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Biomedical subjects

R S Blumberg

Publications and source records attributed to R S Blumberg.

At least 19 recordsLinked to original sources
PubMed2006

Antibody targeting of TIRC7 results in significant therapeutic effects on collagen-induced arthritis in mice.

TIRC7 is a cell surface molecule which is expressed in T and B lymphocytes and negatively regulates their function. Anti-TIRC7 specific monoclonal antibody (mAb) inhibited T cell memory response to recall antigens. Up-regulation of TIRC7 on lymphocytes from joint tissue of patients with Rheumatoid Arthritis (RA) and mice with collagen induced arthritis (CIA) suggested TIRC7 as a novel target to promote anti-inflammatory reaction. Anti-TIRC7 mAb administration significantly inhibited the induction and progression of CIA and the anti-collagen IgG1 and IgG2a antibody response. Combination therapy of anti-TIRC7 mAb and soluble TNF-alpha receptor demonstrated an increased inhibitory effect over the single compounds on CIA. The results demonstrate the therapeutic potential of TIRC7 targeting with mAb in diseases associated with exaggerated T and B cell responses.

Animals↗
PubMed2002

The transcription factor T-bet regulates mucosal T cell activation in experimental colitis and Crohn's disease.

The balance between pro and antiinflammatory cytokines secreted by T cells regulates both the initiation and perpetuation of inflammatory bowel diseases (IBD). In particular, the balance between interferon (IFN)-gamma/interleukin (IL)-4 and transforming growth factor (TGF)-beta activity controls chronic intestinal inflammation. However, the molecular pathways that evoke these responses are not well understood. Here, we describe a critical role for the transcription factor T-bet in controlling the mucosal cytokine balance and clinical disease. We studied the expression and function of T-bet in patients with IBD and in mucosal T cells in various T helper (Th)1- and Th2-mediated animal models of chronic intestinal inflammation by taking advantage of mice that lack T-bet and retroviral transduction techniques, respectively. Whereas retroviral transduction of T-bet in CD62L(+) CD4(+) T cells exacerbated colitis in reconstituted SCID mice, T-bet-deficient T cells failed to induce colitis in adoptive transfer experiments suggesting that overexpression of T-bet is essential and sufficient to promote Th1-mediated colitis in vivo. Furthermore, T-bet-deficient CD62L(-) CD4(+) T cells showed enhanced protective functions in Th1-mediated colitis and exhibited increased TGF-beta signaling suggesting that a T-bet driven pathway of T cell activation controls the intestinal balance between IFN-gamma/IL-4 and TGF-beta responses and the development of chronic intestinal inflammation in T cell-mediated colitis. Furthermore, TGF-beta was found to suppress T-bet expression suggesting a reciprocal relationship between TGF-beta and T-bet in mucosal T cells. In summary, our data suggest a key regulatory role of T-bet in the pathogenesis of T cell-mediated colitis. Specific targeting of this pathway may be a promising novel approach for the treatment of patients with Crohn's disease and other autoimmune diseases mediated by Th1 T lymphocytes.

Adult↗
PubMed2001

Homophilic adhesion of human CEACAM1 involves N-terminal domain interactions: structural analysis of the binding site.

CEACAM1 on leukocytic, endothelial, and epithelial cells functions in homophilic adhesion, tumor suppression, regulating cell adhesion and proliferation, and in heterophilic adhesion as a receptor for E-selectin and Neisseria meningiditis, Neisseria gonorrhoeae, Haemophilus influenzae, and murine coronaviruses. The 8 transmembrane isoforms of human CEACAM1 possess an extracellular N-terminal IgV domain, followed by variable numbers of IgC2 domains. To establish which key amino acids contribute specifically to CEACAM1 homophilic adhesion, exposed amino acids in the N-terminal domain of a soluble form of CEACAM1 were subjected to mutagenesis. Analyses of mutant proteins with conformationally dependent antibodies indicated that most mutations did not substantially affect the structural integrity of CEACAM1. Nevertheless, decreased adhesion was observed for the single mutants V39A or D40A (single-letter amino acid codes) in the CC' loop and for the triple mutants located in the GFCC'C" face of the N-terminal domain. Interestingly, whereas single mutations in R64 or D82 that are predicted to form a salt bridge between the base of the D and F beta strands close to the critical V39 and D40 residues also abolish adhesion, an amino acid swap (R64D and D82R), which maintains the salt bridge was without significant effect. These studies indicate that the CC' loop plays a crucial role in the homophilic adhesion of CEACAM1. They further predict that specific hydrophobic amino acid residues on the nonglycosylated GFCC'C" face of CEACAM1 N-terminal domain are not only involved in heterophilic interactions with Opa proteins and H influenzae, but are also critical for protein-protein interactions between 2 CEACAM1 molecules on opposing cells.

