Jeffrey B. Brown

Regulation of induced colonic inflammation by Lactobacillus acidophilus deficient in lipoteichoic acid

Imbalance in the regulatory immune mechanisms that control intestinal cellular and bacterial homeostasis may lead to induction of the detrimental inflammatory signals characterized in humans as inflammatory bowel disease. Induction of proinflammatory cytokines (i.e., IL-12) induced by dendritic cells (DCs) expressing pattern recognition receptors may skew naive T cells to T helper 1 polarization, which is strongly implicated in mucosal autoimmunity. Recent studies show the ability of probiotic microbes to treat and prevent numerous intestinal disorders, including Clostridium difficile-induced colitis. To study the molecular mechanisms involved in the induction and repression of intestinal inflammation, the phosphoglycerol transferase gene that plays a key role in lipoteichoic acid (LTA) biosynthesis in Lactobacillus acidophilus NCFM (NCK56) was deleted. The data show that the L. acidophilus LTA-negative in LTA (NCK2025) not only down-regulated IL-12 and TNFα but also significantly enhanced IL-10 in DCs and controlled the regulation of costimulatory DC functions, resulting in their inability to induce CD4+ T-cell activation. Moreover, treatment of mice with NCK2025 compared with NCK56 significantly mitigated dextran sulfate sodium and CD4+CD45RBhighT cell-induced colitis and effectively ameliorated dextran sulfate sodium-established colitis through a mechanism that involves IL-10 and CD4+FoxP3+ T regulatory cells to dampen exaggerated mucosal inflammation. Directed alteration of cell surface components of L. acidophilus NCFM establishes a potential strategy for the treatment of inflammatory intestinal disorders.

Phosphoinositide 3-Kinase Signaling Mediates β-Catenin Activation in Intestinal Epithelial Stem and Progenitor Cells in Colitis

BACKGROUND & AIMS Mechanisms responsible for crypt architectural distortion in chronic ulcerative colitis (CUC) are not well understood. Data indicate that serine/threonine protein kinase Akt (Akt) signaling cooperates with Wingless (Wnt) to activate beta-catenin in intestinal stem and progenitor cells through phosphorylation at Ser552 (P-beta-catenin(552)). We investigated whether phosphoinositide 3-kinase (PI3K) is required for Akt-mediated activation of beta-catenin during intestinal inflammation. METHODS The class IA subunit of PI3K was conditionally deleted from intestinal epithelial cells in mice named I-pik3r1KO. Acute inflammation was induced in mice and intestines were analyzed by biochemical and histologic methods. The effects of chemically blocking PI3K in colitic interleukin-10(-/-) mice were examined. Biopsy samples from patients were examined. RESULTS Compared with wild-type, I-pik3r1KO mice had reduced T-cell-mediated Akt and beta-catenin signaling in intestinal stem and progenitor cells and limited crypt epithelial proliferation. Biochemical analyses indicated that PI3K-Akt signaling increased nuclear total beta-catenin and P-beta-catenin(552) levels and reduced N-terminal beta-catenin phosphorylation, which is associated with degradation. PI3K inhibition in interleukin-10(-/-) mice impaired colitis-induced epithelial Akt and beta-catenin activation, reduced progenitor cell expansion, and prevented dysplasia. Human samples had increased numbers of progenitor cells with P-beta-catenin(552) throughout expanded crypts and increased messenger RNA expression of beta-catenin target genes in CUC, colitis-associated cancer, tubular adenomas, and sporadic colorectal cancer, compared with control samples. CONCLUSIONS PI3K-Akt signaling cooperates with Wnt to increase beta-catenin signaling during inflammation. PI3K-induced and Akt-mediated beta-catenin signaling are required for progenitor cell activation during the progression from CUC to CAC; these factors might be used as biomarkers of dysplastic transformation in the colon.

