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Biomedical subjects

W Born

Publications and source records attributed to W Born.

At least 19 recordsLinked to original sources
PubMed1995

Bacterial infection of the testis leading to autoaggressive immunity triggers apparently opposed responses of alpha beta and gamma delta T cells.

The mechanisms that lead to the breakdown of self-tolerance and testis-specific immune reactivity in the murine orchitis model are understood only in part. We investigated the histopathologic and immunologic consequences of a unilateral bacterial (Listeria monocytogenes) infection of the testis. Both infected and contralateral sides of this bilateral organ suffered severe inflammatory responses despite a conspicuous absence of bacteria in the contralateral tissue. Also, in both testicles, T cell populations increased, involving both alpha beta and gamma delta T cell subsets. Concomitant with the bilateral orchitis, testis-specific delayed type hypersensitivity and Ab responses developed. Ab depletion experiments indicated that in this orchitis model, as in others, alpha beta T cells are initiators of the autoaggressive reactivity. In contrast, Ab depletion of gamma delta T cells accelerated the inflammatory response in both testicles, suggesting a regulatory role for this type of T cells in both infection-induced and autoimmune orchitis.

Animals↗
PubMed1995

A human orphan calcitonin receptor-like structure.

A novel calcitonin receptor-like protein of 461 amino acids with seven putative transmembrane domains has been identified through molecular cloning in a cDNA library of the human cerebellum. 91% and 56% of the amino acids are identical in a rat orphan calcitonin receptor-like sequence and the human calcitonin receptor, respectively. 5.2 kb mRNA is predominantly expressed in the lung, heart and kidney. Specific binding of 125I-labeled salmon calcitonin and human calcitonin gene-related peptide-I to COS-7 cells transiently transfected with the receptor cDNA was less then 0.5%. Cellular cAMP accumulation was indistinguishable in cDNA transfected and non-transfected control COS-7 and renal tubular cells from the American opossum stimulated with human and salmon calcitonin, human calcitonin gene-related peptide-I and -II, human amylin, human adrenomedullin, lizard helodermin, salmon stanniocalcin and chicken parathyroid hormone-related protein. The receptor-like protein whose ligand remains to be discovered belongs to the family of receptors of calcitonin, parathyroid hormone, secretin, vasointestinal peptide and pituitary adenylate cyclase-activating polypeptide.

Amino Acid Sequence↗
PubMed1995

Calcitonin, calcitonin gene-related peptide, adrenomedullin and amylin: homologous peptides, separate receptors and overlapping biological actions.

Calcitonin, calcitonin gene-related peptide, adrenomedullin and amylin are structurally related peptides with N-terminal 6-7 amino acid ring structures linked by a disulfide bridge and with amidated C-termini. Among the related bioactive peptides, the structures of the calcitonin receptor and subtypes thereof have been identified so far through molecular cloning. Cross-reaction between receptors of calcitonin, calcitonin gene-related peptide, adrenomedullin and amylin, as well as overlapping biological actions, anticipate that the respective receptors belong to a family of G-protein-coupled receptors that include those of parathyroid hormone, secretin and vasointestinal peptide.

Adrenomedullin↗
PubMed1994

Functional expression of a stably transfected parathyroid hormone/parathyroid hormone related protein receptor complementary DNA in CHO cells.