Amino Acid Sequence↗
PubMed2001

MHC class I-related neonatal Fc receptor for IgG is functionally expressed in monocytes, intestinal macrophages, and dendritic cells.

The neonatal Fc receptor (FcRn) for IgG, an MHC class I-related molecule, functions to transport IgG across polarized epithelial cells and protect IgG from degradation. However, little is known about whether FcRn is functionally expressed in immune cells. We show here that FcRn mRNA was identifiable in human monocytes, macrophages, and dendritic cells. FcRn heavy chain was detectable as a 45-kDa protein in monocytic U937 and THP-1 cells and in purified human intestinal macrophages, peripheral blood monocytes, and dendritic cells by Western blot analysis. FcRn colocalized in vivo with macrosialin (CD68) and Ncl-Macro, two macrophage markers, in the lamina propria of human small intestine. The heavy chain of FcRn was associated with the beta(2)-microglobulin (beta(2)m) light chain in U937 and THP-1 cells. FcRn bound human IgG at pH 6.0, but not at pH 7.5. This binding could be inhibited by human IgG Fc, but not Fab. FcRn could be detected on the cell surface of activated, but not resting, THP-1 cells. Furthermore, FcRn was uniformly present intracellularly in all blood monocytes and intestinal macrophages. FcRn was detectable on the cell surface of a significant fraction of monocytes at lower levels and on a small subset of tissue macrophages that expressed high levels of FcRn on the cell surface. These data show that FcRn is functionally expressed and its cellular distribution is regulated in monocytes, macrophages, and dendritic cells, suggesting that it may confer novel IgG binding functions upon these cell types relative to typical Fc gamma Rs: Fc gamma RI, Fc gamma RII, and Fc gamma RIII.

Adult↗
PubMed2001

Prospects for research in inflammatory bowel disease.

Inflammatory bowel disease is a chronic inflammatory condition of the gastrointestinal tract that manifests as ulcerative colitis and Crohn disease. Both these clinical entities result from interrelated genetic and environmental factors that may be channeled through an abnormality in mucosal immune function, possibly due to dysregulated or excessive T helper cell (T(H))1 (Crohn disease) or T(H)2 (ulcerative colitis) responses. This article reviews current knowledge of the role of immune factors in inflammatory bowel disease and the potential therapeutic strategies that target the pathways of T(H)1- or T(H)2-induced inflammation.

Animals↗
PubMed2001

PPARgamma and inflammatory bowel disease: a new therapeutic target for ulcerative colitis and Crohn's disease.

Peroxisome proliferator-activated receptor gamma (PPARgamma) is a nuclear receptor that is known to play a central role in adipocyte differentiation and insulin sensitivity. Through work in several animal models of intestinal inflammation, it is now recognized that PPARgamma also inhibits tissue injury associated with immune activation. These studies point to PPARgamma as a novel anti-inflammatory mediator with broad therapeutic potential.

Animals↗
PubMed2001

Prevalence of an ulcerative colitis-associated CD8+ T cell receptor beta-chain CDR3-region motif and its association with disease activity.