P-Selectin and P-Selectin Glycoprotein Ligand 1 Are Major Determinants for Th1 Cell Recruitment to Nonlymphoid Effector Sites in the Intestinal Lamina Propria

The recruitment of activated T cell subsets to sites of effector immune responses is mediated by homing receptors induced upon activation in secondary lymphoid tissue. Using an adoptive transfer model, the intestinal recruitment of CD4+ T cells activated with intraperitoneal antigen in complete Freunds adjuvant was examined. The data demonstrate that activated CD4+ T cells recruited to intestinal Peyers patches (PP) and lamina propria (LP) up-regulate functional P-selectin glycoprotein ligand 1 (PSGL-1). Blockade of IL-12 inhibited functional PSGL-1 expression and reduced PP and LP CD4+ T cell recruitment by >40%. P-Selectin blockade reduced LP recruitment of activated cells by 56% without affecting PP recruitment. Studies of mice examined 3 d after adoptive transfer of differentiated T cell subsets revealed that Th1 but not Th2 cells were recruited to small intestine PP and LP. Mucosal addressin cell adhesion molecule blockade reduced Th1 recruitment to PP by 90% and to LP by >72%, whereas P-selectin blockade reduced Th1 recruitment to PP by 18% and Th1 recruitment to LP by 84%. These data suggest that IL-12–induced functional PSGL-1 expression is a major determinant for the recruitment of Th1 effector cells to noninflamed as well as inflamed intestine.

Recombinant factor VIIa improves coagulopathy caused by liver failure.

Objective Coagulopathy is an important cause of morbidity and mortality in patients with liver failure. The benefit of traditional therapies to correct coagulation is often limited and short-lived. Our aim is to identify indications for rFVIIa use and the outcome of treatment in children with liver failure. Methods A retrospective review from July 2000 to December 2001 was performed to identify consecutive patients with acute or chronic liver failure who received rFVIIa. Prothrombin times (PT) before and after therapy were compared by paired t test. Results Fifteen patients were treated with rFVIIa for coagulopathy caused by liver failure. All were receiving fresh frozen plasma (mean infusion rate, 39.7 mL/kg/day) when rFVIIa therapy was started. The mean PT before rFVIIa was 32.0 ± 7.0 seconds. One hour after infusion, the PT normalized to 13.7 ± 2.4 seconds (P < 0.0001) and remained significantly reduced at 6 hours (19.8 ± 5.3 seconds; P < 0.0001). A sustained improvement was maintained during the subsequent 3 days. Five of seven patients with bleeding complications improved clinically after rFVIIa treatment. Two of the bleeding patients also benefited from improved fluid balance as fresh frozen plasma support was reduced. No thrombotic events were attributed to rFVIIa therapy. Conclusions In patients with liver failure, rFVIIa therapy quickly normalizes the PT and maintains improved hemostasis, even when coagulopathy has been refractory to fresh frozen plasma. Therapy subjectively reduces clinical bleeding and can improve fluid balance, without complications.

Anti-interferon-inducible chemokine, CXCL10, reduces colitis by impairing T helper-1 induction and recruitment in mice.

Background: Colitis in interleukin (IL)‐10−/− mice is a CD4+ T helper 1 (TH1)‐mediated disease characterized by intermittent, transmural inflammation reminiscent of human Crohns disease. In this study, we investigated the hypothesis that production of the CXC chemokine CXCL10 (interferon [IFN]&ggr;‐inducible protein 10) enhances induction of inflammatory responses in draining lymph nodes (LNs) and promotes colonic TH1 cell recruitment. Methods: Colitis was induced in B6 IL‐10−/− mice. Mice were given anti‐CXCL10 mAb in 2‐week intervals before and after peak colitis. Colitis severity was graded and cytokine/chemokine levels were analyzed by real‐time polymerase chain reaction. Cell yields were quantitated and effector cell recruitment was assessed by recovery of transferred D011.10 TH1 cells shortly (72 h) after transfer. Results: Treatment with anti‐CXCL10 during colitis development decreased clinical and histologic disease severity as well as cytokine/chemokine mRNA and accumulation of mononuclear cells in LNs and colon. Treatment of mice with severe colitis reduced colitis scores and cell yields to lesser degrees. Anti‐CXCL10 specifically decreased recruitment of transferred TH1 cells into mesenteric LNs (MLNs) and colon of IL‐10−/− mice by 75% (P < 0.05). Conclusion: These results suggest that CXCL10 plays a dual role in colitis development by enhancing TH1 cell generation in inductive sites and promoting effector cell recruitment to inflamed tissue. Blockade of CXCL10 may be a useful adjunct to remission‐inducing therapies in inflammatory bowel disease (IBD) by impairing disease recurrence through selective inhibition of effector cell generation and trafficking in vivo.

