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Thomas A Wynn

Publications and source records attributed to Thomas A Wynn.

At least 19 recordsLinked to original sources
PubMed2026

Unleashing innovative cross-organ fibrosis therapies by harnessing the omics revolution.

Fibrosis is a major cause of mortality and morbidity worldwide with limited therapeutic options. Our understanding of fibrosis has significantly improved and led to the identification of "core" fibrogenic mechanisms that fuel a self-sustaining vicious cycle following the initial insult. The fibrotic niche is the result of complex cellular and molecular interactions that need to be disrupted to achieve transformational therapies. In this Review, we describe the current understanding of fibrogenic mechanisms, the progress and limitations of omics approaches in the identification of novel fibrotic pathways, and advances in therapeutic modalities that all together have the potential to unleash innovative cross-organ antifibrotic therapies.

Humans↗
PubMed2006

Immunopathology of schistosomiasis.

Waterborne parasitic diseases plague tropical regions of the world with the development of water resources often increasing transmission. Skin-penetrating cercariae (infectious stages of schistosome parasites) mature within their mammalian host, form sexual pairs and produce several hundred eggs per day. Many eggs are swept within the circulation and in the case of Schistosoma mansoni and S. japonicum, become lodged within hepatic sinusoids, invoking a fibrotic granulomatous response. Animal studies have identified a moderate type 1 helper (Th1) response to parasite antigens; however, a robust Th2 response to egg-derived antigens dominates and propagates fibrogenesis within the liver. Elegant T helper cell polarization studies have highlighted that critical control of Th1, Th2 and interleukin (IL)-17-secreting lymphocytes is necessary to prevent severe liver pathology. Alternatively activated macrophages develop in the Th2 milieu and upregulate Fizz1, Ym-1 and Arg-1. The possible contribution of macrophages to fibrogenesis and their role in immune regulation are discussed. Within the liver, natural (CD4(+)CD25(+) Forkhead box protein 3 (Foxp3)(+)) and inducible (CD4(+)Foxp3(-)) Treg's are recruited, providing an essential regulatory arm to stabilize the immune response and limit immunopathology. This review ties together current thinking of how the granulomatous response develops, causing much of the associated immunopathology, with extensive discussions on how regulatory cells and cytokine decoy receptors serve to limit the extent of immune-mediated pathology during schistosomiasis.

Animals↗
PubMed2006

NK cell-derived IFN-gamma differentially regulates innate resistance and neutrophil response in T cell-deficient hosts infected with Mycobacterium tuberculosis.

Although it is known that IFN-gamma-secreting T cells are critical for control of Mycobacterium tuberculosis infection, the contribution of IFN-gamma produced by NK cells to host resistance to the pathogen is less well understood. By using T cell-deficient RAG(-/-) mice, we showed that M. tuberculosis stimulates NK cell-dependent IFN-gamma production in naive splenic cultures and in lungs of infected animals. More importantly, common cytokine receptor gamma-chain(-/-)RAG(-/-) animals deficient in NK cells, p40(-/-)RAG(-/-), or anti-IFN-gamma mAb-treated RAG(-/-) mice displayed significantly increased susceptibility to M. tuberculosis infection compared with untreated NK-sufficient RAG(-/-) controls. Studies comparing IL-12 p40- and p35-deficient RAG(-/-) mice indicated that IL-12 plays a more critical role in the induction of IFN-gamma-mediated antimycobacterial effector functions than IL-23 or other p40-containing IL-12 family members. The increased susceptibility of IL-12-deficient or anti-IFN-gamma mAb-treated RAG(-/-) mice was associated not only with elevated bacterial loads, but also with the development of granulocyte-enriched foci in lungs. This tissue response correlated with increased expression of the granulocyte chemotactic chemokines KC and MIP-2 in NK as well as other leukocyte populations. Interestingly, depletion of granulocytes further increased bacterial burdens and exacerbated pulmonary pathology in these animals, revealing a compensatory function for neutrophils in the absence of IFN-gamma. The above observations indicate that NK cell-derived IFN-gamma differentially regulates T-independent resistance and granulocyte function in M. tuberculosis infection and suggest that this response could serve as an important barrier in AIDS patients or other individuals with compromised CD4+ T cell function.

