Influence of Dipeptidyl Peptidase IV (DPP IV/CD26) Deficiency on Wound Healing Process in Mice

Uvod: Dipeptidil-peptidaza IV, odnosno molekula CD26 (DPP IV/CD26) ubikvitarna je proteaza i kostimulacijska molekula s važnom ulogom u brojnim fiziološkim i patološkim procesima. Dosadašnja istraživanja su pokazala da DPP IV/CD26 ima ulogu i u angiogenezi, adheziji, migraciji i apoptozi stanica, mehanizmima od osobitog značaja u procesu cijeljenja rana. Međutim, uloga DPP IV/CD26 u ovim procesima još uvijek nije dovoljno razjašnjena. Pretpostavka ovog istraživanja jest da DPP IV/CD26 ima značajnu ulogu u procesima cijeljenja ranjenog tkiva. Cilj istraživanja: Cilj ovog istraživanja bio je utvrditi postoji li razlika u dinamici i intenzitetu cijeljenja rana u uvjetima nedostataka molekule DPP IV/CD26 u odnosu na fiziološke uvjete. Željeli smo utvrditi povezanost DPP IV/CD26 i procesa cijeljenja rana, uspostavom eksperimentalnog modela cijeljenja rana, te pratiti makroskopske i mikroskopske promjene, kao i promjene neovaskularizacije i proliferacije ranjenog tkiva koji se odvijaju prilikom cijeljenja rana u različitim vremenskim intervalima. Nadalje, cilj nam je bio i ispitati postoje li promjene u serumskoj aktivnosti DPP IV/CD26 u divljem tipu miša tijekom procesa cijeljenja rana. Materijal i metode: Eksperimentalni model cijeljenja rana na dorzalnom dijelu eksperimentalnih životinja uspostavljen je u CD26 deficijentnim (CD26-/-) te divljem tipu miševa (C57BL/6). Eksperimentalne životinje bile su žrtvovane drugog, četvrtog, sedmog,desetog i petnaestog dana od nastalog oštećenja tkiva. Uzorci tkiva rana i kontrolne kože su bili podvrgnuti makroskopskoj i mikroskopskoj analizi. Učinjena su histomorfometrijska, patohistološka i imunohistokemijska istraživanja. Određivan je stupanj regeneracije koriuma, pratio se proces neovaskularizacije (broj CD31+ stanica) te stupanj proliferacije epidermisa (izražaj Ki-67). Aktivnost DPP IV/CD26 u serumu divljeg tipa miševa tijekom procesa cijeljenja rana pratila se spektrofotometrijski. Rezultati: Analizom rezultata dobivenih ovim istraživanjem utvrđeno je da je u uvjetima nedostatka DPP IV/CD26 stupanj regeneracije koriuma sedmog dana statistički značajno veći ( ) u odnosu na C57BL/6 miševe. U kontrolnoj koži CD26-/- miševa broj kapilara je statistički značajno manji ( ) u odnosu na divlji tip miša no stvaranje novih kapilara počinje znatno brže i već je drugog dana cijeljenja rana njihov broj statistički značajno veći ( ) kod CD26-/- miševa. U uvjetima nedostatka DPP IV/CD26 proliferacija stanica bazalnog sloja epidermisa je jače izražena, raste s vremenom cijeljenja rana te je sedmog dana statistički značajno veća ( ) u odnosu na divlji tip miševa. Enzimska aktivnost DPP IV/CD26 u serumu C57BL/6 životinja statistički je značajno snižena ( ) četvrtog dana cijeljenja rana u odnosu na fiziološke uvjete. Zaključak: Dobiveni rezultati ukazuju na postojanje razlike u intenzitetu i dinamici cijeljenja ranjenog tkiva u uvjetima nedostatka DPP IV/CD26 u odnosu na fiziološke uvjete. Potvrđena je pretpostavka o značajnoj ulozi DPP IV/CD26 u procesima neovaskularizacije, proliferacije i cijeljenja oštećenog tkiva, no potrebna su daljnja istraživanja kako bi se utvrdili mehanizmi kojima DPP IV/CD26 regulira ključne događaje uključene u procese cijeljenja rana.Introduction: Dipeptidyl peptidase IV, also known as CD26 molecule (DPP IV / CD26), is a ubiquitous protease and costimulatory molecule with important roles in many physiological and pathological processes. Previous studies have shown that DPP IV/CD26 plays a role in angiogenesis, adhesion, migration, and cell apoptosis, all mechanisms of particular importance in the process of wound healing. However, the role of DPP IV/CD26 in this process is still not sufficiently understood. The hypothesis of this research is that DPP IV/CD26 plays an important role in the process of healing of wounded tissue. Aim: The aim of this study was to determine whether there is a difference in the dynamics and intensity of wound healing in conditions of DPP IV/CD26 deficiency in comparison to physiological conditions. We wanted to determine the relationship between DPP IV/CD26 and the process of healing of wounded tissue by establishing an experimental model of wound healing, and by analyzing macroscopic and microscopic as well as changes in neovascularization and proliferation that occur during wound healing at different time intervals. Furthermore, our goal was to determine whether there are present changes in serum DPP IV/CD26 activity in the process of wound healing in wild-type mouse. Material and methods: The experimental model of healing of wounds on the mouse dorsal part was established in CD26 deficient (CD26-/-) and wild type mice (C57BL/6). Experimental animals were sacrificed the second, fourth, seventh, tenth and fifteenth day of the resulting tissue damage. Tissue samples of skin wounds and control tissue were subjected to macroscopic and microscopic analysis. Histomorphometric, histopathological and immunohistochemical studies were performed. The degree of regeneration of the corium was measured, the process of neovascularization (number of CD31+ cells) was analyzed and the degree of proliferation of the epidermis (the expression of Ki-67) was assessed. The activity of DPP IV/CD26 in serum of wild-type mice during the process of wound healing was measured spectrophotometrically. Results: Results obtained in this study have shown that the degree of the regeneration of the corium on the seventh day of wound healing is statistically significantly higher ( ) in conditions of DPP IV/CD26 deficiency compared to C57BL/6 mice. The number of capillaries was significantly lower ( ) in the control skin of CD26-/- mice compared to wild-type mouse, but the formation of new capillaries begins more rapidly and on the second day of wound healing their number is significantly higher ( ) in CD26-/- mice. The proliferation of the cells of the basal layer of the epidermis is more pronounced in conditions of DPP IV/CD26 deficiency and was found to be significantly higher ( ) on the seventh day of wound healing, compared to wild-type animals. The enzymatic activity of DPP IV /CD26 in the serum of C57BL/6 animals was significantly decreased ( ) the fourth day of wound healing, compared to physiological conditions. Conclusion: Results obtained in this study indicate the existence of differences in the intensity and dynamics of healing of wounded tissues in conditions of DPP IV/CD26 deficiency in comparison to physiological conditions. The hypothesis of the important role of DPP IV/CD26 in the process of neovascularization, proliferation and healing of damaged tissue is confirmed, however, further research is needed to determine the mechanisms by which DPP IV/CD26 regulates key events involved in wound healing processes