Epithelial Phosphatidylinositol-3-Kinase Signaling Is Required for β-Catenin Activation and Host Defense against Citrobacter rodentium Infection

ABSTRACT Citrobacter rodentium infection of mice induces cell-mediated immune responses associated with crypt hyperplasia and epithelial β-catenin signaling. Recent data suggest that phosphatidylinositol-3-kinase (PI3K)/Akt signaling cooperates with Wnt to activate β-catenin in intestinal stem and progenitor cells through phosphorylation at Ser552 (P-β-catenin552). Our aim was to determine whether epithelial PI3K/Akt activation is required for β-catenin signaling and host defense against C. rodentium. C57BL/6 mice were infected with C. rodentium and treated with dimethyl sulfoxide (DMSO) (vehicle control) or with the PI3K inhibitor LY294002 or wortmannin. The effects of infection on PI3K activation and β-catenin signaling were analyzed by immunohistochemistry. The effects of PI3K inhibition on host defense were analyzed by the quantification of splenic and colon bacterial clearance, and adaptive immune responses were measured by real-time PCR (RT-PCR) and enzyme-linked immunosorbent assay (ELISA). Increased numbers of P-β-catenin552-stained epithelial cells were found throughout expanded crypts in C. rodentium colitis. We show that the inhibition of PI3K signaling attenuates epithelial Akt activation, the Ser552 phosphorylation and activation of β-catenin, and epithelial cell proliferative responses during C. rodentium infection. PI3K inhibition impairs bacterial clearance despite having no impact on mucosal cytokine (gamma interferon [IFN-γ], tumor necrosis factor [TNF], interleukin-17 [IL-17], and IL-1β) or chemokine (CXCL1, CXCL5, CXCL9, and CXCL10) induction. The results suggest that the host defense against C. rodentium requires epithelial PI3K activation to induce Akt-mediated β-catenin signaling and the clearance of C. rodentium independent of adaptive immune responses.

Milk fat globule-EGF factor 8 is a critical protein for healing of dextran sodium sulfate-induced acute colitis in mice

Milk fat globule-EGF factor 8 (MFG-E8) has been shown to play an important role in maintaining the integrity of the intestinal mucosa and to accelerate healing of the mucosa in septic mice. Herein, we (a) analyzed the expression of MFG-E8 in the gut of wild-type (WT) C57BL/6 (MFG-E8+/+) mice with and without dextran sulfate sodium (DSS)-induced colitis, (b) characterized the pathological changes in intestinal mucosa of MFG-E8+/+ and MFG-E8-/- mice with DSS-induced colitis and (c) examined the therapeutic role of MFG-E8 in inflammatory bowel disease by using DSS-induced colitis model. Our data documented that there was an increase in colonic and rectal MFG-E8 expression in MFG-E8+/+ mice during the development of DSS colitis. MFG-E8 levels in both tissues decreased to below baseline during the recovery phase in mice with colitis. Changes in MFG-E8 gene expression correlated to the levels of inflammatory response and crypt-epithelial injury in both colonic and rectal mucosa in MFG-E8+/+ mice. MFG-E8-/- mice developed more severe crypt-epithelial injury than MFG-E8+/+ mice during exposure to DSS with delayed healing of intestinal epithelium during the recovery phase of DSS colitis. Administration of MFG-E8 during the recovery phase ameliorated colitis and promoted mucosal repair in both MFG-E8-/- and MFG-E8+/+ mice, indicating that lack of MFG-E8 causes increased susceptibility to colitis and delayed mucosal healing. These data suggest that MGF-E8 is an essential protective factor for gut epithelial homeostasis, and exogenous administration of MFG-E8 may represent a novel therapeutic target in inflammatory bowel disease.

