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Biomedical subjects

Warren Strober

Publications and source records attributed to Warren Strober.

At least 37 records · Page 2Linked to original sources
PubMed2005

Immunosuppressive therapy in Whipple's disease patients is associated with the appearance of gastrointestinal manifestations.

OBJECTIVES: Whipple's disease is a rare chronic disorder, which is caused by systemic infection with Tropheryma whipplei. The first symptom of Whipple's disease usually is a nondestructive polyarthritis resembling in many aspects seronegative rheumatoid arthritis. This polyarticular inflammatory arthropathy preceding the diagnosis of Whipple's disease for several years frequently is treated with nonsteroidal antiinflammatory drugs (NSAIDs) and with immunosuppressive therapy. There is evidence that altered immune functions play a role in the manifestation of the disease and that Whipple's disease is associated with opportunistic infections. We therefore asked whether immunosuppressive treatment for arthropathy may alter the course of Whipple's disease. PATIENTS AND METHODS: In a series of 27 patients with Whipple's disease clinical data were documented and the patients were followed for 3-4 yr. The patients were classified into three groups according to their medication: (i) patients with immunosuppressive therapy preceding the diagnosis, (ii) patients with NSAIDs before diagnosis, and (iii) patients without such therapies. RESULTS: Arthropathies occurred in the mean 8 yr before diagnosis and were the first symptom in 63% of the patients. Gastrointestinal involvement usually became evident later on and frequently led to the diagnosis of Whipple's disease. In patients with immunosuppressive treatment, diarrhea occurred in the median 4 months after the initiation of such therapy and diagnosis of Whipple's disease was made after another 2 months. In contrast, other medical treatments were not closely followed by the onset of diarrhea. CONCLUSIONS: These results indicate an association between immunosuppressive therapy and the onset of diarrhea in Whipple's disease and thus support the concept that immunologic factors play a role in disease pathogenesis. Further investigation on the interaction of the immune system and Tropheryma whipplei infection are required to understand the factors contributing to the clinical manifestation of this rare disorder and possibly to introduce preventive interventions.

Age of Onset↗
PubMed2004

Anti-interleukin-12 antibody for active Crohn's disease.

BACKGROUND: Crohn's disease is associated with excess cytokine activity mediated by type 1 helper T (Th1) cells. Interleukin-12 is a key cytokine that initiates Th1-mediated inflammatory responses. METHODS: This double-blind trial evaluated the safety and efficacy of a human monoclonal antibody against interleukin-12 (anti-interleukin-12) in 79 patients with active Crohn's disease. Patients were randomly assigned to receive seven weekly subcutaneous injections of 1 mg or 3 mg of anti-interleukin-12 per kilogram of body weight or placebo, with either a four-week interval between the first and second injection (Cohort 1) or no interruption between the two injections (Cohort 2). Safety was the primary end point, and the rates of clinical response (defined by a reduction in the score for the Crohn's Disease Activity Index [CDAI] of at least 100 points) and remission (defined by a CDAI score of 150 or less) were secondary end points. RESULTS: Seven weeks of uninterrupted treatment with 3 mg of anti-interleukin-12 per kilogram resulted in higher response rates than did placebo administration (75 percent vs. 25 percent, P=0.03). At 18 weeks of follow-up, the difference in response rates was no longer significant (69 percent vs. 25 percent, P=0.08). Differences in remission rates between the group given 3 mg of anti-interleukin-12 per kilogram and the placebo group in Cohort 2 were not significant at either the end of treatment or the end of follow-up (38 percent and 0 percent, respectively, at both times; P=0.07). There were no significant differences in response rates among the groups in Cohort 1. The rates of adverse events among patients receiving anti-interleukin-12 were similar to those among patients given placebo, except for a higher rate of local reactions at injection sites in the former group. Decreases in the secretion of interleukin-12, interferon-gamma, and tumor necrosis factor alpha by mononuclear cells of the colonic lamina propria accompanied clinical improvement in patients receiving anti-interleukin-12. CONCLUSIONS: Treatment with a monoclonal antibody against interleukin-12 may induce clinical responses and remissions in patients with active Crohn's disease. This treatment is associated with decreases in Th1-mediated inflammatory cytokines at the site of disease.

Adult↗
PubMed2004

NOD2 is a negative regulator of Toll-like receptor 2-mediated T helper type 1 responses.