Animals↗
PubMed2006

Interleukin-5 does not influence differential transcription of transmembrane and soluble isoforms of IL-5R alpha in vivo.

UNLABELLED: Interleukin-5 (IL-5) promotes signal transduction and expansion of eosinophil colonies in bone marrow via interactions with its heterodimeric receptor (IL-5R). Two variants encoding soluble forms of the alpha subunit (sIL-5R alpha) have been described, although the signals promoting and/or limiting differential transcription remain to be clarified. OBJECTIVES: Our intent was to explore the role of IL-5 in regulating differential transcription of these splice variants in vivo. METHODS: We have designed a quantitative reverse transcriptase-polymerase chain reaction assay to detect transcripts encoding the transmembrane, soluble 1 and 2 forms of IL-5R alpha in two strains of wild-type (BALB/c and C57BL/6) and corresponding IL-5 gene-deleted mice. Wild-type mice respond to S. mansoni infection with a gradual increase in serum IL-5 and eosinophilia, which is not observed in IL-5 gene-deleted mice. RESULTS AND CONCLUSIONS: We find that IL-5 is not necessary for differential splicing to occur in vivo, as all three forms of the IL-5R alpha are detected in both strains of IL-5 gene-deleted mice, with ratios of transcript expression (transmembrane : soluble 1 : soluble 2) that were indistinguishable from their wild-type counterparts. Differential splicing does vary markedly between strains, potentially because of local effects of strain-specific polymorphisms.

Alternative Splicing↗
PubMed2006

Resistance of C57BL/6 mice to amoebiasis is mediated by nonhemopoietic cells but requires hemopoietic IL-10 production.

Resistance to intestinal amoebiasis is mouse strain dependent. C57BL/6 (B6) mice clear Entamoeba histolytica within hours of challenge, whereas C3H and CBA strains are susceptible to infection and disease. In this study, we show using bone marrow (BM) chimeric mice that mouse strain-dependent resistance is mediated by nonhemopoietic cells; specifically, B6 BM --> CBA recipients remained susceptible as measured by amoeba score and culture, whereas CBA BM --> B6 recipients remained resistant. Interestingly, hemopoietic IL-10 was required for maintaining the resistance of B6 mice, in that B6 IL-10-deficient mice and IL-10(-/-) BM --> wild-type recipients, but not IL-10(+/+) BM --> IL-10(-/-) recipients, exhibited higher amoeba scores than their wild-type controls. Additionally, C57BL/10 IL-10(-/-)Rag2(-/-) mice exhibited diminished amoeba scores and culture rates vs IL-10(-/-) mice, indicating that lymphocytes potentiated the susceptibility of IL-10-deficient mice. We conclude that nonhemopoietic cells mediate the natural resistance to intestinal amoebiasis of B6 mice, yet this resistance depends on hemopoietic IL-10 activity.

Animals↗
PubMed2006

The IL-21 receptor augments Th2 effector function and alternative macrophage activation.

The IL-21 receptor (IL-21R) shows significant homology with the IL-4R, and CD4+ Th2 cells are an important source of IL-21. Here we examined whether the IL-21R regulates the development of Th2 responses in vivo. To do this, we infected IL-21R-/- mice with the Th2-inducing pathogens Schistosoma mansoni and Nippostrongylus brasiliensis and examined the influence of IL-21R deficiency on the development of Th2-dependent pathology. We showed that granulomatous inflammation and liver fibrosis were significantly reduced in S. mansoni-infected IL-21R-/- mice and in IL-21R+/+ mice treated with soluble IL-21R-Fc (sIL-21R-Fc). The impaired granulomatous response was also associated with a marked reduction in Th2 cytokine expression and function, as evidenced by the attenuated IL-4, IL-13, AMCase, Ym1, and FIZZ1 (also referred to as RELMalpha) responses in the tissues. A similarly impaired Th2 response was observed following N. brasiliensis infection. In vitro, IL-21 significantly augmented IL-4Ralpha and IL-13Ralpha1 expression in macrophages, resulting in increased FIZZ1 mRNA and arginase-1 activity following stimulation with IL-4 and IL-13. As such, these data identify the IL-21R as an important amplifier of alternative macrophage activation. Collectively, these results illustrate an essential function for the IL-21R in the development of pathogen-induced Th2 responses, which may have relevance in therapies for both inflammatory and chronic fibrotic diseases.

