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Rodney D Newberry

Publications and source records attributed to Rodney D Newberry.

11 recordsLinked to original sources
PubMed2006

Murine isolated lymphoid follicles contain follicular B lymphocytes with a mucosal phenotype.

Isolated lymphoid follicles (ILFs) are organized intestinal lymphoid structures whose formation can be induced by luminal stimuli. ILFs have been demonstrated to act as inductive sites for the generation of immune responses directed toward luminal stimuli; however, the phenotype of the immune response initiated within ILFs has largely been uninvestigated. To gain a better understanding of the immune responses initiated within ILFs, we examined phenotypic and functional aspects of the largest cellular component of the murine ILF lymphocyte population, B lymphocytes. We observed that murine ILF B lymphocytes are composed of a relatively homogenous population of follicular B-2 B lymphocytes. Consistent with their proximity to multiple stimuli, ILF B lymphocytes displayed a more activated phenotype compared with their counterparts in the spleen and Peyer's patch (PP). ILF B lymphocytes also expressed higher levels of immunomodulatory B7 and CD28 family members B7X and programmed death-1 compared with their counterparts in the spleen and PP. ILF B lymphocytes preferentially differentiate into IgA-producing plasma cells and produce more IL-4 and IL-10 and less interferon-gamma compared with their counterparts in the spleen. Immunoglobulin repertoire analysis from individual ILFs demonstrated that ILFs contain a polyclonal population of B lymphocytes. These findings indicate that murine ILFs contain a polyclonal population of follicular B-2 B lymphocytes with a phenotype similar to PP B lymphocytes and that, in unchallenged animals, ILFs promote immune responses with a homeostatic phenotype.

Animals↗
PubMed2005

PEGylated murine Granulocyte-macrophage colony-stimulating factor: production, purification, and characterization.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) regulates proliferation, differentiation, and function of hematopoietic progenitor cells. Aside from expansion of hematopoietic cells, GM-CSF has shown efficacy in other diseases, including Crohn's disease. While GM-CSF being clinically used in humans, the ability to perform mechanistic studies in murine models is difficult due to the limited availability and rapid clearance of murine GM-CSF in the peripheral blood. To address these issues, we efficiently expressed murine GM-CSF under the control of the AOX1 gene promoter in Pichia pastoris using the Mut(S) strain KM71H. We describe the unique conditions that are required for efficient production by high-density fermentation and purification of mGM-CSF protein. Recombinant mGM-CSF protein was purified by tangential flow ultrafiltration and preparative reverse phase chromatography. To address limited half life or rapid clearance in mice, recombinant murine GM-CSF was modified by lysine-directed polyethylene glycol conjugation (PEGylation). PEG-modified and unmodified proteins were characterized by amino terminus sequence analysis and matrix assisted laser desorption ionization time-of-flight mass spectrometry. Under the mild reaction conditions, the recombinant protein is efficiently modified by PEGylation on an average of 2-3 sites per molecule. In vivo treatment of mice with PEGylated mGM-CSF, but not the unmodified recombinant mGM-CSF, reproduces the potent colony stimulating effects of human GM-CSF in patients on myeloid progenitor populations, as assessed by FACs analysis. This simplified approach for the expression, purification, and modification of a biologically potent form of murine GM-CSF should facilitate the study of central mechanisms of action in murine disease models.

Amino Acid Sequence↗
PubMed2005

Adaptive immune responses are dispensable for isolated lymphoid follicle formation: antigen-naive, lymphotoxin-sufficient B lymphocytes drive the formation of mature isolated lymphoid follicles.

Isolated lymphoid follicles (ILFs) are recently appreciated members of the mucosal immune system. The architecture, composition, and inducible nature of these structures indicates that these structures are tertiary lymphoid structures. The process leading to the formation of tertiary lymphoid structures, lymphoid neogenesis, has been observed in a number of inflammatory and autoimmune conditions. Given this association, there is considerable interest in identifying the factors promoting lymphoid neogenesis, and understanding the steps in this process. Using murine ILF formation as a model, we have examined the roles of different cellular sources of lymphotoxin (LT) and the adaptive immune response in lymphoid neogenesis. In this study, we report that, although other cellular sources of LT may supplant B lymphocytes in the formation of immature ILFs (loosely organized clusters of B lymphocytes), LT-sufficient B lymphocytes are required for the progression of immature ILFs to mature ILFs (organized lymphoid aggregates with a follicle-associated epithelium). ILF formation occurs in the absence of T lymphocytes and Ag-specific B lymphocyte responses, and ILF B lymphocytes express elevated levels of LT in the absence of antigenic stimulation. Consistent with a role for chemokines inducing LT expression in Ag-naive B lymphocytes, and a chemokine-driven positive-feedback loop driving mature ILF formation, mature ILFs express elevated levels of B lymphocyte chemoattractant in the absence of Ag-specific B lymphocyte stimulation. These observations indicate that ILFs contain Ag-naive lymphocytes, and suggest that events occurring within ILFs shape subsequent immune responses mediated by these lymphocytes.

