Objective To review the effect of dipeptidyl peptidase 4 (DPP-4) inhibitors on the wound healing and its mechanisms in chronic diabetic foot ulcers. Methods The latest literature concerning DPP-4 inhibitors for chronic diabetic foot ulcers was extensively reviewed, as well as the potential benefit and mechanism of DPP-4 inhibitors on wound healing of diabetic foot ulcers was analyzed thoroughly. Results DPP-4 inhibitors can accelerated the ulcer healing. The mechanisms probably include inhibiting the expression of the matrix metalloproteinase (MMP) and restoring the balance of the wound MMP and the tissue inhibitors of MMP; promoting recruitment of endothelial progenitor cells and augmenting angiogenesis; optimizing extracellular matrix construction and the immune response to persistent hypoxia in chronic diabetes wounds, and so on. At present, clinical researches show that DPP-4 inhibitors may be considered as an adjuvant treatment for chronic diabetic foot ulcers. Conclusion DPP-4 inhibitors show promise in the local wound healing of chronic diabetic foot ulcers. However, more strictly designed, adequately powered, long-term follow-up, and high-quality randomized control trials are needed to further verify their efficacy and safety for chronic diabetic foot ulcers.
Objective To investigate the expression of dipeptidyl peptidase 4 (DPP4) and angiotensin-converting enzyme 2 (ACE2) in lung tissues of patients with four different diseases including coronavirus disease 2019 (COVID-19), chronic obstructive pulmonary disease (COPD), pulmonary sarcoidosis and pulmonary bullae, and to find out the potential risk factors affecting COVID-19. Methods This study retrospectively analyzed the clinical data of 40 patients admitted to Renmin Hospital of Wuhan University with COVID-19 (COVID-19 group), COPD (COPD group), pulmonary sarcoidosis (pulmonary sarcoidosis group) and pulmonary bullae (pulmonary bullae group) and surgically resected paraffin-embedded pathological lung tissues were obtained from their lung tissue pathological specimens after surgery and paraffin embedding. The GEO database (https://www.ncbi.nlm.nih.gov/geo/) was used for bioinformatics analysis to explore the expression difference of DPP4 and ACE2 mRNA in COVID-19, COPD, pulmonary sarcoidosis and normal lung tissues. Immunohistochemistry method was used to detect the expression of DPP4 and ACE2 protein in lung tissues of each group and the average optical density was measured by image analysis software. Results The results of GEO database analysis showed that compared with pulmonary bullae group, the expression level of DPP4 mRNA had no significant difference in the COPD group and pulmonary sarcoidosis group (both P>0.05), but it was increased in the COVID-19 group (P<0.05); There was no significant difference in the expression level of ACE mRNA in the pulmonary sarcoidosis group (P>0.05), but it was increased in the lung tissue of COVID-19 group and COPD group (both P<0.05). The results of immunohistochemistry showed that DPP4 and ACE2 proteins were lowly expressed in the pulmonary sarcoidosis group and pulmonary bullae group, while their expression level was high in COVID-19 and COPD groups without significant difference (P>0.05). The expression of DPP4 and ACE2 proteins in COVID-19 group was not related to the patient’s gender and age (P>0.05), but was related to smoking and long smoking duration (P<0.05), and there was a positive correlation between DPP4 and ACE2 expression (P<0.05). Conclusions DPP4 and ACE2 proteins are lowly expressed in the pulmonary sarcoidosis group and pulmonary bullae group, while their expression level is high in COVID-19 and COPD groups. There is no significant difference in the expression level of DPP4 and ACE2 protein in the COVID-19 and COPD lung tissues. There may be a positive correlation between DPP4 and ACE2 proteins expression in lung tissue, and smoking may be a potential risk factor for COVID-19.