelial growth factor (VEGF) for angiogenesis, resulting in remodeling of the ECM. MMP-9 cleaves laminin for keratinocyte migration. MMP-8 is beneficial for remodeling the ECM and healing the wound. In DFUs, the excess unregulated MMP-9 is detrimental, destroying the ECM and preventing the wound from healing. DFUs are typically infected, many with biofilm-producing bacteria that are resistant to antibiotics. Infection increases the time for wound healing and the likelihood for a lower-limb amputation. Despite the use of antibiotics, amputations occur in 24.5% of patients with DFUs. Clearly, new strategies for treatment of DFUs are needed. With the use of an affinity resin that binds exclusively to the active forms of MMPs and proteomics, we identified two proteinases, MMP-8 and MMP-9, in wounds of diabetic mice and diabetic humans. With the use of selective inhibitors, gene ablation of MMP-9, and exogenous application of MMP-8, we demonstrated that MMP-8 is beneficial to wound repair and that MMP-9 prevents the diabetic wound from healing. Our research has shown that infection increases active MMP-9, increasing inflammation and decreasing angiogenesis. As a result, infected diabetic wounds take a longer time to heal than uninfected ones. We found that active MMP-9 and NF-κB increased in human DFUs with wound severity and infection. The best strategy for treatment of DFUs is to selectively inhibit the detrimental proteinase MMP-9 without affecting the beneficial MMP-8 so that the body can repair the wound. Lead optimization of the thiirane class of inhibitors led to the discovery of (R)-ND-336, a potent (19 nM) and selective (450-fold) MMP-9 inhibitor. (R)-ND-336 accelerated wound healing in diabetic mice by decreasing ROS and NF-κB, lowering inflammation, and increasing angiogenesis. (R)-ND-336 in combination with the antibiotic linezolid improved wound healing in infected diabetic mice by inhibiting MMP-9, which mitigated macrophage infiltration and increased angiogenesis, thereby restoring the normal wound healing process.

Nonhealing chronic wounds are major complications of diabetes resulting in >70,000 annual lower-limb amputations in the United States alone. The reasons the diabetic wound is recalcitrant to healing are not fully understood, and there are limited therapeutic agents that could accelerate or facilitate its repair. We previously identified two active forms of matrix metalloproteinases (MMPs), MMP-8 and MMP-9, in the wounds of db/db mice. We argued that the former might play a role in the body's response to wound healing and that the latter is the pathological consequence of the disease with detrimental effects. Here we demonstrate that the use of compound ND-336, a novel highly selective inhibitor of gelatinases (MMP-2 and MMP-9) and MMP-14, accelerates diabetic wound healing by lowering inflammation and by enhancing angiogenesis and re-epithelialization of the wound, thereby reversing the pathological condition. The detrimental role of MMP-9 in the pathology of diabetic wounds was confirmed further by the study of diabetic MMP-9-knockout mice, which exhibited wounds more prone to healing. Furthermore, topical administration of active recombinant MMP-8 also accelerated diabetic wound healing as a consequence of complete re-epithelialization, diminished inflammation, and enhanced angiogenesis. The combined topical application of ND-336 (a small molecule) and the active recombinant MMP-8 (an enzyme) enhanced healing even more, in a strategy that holds considerable promise in healing of diabetic wounds.

Diabetic foot ulcers (DFUs) are a significant health problem. A single existing FDA-approved drug for this ailment, becaplermin, is not standard-of-care. We previously demonstrated that upregulation of active matrix metalloproteinase (MMP)-9 is the reason that the diabetic wound in mice is recalcitrant to healing and that MMP-8 participates in wound repair. In the present study, we validate the target MMP-9 by identifying and quantifying active MMP-8 and MMP-9 in human diabetic wounds using an affinity resin that binds exclusively to the active forms of MMPs coupled with proteomics. Furthermore, we synthesize and evaluate enantiomerically pure ( R)- and ( S)-ND-336, as inhibitors of the detrimental MMP-9, and show that the ( R)-enantiomer has superior efficacy in wound healing over becaplermin. Our results reveal that the mechanisms of pathology and repair are similar in diabetic mice and diabetic humans and that ( R)-ND-336 holds promise for the treatment of DFUs as a first-in-class therapeutic.

Activated Wnt/β-catenin signaling is frequently associated with colorectal cancer. Wnt inhibitors, including tankyrase inhibitors, are being explored as potential anticancer agents. Wnt signaling is also critical for intestinal tissue homeostasis, and Wnt inhibitors have been shown to cause intestinal toxicity in mice by affecting intestinal stem cells. This study sought to characterize the intestinal toxicity of tankyrase inhibitors, including reversibility, and to assess their therapeutic index. Novel tankyrase inhibitor G-631 caused dose-dependent intestinal toxicity with a therapeutic index < 1 after 14 days of dosing in mice. At a tolerated subtherapeutic dose level, the intestinal toxicity was composed of enteritis characterized by villus blunting, epithelial degeneration, and inflammation, which fully reversed after 14 days of recovery. Doubled exposure showed weak antitumor activity in a xenograft colorectal cancer model but also caused more severe intestinal toxicity characterized by multifocal-regionally extensive necrotizing and ulcerative enteritis leading to morbidity or moribundity in some animals. This toxicity was only partially reversed after 14 days of recovery, with evidence of crypt and villus regeneration, mildly blunted villi, and/or scarring in association with chronic inflammation of the submucosa. Therefore, the clinical utility of tankyrase inhibitors is likely limited by the on-target intestinal toxicity and a therapeutic index < 1 in mice.