Animals↗
PubMed2006

Schistosoma mansoni infection in eosinophil lineage-ablated mice.

We explore the controversial issue of the role of eosinophils in host defense against helminthic parasites using the established Schistosoma mansoni infection model in 2 novel mouse models of eosinophil lineage ablation (DeltadblGATA and TgPHIL). No eosinophils were detected in bone marrow of infected DeltadblGATA or TgPHIL mice, despite the fact that serum IL-5 levels in these infected mice exceeded those in infected wild type by approximately 4-fold. Liver granulomata from infected DeltadblGATA and TgPHIL mice were likewise depleted of eosinophils compared with those from their respective wild types. No eosinophil-dependent differences in granuloma number, size, or fibrosis were detected at weeks 8 or 12 of infection, and differential accumulation of mast cells was observed among the DeltadblGATA mice only at week 12. Likewise, serum levels of liver transaminases, alanine aminotransferase (ALT), and aspartate aminotransferase (AST) increased in all mice in response to S mansoni infection, with no eosinophil-dependent differences in hepatocellular damage observed. Finally, eosinophil ablation had no effect on worm burden or on egg deposition. Overall, our data indicate that eosinophil ablation has no impact on traditional measures of disease in the S mansoni infection model in mice. However, eosinophils may have unexplored immunomodulatory contributions to this disease process.

Animals↗
PubMed2006

Functional importance of regional differences in localized gene expression of receptors for IL-13 in murine gut.

IL-13 induces a STAT6-dependent hypercontractility of intestinal smooth muscle that is mediated by binding to the IL-13Ralpha1 component of the type 2 IL-4R that is linked to STAT6. IL-13 also binds to the IL-13Ralpha2 that is not linked to STAT6 and functions to limit the effects of IL-13 in vivo. In this study we assessed the contributions of regional and cellular differences in the distribution of the IL-13R components to the physiological regulation of smooth muscle function in wild-type mice and mice deficient in STAT6 or IL-13Ralpha2. The expression of IL-13 and IL-13Ralpha2 was higher in colon than in small intestine. Laser capture microdissection of specific cell types revealed that the expression of IL-13Ralpha2 was higher in the smooth muscle layer compared with levels in the epithelial cells of the mucosa. In contrast, there was a uniform distribution of IL-13alpha1 in smooth muscle, epithelia, and myenteric neurons. The significant hypercontractility of smooth muscle in mice deficient in IL-13Ralpha2, but not in STAT6, shows the physiological importance of IL-13 binding to IL-13Ralpha2. The pronounced differences in the expression of IL-13Ralpha2 suggest that the gut has developed sophisticated mechanisms for controlling the physiological and pathophysiological activities of IL-13.

Animals↗
PubMed2006

Interleukin-5 (IL-5) augments the progression of liver fibrosis by regulating IL-13 activity.

Eosinophils are frequently found in increased numbers in a variety of chronic fibrotic diseases; however, their role in the development of hepatic fibrosis has not been dissected in vivo. Here, we used interleukin-5 (IL-5) knockout (KO) mice to determine whether eosinophils contribute to the progressive liver fibrosis that develops in response to chronic Schistosoma mansoni infection. Although infection intensities were similar in C57BL/6 and IL-5 KO mice, the average size of granulomas was significantly smaller in both acutely and chronically infected IL-5 KO mice. Their granulomas were also completely devoid of eosinophils. In addition, the knockout mice displayed over a 40% reduction in hepatic fibrosis by week 16 postinfection. The reduced fibrosis was associated with increased production of the antifibrotic cytokine gamma interferon. Moreover, although IL-13 production did not decrease consistently in the absence of IL-5, IL-13-triggered responses were substantially reduced in the granulomatous tissues. This was confirmed by analyzing the expression of several genes associated with alternative macrophage activation, including arginase 1, Fizz-1, and YM-1. Importantly, all of these IL-13-regulated genes have been linked with the mechanisms of wound healing and fibrosis. In addition to IL-5 polarizing the antigen-specific CD4+ Th2 cell response, we found that granuloma eosinophils were themselves a significant source of IL-13. Thus, by producing profibrotic mediators and polarizing the Th2 response, these findings illustrate both direct and indirect roles for eosinophils and IL-5 in the pathogenesis of schistosomiasis-induced liver fibrosis. Thus, inhibiting the activity of IL-5 or eosinophils may prove effective for a variety of chronic fibrotic diseases.

