PubMed Health⌕ Search

Biomedical subjects

J V Weinstock

Publications and source records attributed to J V Weinstock.

At least 55 records · Page 3Linked to original sources
PubMed1993

IL-2 contributes to the IL-5 response in granulomas from mice infected with Schistosoma mansoni.

Th cells within the granulomas of murine schistosomiasis mansoni produce IL-5, which is essential for granuloma eosinophil growth and development. The mechanisms regulating granuloma IL-5 production are unknown. The granulomas also make IL-2 in small quantities. rIL-2 therapy stimulates eosinophilia and IL-5 synthesis. Therefore, we studied the effect of IL-2 on IL-5 production within the liver granulomas of murine Schistosoma mansoni. Dispersed granuloma cells and intact granulomas cultured in vitro released IL-5. Adding anti-IL-2 or anti-IL-2R to the cultures, to block IL-2 activity, significantly inhibited IL-5 production. However, supplementing the cultures with small quantities of rIL-2 markedly stimulated IL-5 release in a dose-dependent fashion. Blocking anti-IL-4 mAb had no effect. Also, granuloma T cells were isolated by FACS. These highly purified T cells produced IL-5 both in the presence and absence of plate-bound anti-CD3. Once again, the IL-5 production was dependent on IL-2. The requirement of IL-2 for normal IL-5 production was not dependent on an IL-2-induced expansion of the IL-5-producing, T lymphocyte population. Thus, IL-2 mediates T cell interactions within the granuloma that regulate granuloma IL-5 secretion.

Animals↗
PubMed1993

Modulation of T lymphocyte proliferation in mice infected with Schistosoma mansoni: VIP suppresses mitogen- and antigen-induced T cell proliferation possibly by inhibiting IL-2 production.

Mice infected with Schistosoma mansoni mount focal granulomatous responses around each ovum that deposits in the liver and intestinal wall. The granulomas ultimately destroy the ova while absorbing the released toxic, injurious agents. The granulomas contain T cells and other cell types, all of which are under control. For example, T lymphocyte proliferation in situ within the granulomas is probably restrained by various regulatory mechanisms. Granuloma eosinophils make VIP, and granuloma T cells have VIP receptors. Yet, the function of VIP within the granulomatous response is unknown. We studied the effect of VIP on granuloma and splenic T cell proliferation in response to Con A or soluble egg antigens (SEA). [3H]Thymidine incorporation was used to assess the rate of proliferation. VIP decreased Con A- or SEA-induced, T lymphocyte proliferation. Suppression of proliferation was most evident for T cells stimulated submaximally with mitogen or antigen. Since T lymphocyte proliferation in response to antigen or mitogen requires soluble lymphokines, we investigated the capacity of VIP to alter the expression of several lymphokines as a possible mechanism for mediating suppression of T cell proliferation. VIP decreased IL-2 production, but did not effect IL-5 or IFN-gamma release. The effect of VIP on IL-2 production was dependent on the presence of a CD4+ T lymphocyte subset. VIP could no longer modulate lymphocyte proliferation if exogenous rIL-2 was added to the cultures. The addition of neutralizing anti-IL-2 mAb, but not anti-IL-4 mAb, substantially decreased granuloma lymphocyte proliferation in response to antigen or mitogen. This suggested that granuloma T cell proliferation required endogenously produced IL-2. These findings suggest that VIP may help modulate granuloma T cell proliferation through regulation of IL-2 production.

Animals↗
PubMed1993

Lymphokine expression in granulomas of Schistosoma mansoni-infected mice.

Lymphokine mRNA for IL-2, IL-4, IL-5, IL-10, and IFN-gamma was identified in total RNA, extracted from granuloma and spleen cells of Schistosoma mansoni-infected mice. The specific mRNA in these preparations was identified after reverse transcription and polymerase chain reaction amplification. In some experiments, spleen cells were incubated in the presence of soluble egg antigens or mitogen before RNA extraction. Also, the secretion of these lymphokines from cells maintained in vitro was measured by ELISA or bioassay. The spleen cells from either uninfected or infected mice constitutively released no detectable cytokines and expressed only IL-10 mRNA prominently. Mitogen induced spleen cells from either source to express IL-2 and IFN-gamma mRNAs and their corresponding proteins. Also, spleen cells from noninfected mice stimulated with mitogen expressed IL-4 mRNA, but not IL-5 mRNA, and no detectable protein products. Yet, IL-5 was inducible in spleen cells from infected animals. Soluble egg antigens induced spleen cells from infected mice to prominently express a variety of cytokine genes and produced large amounts of cytokine proteins, but spleen cells from uninfected mice did not respond. Unlike the spleen, the granulomas constitutively expressed mRNAs for all the cytokines examined. Yet, there was limited expression of IL-2 mRNA as compared to that of other cytokines. Except for IL-5, unfractionated granuloma cells constitutively released cytokines at low or undetectable levels. Soluble egg antigens or mitogen enhanced the production of all cytokines to different extents. These observations indicate that schistosome granulomas and spleens express both Th1 and Th2 cytokines. The various lymphokines display complex differences in both lymphokine mRNA and product expression. These results suggest that the production of granuloma lymphokines is governed selectively, possibly by a variety of undetermined regulatory pathways.