The normal human intestinal mucosa contains clonal T cell expansions. Clonal populations of T cells can be determined through evaluation of the idiotypic, hypervariable region of their T cell receptor (TCR). We have previously reported that there exists a highly conserved TCR pattern among intestinal CD8+ T cells in the majority of ulcerative colitis (UC) patients undergoing colectomy that was not present in normal control individuals. This TCR pattern, or motif, was characterized by particular beta-chain usage (TCRBV3 and TCRBJ1S6) and a defined length in the hypervariable third complementarity determining region (CDR3). The aim of this study was to assess the motif's relationship to disease activity. Subjects were 66 with UC, 19 with Crohn's disease, 14 inflammatory controls, and 6 normal controls. cDNA and gDNA were prepared from colonic biopsies and paraffin blocks, respectively, obtained from study subjects and used to assess TCRBV CDR3 region length and usage, as well as for cloning and sequencing of TCRs. The TCRBV CDR3 region was present in 25 of a series of 48 UC subjects but only 3 of 19 Crohn's disease patients and 3 of 14 inflammatory controls. The motif was more common in UC than either Crohn' s disease or inflammatory controls (chi2 = 7.5, P = 0.006, and chi2 = 4.1, P = 0.04, respectively). The motifs presence was not dependent upon histologic disease activity (either active or inactive UC). Clinical UC disease activity was also not significantly associated with an increased presence of the motif in 14 paired biopsies, which were taken during times of clinical activity or inactivity. There was a trend toward persistence of the motif, as it was present in 6 of 14 subjects over a 3- to 6-month time period. The previously described UC-associated TCRBV CDR3 region motif located in the intestinal CD8+ T-cell subset is found in a significant proportion of UC subjects. The TCR motif does not significantly discriminate active from inactive disease states. The persistent and diffuse nature of this TCR-associated motif in UC suggests that an ongoing T-cell response to a particular antigen(s) is occuring in this disorder.

Amino Acid Sequence↗
PubMed2001

Endogenous PPAR gamma mediates anti-inflammatory activity in murine ischemia-reperfusion injury.

BACKGROUND & AIMS: Peroxisome proliferator-activated receptor gamma (PPAR gamma) is a nuclear receptor whose activation has been linked to several physiologic pathways including those related to the regulation of intestinal inflammation. We sought to determine whether PPAR gamma could function as an endogenous anti-inflammatory pathway in a murine model of intestinal ischemia-reperfusion (I/R) injury. METHODS: PPAR gamma-deficient and wild-type mice were examined for their response to I/R procedure. Treatment with a PPAR gamma-specific ligand was also performed. RESULTS: In a murine model of intestinal I/R injury, we observed more severe injury in PPAR gamma-deficient mice and protection against local and remote tissue injury in mice treated with a PPAR gamma-activating ligand, BRL-49653. Activation of PPAR gamma resulted in down-regulation of intercellular adhesion molecule 1 expression by intestinal endothelium and tissue tumor necrosis factor alpha messenger RNA levels most likely by inhibition of the NF-kappa B pathway. CONCLUSIONS: These data strongly suggest that an endogenous PPAR gamma pathway exists in tissues that may be amenable to therapeutic manipulation in I/R-related injuries.

Animals↗
PubMed2001

The multiple roles of major histocompatibility complex class-I-like molecules in mucosal immune function.

The human major histocompatibility complex (MHC) on chromosome 6 encodes three classical class-I genes: human leukocyte antigens (HLA) A, B, and C. These polymorphic genes encode a 43- to 45-kDa cell surface glycoprotein that, in association with the 12-kDa beta2-microglobulin molecule, functions in the presentation of nine amino acid peptides to the T-cell receptor of CD8-bearing T lymphocytes and killer inhibitory receptors on natural killer cells. In addition to these ubiquitously expressed, polymorphic proteins, the human genome also encodes several nonclassical MHC class-I-like, or class Ib, genes that, in general, encode nonpolymorphic molecules involved in various specific immunological functions. Many of these genes, including CD1, the neonatal Fc receptor for IgG, HLA-G, HLA-E, the MHC class-I chain-related gene A, and Hfe, are prominently displayed on epithelial cells, suggesting an important role in epithelial cell biology.

