Utjecaj nedostatka dipeptidil-peptidaze IV na ekspresiju kemokina u debelom crijevu miševa s eksperimentalnim kolitisom

Dipeptidil-peptidaza IV (DPP IV/CD26), transmembranski je glikoprotein koji kroz proteolitičku, kostimulacijsku i signalnu ulogu sudjeluje u modulaciji imunološkog odgovoru. Dosadašnjim istraživanjima pokazane su izmijenjene vrijednosti DPP IV/CD26 kod oboljelih od upalne bolesti crijeva (UBC). UBC su imunološki posredovani kronični poremećaji kompleksne etiologije, a u ovisnosti o lokalizaciji i stupnju zahvaćenosti probavne cijevi razlikuju se dva klinička, patomorfološka oblika, ulcerozni kolitis (UK) i Crohnova bolest. Istraživanja ukazuju da tijek razvoja UK, priroda i intenzitet upalnog odgovora, ovisi o profilu upalnih stanica i medijatora. Kako bi proširili saznanja o ulozi DPP IV/CD26 u modulaciji imunološkog odgovora cilj istraživanja bio je na in vivo modelu kolitisa ispitati utjecaj nedostatka DPP IV/CD26 na aktivaciju makrofaga i ekspresiju kemokina, kemotaksijskog proteina monocita (MCP)-1 i upalnog protein makrofaga (MIP)-1. Pokusni model kolitisa izazvan je primjenom natrijevog dekstran-sulfata u divljem tipu (C57BL/6) i DPP IV/CD26 deficijentnim miševima (CD26-/-). Uspostava, razvoj i rezolucija kolitisa pratila se temeljem kliničkih i patohistoloških parametara. Karakterizacija stanica u sluznici crijeva određena je imunohistokemijski, a ekspresija gena metodom lančane reakcije polimerazom u stvarnom vremenu. Razvoj kolitisa u obje ispitivane skupine miševa praćen je značajnim padom tjelesne mase, promjenom duljine debelog crijeva te porastom mase slezene i indeksa aktivnosti bolesti. Značajniji gubitak tjelesne mase i porast indeksa aktivnost bolesti zabilježeni su u CD26-/- miševa unatoč sličnim histopatološkim promjenama. Tijekom oporavka, CD26-/- miševi brže nadoknađuju izgubljenu tjelesnu masu nego C57BL/6 miševi. U akutnoj fazi zabilježen je dvostruko veći porast broja makrofaga u CD26-/- miševa u usporedbi s C57BL/6 miševima. Razvoj kolitisa popraćen je značajnim povećanjem ekspresije MCP-1 i MIP-1 u obje ispitivane skupine ali je porast u akutnoj fazi kolitisa bio značajno veći u CD26-/- miševa. Istraživanje daje novi korak u razumijevanju uloge DPP IV/CD26 u aktivaciji makrofaga, a time i modulaciji imunosnog odgovora tijekom razvoja i cijeljenja kolitisa.Dipeptidyl-peptidase IV (DPP IV/ CD26) is a transmembrane glycoprotein involved in the modulation of immune response through its proteolytic, costimulatory and signaling function. Previous studies have shown decreased DPP IV/CD26 activity in patients with inflammatory bowel disease (IBD). IBD are immune-mediated chronic disorders of complex etiology. Depending on the localization and symptoms two clinical, pathomorphological forms are present, ulcerative colitis (UC) and Crohn's disease. Recent data suggest that the course of development of UC, nature and intensity of the inflammatory response, depends on the profile of inflammatory cells and mediators. In order to expand knowledge about the role of DPP IV/CD26 in modulation of the immune response, the aim of this study was to examine the impact of DPP IV/CD26 deficiency on the activation of macrophages and the expression of chemokines, monocyte chemotactic protein (MCP) -1 and macrophage inflammatory protein (MIP) -1 in vivo model of colitis. The experimental model of colitis was induced in wild type (C57BL/6) and DPP IV/CD26 deficient mice (CD26-/-) using sodium dextran sulfate solution. The establishment, development and resolution of colitis were monitored on the basis of clinical and histopathological parameters. Characterization of cells in intestinal mucosa was determined by immunohistochemistry and the expression of genes by polymerase chain reaction. Development of colitis was followed by a significant decline in body weight, change of the length of the colon and increase in spleen weight and disease activity index in both groups of mice. Significant loss of body mass and disease activity index were observed in CD26-/- was more intensive than in C57BL/6 mice, in spite of similar histopathological changes at the local level. During recovery, CD26-/- mice restore body mass faster than C57BL/6 mice. In the acute phase increase in the number of macrophage was present in both mouse strains. In CD26-/- the increase was twice than in C57BL/6 animals. The development of colitis was accompanied with a significant increase in the expression of MCP-1 and MIP-1 in both mouse strains but the increase in the acute phase of colitis was significantly higher in CD26-/- mice. This research offers a new insight into the role of DPP IV/ CD26 in activation of macrophages and thereby modulating the immune response during the development of colitis