Animals↗
PubMed1993

Functional and morphological characteristics of neuronal substance P in the canine gastroesophageal junction.

The specific functions of the numerous substance P (SP) nerve fibers present within the gastrointestinal tract are not clearly defined. This study examines both functional aspects and distribution of immunoreactive SP (IR-SP) in the canine gastroesophageal junctional (GEJ) region. Lower esophageal sphincter pressure (LESP), mean arterial pressure (MAP), pulse rate (PR), and respiratory rate (RR) were monitored before and after topical application of 2 ml capsaicin (8-methyl-N-vanillyl-6-nonenamide) to the distal esophageal mucosa of anesthetized dogs. Animals then underwent a capsaicin desensitization protocol over a 12-day period. The responses of monitored variables were compared on Day 1 and Day 12 of repetitive capsaicin application. Immunohistochemistry and radioimmunoassay (RIA) were performed on GEJ segments to study the distribution and content of IR-SP in both control (untreated) and capsaicin-treated dogs. The IR-SP was extracted from tissue for RIA and analysis by reverse-phase high-performance liquid chromatography (HPLC). On Day 1, a 2-ml capsaicin application stimulated increases in LESP (44.3 +/- 7.8 cm H2O; P < 0.05), MAP (48 +/- 8.7 mm Hg; P < 0.05), PR (52.6 +/- 20.5 beats/min; P < 0.05), and RR (26.3 +/- 15.6 breaths/min; P > 0.2). No response was observed on Day 12 of treatment. This was accompanied by a 43.3% decrease of IR-SP content in the mucosa of the distal esophagus of desensitized animals. Capsaicin applied at greater concentrations on Day 12 stimulated a return of responses (P < 0.05). Ganglia, cell bodies, nerve fascicles, and neurites stained positively for IR-SP. IR-SP content was markedly higher in esophageal mucosa than in gastric mucosa (P < 0.05). The authenticity of the IR-SP molecule was confirmed by elution time on HPLC. In conclusion, repetitive capsaicin application induced a state of homologous desensitization which was accompanied by a partial depletion of mucosal SP. The GEJ region contains a high SP content with a broad neural distribution. These findings are consistent with the hypothesis that SP may act as a neurotransmitter for chemonociceptive stimuli in the canine distal esophagus.

Animals↗
PubMed1992

Granuloma T lymphocytes in murine schistosomiasis mansoni have somatostatin receptors and respond to somatostatin with decreased IFN-gamma secretion.

The granulomas of mice infected with Schistosoma mansoni for 8 wk have macrophages that secrete somatostatin 1-14 (SOM). Within the granuloma, SOM has no known function. To uncover the possible significance of SOM produced within this granulomatous inflammation, we sought SOM receptors on distinct cellular components of the granuloma to identify cells targeted for SOM action. [125I]SOM 1-14 bound to dispersed granuloma inflammatory cells specifically and reversibly. Scatchard analysis suggested one receptor type (kDa 4.28 x 10(-9) M). Octreotide, a stable SOM derivative, displaced radioligand (kDa 1.01 x 10(-10) M), but SOM 1-28, substance P, and vasoactive intestinal peptide did not. The SOM receptor localized exclusively to a subset of granuloma CD4+ T lymphocytes. Using IL-5 and IFN-gamma ELISA, it was shown that granuloma T cells can secrete appreciable IL-5 and IFN-gamma when stimulated with Ag or mitogen. Both SOM and octreotide at concentrations as low as 10(-10) M substantially decreased IFN-gamma secretion from Ag or mitogen-stimulated T cells, but at concentrations as high as 10(-6) did not affect IL-5 production. Octreotide administered to animals in vivo decreased the intensity of the granulomatous response. Thus, some granuloma T cells have SOM 1-14 receptors. SOM 1-14, a product of granuloma macrophages, may participate in regulation of the granulomatous response by modulating the secretion of some lymphokines. Octreotide, a clinically useful SOM analog, mimics the action of SOM on the immune system.