CD8 Antigens↗
PubMed2001

The expression of IL-12 p40 and its homologue, Epstein-Barr virus-induced gene 3, in inflammatory bowel disease.

BACKGROUND: It has recently been suggested that Crohn's Disease (CD) is associated with an exaggerated T helper 1 cytokine response as manifest by increased production of interleukin-12 (IL-12) and interferon-gamma (IFN-gamma). Epstein-Barr virus-induced gene 3 (EBI3) encodes a 34-kDa glycoprotein that is 27% identical to the p40 unit of IL-12 and has recently been reported to be up-regulated in ulcerative colitis (UC). AIM: To determine whether mucosal expression of IL-12 p40 or EBI3 correlates with inflammatory bowel disease (IBD). PATIENTS/METHODS: mRNA expression in colonic mucosa from patients with UC, Crohn's disease (CD) and non-IBD controls was measured by reverse-transcribed real-time polymerase chain reaction (PCR). RESULTS: EBI3 was significantly increased in both involved and uninvolved colonic mucosa in patients with UC. Although IL-12 p40 was increased in some patients with CD relative to non-IBD controls, the increase was not statistically significant. However, 5-aminosalicylic acid (5-ASA) use was significantly correlated with reduced IL-12 p40 levels in the patients with CD, but not in UC cases. A similar reduction was not seen in 5-ASA-treated UC patients. CONCLUSION: IL-12 p40 expression in CD is heterogeneous. In contrast, expression of the IL-12 p40 homologue, EBI3, is up-regulated in nearly all UC cases and in a subset of CD.

Adult↗
PubMed2001

Characterization of CD1d in mucosal immune function: an immunotherapeutic target for inflammatory bowel disease.

In addition to the classical MHC class I and class II molecules, human intestinal epithelial cells also express nonclassical MHC class I-like molecules on their cell surface. CD1d is a non-polymorphic MHC-like molecule whose expression is mainly localized to the epithelial cells of the gastrointestinal tract. The biochemical structure of CD1d on intestinal epithelial cells (IECs) exists in two forms: a 37-kD nonglycosylated, beta 2-microglobulin (beta 2M) independent and a 48-kD glycosylated, beta 2M dependent form. Immunolocalization studies suggest that the 37-kD nonglycosylated form of CD1d is limited to the apical cell surface whereas the 48-50-kD glycosylated, beta 2M dependent form of CD1d is expressed both on the apical and the basolateral surfaces. The beta 2M association with CD1d seems to be important in regulating the pattern of glycosylation and the localization of CD1d within the cell based upon studies of the structure of CD1d in a transfected model cell line and in polarized epithelial cell monolayers. The functional role of intestinal CD1d remains unknown. However, based upon in vitro studies of the antigens presented by human CD1d and mouse CD1d, CD1d expressed on IECs likely presents a very hydrophobic glycolipid molecule possibly from the cell wall of bacteria or host cells. The processed-lipid antigen presented by CD1d may then involve a yet-to-be-identified subpopulation of the resident, oligoclonal alpha beta TCR CD8+ intestinal intraepithelial lymphocyte (iIEL) T cells. Subsequently, these T cells would be very important in regulating the local immune response by producing cytokines and recruiting other immune modulating cells to destroy infected cells, regenerate normal IECs, and possibly downregulate activated T cells to maintain mucosal integrity.

Animals↗
PubMed2000

Fractalkine is an epithelial and endothelial cell-derived chemoattractant for intraepithelial lymphocytes in the small intestinal mucosa.