Chinese hamster ovary (CHO) cells were stably transfected with OK-O complementary DNA encoding the parathyroid hormone/parathyroid hormone related protein (PTH/PTHrP) receptor derived from opossum kidney (OK) cells (Jüppner et al., 1991). A subclone of transfected CHO cells, CHO-E2, presented high affinity binding of 125I-labeled [Tyr36]chickenPTHrP(1-36)amide ([125I]chPTHrP(1-36)) (Kd 1.28 +/- 0.10 nM) similar to that of wildtype OK cells (Kd 2.23 +/- 0.16 nM) (P < 0.01). Photoaffinity labeling of the PTH/PTHrP receptors using N-hydroxysuccinimidyl-4-azidobenzoate modified [125I]chPTHrP(1-36) revealed the same specifically labeled 90 kDa protein in CHO-E2 and OK cells. In CHO-cells, chPTHrP(1-36) stimulated cyclic AMP accumulation in dose-dependent fashion (EC50 0.15 +/- 0.04 nM) and raised peak cytosolic free calcium concentration (EC50 2.90 +/- 0.36 nM) independent of extracellular calcium, and stimulated phosphate uptake (EC50 0.21 +/- 0.07 nM). Both, chPTHrP(1-36) and 12-O-tetradecanoylphorbol-13-acetate stimulated phosphate uptake were suppressed by staurosporine. But, Sp-cyclic adenosine-3',5'-monophosphothioate did not affect phosphate uptake in CHO-E2 cells. In conclusion, a PTH/PTHrP receptor stably expressed in CHO cells is linked to stimulation of phosphate uptake. Receptor coupling presumably occurred through the protein kinase C rather than the protein kinase A pathway.

Alkaloids↗
PubMed1993

Molecular chaperones and the immune response.

Molecular chaperones belonging to heat shock protein families have been identified as prominent antigens in the immune response to a wide variety of infections. Recognition of such highly conserved antigens may contribute to protective immunity but, in some circumstances, may also have pathological autoimmune consequences. Recognition of chaperones may be an inherent feature of the immune system. Peptide mapping experiments revealed an overlap between hsp 70-binding sites and immunodominant regions of three protein antigens, consistent with a possible functional activity for molecular chaperones in the processing and presentation of peptides during class II-restricted T lymphocyte responses. A functional role for molecular chaperones in antigen processing may be a factor which contributes to their immunogenicity.

Animals↗
PubMed1992

Comparison of a calcitonin gene-related peptide receptor in a human neuroblastoma cell line (SK-N-MC) and a calcitonin receptor in a human breast carcinoma cell line (T47D).

A specific CGRP-binding protein of M(r) 60,000 has been identified in the human neuroblastoma cell line SK-N-MC. After N-deglycosylation a M(r) of 48,000 was found. The M(r) were indistinguishable from those determined in the human cerebellum. Receptor binding of CGRP is coupled to cyclic AMP formation. The latter is antagonized by hCGRP-I8-37. CT and DAPamide interact only minimally with the CGRP receptor, whereas CGRP and DAPamide are full agonists in T47D cells. The CT receptor on human breast cancer cell line T47D is clearly different from the human CGRP receptor.

Amino Acid Sequence↗
PubMed1992

Heat shock protein Hsp60-reactive gamma delta cells: a large, diversified T-lymphocyte subset with highly focused specificity.

Previously, we detected a subset of gamma delta T cells in the newborn mouse thymus that responded to the mycobacterial heat shock protein Hsp60, as well as with what seemed to be a self-antigen. All of these cells expressed V gamma 1, most often in association with V delta 6+. It was not clear, however, whether similar, mature gamma delta cells with Hsp60 reactivity are common outside of the thymus, or rather, whether they are largely eliminated during development. From the data presented here, we estimate that gamma delta cells responding to Hsp60 comprise 10-20% of normal splenic and lymph node gamma delta T cells. Such cells, derived from adult spleen, always express a V gamma 1-J gamma 4-C gamma 4 gamma chain, although not all cells with this gamma chain show Hsp60 reactivity. Many of these V gamma 1+ cells also express V delta 6-J delta 1-C delta, though fewer than in V gamma 1+ cells from the newborn thymus. Extensive diversity is evident in both the gamma and delta chain junctional amino acids of the receptors of these cells, indicating that they may largely develop in the thymus of older animals or undergo peripheral expansion. Finally, we found that all such cells responding to both a putative self-antigen and to mycobacterial Hsp60 respond to a 17-amino acid synthetic peptide representing amino acids 180-196 of the Mycobacterium leprae Hsp60 sequence. This report demonstrates that a large subset of Hsp60-reactive peripheral lymphoid gamma delta T cells preexists in normal adult mice, all members of which respond to a single segment of this common heat shock protein.

Animals↗
PubMed1992

Intracolonic bioavailability of human calcitonin in man.

