| Abstract | Uvod: Dipeptidil-peptidaza IV, odnosno molekula CD26 (DPP IV/CD26), multifunkcionalan je protein s ulogom u imunomodulaciji, proliferaciji, migraciji, adheziji, apoptozi stanica te angiogenezi, ključnim mehanizmima u procesu cijeljenja rana. Glavni regulator angiogeneze je faktor rasta VEGF koji potiče migraciju i proliferaciju endotelnih stanica. Važan poticaj za izlučivanje VEGF-a ima podjedinica HIF-1α transkripcijskog faktora HIF-1, čiji izražaj ovisi o hipoksiji u rani. Pretpostavka ovog istraživanja je da DPP IV/CD26 ima značajnu ulogu u procesu cijeljenja rana putem modulacije učinaka faktora uključenih u angiogenezu.
Cilj istraživanja: Cilj ovog istraživanja bio je utvrditi utječe li i na koji način DPP IV/CD26 na ključne čimbenike u nastanku novih krvnih žila te u regeneraciji i reparaciji tkiva. Specifični ciljevi bili su utvrditi makroskopske i mikroskopske značajke cijeljenja rana u uvjetima nedostatka DPP IV/CD26, ispitati izražaj VEGF i HIF-1α te utvrditi lokalnu enzimsku aktivnost DPP IV/CD26 u uzorcima kože i rana pokusnih životinja tijekom procesa cijeljenja rana.
Materijal i metode: Istraživanje je obuhvatilo dva soja pokusnih životinja: CD26 deficijentne (CD26-/-) te miševe divljeg tipa (C57BL/6). Miševima su na dorzalnom dijelu inducirane dvije rane promjera 5 mm, a tijek cijeljenja rana pratio se u definiranim vremenskim intervalima: 2, 4, 7, 10 i 15 dana od indukcije rana makroskopskom i mikroskopskom analizom. Uzorci tkiva rana i kontrolne kože podvrgnuti su histomorfometrijskoj, patohistološkoj, imunohistokemijskoj te biokemijskoj analizi. Određivao se postotak zatvaranja rane, stupanj regeneracije koriuma, izražaj molekula VEGF i HIF-1α te enzimska aktivnost DPP IV/CD26 u tkivu kože i rana pokusnih životinja.
Rezultati: Utvrđena je različita dinamika cijeljenja rana u uvjetima nedostatka DPP IV/CD26: kod CD26-/- miševa dolazi do većeg postotka zatvaranja rane, stupanj regeneracije koriuma je veći, upalna faza traje kraće, brže dolazi do reepitelizacije, proliferacija stanica je izraženija, te dolazi do bržeg formiranja ožiljkastog tkiva. Oba soja pokazuju statistički značajno manji (p < 0,05) izražaj HIF-1α drugog dana cijeljenja rane u odnosu na kontrolnu kožu, ali već četvrtog dana taj je izražaj statistički značajno veći (p < 0,05) kod oba soja. Razlika među sojevima primijećena je četvrtog i sedmog dana gdje je vidljivo da CD26-/- miševi imaju statistički značajno veći (p < 0,05) izražaj HIF-1α u odnosu na divlji tip. Nadalje, kod CD26-/- miševa izražaj VEGF-a je statistički značajno viši (p < 0,05) tijekom svih dana cijeljenja rana u odnosu na divlji tip, dok u kontrolnoj koži nema statistički značajne razlike. Enzimska aktivnost DPP IV/CD26 u tkivu rana C57BL/6 miševa statistički je značajno snižena (p < 0,05) drugog, četvrtog i sedmog dana cijeljenja rane u odnosu na fiziološke uvjete.
Zaključak: Dobiveni rezultati potvrđuju pretpostavku da DPP IV/CD26 ima značajnu ulogu u procesu cijeljenja rane i putem modulacije izražaja VEGF i HIF-1α, ključnih faktora angiogeneze. Potrebna su daljnja istraživanja kako bi se razjasnio utjecaj DPP IV/CD26 na učinke ostalih čimbenika u nastanku novih krvnih žila te regeneraciji i reparaciji tkiva. |
| Abstract (english) | Introduction: Dipeptidyl-peptidase IV, or CD26 molecule (DPP IV/CD26), is a multifunctional protein with roles in immunomodulation, proliferation, migration, adhesion, apoptosis and angiogenesis, key mechanisms in the wound healing process. The main angiogenesis regulator is VEGF, a growth factor that promotes migration and proliferation of endothelial cells. An important stimulus for the secretion of VEGF has a transcription factor HIF-1α, a subunit of HIF-1, whose expression depends on early hypoxia. The hypothesis of this study is that DPP IV/CD26 plays a significant role in the wound healing process by modulating the effects of factors involved in angiogenesis.
Aim: The aim of this study was to determine whether and how DPP IV/CD26 modulates the activity of key factors in the formation of new blood vessels and in regeneration and repair of tissues. Specific goals were to determine macroscopic and microscopic features of wound healing in conditions of DPP IV/CD26 deficiency, to investigate the expression of VEGF and HIF-1α, and to determine the local DPP IV/CD26 enzyme activity in skin and wound during the wound healing process.
Material and Methods: The study included two strains of experimental animals: CD26 deficient (CD26-/-) and wild type mice (C57BL/6). Mice were experimentally wounded on the dorsal region with two wounds with diameters of 5 mm. The wound healing course was monitored at defined time intervals: 2, 4, 7, 10 and 15 days after wounding, by macroscopic and microscopic analysis. Wound and control skin samples were subjected to histomorphometric, pathohistological, immunohistochemical and biochemical analysis. The percentage of wound closure, the rate of corium regeneration, the expression of the VEGF and HIF-1α molecules, and DPP IV/CD26 enzyme activity in skin and wound tissues were determined.
Results: Different wound healing dynamics was noticed in conditions of DPP IV/CD26 deficiency: in CD26-/- mice a higher percentage of wound closure was noticed, the rate of corium regeneration is higher, the inflammatory phase is shorter, faster reepithelification was observed, cell proliferation is more pronounced, and the formation of scar was faster. Both strains showed statistically significantly lower (p < 0.05) expression of HIF-1α on the second day of wound healing compared to the control skin, but on the fourth day this expression was statistically significantly higher (p < 0.05) for both strains. The difference between strains was observed on the fourth and seventh days where it was shown that CD26-/- mice exhibit statistically significantly higher (p < 0.05) expression of HIF-1α compared to wild type. Furthermore, in CD26-/- mice the expression of VEGF is statistically significantly higher (p < 0.05) throughout all wound healing process compared to wild-type mice, while in the control skin there are no statistically significant differences. DPP IV/CD26 enzyme activity in wounds of C57BL/6 mice was statistically significantly reduced (p < 0.05) on the second, fourth and seventh days of wound healing compared to physiological values.
Conclusion: Obtained results confirm the hypothesis that DPP IV/CD26 has a significant role in the wound healing process also by modulation of VEGF and HIF-1α expression, which are key factors in angiogenesis. Further studies are required to clarify the effects of DPP IV/CD26 on other factors involved in the formation of new blood vessels as well as in tissue regeneration and reparation. |