Therapeutic benefit of pentostatin in severe IL-10−/− Colitis

Background: Pentostatin, an adenosine deaminase (ADA) inhibitor, is a purine antimetabolite used for the treatment of leukemias. ADA inhibition blunts expansion of proliferating lymphocytes and increases adenosine release, a potent anti‐inflammatory molecule. Human inflammatory bowel disease (IBD) is driven by expansion of effector T cells (Teff) that overwhelm reulatory T cells (Treg) and propagate innate immune reponses. Here we study the therapeutic benefits of ADA inhibition to impair Teff cell expansion and reduce inflammatory cytokine release in IL‐10‐deficient (IL‐10‐/‐) mice. Methods: Colitis was induced in IL‐10‐/‐ mice by administering piroxicam for two weeks. Mice were treated with daily pentostatin or phosphate‐buffered saline for 1 week and effects on tissue inflammation, lymphocyte numbers and cytokine production examined. Results: Pentostatin reduced inflammation by >50% and nearly normalized serum amyloid A levels. Lymphocyte expansions in the colon and mesenteric lymph node (MLN) (3.5‐fold and >5‐fold respectively) dropped by >50‐90%. Pro‐inflammatory factors in the colon and MLN (IL‐1&bgr;, IFN‐&ggr;, IL‐6, CXCL10, TNF) dropped whereas FoxP3 and TGF‐&bgr; were unchanged. Reductions in cytokine production from equivalent numbers of T cells from pentostatin‐treated mice after in vitro (36h) or in vivo (3h) activation suggested anti‐inflammatory effects of pentostatin independent of lymphodepletion contributed to its therapeutic benefit. Analysis of mucosal lymphocyte subsets suggested pentostatin reduced numbers of effector CD4+ CD69+ T cells, while sparing CD4+ CD62L+ T cells. Conclusions: Pentostatin dosages that avoid severe lymphocyte depletion effectively treat colitis by impairing Teff cell expansion and reducing pro‐inflammatory cytokine production while preserving regulatory Treg populations and function.

P-selectin glycoprotein ligand-1 is needed for sequential recruitment of T-helper 1 (Th1) and local generation of Th17 T cells in dextran sodium sulfate (DSS) colitis.

Background: Activated effector T cells contribute to tissue injury observed in inflammatory bowel disease. T cells are recruited to effector sites after activation in peripheral lymph nodes directs expression of tissue‐specific homing receptors. One such mechanism for effector T cell recruitment employs activation‐induced fucosylation of P‐selectin glycoprotein ligand (PSGL)‐1 that mediates binding to endothelial P‐selectin. Here we examine the differential role of PSGL‐1 in recruiting effector T‐cell subsets in colitis. Methods: C57BL/6 wildtype and PSGL‐1−/− mice received 2.5% dextran sodium sulfate (DSS) for 6 days and were euthanized 7 and 14 days after the initiation of DSS. Disease activity was monitored throughout. Histologic colitis scores, colonic CD4+ accumulation, and cytokine production were assessed at days 7 and 14. Recruitment of T‐helper (Th) subsets was assessed by enumerating adoptively transferred Th1 or Th17 CD4+ cells 2 days after transfer to DSS‐treated mice. Results: DSS colitis increases CD4+ T cells in colonic tissue and induces Th1 (interferon gamma [IFN‐&ggr;], tumor necrosis factor [TNF]) and Th17 (interleukin [IL]‐17, IL‐22) cytokines. Loss of PSGL‐1 attenuates DSS colitis, decreases colonic CD4+ T cell numbers, and reduces both Th1 and Th17 cytokine production. Colitis increases recruitment of Th1 (19‐fold) and Th17 (2.5‐fold) cells. PSGL‐1 deficiency in transferred T cells abrogates colonic recruitment of Th1 cells in DSS colitis, whereas Th17 recruitment is unaffected. Conclusions: PSGL‐1 selectively controls Th1 recruitment in colitis. Whereas Th17 recruitment is independent of PSGL‐1, generation of colonic Th17 cytokine requires initial Th1 recruitment. Therefore, attenuating PSGL‐1 binding may prevent colonic recruitment of disease‐causing Th1 cells that promote local Th17 generation. (Inflamm Bowel Dis 2011;)

Tubulointerstitial nephritis: an extraintestinal manifestation of Crohn disease in children.

Extraintestinal manifestations and complications occur in up to 35% of pediatric patients with inflammatory bowel disease (IBD) and can involve almost any organ system (1). The association of renal and urinary complications with Crohn disease (CD) has been well described (2,3). Although the most com