Animals↗
PubMed2005

Organizing a mucosal defense.

Gastrointestinal associated lymphoid tissue can be divided into loosely organized effector sites, which include the lamina propria and intraepithelial lymphocytes, and more organized structures, such as mesenteric lymph nodes (LNs), Peyer's patches (PPs), isolated lymphoid follicles, and cryptopatches (CPs). These organized structures in the gastrointestinal tract have been hypothesized to play the role of primary lymphoid organ, supporting the extrathymic development of T lymphocytes (CPs), secondary lymphoid organs involved in the induction of the mucosal immune response (PPs), and tertiary lymphoid structures whose function is still under debate (isolated lymphoid follicles). The most widely studied lymphoid structure found in the small intestine is the PP. PPs are secondary lymphoid structures, and their development and function have been extensively investigated. However, single lymphoid aggregates resembling PPs have been also described in humans and in the murine small intestines. These isolated lymphoid follicles have both germinal centers and an overlying follicle-associated epithelium, suggesting that they also can function as inductive sites for the mucosal immune response. This review compares and contrasts the development and function of the four main organized gastrointestinal lymphoid tissues: CPs, isolated lymphoid follicles, PPs, and mesenteric LNs.

Animals↗
PubMed2004

Isolated lymphoid follicles can function as sites for induction of mucosal immune responses.

Isolated lymphoid follicles (ILFs) are organized lymphoid structures in the small intestine. ILFs were recently identified in the murine small intestine; however, the function of ILFs is unknown. To better understand ILFs and the role they play in the intestinal immune response, we have examined the composition of ILFs, the factors that are involved in the genesis of ILFs, and the ability of ILFs to support antigen-specific immunoglobulin production. We found that ILFs contain predominantly B-2 B lymphocytes, and CD4(+) TCRbeta(+) T lymphocytes. Similar to the formation of Peyer's patches (PPs), lymphotoxin beta receptor (LTbetaR)-dependent events are required for ILF formation; however, the timing of these events and the cellular source of LT differ. ILF formation can occur de novo in response to luminal stimuli and requires LT-sufficient B lymphocytes and TNF receptor I function for full maturation. The epithelium over ILFs resembles the PP follicle-associated epithelium, as M cells are present and pathogens such as Yersinia can be bound and taken up into the underlying follicle. Total fecal IgA production is not augmented in animals possessing ILFs; however, the production of antigen-specific IgA is increased in animals possessing ILFs orally challenged with Salmonella typhimurium. Similar to PPs, ILFs can support antigen-specific IgA production following oral immunization. These findings support the concept that ILFs are formed in response to mucosal challenges, and may play a physiological role in the production of antigen-specific intestinal IgA.

Animals↗
PubMed2003

TNFR1 mediates the radioprotective effects of lipopolysaccharide in the mouse intestine.

LPS is radioprotective in the mouse small intestine through a mechanism that includes the synthesis of cyclooxygenase-2 (COX-2) and PGE2. The goal of this study was to identify the intermediate steps in this process. We used wild-type (WT) C57BL/6 mice and knockouts for tumor necrosis factor receptors 1 and 2 (TNFR1-/-, TNFR2-/-) and recombination-activating gene 1-/- mice. Mice were given parenteral LPS and then subjected to 12 Gy total body gamma irradiation. The number of surviving intestinal crypts was assessed 3.5 days after irradiation using a clonogenic assay. Crypt cell apoptosis was assessed by histology. Parenteral administration of LPS induced COX-2 expression, PGE2 production, and radioprotection in WT and TNFR2-/- mice but not in TNFR1-/- mice. TNFR1-/- mice were radioprotected by administration of exogenous 16,16-dimethyl PGE2. Immunohistochemical studies localized TNFR1 and COX-2 expression to subeptihelial fibroblasts and villus epithelial cells. Radiation-induced apoptosis was reduced by pretreatment with LPS in WT and TNFR2-/- mice but not in TNFR1-/- mice. In the absence of LPS, crypt survival was elevated in TNFR1-/- when compared with WT mice. These findings demonstrate that TNFR1 function is required for LPS-induced radioprotection in C57BL/6 mice and define an essential role for TNFR1 function in the induction of COX-2 expression and PGE2 production in this process. The immunolocalization of TNFR1 and COX-2 expression to subepithelial fibroblasts following LPS administration suggests that this cell type plays an intermediate role in LPS-induced radioprotection in the intestine.