Human calcitonin (hCT) injected into the lumen of the descending colon of normal human subjects was absorbed within minutes and could be recognized intact in plasma as shown by RIA in combination with reverse-phase HPLC. The absorption was low and variable, with bioavailabilities ranging from 0.01% to 2.7% relative to intravenously administered hCT (area under the concentration-time curve). With intravenous hCT serum calcium was lowered and the fractional urinary excretion of calcium, phosphorus, sodium and chloride was significantly stimulated. With the intracolonic hCT, the fractional urinary excretions of calcium, sodium and chloride were also marginally stimulated relative to intracolonic vehicle (placebo). In conclusion, hCT is absorbed intact from the colon, but the bioavailability is low and highly variable.

Adult↗
PubMed1991

Characterization and photoaffinity labeling of a calcitonin gene-related peptide receptor solubilized from human cerebellum.

Calcitonin gene-related peptide (CGRP) receptors were solubilized from human (h) cerebellum with use of the zwitterionic detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid (CHAPS). Scatchard analysis of equilibrium binding data indicated that the soluble extract contained a single class of CGRP binding sites with apparent dissociation constants of 50 pM for the intact 125I-hCGRP-I(1-37) and 160 pM for the antagonist 125I-hCGRP-I(8-37). Unlabeled hCGRP-I and -II and hCGRP-I(8-37) displaced 125I-hCGRP-I from solubilized CGRP receptors with similar potencies (ID50 = 70-150 pM). Human CGRP-I(15-37), -(21-37), and -(28-37) were less potent (ID50 greater than or equal to 70 nM), suggesting that amino acid residues 8-14 may be important for maintaining high binding affinity. A novel photoreactive analogue of hCGRP-I, 125I-[C gamma-(4-azidoanilino)Asp3] hCGRP-I, was prepared by carbodiimide coupling of 4-azidoaniline to 125I-hCGRP-I. Photoaffinity labeling of soluble CGRP receptors with the photoreactive analogue and analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography revealed three specifically labeled binding proteins with apparent molecular weights (Mr) of 60,000, 54,000, and 17,000. Cross-linking of 125I-hCGRP-I and -II and 125I-hCGRP-I(8-37) to soluble CGRP binding sites using disuccinimidyl suberate revealed three specifically labeled binding proteins with the same Mr. The C-terminal fragment 125I-hCGRP-I(8-37), unlike the intact peptide, was, furthermore, cross-linked specifically to a 95,000 Mr protein. The CGRP receptor is N-glycosylated. Treatment with endoglycosidase F/N-glycosidase F converted the 60,000 and 54,000 to 46,000 and 41,000 Mr components.(ABSTRACT TRUNCATED AT 250 WORDS)

Affinity Labels↗
PubMed1991

Diagnostic relevance of the amino-terminal cleavage peptide of procalcitonin (PAS-57), calcitonin and calcitonin gene-related peptide in medullary thyroid carcinoma patients.

We have identified the amino-terminal cleavage peptide of procalcitonin (PAS-57) in the plasma of normal human subjects and of medullary thyroid carcinoma (MTC) patients together with calcitonin (CT) and CT gene-related peptide (CGRP). Major components on reversed-phase high-pressure liquid chromatography had the retention times of synthetic PAS-57, CT and CGRP as well as of precursor proteins. Plasma levels of PAS-57 (290 +/- 50 pgeq/ml; mean +/- S.E.M.), CT (27 +/- 8 pgeq/ml) and CGRP (8.4 +/- 0.8 pgeq/ml) were respectively 2.3-, 1.6- and 1.5-fold higher in normal men (n = 10) than in women (n = 8). In response to 1 min intravenous calcium infusions (2 mg per kilogram body weight) PAS-57 and CT were increased 3.5- and 2.7-fold (P less than 0.001), respectively, but CGRP remained unchanged. In MTC patients (n = 57) with raised levels of PAS-57 and CT, the molar ratio between PAS-57 and CT was 1.7-times higher than in normal subjects (P less than 0.01). We have found that PAS-57 is a predominant CT/CGRP gene derived product in the circulation of normal subjects and of MTC patients and a potential new MTC tumor marker.