The irst section of this chapter provides an up-to-date general view of air pollution/air quality topic. It indicates main pollutants and their sources and impacts and presents and discusses current air quality standards and air quality indexes worldwide; how datasets are acquired, gathered and analyzed and how the measurements are then interpreted are also presented. Recent works containing updated and detailed technical discussions for each issue addressed and additional web resources are mentioned. The great importance of air pollution monitoring is emphasized. Second, in the international context of incomplete information on air pollution in East Europe, the chapter includes a section presenting an assessment of air pollution at some sites in Romania together with its evolution from the beginning of the monitoring up to present. Availability of PM 10 , PM 2.5, NO x , SO 2 and CO concentrations is site and pollutant dependent and varies from 3 to 9 years. Investigation of temporal and spatial variation of pollutant levels, as well as of PM 10 and PM 2.5 relationships with the measured gaseous air pollutants and with meteorological variables, includes correlation and linear regression analysis and temporal-trend analysis; coeicient of divergence was calculated to check up on the air pollution inter-sites' diferences and pollutant seasonal variation intra-site.

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Diabetic foot ulcers (DFUs) are significant complications of diabetes and an unmet medical need. Matrix metalloproteinases (MMPs) play important roles in the pathology of wounds and in the wound healing process. However, because of the challenge in distinguishing active MMPs from the two catalytically inactive forms of MMPs and the clinical failure of broad-spectrum MMP inhibitors in cancer, MMPs have not been a target for treatment of DFUs until recently. This review covers the discovery of active MMP-9 as the biochemical culprit in the recalcitrance of diabetic wounds to healing and targeting this proteinase as a novel approach for the treatment of DFUs. Active MMP-8 and MMP-9 were observed in mouse and human diabetic wounds using a batimastat affinity resin and proteomics. MMP-9 was shown to play a detrimental role in diabetic wound healing, whereas MMP-8 was beneficial. A new class of selective MMP-9 inhibitors shows clinical promise for the treatment of DFUs.

Enzymes that modify DNA are faced with significant challenges in specificity for both substrate binding and catalysis. We describe how single hydrogen bonds between M.HhaI, a DNA cytosine methyltransferase, and its DNA substrate regulate the positioning of a peptide loop which is ϳ28 Å away. Stopped-flow fluorescence measurements of a tryptophan inserted into the loop provide real-time observations of conformational rearrangements. These long-range interactions that correlate with substrate binding and critically, enzyme turnover, will have broad application to enzyme specificity and drug design for this medically relevant class of enzymes.Sequence-specific modification of DNA is essential for nearly all forms of life and contributes to a myriad of biological processes including gene regulation, mismatch repair, host defense, DNA replication, and genetic imprinting. Methylation of cytosine and adenine bases is a key epigenetic process whereby phenotypic changes are inherited without altering the DNA sequence (1). The central role of the bacterial and mammalian S-adenosylmethionine (AdoMet) 2 -dependent DNA methyltransferases in virulence regulation and tumorigenesis, respectively, have led these enzymes to be validated targets for antibiotic and cancer therapies (2, 3). However, AdoMet-dependent enzymes catalyze diverse reactions, and the design of potent and selective DNA methyltransferase inhibitors is particularly challenging (4, 5). The design of drugs that bind outside the active site is a particularly attractive means of inhibition for enzymes with common cofactors like AdoMet because off-target inhibition often leads to toxicity (6). Unfortunately, robust methods to identify and characterize such critical binding sites distal from the active site have not been developed.DNA methyltransferases bind to a particular DNA sequence, stabilize the target base into an extrahelical position within the enzyme active site, and transfer the methyl moiety from AdoMet to the DNA (7). During this process, dramatic changes in the DNA structure such as bending, base flipping, or the intercalation of residues into the recognition sequence are often accompanied by large scale protein rearrangements (8).Here we characterized a specific conformational rearrangement of M.HhaI, a model DNA cytosine C 5 methyltransferase with a cognate recognition sequence of 5Ј-GCGC-3Ј. Many structures of M.HhaI are available at high resolution including an ensemble of complexes with either cognate or nonspecific DNA (9, 10). Reorganization of an essential catalytic loop (residues 80 -100) is regulated by sequence-specific protein-DNA interactions that occur ϳ28 Å away from the catalytic loop (Fig. 1). Our work quantifies the importance of such distal communication in sequence-specific DNA modification and provides plausible structural mechanisms.DNA-dependent positioning of the catalytic loop in M.HhaI was first observed crystallographically; cognate DNA stabilizes the loop-closed conformer, while nonspecific DNA leaves the loop in the open c...