Inhibitor of PI3Kγ ameliorates TNBS-induced colitis in mice by affecting the functional activity of CD4+CD25+FoxP3+ regulatory T cells.
OBJECTIVE
Phosphoinositide 3-kinase-γ (PI3Kγ) is implicated in many pathophysiological conditions, and recent evidence has suggested its involvement in colitis. In the present study, we investigated the effects of AS605240, a relatively selective PI3Kγ inhibitor, in experimental colitis and its underlying mechanisms.


METHODS
Acute colitis was induced in mice by treatment with trinitrobenzene sulphonic acid (TNBS), and the effect of AS605240 on colonic injury was assessed. Pro-inflammatory mediators and cytokines were measured by immunohistochemistry, elisa, real time-polymerase chain reaction and flow cytometry.


RESULTS
Oral administration of AS605240 significantly attenuated TNBS-induced acute colitis and diminished the expression of matrix metalloproteinase-9 and vascular endothelial growth factor. The colonic levels and expression of IL-1β, CXCL-1/KC, MIP-2 and TNF-α were also reduced following therapeutic treatment with AS605240. Moreover, AS605240 reduced MIP-2 levels in a culture of neutrophils stimulated with lipopolysaccharide. The mechanisms underlying these actions of AS605240 are related to nuclear factor-κ (NF-κB) inhibition. Importantly, the PI3Kγ inhibitor also up-regulated IL-10, CD25 and FoxP3 expression. In addition, a significant increase in CD25 and FoxP3 expression was found in isolated lamina propria CD4+ T cells of AS605240-treated mice. The effect of AS605240 on Treg induction was further confirmed by showing that concomitant in vivo blockade of IL-10R significantly attenuated its therapeutic activity.


CONCLUSIONS
These results suggest that AS605240 protects mice against TNBS-induced colitis by inhibiting multiple inflammatory components through the NF-κB pathway while simultaneously inducing an increase in the functional activity of CD4+CD25+ Treg. Thus, AS605240 may offer a promising new therapeutic strategy for the treatment of inflammatory bowel diseases.
Department of Pharmacology, Center of Biological Sciences, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil.
R C
RC
Dutra
M
M
Cola
D F P
DF
Leite
A F
AF
Bento
R F
RF
Claudino
A F Z
AF
Nascimento
P C
PC
Leal
J B
JB
Calixto
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D015704:CD4 Antigens / Q000378:metabolism*; D002478:Cells, Cultured; D003092:Colitis / Q000139:chemically induced / Q000188:drug therapy* / Q000276:immunology; D003106:Colon / Q000187:drug effects / Q000276:immunology / Q000473:pathology; D016207:Cytokines / Q000378:metabolism; D051858:Forkhead Transcription Factors / Q000378:metabolism*; D053645:Interleukin-2 Receptor alpha Subunit / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000187:drug effects / Q000276:immunology / Q000473:pathology; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000096:biosynthesis; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D020556:Neutrophil Infiltration; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011810:Quinoxalines / Q000494:pharmacology / Q000627:therapeutic use*; D050378:T-Lymphocytes, Regulatory / Q000378:metabolism*; D045162:Thiazolidinediones / Q000494:pharmacology / Q000627:therapeutic use*; D014302:Trinitrobenzenesulfonic Acid; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis
C505144:5-quinoxalin-6-ylmethylenethiazolidine-2,4-dione; D015704:CD4 Antigens; D016207:Cytokines; D051858:Forkhead Transcription Factors; C500522:Foxp3 protein, rat; D053645:Interleukin-2 Receptor alpha Subunit; D016328:NF-kappa B; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011810:Quinoxalines; D045162:Thiazolidinediones; D042461:Vascular Endothelial Growth Factor A; D014302:Trinitrobenzenesulfonic Acid; D020780:Matrix Metalloproteinase 9
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