Animals↗
PubMed2005

Immunopathogenic mechanisms in schistosomiasis: what can be learnt from human studies?

Studies in mice indicate that schistosome egg-induced granuloma formation and hepatic fibrosis depend markedly on cytokine regulation, with interleukin 10 having a central role. There is no clear consensus about the pattern of cytokine production and regulation that causes a minority of chronically exposed patients to develop severe hepatosplenic (HS) disease, which is characterized by periportal fibrosis and portal hypertension. HS disease and the progression of hepatic fibrosis are associated with the production of profibrotic type 2 cytokines in the early stages of infection with Schistosoma mansoni. However, other studies indicate that HS disease is characterized by a predominant T helper 1 profile. Until new tools and approaches are developed to study human disease in endemic areas, investigators must either speculate about indirect evidence from human studies or rely more heavily on findings generated from experimental models of the disease.

Animals↗
PubMed2005

High-Throughput GoMiner, an 'industrial-strength' integrative gene ontology tool for interpretation of multiple-microarray experiments, with application to studies of Common Variable Immune Deficiency (CVID).

BACKGROUND: We previously developed GoMiner, an application that organizes lists of 'interesting' genes (for example, under-and overexpressed genes from a microarray experiment) for biological interpretation in the context of the Gene Ontology. The original version of GoMiner was oriented toward visualization and interpretation of the results from a single microarray (or other high-throughput experimental platform), using a graphical user interface. Although that version can be used to examine the results from a number of microarrays one at a time, that is a rather tedious task, and original GoMiner includes no apparatus for obtaining a global picture of results from an experiment that consists of multiple microarrays. We wanted to provide a computational resource that automates the analysis of multiple microarrays and then integrates the results across all of them in useful exportable output files and visualizations. RESULTS: We now introduce a new tool, High-Throughput GoMiner, that has those capabilities and a number of others: It (i) efficiently performs the computationally-intensive task of automated batch processing of an arbitrary number of microarrays, (ii) produces a human-or computer-readable report that rank-orders the multiple microarray results according to the number of significant GO categories, (iii) integrates the multiple microarray results by providing organized, global clustered image map visualizations of the relationships of significant GO categories, (iv) provides a fast form of 'false discovery rate' multiple comparisons calculation, and (v) provides annotations and visualizations for relating transcription factor binding sites to genes and GO categories. CONCLUSION: High-Throughput GoMiner achieves the desired goal of providing a computational resource that automates the analysis of multiple microarrays and integrates results across all of the microarrays. For illustration, we show an application of this new tool to the interpretation of altered gene expression patterns in Common Variable Immune Deficiency (CVID). High-Throughput GoMiner will be useful in a wide range of applications, including the study of time-courses, evaluation of multiple drug treatments, comparison of multiple gene knock-outs or knock-downs, and screening of large numbers of chemical derivatives generated from a promising lead compound.

Binding Sites↗
PubMed2005

Exploiting worm and allergy models to understand Th2 cytokine biology.

PURPOSE OF REVIEW: Helminthic parasites and many allergens trigger highly polarized Th2-type immune responses. In most helminth infections, the Th2 response often leads to parasite expulsion or sequestration. During murine Schistosoma mansoni infection, however, the parasites persist and the chronic Th2 response induces severe pathological changes in the gut and liver. Thus, the study of schistosome infections in mice has become a popular model to study the pathogenesis of Th2 cytokine-mediated disease. This review will discuss recent findings from the schistosomiasis model that may be relevant to the understanding of allergic inflammation, asthma and Th2 cytokine biology in general. RECENT FINDINGS: Evidence is accumulating that the Th2 pathway is not a 'default pathway' but one that is actively instructed by mechanisms that are only beginning to be understood. Other areas of intensive investigation include studies on alternatively activated macrophages, the role of dendritic cells in Th2 response development, the inhibitory function of IL-10, regulatory T-cells and decoy receptors on chronic Th2-mediated inflammation, and the role of chitinases in mediating Th2 disease. Finally, the development of novel eosinophil-deficient mice has also accelerated our understanding of the contribution of this important cell type to Th2 immunity. SUMMARY: Many findings from the schistosomiasis model have been subsequently demonstrated in models of allergic disease, illustrating the utility of this model to dissect basic mechanisms of Th2-mediated inflammation. Further study of helminth-induced Th2 responses may expedite the discovery of new therapeutics for a wide range of Th2-associated diseases.