Fractalkine is a unique chemokine that combines properties of both chemoattractants and adhesion molecules. Fractalkine mRNA expression has been observed in the intestine. However, the role of fractalkine in the healthy intestine and during inflammatory mucosal responses is not known. Studies were undertaken to determine the expression and function of fractalkine and the fractalkine receptor CX3CR1 in the human small intestinal mucosa. We identified intestinal epithelial cells as a novel source of fractalkine. The basal expression of fractalkine mRNA and protein in the intestinal epithelial cell line T-84 was under the control of the inflammatory mediator IL-1beta. Fractalkine was shed from intestinal epithelial cell surface upon stimulation with IL-1beta. Fractalkine localized with caveolin-1 in detergent-insoluble glycolipid-enriched membrane microdomains in T-84 cells. Cellular distribution of fractalkine was regulated during polarization of T-84 cells. A subpopulation of isolated human intestinal intraepithelial lymphocytes expressed the fractalkine receptor CX3CR1 and migrated specifically along fractalkine gradients after activation with IL-2. Immunohistochemistry demonstrated fractalkine expression in intestinal epithelial cells and endothelial cells in normal small intestine and in active Crohn's disease mucosa. Furthermore, fractalkine mRNA expression was significantly up-regulated in the intestine during active Crohn's disease. This study demonstrates that fractalkine-CX3CR1-mediated mechanism may direct lymphocyte chemoattraction and adhesion within the healthy and diseased human small intestinal mucosa.

CX3C Chemokine Receptor 1↗
PubMed2000

Human CD1d associates with prolyl-4-hydroxylase during its biosynthesis.

Recent studies have shown that the CD1 family of proteins present various glycolipid antigens to subsets of T cells. CD1d is expressed on human intestinal epithelial cells (IEC) and exists in two biochemical forms: 37-kDa, beta2-microglobulin (beta2m) independent, nonglycosylated, and 47-kDa, beta2m dependent, glycosylated forms. The biosynthetic pathways and the mechanisms of generation of these two biochemically distinct forms of CD1d in human IEC are unknown. Using a human colonic cell line, T84, transfected with CD1d, the biosynthesis of CD1d was investigated. Pulse-chase metabolic labeling studies of T84 transfected with wild type CD1d demonstrated that CD1d was a stable protein over a 4-day chase period. During the first 24 h of the chase, a novel 65-kDa glycoprotein was co-immunoprecipitated with CD1d. Microsequencing of this protein identified the glycoprotein as the alpha and beta subunits of the resident endoplasmic reticulum protein, prolyl-4-hydroxylase (P4H), an enzyme responsible for hydroxyl modification of proline residues. To study if either one or both biochemical forms of CD1d contained hydroxyproline residues, amino acid composition analysis of the 37 and 48 kDa was performed, and demonstrated that only the 37-kDa, but not the 48-kDa form of CD1d, contained hydroxyproline residues. These studies demonstrate that CD1d exhibits a prolonged association with P4H and that the 37-kDa form contains hydroxyproline residues. This suggests that P4H association with CD1d during its biosynthesis results in a novel post-translational modification of CD1d.

Antigens, CD1↗
PubMed2000

CD1d structure and regulation on human thymocytes, peripheral blood T cells, B cells and monocytes.

Human T cells expressing CD161 and an invariant T-cell receptor (TCR) alpha-chain (Valpha24invt T cells) specifically recognize CD1d and appear to have immunoregulatory functions. However, the physiological target cells for this T-cell population, and whether alterations in CD1d expression contribute to the regulation of Valpha24invt T-cell responses, remain to be determined. A series of antibodies were generated to assess CD1d expression, structure and regulation on human lymphoid and myeloid cells. CD1d was expressed at high levels by human cortical thymocytes and immunoprecipitation analyses showed it to be a 48 000-MW glycosylated protein. However, after solubilization, the majority of the thymocyte CD1d protein, but not CD1d expressed by transfected cells, lost reactivity with monoclonal antibodies (mAbs) against native CD1d, indicating that it was alternatively processed. Moreover, thymocytes were not recognized by CD1d-reactive Valpha24invt T-cell clones. Medullary thymocytes and resting peripheral blood T cells were CD1d-, but low-level CD1d expression was induced on activated T cells. CD1d was expressed by B cells in peripheral blood and lymph node mantle zones, but germinal centres were CD1d-. Resting monocytes were CD1d+ but, in contrast to CD1a, b and c, their surface expression of CD1d was not up-regulated by granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4) activation. These results demonstrate constitutive CD1d expression by human professional antigen-presenting cells and that post-translational processing of CD1d may contribute to regulation of the activity of CD1d-specific T cells.