Adult↗
PubMed1991

Alpha beta T-lymphocyte depleted mice, a model for gamma delta T-lymphocyte functional studies.

Adult mice can be depleted of essentially all mature alpha beta T lymphocytes by chronic treatment with the framework-recognizing, pan-specific anti-TCR alpha beta mAb, H57-597. Similar findings have been reported in rats, gamma delta cell populations remain essentially unaltered in size and reactivity. Suppression of alpha beta T-cell development results in the loss of alloantigen reactivity and of B-cell help, suggesting that gamma delta and alpha beta populations differ in their functional capabilities. Indirect effects of the antibody treatment include quantitative changes in splenic B cells, as well as reduced sizes and weights of experimental animals. alpha beta-suppressed mice and rats may provide model systems for studies on gamma delta cell function in vivo.

Animals↗
PubMed1991

Recognition of a single hsp-60 epitope by an entire subset of gamma delta T lymphocytes.

We can conclude that a large subset of gamma delta cells, present in both murine newborn thymus and in adult spleen, respond to the stress protein, hsp60. hsp60 seems to be stimulatory whether it is derived from a foreign pathogen such as mycobacteria, or whether it originates from the mouse's own cells. The gamma delta cells that respond to this antigen bear very similar receptors, all expressing V gamma 1 and most expressing V delta 6, although their junctional variations indicate that not all members of the subset stem from clonal expansion of only one or a few cells. The hsp60-reactive subset has not at this time been shown to "home" to an epithelial location, in contrast to other known gamma delta cell subsets, and may rather carry out its functions while in circulation. Whether the hsp60 antigen requires a "presenting" molecule remains at this point unclear, but because the gamma delta cells all respond to a synthetic peptide representing an epitope of hsp60, presentation is implied. Human gamma delta cells that respond to PPD from mycobacteria, as do the mouse hsp60-reactive gamma delta cells, have also been described, many as members of a major subset in peripheral blood, although only rarely have these been reported to respond to mycobacterial hsp60. The antigenic source in PPD for these cells has not yet been determined, but as for the mouse, a low molecular weight peptide appears to be sufficient for stimulation (P. Brennan and R. Modlin, personal communication). The PPD-reactive gamma delta cells, when their receptors have been characterized, have been found to express a V gamma 9+ chain. Some evidence indicates that these cells can also recognize self hsp60; hence, in several ways, this human subset has characteristics similar to the mouse hsp60-reactive subset. Perhaps gamma delta cells that respond to hsp60 play an important role, in both mice and humans, in the detection of transformed self cells or cells containing intracellular pathogens, that escape detection by alpha beta T cells.

Amino Acid Sequence↗
PubMed1991

Possible links between immune system and stress response: the role of gamma delta T lymphocytes.

Heterologous heat shock proteins (hsps) are antigens in many infectious diseases involving bacteria, parasites and perhaps even fungi. T and B lymphocytes recognize multiple epitopes on these proteins. Recently, lymphocytes expressing gamma delta T cell receptors (gamma delta cells) were also found to react with hsps that are members of the 60 kiloDalton (kDa) family. The response of gamma delta cells to hsp 60 differs from that of alpha beta T cells and B cells in several ways: the frequency of reactive gamma delta clones is high. Many clones recognize the same portion of this protein instead of scattered antigenic epitopes; and most gamma delta cells that react with the mycobacterial hsp-60 homolog are also stimulated by the autologous homolog. Perhaps, such (self) hsp-reactive gamma delta populations function by distinguishing stressed from not stressed states in autologous cells and tissues, rather than by discriminating 'self' and 'non-self'.

Bacterial Proteins↗
PubMed1991

Heat shock proteins as antigens for gamma delta T cells.

Recently, there have been a number of reports that gamma delta T cells are stimulated by heat shock, or stress, proteins. Although some alpha beta T cells are capable of recognizing heat shock proteins, we speculate that most or a group of gamma delta cells generally recognize this type of antigen. Recognition of heat shock proteins would enable gamma delta cells to respond to autologous tissue, and perhaps thus eliminate those cells that exhibit signs of stress, due for example to intracellular infection or transformation.

Animals↗