Animals↗
PubMed2004

Immunoglobulin class switch recombination is impaired in Atm-deficient mice.

Immunoglobulin class switch recombination (Ig CSR) involves DNA double strand breaks (DSBs) at recombining switch regions and repair of these breaks by nonhomologous end-joining. Because the protein kinase ataxia telengiectasia (AT) mutated (ATM) plays a critical role in DSB repair and AT patients show abnormalities of Ig isotype expression, we assessed the role of ATM in CSR by examining ATM-deficient mice. In response to T cell-dependent antigen (Ag), Atm-/- mice secreted substantially less Ag-specific IgA, IgG1, IgG2b, and IgG3, and less total IgE than Atm+/+ controls. To determine whether Atm-/- B cells have an intrinsic defect in their ability to undergo CSR, we analyzed in vitro responses of purified B cells. Atm-/- cells secreted substantially less IgA, IgG1, IgG2a, IgG3, and IgE than wild-type (WT) controls in response to stimulation with lipopolysaccharide, CD40 ligand, or anti-IgD plus appropriate cytokines. Molecular analysis of in vitro responses indicated that WT and Atm-/- B cells produced equivalent amounts of germline IgG1 and IgE transcripts, whereas Atm-/- B cells produced markedly reduced productive IgG1 and IgE transcripts. The reduction in isotype switching by Atm-/- B cells occurs at the level of genomic DNA recombination as measured by digestion-circularization PCR. Analysis of sequences at CSR sites indicated that there is greater microhomology at the mu-gamma1 switch junctions in ATM B cells than in wild-type B cells, suggesting that ATM function affects the need or preference for sequence homology in the CSR process. These findings suggest a role of ATM in DNA DSB recognition and/or repair during CSR.

Animals↗
PubMed2004

IL-13 activates a mechanism of tissue fibrosis that is completely TGF-beta independent.

Fibrosis is a characteristic feature in the pathogenesis of a wide spectrum of diseases. Recently, it was suggested that IL-13-dependent fibrosis develops through a TGF-beta1 and matrix metalloproteinase-9-dependent (MMP-9) mechanism. However, the significance of this pathway in a natural disorder of fibrosis was not investigated. In this study, we examined the role of TGF-beta in IL-13-dependent liver fibrosis caused by Schistosoma mansoni infection. Infected IL-13-/- mice showed an almost complete abrogation of fibrosis despite continued and undiminished production of TGF-beta1. Although MMP-9 activity was implicated in the IL-13 pathway, MMP-9-/- mice displayed no reduction in fibrosis, even when chronically infected. To directly test the requirement for TGF-beta, studies were also performed with neutralizing anti-TGF-beta Abs, soluble antagonists (soluble TGF-betaR-Fc), and Tg mice (Smad3-/- and TGF-betaRII-Fc Tg) that have disruptions in all or part of the TGF-beta signaling cascade. In all cases, fibrosis developed normally and with kinetics similar to wild-type mice. Production of IL-13 was also unaffected. Finally, several genes, including interstitial collagens, several MMPs, and tissue inhibitors of metalloprotease-1 were up-regulated in TGF-beta1-/- mice by IL-13, demonstrating that IL-13 activates the fibrogenic machinery directly. Together, these studies provide unequivocal evidence of a pathway of fibrogenesis that is IL-13 dependent but TGF-beta1 independent, illustrating the importance of targeting IL-13 directly in the treatment of infection-induced fibrosis.

Animals↗
PubMed2004

Plasminogen activator inhibitor-2 (PAI-2) in eosinophilic leukocytes.