Antibody Specificity↗
PubMed2000

Staphylococcal enterotoxin B induces potent cytotoxic activity by intraepithelial lymphocytes.

In food poisoning, Staphylococcus aureus secretes staphylococcal enterotoxin B (SEB), a superantigen that causes intense T-cell proliferation and cytotoxicity. The effects of SEB on lytic activity by human intestinal intraepithelial lymphocytes (IEL) were investigated. Jejunal IEL, from morbidly obese individuals undergoing gastric bypass operations, were tested for SEB-induced cytotoxicity against C1R B-lymphoblastoid cells, HT-29 adenocarcinoma cells, or CD1d-transfected cells using the 51Cr-release assay. Fas and Fas ligand expression were detected by immunofluorescence and flow cytometry and soluble ligand by enzyme-linked immunosorbent assay (ELISA). In the presence of SEB, IEL became potently cytotoxic against C1R cells and interferon-gamma (IFN-gamma)-precultured HT-29 cells, causing 55+/-10% and 31+/-6% lysis, respectively, greater than that by phytohaemagglutinin (PHA)-, interleukin-2 (IL-2)-, or anti-T-cell receptor (TCR)-activated IEL. SEB-stimulated peripheral blood (PB) CD8+ T cells lysed similar numbers of C1R cells but fewer HT-29 cells (53+/-13% and 8+/-5%, respectively). IEL killing of C1R cells involved interaction of major histocompatibility complex (MHC) class II with TCR, CD2 with CD58, and CD11a with CD54, and was perforin mediated. SEB-induced IEL lysis of HT-29 cells, in contrast, was caused by an unknown target cell structure, not MHC class II or CD1d, and resulted from a combination of perforin and Fas-mediated events. The potent cytotoxic activities of IEL promoted by SEB utilize two different mechanisms, depending on the surface receptors expressed by the target cells.

Antigens, CD1↗
PubMed2000

Limited CD4 T-cell diversity associated with colitis in T-cell receptor alpha mutant mice requires a T helper 2 environment.

BACKGROUND & AIMS: T-cell receptor alpha mutant (TCRalpha(-/-)) mice spontaneously develop chronic colitis mediated by CD4(+) TCRalpha(-)beta(+) T cells. The aim of this study was to analyze the mechanisms of expansion of these cells by characterization of the TCRbeta repertoire. METHODS: TCRbeta repertoire was analyzed by reverse-transcription polymerase chain reaction/Southern blot and DNA sequencing. Clonality of T cells was examined in the lymphoid tissues and colons of TCRalpha(-/-) mice and interleukin 4-deficient TCRalpha(-/-) mice. In addition, an in vitro culture system using syngeneic colonic epithelial cells as antigens was used. RESULTS: The clonal expansion of a restricted subset of Vbeta8.2(+) T cells was characterized by conservation of a single negatively charged amino acid residue in the second position of the complementarity-determining region 3 (CDR3). These T cells were observed in the diseased colon and appendix (cecal patch) of TCRalpha(-/-) mice, but not germfree TCRalpha(-/-) mice. Culture of polyclonal T cells from young TCRalpha(-/-) mice with colonic epithelial cells under T helper 2 conditions resulted in the survival of Vbeta8.2(+) T cells characterized by the same CDR3 pattern. In addition, the transfer of the cultivated T cells induced mild colitis in recombination-activating gene 1 mutant mice. CONCLUSIONS: In the TCRalpha(-/-) mice, the development of colitis is associated with the presence of a restricted diversity of Vbeta8. 2(+) T-cell subsets characterized by a specific TCR motif. The limited diversity of lamina propria T cells that are derived from naive T cells expanded by reacting with luminal bacterial antigens is likely caused by the survival of these T cells after stimulation with self-antigens in the presence of a T helper 2 environment.

Amino Acid Sequence↗