16,16-Dimethylprostaglandin E2↗
PubMed2003

Isolated lymphoid follicle formation is inducible and dependent upon lymphotoxin-sufficient B lymphocytes, lymphotoxin beta receptor, and TNF receptor I function.

The gastrointestinal mucosa contains a complex network of lymphoid compartments that have evolved to efficiently protect the host from invading pathogens. Recently, an additional lymphoid structure resembling Peyer's patches (PP) in composition and architecture has been identified in the murine small intestine, the isolated lymphoid follicle (ILF). In this study we examine the nature and factors required for ILF formation. We observed a spectrum of structures fitting the previous descriptions of ILFs, ranging from clusters of B220(+) cells (which we have termed immature ILFs) to well-organized lymphoid nodules (which we have termed mature ILFs). Here we demonstrate that that similar to PP formation, ILF formation requires lymphotoxin (LT)- and LT beta receptor-dependent events. However unlike PP formation, the LT- and LT beta receptor-dependent events required for ILF formation can occur in adulthood and require LT-sufficient B lymphocytes. We demonstrate that mature ILF formation occurs in response to lumenal stimuli, including normal bacterial flora, and requires TNF receptor I function. These findings suggest that ILFs are organized intestinal lymphoid structures whose formation can be induced and whose mass can be expanded in response to mucosal challenges.

Aging↗
PubMed2003

Inhibition of indoleamine 2,3-dioxygenase augments trinitrobenzene sulfonic acid colitis in mice.

BACKGROUND & AIMS: Indoleamine 2,3-dioxygenase (IDO), an interferon gamma-induced intracellular enzyme, inhibits lymphocyte proliferation through tryptophan degradation. IDO is highly expressed in the mammalian intestine. We sought to determine whether IDO played a regulatory role in the T-cell helper 1 (Th1)-mediated trinitrobenzene sulfonic acid (TNBS) model of colitis. METHODS: Intrarectal TNBS was given to SJL/J mice along with either placebo or a specific IDO inhibitor. IDO protein and mRNA expression were assessed by Western blotting and real-time PCR. Colonic lamina propria mononuclear cells (LPMNCs) were isolated, fractionated, and cultured, in the presence and absence of IFN-gamma, to determine the cell type(s) expressing IDO. RESULTS: IDO is expressed by professional antigen-presenting cells in the lamina propria. Induction of TNBS colitis resulted in a significant increase in IDO mRNA (P = 0.005) and protein expression. IDO inhibition during TNBS colitis resulted in an 80% mortality compared with 10% for placebo-treated animals (P = 0.0089). IDO inhibition resulted in a more severe colitis both histologically and morphologically (P < 0.05) and significantly increased colonic proinflammatory cytokine expression compared with placebo-treated animals. CONCLUSIONS: IDO is expressed in the normal colon and is up-regulated in the setting of TNBS colitis. Inhibition of IDO during TNBS colitis resulted in increased mortality and an augmentation of the normal inflammatory response. These findings suggest that IDO plays an important role in the down-regulation of Th1 responses within the gastrointestinal tract.

Animals↗
PubMed2002

Postgestational lymphotoxin/lymphotoxin beta receptor interactions are essential for the presence of intestinal B lymphocytes.

Lymphotoxin (LT), a cytokine belonging to the TNF family, has established roles in the formation of secondary lymphoid structures and in the compartmentalization of T and B lymphocyte areas of the spleen. In this study, we examine the role of LT in directing the composition of intestinal lymphocytes. We report that mice deficient in LT have a normal composition of intestinal lamina propria (LP) T lymphocytes, and an absence of intestinal LP B lymphocytes. We further refine this observation to demonstrate that the interaction of LT with the LTbetaR is essential for the presence LP B lymphocytes. The LT/LTbetaR-dependent events relevant for the presence of LP B lymphocytes occur after birth, do not require the presence of Peyer's patches, lymph nodes, or the spleen; and therefore, are distinct and independent from the previously identified roles of LT/LTbetaR. The LT-dependent signal relevant for the presence of LP B lymphocytes is optimally supplied by a LT-sufficient B lymphocyte, and requires a LTbetaR-sufficient radio-resistant, non-bone marrow-derived cell. Based upon the severity of the deficit of LP B lymphocytes we observed, these novel LT/LTbetaR-dependent events are of primary importance in directing the entry and residence of LP B lymphocytes.

Animals↗