Plasminogen activator inhibitor-2 (PAI-2) as a potential eosinophil protein was inferred from our gene microarray study of mouse eosinophilopoiesis. Here, we detect 47 kDa intracellular and approximately 60 kDa secretory forms of PAI-2 in purified human eosinophil extracts. PAI-2 is present at variable concentrations in eosinophil lysates, ranging from 30 to 444 ng/10(6) cells, with a mean of 182 ng/10(6) cells from 10 normal donors, which is the highest per-cell concentration among all leukocyte subtypes evaluated. Enzymatic assay confirmed that eosinophil-derived PAI-2 is biologically active and inhibits activation of its preferred substrate, urokinase. Immunohistochemical and immunogold staining demonstrated PAI-2 localization in eosinophil-specific granules. Immunoreactive PAI-2 was detected in extracellular deposits in and around the eosinophil-enriched granuloma tissue encapsulating the parasitic egg in livers of wild-type mice infected with the helminthic parasite Schistosoma mansoni. Among the possibilities, we consider a role for eosinophil-derived PAI-2 in inflammation and remodeling associated with parasitic infection as well as allergic airways disease, respiratory virus infection, and host responses to tumors and metastasis in vivo.

Animals↗
PubMed2004

The pathogenesis of schistosomiasis is controlled by cooperating IL-10-producing innate effector and regulatory T cells.

IL-10 reduces immunopathology in many persistent infections, yet the contribution of IL-10 from distinct cellular sources remains poorly defined. We generated IL-10/recombination-activating gene (RAG)2-deficient mice and dissected the role of T cell- and non-T cell-derived IL-10 in schistosomiasis by performing adoptive transfers. In this study, we show that IL-10 is generated by both the innate and adaptive immune response following infection, with both sources regulating the development of type-2 immunity, immune-mediated pathology, and survival of the infected host. Importantly, most of the CD4(+) T cell-produced IL-10 was confined to a subset of T cells expressing CD25. These cells were isolated from egg-induced granulomas and exhibited potent suppressive activity in vitro. Nevertheless, when naive, naturally occurring CD4(+)CD25(+) cells were depleted in adoptive transfers, recipient IL-10/RAG2-deficient animals were more susceptible than RAG2-deficient mice, confirming an additional host-protective role for non-T cell-derived IL-10. Thus, innate effectors and regulatory T cells producing IL-10 cooperate to reduce morbidity and prolong survival in schistosomiasis.

Adoptive Transfer↗
PubMed2004

P-selectin suppresses hepatic inflammation and fibrosis in mice by regulating interferon gamma and the IL-13 decoy receptor.

The selectin family of cell adhesion molecules is widely thought to promote inflammatory reactions by facilitating leukocyte recruitment. However, it was unexpectedly found that mice with targeted deletion of the P-selectin gene (PsKO mice) developed unpolarized type 1/type 2 cytokine responses and severely aggravated liver pathology following infection with the type 2-promoting pathogen Schistosoma mansoni. In fact, liver fibrosis, which is dependent on interleukin 13 (IL-13), increased by a factor of more than 6, despite simultaneous induction of the antifibrotic cytokine interferon gamma (IFN-gamma). Inflammation, as measured by granuloma size, also increased significantly in the absence of P-selectin. When infected PsKO mice were treated with neutralizing anti-IFN-gamma monoclonal antibodies, however, granuloma size was restored to wild-type levels; this finding revealed the potent proinflammatory role of IFN-gamma when expressed concomitantly with IL-13. Untreated PsKO mice also exhibited a significant (sixfold) reduction in decoy IL-13 receptor (IL-13 receptor alpha-2) expression when compared with infected wild-type animals. It is noteworthy, however, that when decoy receptor activity was restored in PsKO mice by treatment with soluble IL-13 receptor alpha-2-Fc, the exacerbated fibrotic response was completely inhibited. Thus, reduced expression of the decoy IL-13 receptor mediated by the elevated type 1 cytokine response probably accounts for the enhanced activity of IL-13 in PsKO mice and for the resultant increase in collagen deposition. In conclusion, the current study has revealed the critical role of P-selectin in the progression of chronic liver disease caused by schistosome parasites. By suppressing IFN-gamma and up-regulating the decoy IL-13 receptor, P-selectin dramatically inhibits the pathologic tissue remodeling that results from chronic type 2 cytokine-mediated inflammation.

Animals↗