Background: Caveolin-1 (Cav-1), the major component of caveolae, is a multifunctional scaffolding protein that serves as a platform for the cell’s signal-transduction and plays a role in inflammation. However, its role in inflammatory bowel disease (IBD), a chronic inflammatory condition in the gastrointestinal tract, is not clear. A recent study shows that Cav-1 mediates angiogenesis in dextran sodium sulphate (DSS)-induced colitis. These results contradict our data, in which Cav-1 levels decreased significantly in 2,4,6-trinitrobenzene sulphonic acid (TNBS)–induced colitis. Methods: To test whether Cav-1 is involved in IBD pathogenesis, various models representing different dominant Th subtype responses and mimicking the immune pathologic mechanisms of different clinical IBD setting were employed: acute colitis was induced by intra-rectal administration of a single dose of TNBS in BALB/c and C57BL/6J mice, or by drinking 3% DSS water for 6 days in C57BL/6J mice. Chronic colitis was induced by administration of TNBS once a week for 7 weeks in BALB/c mice. To assess the effects of complete loss of Cav-1, Cav-1 knock-out (Cav-1-/-) and control wild-type C57BL/6J mice received a single TNBS administration. To further test the possible role of Cav-1, one of two peptides (that either mimicked (Caveolin scaffolding domain; CSD) or antagonized (Caveolin-1 binding domain; CBD1) Cav-1)) was administered intraperitoneally to mice receiving TNBS. Body weight and clinical scores were monitored. Colon Cav-1 and pro-inflammatory cytokine levels were quantified by ELISA. Inflammation was evaluated through histological analysis. Results: Cav-1 levels in mouse colon tissue were significantly decreased in TNBS-induced colitis mice when compared to normal mice and also inversely correlated with colon inflammation and cytokine levels. Furthermore, a loss of Cav-1 (Cav-1-/-) showed increased clinical and inflammatory scores and increased body weight loss. Mice receiving peptides to alter Cav-1 levels, showed surprising effects. The mimicking peptide (CSD) showed decreased Cav-1 levels, while the antagonizing peptide (CBD1) showed increased Cav-l levels. These changes in levels were associated with clinical and inflammatory scores and body weight loss that supported the TNBS-induced data. DSS-induced colitis mice showed increased disease activity index, however no significant difference in Cav-1 levels was found between colitis and normal mice. Conclusions: Cav-1 plays an important role in the protection of TNBS-induced colitis, but not in DSS-induced colitis, an entirely different result from a previous report, suggesting that enhancement of Cav-1 expression and functions may be beneficial to IBD treatment in some specific clinical settings. Further studies are warranted.

Background: Caveolin-1 (Cav-1), the major component of caveolae, is a multifunctional scaffolding protein that serves as a platform for the cell’s signal-transduction and plays a role in inflammation. However, its role in inflammatory bowel disease (IBD), a chronic inflammatory condition in the gastrointestinal tract, is not clear. A recent study shows that Cav-1 mediates angiogenesis in dextran sodium sulphate (DSS)-induced colitis. These results contradict our data, in which Cav-1 levels decreased significantly in 2,4,6-trinitrobenzene sulphonic acid (TNBS)–induced colitis. Methods: To test whether Cav-1 is involved in IBD pathogenesis, various models representing different dominant Th subtype responses and mimicking the immune pathologic mechanisms of different clinical IBD setting were employed: acute colitis was induced by intra-rectal administration of a single dose of TNBS in BALB/c and C57BL/6J mice, or by drinking 3% DSS water for 6 days in C57BL/6J mice. Chronic colitis was induced by administration of TNBS once a week for 7 weeks in BALB/c mice. To assess the effects of complete loss of Cav-1, Cav-1 knock-out (Cav-1-/-) and control wild-type C57BL/6J mice received a single TNBS administration. To further test the possible role of Cav-1, one of two peptides (that either mimicked (Caveolin scaffolding domain; CSD) or antagonized (Caveolin-1 binding domain; CBD1) Cav-1)) was administered intraperitoneally to mice receiving TNBS. Body weight and clinical scores were monitored. Colon Cav-1 and pro-inflammatory cytokine levels were quantified by ELISA. Inflammation was evaluated through histological analysis. Results: Cav-1 levels in mouse colon tissue were significantly decreased in TNBS-induced colitis mice when compared to normal mice and also inversely correlated with colon inflammation and cytokine levels. Furthermore, a loss of Cav-1 (Cav-1-/-) showed increased clinical and inflammatory scores and increased body weight loss. Mice receiving peptides to alter Cav-1 levels, showed surprising effects. The mimicking peptide (CSD) showed decreased Cav-1 levels, while the antagonizing peptide (CBD1) showed increased Cav-l levels. These changes in levels were associated with clinical and inflammatory scores and body weight loss that supported the TNBS-induced data. DSS-induced colitis mice showed increased disease activity index, however no significant difference in Cav-1 levels was found between colitis and normal mice. Conclusions: Cav-1 plays an important role in the protection of TNBS-induced colitis, but not in DSS-induced colitis, an entirely different result from a previous report, suggesting that enhancement of Cav-1 expression and functions may be beneficial to IBD treatment in some specific clinical settings. Further studies are warranted.