The mechanism by which mutations in CARD15, which encodes nucleotide-binding oligomerization domain 2 (NOD2), cause Crohn disease is poorly understood. Because signaling via mutated NOD2 proteins leads to defective activation of the transcription factor NF-kappa B, one proposal is that mutations cause deficient NF-kappa B-dependent T helper type 1 (T(H)1) responses and increased susceptibility to infection. However, this idea is inconsistent with the increased T(H)1 responses characteristic of Crohn disease. Here we used Card15(-/-) mice to show that intact NOD2 signaling inhibited Toll-like receptor 2-driven activation of NF-kappa B, particularly of the NF-kappa B subunit c-Rel. Moreover, NOD2 deficiency or the presence of a Crohn disease-like Card15 mutation increased Toll-like receptor 2-mediated activation of NF-kappa B-c-Rel, and T(H)1 responses were enhanced. Thus, CARD15 mutations may lead to disease by causing excessive T(H)1 responses.

Animals↗
PubMed2004

TGF-beta 1 plays an important role in the mechanism of CD4+CD25+ regulatory T cell activity in both humans and mice.

In previous studies, we have shown that murine CD4+CD25+ regulatory T cells produce high levels of TGF-beta1 in a cell surface and/or secreted form, and blockade of such TGF-beta1 by anti-TGF-beta curtails the ability of these cells to suppress CD25- T cell proliferation and B cell Ig production in in vitro suppressor assays. In further support for the role of TGF-beta1 in suppression by CD4+CD25+ T cells, we show in this study that another TGF-beta1-blocking molecule, recombinant latency-associated peptide of TGF-beta1 (rLAP), also reverses suppression by mouse CD4+CD25+ T cells as well as their human counterparts, CD4+CD25(high) T cells. In addition, we show that CD25- T cells exposed to CD4+CD25+ T cells in vitro manifest activation of Smad-2 and induction of CD103, the latter a TGF-beta-inducible surface integrin. In further studies, we show that while CD4+CD25+ T cells from TGF-beta1-deficient mice can suppress CD25- T cell proliferation in vitro, these cells do not protect recipient mice from colitis in the SCID transfer model in vivo, and, in addition, CD4+LAP+, but not CD4+LAP- T cells from normal mice protect recipient mice from colitis in this model. Together, these studies demonstrate that TGF-beta1 produced by CD4+CD25+ T cells is involved in the suppressor activity of these cells, particularly in their ability to regulate intestinal inflammation.

Adoptive Transfer↗
PubMed2004

CD1d-restricted T cell pathways at the epithelial-lymphocyte-luminal interface.

The mucosal-associated lymphoid tissues, including the gut-associated lymphoid tissues, represent a tightly regulated environment that, on the one hand, must resist microbial invasions and on the other hand, when perturbed, causes inflammation such as that associated with inflammatory bowel disease. One type of regulatory cellular subset that has recently gained attention in this compartment is the subset of T cells that are associated with CD1d-restricted responses. Recently, CD1d-restricted T cells have been increasingly appreciated to play a significant role in mucosal tissues of the intestine and lung, for example. In this review, we focus on recent observations in the characteristics of CD1d-restricted pathways in mucosal compartments after a brief introduction to the biology of CD1d and CD1d-restricted T cells.

Antigens, CD1↗
PubMed2004

Nonclassical CD1d-restricted NK T cells that produce IL-13 characterize an atypical Th2 response in ulcerative colitis.

While Crohn disease (CD) has been clearly identified as a Th1 inflammation, the immunopathogenesis of its counterpart inflammatory bowel disease, ulcerative colitis (UC), remains enigmatic. Here we show that lamina propria T (LPT) cells from UC patients produce significantly greater amounts of IL-13 (and IL-5) than control cells and little IFN-gamma, whereas comparable cells from CD patients produce large amounts of IFN-gamma and small amounts of IL-13. We then show that stimulation of UC LPT cells bearing an NK marker (CD161) with anti-CD2/anti-CD28 or with B cells expressing transfected CD1d induces substantial IL-13 production. While this provided firm evidence that the IL-13-producing cell is an NK T (NKT) cell, it became clear that this cell does not express invariant NKT cell receptors characteristic of most NKT cells since there was no increase in cells binding alpha-galactosylceramide-loaded tetramers, and alpha-galactosylceramide did not induce IL-13 secretion. Finally, we show that both human NKT cell lines as well as UC CD161(+) LPT cells are cytotoxic for HT-29 epithelial cells and that this cytotoxicity is augmented by IL-13. These studies show that UC is associated with an atypical Th2 response mediated by nonclassical NKT cells producing IL-13 and having cytotoxic potential for epithelial cells.

