DSS Mice Research Articles

ADRENOMEDULLIN (ADM) ACTS AS AN ANTI‐INFLAMMATORY MEDIATOR THROUGH CONCOMITANT DE‐NEDDYLATION OF CUL‐1 AND CUL‐2.

Local hypoxia (HX) has been identified as an anti‐inflammatory mediator through induction of HIF‐ dependent genes. Microarray analysis of HMECs exposed to HX identified ADM as a prominent HX‐inducible gene. ADM has been shown to diminish the severity of inflammation in a number of models. We sought to determine the molecular pathways which converge to confer an anti‐inflammatory phenotype. rhADM treatment resulted in a de‐neddylation of Cullin family members, reported to control NF¿B & HIF activity, respectively. NF¿B & HRE luciferase reporter assays confirmed suppression of NF¿B & activation of HRE by ADM. To address ADM signaling on HIF‐1 activation, we identified an increase in canonical HIF‐1 dependent genes following stimulation with ADM. As an in vivo model, we investigated the role of ADM in treating a DSS model of colitis. Mice treated with ADM had reduced inflammatory indices compared with sham‐ treated DSS mice, which lost more weight & had significant shortening of the colon compared with healthy controls. Furthermore, histological analysis identified less inflammation in ADM treated mice compared to sham‐treated. Whole colon & serum cytokine analysis showed a marked inhibition of DSS colitis‐associated TNF‐α, IL‐1β & KC. Together, these results demonstrate that ADM may act as an administrable therapy to reduce the severity of inflammation through the central action on Cullin family members.

Venular Constriction of Submucosal Arterioles Induced by Dextran Sodium Sulfate

Leukocyte and platelet adherence in postcapillary venules has been speculated to induce constriction of closely paired arterioles. This mechanism was investigated in the current study, in a model of intestinal inflammation induced by dextran sodium sulfate (DSS; 5,000 molecular weight). Closely paired, parallel arterioles and venules in the submucosa of the mouse intestine were observed using fluorescent intravital microscopy. Arterioles in control mice were compared to arterioles in mice given 5% DSS in drinking water for 11 days. DSS induced an inflammatory response in which fluorescently labeled leukocytes and platelets were observed adhering to venules. Arterioles constricted and flow decreased significantly when the arterioles were paired with venules having adherent leukocytes and platelets, although the decreases in flow and diameter appeared to be more dependent on platelet than leukocyte adherence. No significant constriction was observed in arterioles paired with venules having minimal platelet adherence. Inhibition of thromboxane with 100 mg/kg ozagrel induced a significant dilation of arterioles in DSS mice that was absent in control mice. The results are consistent with a proposed mechanism in which thromboxane constricts submucosal arterioles when the arterioles are closely paired with platelet-bearing venules in DSS-induced inflammation.

13-hydroxy-octadecatrienic acid (Hox alpha) ameliorates chronic murine colitis

Introduction: ~he therapeutlc options for inflammatory bowel disease (IBD) remain limited, especially tor remission prolongation knti-TNF-a antibodies such as lntltxinmb are effective in the treatment ol flares but ohen lose their ethcacy with repetitive applications, 13Hydroxyoctadecatnen*~ acid a componem of the sungnig nettle leaf (Hox alpha, Strathmann (krrnany) reduces TNF-c~ secretion and is a known therapy m the setting of rheumatoid arthritis Aim: 1o investigate the etlect of Hox alpha on murine colitis disease activity in difli:rent colitic mouse models Methods: C3}tIHeJBir,IL-10-/and BALB/{ mice with DSSreduced acute and cbronic colitis were treated with 0 5mg/ml Hox alpha and compared to untreated controls Mice were clniically monitorvd and inflammation was assessed by histological scoring, analysis oi kcal/I.113 and measurement ot mucosal cytokine production by EL/SA Probkration of lynlphocytes ot the spleen and Peyers patches was quantified by 3H-thynlidine nico~)oration. Resuhs: Hox alpha-treated mice ,aqth chronic DSS colitis as well as Hox alpha-treated ID 10-A mice displayed signihcantly reduced clniical and histologB <al signs ot colitis than untreated mice (p<0 05) Fecal IL-113, mucosal IL-113 as well as TNF-~ concentrations were signit~cantly lowe* in Hox alpha-treated chronic DSS mice as well as in ttox alpha-treated lL-10-/mice m comparison with control rnice (p<0.05). Furthe*r~mre, 1ympbocyte prolfl~'ration postdipopolysaccharide stimulation was significantly reduced in Hox alpha-treated mice ( p < 0 0 0 1 ) Conclusions: The continuous use of Hox alpha is effective in the amelioration of chronic murme colitis, an effect we attribute to a decreased Thl immune response Hox alpha thus possibly presents us with a new therapeutic option fur prolonging remission in 1BD.

Mouse leukaemia, a dichotomy of virus neutralizing and cytotoxic antibodies

Mice exposed to subliminal doses of live, or to large doses of properly inactivated mouse leukaemia viruses, or cells, will develop antibodies. These antibodies can be detected by virus neutralization (1, 2, 3, 4) and cytotoxic tests (5, 6, 7), among other techniques. I t is not known how these serologic faculties are correlated. Studies in progress suggest tha t the virusneutralizing and cytotoxic antibodies are not identical. The following is a preliminary report on these studies. An immune serum was obtained from mice with adoptive immunity. The cell donors were low leukaemia Timco (Texas Inbred Mouse Company, Houston) S~dss mice vaccinated with photodynamieally inactivated Rauseher mouse leukaemia virus. The technique of photodynamic inactivation of this virus has recently been reported (4, 8). A cell-free spleen extract of leukaemic mice is mixed with high dilution of methylene blue and the mixture is transill~minated with visible light for 25 minutes a t 37 ~ C. Due to photooxidation, the virus loses its infectivity. In the experiment described here, 3 doses of such inactivated virus were injected intraperitoneally into young adult mice a t 3-week intervals. The second dose of the vaccine was given together with Freund's complete adjuvant. These mice produced both virus neutralizing and cytotoxic antibodies. The pooled and inactivated (56 ~ C for 20 minutes) serum neutralized more than 102 LDs0 of the Rauscher virus (8). In the cytotoxic test, 15 per cent of Rauscher leukaemic spleen cells responded with swelling and pinkish