Overexpression of IL-12 and IL-23 has been implicated in the pathogenesis of Crohn’s disease. Targeting these cytokines with monoclonal antibodies has emerged as an effective therapy, but one with adverse reactions. In this study, we sought to develop peptide-based virus-like particle vaccines specific to p40 unit (shared by IL-12 and IL-23) or IL-12 (p35) or IL-23 (p19) and evaluate the effects of the vaccine in 2,4,6-trinitrobenzene sulphonic acid (TNBS)- and dextran sodium sulfate (DSS)-induced acute and chronic murine colitis. Three vaccines against p40 induced high-titered and long-lasting antibodies to IL-12, IL-23 and p40 without the use of adjuvants. Vaccine-induced antibodies could block IL-12- and IL-23-induced biological functions in vitro dose-dependently. One of the three p40 vaccines was selected for further evaluation in acute and chronic colitis. Administration of the vaccine before or after the commencement of TNBS or DSS delivery, significantly improved body weight loss and decreased inflammatory scores, collagen deposition, and the expression of p40, IL-12, IL-23, IL-17 and TNF in colon tissues, compared with mice receiving carrier protein (HBcAg) or saline. Moreover, in mesenteric lymph nodes, vaccinated mice exhibited a trend to lower percentages of Th1 cells in acute colitis and of Th17 cells in chronic colitis compared to carrier and saline controls. Vaccinated mice also had higher ratios of Treg/Th1 and Treg/Th17 and higher percentages of apoptosis in Th1 and Th17 cells than controls. Vaccine treatment decreased the infiltration of CD11c+ cells into the gut, but promoted the production of IL-10 from these cells. Safety evaluation indicated that vaccine immunization did not increase the susceptibility to the infection of chlamydia muridarum. Two vaccines specific to IL-12 (against p35) and one vaccine to IL-23 (against p19) were also developed. They induced specific antibodies against IL-12 and IL-23, respectively. IL-23p19 vaccine immunization, not IL-12p23 vaccine, ameliorated TNBS-induced chronic colitis. In summary, IL-12/IL-23p40 vaccine treatment ameliorated murine colitis through rebalancing Th1/Th17/Treg responses, promoting Th1 and Th17 apoptosis, and promoting IL-10 production, and did not increase the severity of chlamydia muridarum infection. This vaccine strategy may provide a novel long-term treatment for Crohn’s disease.

Overexpression of IL-12 and IL-23 has been implicated in the pathogenesis of Crohn’s disease. Targeting these cytokines with monoclonal antibodies has emerged as an effective therapy, but one with adverse reactions. In this study, we sought to develop peptide-based virus-like particle vaccines specific to p40 unit (shared by IL-12 and IL-23) or IL-12 (p35) or IL-23 (p19) and evaluate the effects of the vaccine in 2,4,6-trinitrobenzene sulphonic acid (TNBS)- and dextran sodium sulfate (DSS)-induced acute and chronic murine colitis. Three vaccines against p40 induced high-titered and long-lasting antibodies to IL-12, IL-23 and p40 without the use of adjuvants. Vaccine-induced antibodies could block IL-12- and IL-23-induced biological functions in vitro dose-dependently. One of the three p40 vaccines was selected for further evaluation in acute and chronic colitis. Administration of the vaccine before or after the commencement of TNBS or DSS delivery, significantly improved body weight loss and decreased inflammatory scores, collagen deposition, and the expression of p40, IL-12, IL-23, IL-17 and TNF in colon tissues, compared with mice receiving carrier protein (HBcAg) or saline. Moreover, in mesenteric lymph nodes, vaccinated mice exhibited a trend to lower percentages of Th1 cells in acute colitis and of Th17 cells in chronic colitis compared to carrier and saline controls. Vaccinated mice also had higher ratios of Treg/Th1 and Treg/Th17 and higher percentages of apoptosis in Th1 and Th17 cells than controls. Vaccine treatment decreased the infiltration of CD11c+ cells into the gut, but promoted the production of IL-10 from these cells. Safety evaluation indicated that vaccine immunization did not increase the susceptibility to the infection of chlamydia muridarum. Two vaccines specific to IL-12 (against p35) and one vaccine to IL-23 (against p19) were also developed. They induced specific antibodies against IL-12 and IL-23, respectively. IL-23p19 vaccine immunization, not IL-12p23 vaccine, ameliorated TNBS-induced chronic colitis. In summary, IL-12/IL-23p40 vaccine treatment ameliorated murine colitis through rebalancing Th1/Th17/Treg responses, promoting Th1 and Th17 apoptosis, and promoting IL-10 production, and did not increase the severity of chlamydia muridarum infection. This vaccine strategy may provide a novel long-term treatment for Crohn’s disease.