Antigens, CD1↗
PubMed2004

Insights into the mechanism of oral tolerance derived from the study of models of mucosal inflammation.

Murine models of mucosal inflammation are frequently due to the inability of the mouse to mount a regulatory T cell response. To the extent that such responses arise from oral tolerance mechanisms, these models provide a unique way of studying oral tolerance. In this paper we focus on the regulatory cells generated in two of the most well-studied of such models, the cell-transfer model and the TNBS-colitis model. Our analysis leads to the view that regulatory cells generated by the oral tolerance seen in mucosal inflammation are, at least in part, cells that recognize self-antigens or antigens in the mucosal microflora whose effector function relies on the expression of TGF-beta.

Animals↗
PubMed2004

Natural killer T cells in mucosal homeostasis.

The mucosal-associated lymphoid tissues (MALT), including the gut-associated lymphoid tissues, are a tightly regulated environment. In fact, it might be stated that on the basis of studies from animal models of inflammatory bowel disease (IBD), the major means of peripheral regulation of immune responses in the intestine is not necessarily from processes such as deletion or anergy, but more likely from the controls imposed upon responses due to the activities of a variety of regulatory subsets of cells. One type of regulatory cellular subset that has recently gained attention is the subset of T cells that are associated with CD1d-restricted responses. Recently, CD1d-restricted T cells have been increasingly appreciated to play a significant role in mucosal tissues of the intestine and lung, for example. Insights from these studies have clearly elevated these cells to particular importance in the regulation of a variety of infectious and inflammatory conditions, such as those associated with idiopathic IBD. In this review, we focus on recent observations on the characteristics of CD1d-restricted pathways in mucosal compartments, after a brief introduction into the biology of CD1d and CD1d-restricted T cells.

Animals↗
PubMed2004

Mucosal HIV vaccines: where are we now?

Around the world, approximately 5 million people became infected with HIV in 2001, an estimated 70% via sexual transmission. Numerous studies have demonstrated that it is difficult to achieve total protection from vaginally or rectally acquired HIV/SIV when using parenteral immunization. Mucosal immunization was seen as the best approach to achieve sustainable immune responses at mucosal sites of viral entry. This was further emphasized when several studies implicated rectal and vaginal mucosa as latent reservoirs for the HIV virus and virus-specific CD8+ T cell immune responses in gastrointestinal mucosa were shown to be less efficient than in systemic tissues. Mucosal vaccines utilizing various routes of immunization including intranasal, intrarectal, intravaginal and oral immunization have been tested for their potency to induce virus-specific immune responses systemically but especially at mucosal sites of viral entry. The unsatisfactory results in initiating simultaneously sufficient immune responses at mucosal and systemic sites are being overcomed by use of appropriate and novel adjuvants such as Cholera toxin, Escherichia coli heat-labile toxin, immunostimulatory CpG motifs, coinjection of cytokines and others. Various routes of immunization are now being compared and combinations of mucosal immunization and parenteral boost and vice versa have also been tested. Generations of new vaccines, such as DNA-based vaccines, multipeptide, lipopeptide and alphavirus replicon particles-based vaccines have been created and studied for their efficiency.

AIDS Vaccines↗
PubMed2003

Transforming growth factor (TGF)-beta1-producing regulatory T cells induce Smad-mediated interleukin 10 secretion that facilitates coordinated immunoregulatory activity and amelioration of TGF-beta1-mediated fibrosis.

Interleukin (IL)-10 and transforming growth factor (TGF)-beta1 are suppressor cytokines that frequently occur together during a regulatory T cell response. Here we used a one gene doxycycline (Dox)-inducible plasmid encoding TGF-beta1 to analyze this association and test its utility. In initial studies, we showed that intranasal administration of this plasmid (along with Dox) led to the appearance of TGF-beta1-producing cells (in spleen and lamina propria) and the almost concomitant appearance of IL-10-producing cells. Moreover, we showed that these cells exert Dox-regulated suppression of the T helper cell (Th)1-mediated inflammation in trinitrobenzene sulfonic acid colitis. In subsequent in vitro studies using retroviral TGF-beta1 expression, we established that IL-10 production by Th1 cells occurs after exposure to TGF-beta1 from either an endogenous or exogenous source. In addition, using a self-inactivating retrovirus luciferase reporter construct we showed that TGF-beta1 induces Smad4, which then binds to and activates the IL-10 promoter. Furthermore, intranasal TGF-beta1 plasmid administration ameliorates bleomycin-induced fibrosis in wild-type but not IL-10-deficient mice, strongly suggesting that the amelioration is IL-10 dependent and that IL-10 protects mice from TGF-beta1-mediated fibrosis. Taken together, these findings suggest that the induction of IL-10 by TGF-beta1 is not fortuitous, but instead fulfills important requirements of TGF-beta1 function after its secretion by regulatory T cells.

Animals↗
PubMed2003

GATA-3 suppresses Th1 development by downregulation of Stat4 and not through effects on IL-12Rbeta2 chain or T-bet.

To further understand the interaction among GATA-3, Stat4, and T-bet in helper T cell development, we first showed that retroviral expression of GATA-3 in developing Th1 cells suppresses Th1 development through downregulation of Stat4 rather through downregulation of the IL-12Rbeta2 chain. Correspondingly, Stat4 levels are greatly suppressed during physiological Th2 development. Then, using cells doubly infected with GFP- and YFP-expressing retroviruses, we showed that retroviral GATA-3 expression in developing Th1 cells does not block Th1 development in cells coexpressing Stat4 but does so in cells coexpressing T-bet. Finally, we showed that retroviral Stat4 expression could facilitate Th2-->Th1 conversion in cells bearing an IL-12Rbeta2 transgene, even in cells lacking T-bet. These findings reassert that Stat4 signaling is a central element of Th1/Th2 development.

Animals↗
PubMed2003

The immunological and genetic basis of inflammatory bowel disease.

The inflammatory bowel diseases (IBDs), Crohn's disease and ulcerative colitis, are chronic inflammatory disorders of the gastrointestinal tract. Enormous progress has been made recently in understanding the pathogenesis of these diseases. Through the study of patients and mouse models, it has emerged that Crohn's disease is driven by the production of interleukin-12 (IL-12) and interferon-gamma (IFN-gamma), whereas ulcerative colitis is probably driven by the production of IL-13. A second area of progress is in the identification of specific genetic abnormalities that are responsible for disease. The most important finding is the identification of mutations in the gene that encodes NOD2 (nucleotide-binding oligomerization domain 2) protein in a subgroup of patients with Crohn's disease. Here, we discuss these recent findings and the implications for therapy.

Animals↗
PubMed2002

Activated STAT4 has an essential role in Th1 differentiation and proliferation that is independent of its role in the maintenance of IL-12R beta 2 chain expression and signaling.

In this study we demonstrated that CD4(+) T cells from STAT4(-/-) mice exhibit reduced IL-12R expression and poor IL-12R signaling function. This raised the question of whether activated STAT4 participates in Th1 cell development mainly through its effects on IL-12 signaling. In a first approach to this question we determined the capacity of CD4(+) T cells from STAT4(-/-) bearing an IL-12Rbeta2 chain transgene (and thus capable of normal IL-12R expression and signaling) to undergo Th1 differentiation when stimulated by Con A and APCs. We found that such cells were still unable to exhibit IL-12-mediated IFN-gamma production. In a second approach to this question, we created Th2 cell lines (D10 cells) transfected with STAT4-expressing plasmids with various tyrosine-->phenylalanine mutations and CD4(+) T cell lines from IL-12beta2(-/-) mice infected with retroviruses expressing similarly STAT4 mutations that nevertheless express surface IL-12Rbeta2 chains. We then showed that constructs that were unable to support STAT4 tyrosine phosphorylation (in D10 cells) as a result of mutation were also incapable of supporting IL-12-induced IFN-gamma production (in IL-12Rbeta2(-/-) cells). Thus, by two complementary approaches we demonstrated that activated STAT4 has an essential downstream role in Th1 cell differentiation that is independent of its role in the support of IL-12Rbeta2 chain signaling. This implies that STAT4 is an essential element in the early events of Th1 differentiation.

Animals↗
PubMed2002

STAT4 serine phosphorylation is critical for IL-12-induced IFN-gamma production but not for cell proliferation.

T helper 1 (T(H)1) differentiation and IFN-gamma production are crucial in cell-mediated immune responses. IL-12 is an important regulator of this process and mediates its effects through signal transducer and activator of transcription 4 (STAT4). IFN-gamma production is also regulated by the p38 mitogen-activated kinase pathway, although the mechanisms are ill-defined. We show here that GADD45-beta and GADD45-gamma can induce STAT4 S721 phosphorylation via the MKK6/p38 pathway. Thus, STAT4 could be a target that accounts for the defects in cell-mediated immunity associated with perturbations in the p38 pathway. To investigate the biological significance of STAT4 S721 phosphorylation, we reconstituted primary spleen cells from STAT4-deficient mice with wild-type and mutated STAT4, by using a retroviral gene transduction. We demonstrated that expression of wild-type STAT4, but not the S721A mutant, restored normal T(H)1 differentiation and IFN-gamma synthesis. The inability of STAT4 S721 to restore IFN-gamma production was not caused by decreased IL-12R expression because the STAT4 S721 mutant also failed to restore IFN-gamma production in STAT4-deficient IL-12Rbeta2 transgenic cells. Importantly, STAT4 S721A-transduced cells showed normal proliferative response to IL-12, illustrating that serine phosphorylation is not required for IL-12-induced proliferation. Additionally, the results imply the existence of STAT4 serine phosphorylation-dependent and -independent target genes. We conclude that phosphorylation of STAT4 on both tyrosine and serine residues is important in promoting normal T(H)1 differentiation and IFN-gamma secretion.

Animals↗
PubMed2002

The interrelated roles of TGF-beta and IL-10 in the regulation of experimental colitis.

In the present study, we define the relation between TGF-beta and IL-10 in the regulation of the Th1-mediated inflammation occurring in trinitrobenzene sulfonic acid (TNBS)-colitis. In initial studies, we showed that the feeding of trinitrophenol-haptenated colonic protein to SJL/J mice induces CD4(+) regulatory T cells that transfer protection from induction of TNBS-colitis, and that such protection correlates with cells producing TGF-beta, not IL-10. Further studies in which SJL/J mice were fed haptenated colonic protein, and then administered either anti-TGF-beta or anti-IL-10 at the time of subsequent TNBS administration per rectum, showed that while both Abs abolished protection, anti-TGF-beta administration prevented TGF-beta secretion, but left IL-10 secretion intact; whereas anti-IL-10 administration prevented both TGF-beta secretion and IL-10 secretion. Thus, it appeared that the protective effect of IL-10 was an indirect consequence of its effect on TGF-beta secretion. To establish this point further, we conducted adoptive transfer studies and showed that anti-IL-10 administration had no effect on induction of TGF-beta producing T cells in donor mice. However, it did inhibit their subsequent expansion in recipient mice, probably by regulating the magnitude of the Th1 T cell response which would otherwise inhibit the TGF-beta response. Therefore, these studies suggest that TGF-beta production is a primary mechanism of counter-regulation of Th1 T cell-mediated mucosal inflammation, and that IL-10 is necessary as a secondary factor that facilitates TGF-beta production.

Adjuvants, Immunologic↗
PubMed2002

Oxazolone colitis, a Th2 colitis model resembling ulcerative colitis, is mediated by IL-13-producing NK-T cells.

Oxazolone colitis (OC) is an experimental colitis that has a histologic resemblance to human ulcerative colitis. Here we show that IL-13 production is a significant pathologic factor in OC since its neutralization by IL-13Ralpha2-Fc administration prevents colitis. We further show that OC is mediated by NK-T cells since it can be induced neither in mice depleted of NK-T cells nor in mice that cannot present antigen to NK-T cells and mice lacking an NK-T cell-associated TCR. Finally, we show that NK-T cells are the source of the IL-13, since they produce IL-13 upon stimulation by alpha-galactosylceramide, an NK-T cell-specific antigen. These data thus describe a cellular mechanism underlying an experimental colitis that may explain the pathogenesis of ulcerative colitis.

Adjuvants, Immunologic↗