Animals↗
PubMed1992

Vasoactive intestinal peptide stimulates T lymphocytes to release IL-5 in murine schistosomiasis mansoni infection.

In murine schistosomiasis, granulomas form around ova deposited in the liver and intestines of infected mice. The granulomas have eosinophils that produce vasoactive intestinal peptide (VIP) and T cells that display VIP receptors. IL-5 is a lymphokine important for the development and maturation of eosinophils. It seemed plausible that VIP, released from eosinophils, may interact with lymphocyte VIP receptors and modulate IL-5 production as part of a feedback regulatory circuit. Thus, we determined whether granuloma T cells make IL-5 and whether VIP modulates IL-5 production. Isolated granuloma cells enriched for T lymphocytes spontaneously released IL-5. Culture of these cells in the presence of VIP increased IL-5 secretion. Spleen cells were also studied. Spleen cells from infected mice did not spontaneously release IL-5 or express IL-5 mRNA and VIP did not stimulate these resting spleen cells to produce this IL. However, these cells did express IL-5 mRNA and secreted IL-5 in response to Con A or soluble egg Ag. VIP could not appreciably modulate IL-5 release when cells were cultured with VIP and the Ag or mitogen. Spleen cells washed free of Con A ceased IL-5 secretion within 24 h. These preactivated splenic T cells resumed vigorous IL-5 secretion in response to either Con A or VIP. Yet only Con A prominently induced IL-5 mRNA expression. VIP was an effective stimulus at concentrations equal to or above the kDa of the VIP receptor on both splenic and granuloma T cells (10(-8) M). It is concluded that, in murine schistosomiasis, VIP invokes IL-5 release from activated T cells that are not undergoing immediate TCR stimulation.

Animals↗
PubMed1992

Murine mucosal T cells have VIP receptors functionally distinct from those on intestinal epithelial cells.

Reports suggest that vasoactive intestinal peptide (VIP) binds to lymphocytes and modulates immune responses. The intestines are richly innervated with VIP-producing nerves. Thus, VIP from nerves or other sources may participate in mucosal immunoregulation. To explore this hypothesis further, murine intestinal mucosal inflammatory cells were scrutinized for functional VIP receptors. An [125I]VIP competitive binding assay characterized VIP receptors. Unfractionated lamina propria inflammatory cells bound [125I]VIP specifically. This binding was abrogated by T cell depletion. The VIP receptor on lamina propria T cells was of a single class with a Kd of 9.08 x 10(-9) M. It bound PHI and other peptide analogs poorly. The intestinal epithelial cell had a high-affinity VIP receptor (Kd 4.17 x 10(-10) M) that bound one VIP analog with moderate affinity. Both VIP and ConA stimulated mucosal inflammatory cells to release interleukin-5 (IL-5). Mucosal inflammatory cells depleted of T cells did not release IL-5 in response to VIP or ConA. It is concluded that: (1) some murine mucosal T lymphocytes have VIP receptors that may be distinct from those displayed on mucosal epithelial cells; (2) VIP affects mucosal T lymphocyte function.

Animals↗
PubMed1991

Tachykinins in the canine gastroesophageal junction.

Lower esophageal sphincter (LES) effects produced by the mammalian tachykinins were evaluated in anesthetized dogs. The distribution and content of substance P (SP) and neurokinin A (NKA) in the region of the canine gastroesophageal junction was also studied. SP and NKA stimulated a linear dose-dependent contraction of the LES after intra-arterial administration. Neurokinin B (NKB) failed to stimulate an increase in LES pressure (LESP). SP was characterized by an immediate but short-lived contraction followed by a period of relaxation. NKA stimulated a potent LES contraction that was slow in onset but long-lasting. On an equimolar basis, both SP and NKA were approximately 100 times more potent LES stimulants than bethanechol or phenylephrine. Pretreatment with atropine (muscarinic blockade) or tetrodotoxin (neural blockade) inhibited the effect produced by SP. NKA appeared to stimulate LES contraction independent of neural or cholinergic mechanisms. Radioimmunoassay revealed a regional variation in tachykinin content in the gastroesophageal junction. Ganglia, cell bodies, nerve fascicles, and neurites stained specifically for both SP and NKA. The variable effects, potencies, and mechanisms of action observed in this study suggest the presence of specific tachykinin receptor subtypes in the gastroesophageal junction. Both SP and NKA were found to have a broad neural distribution in this region. These findings suggest that the tachykinins may play an important role in neuroregulation of LES smooth muscle.

Animals↗
PubMed1991

Substance P but not vasoactive intestinal peptide modulates immunoglobulin secretion in murine schistosomiasis.

Neuropeptides including SP and VIP modulate Ig secretion by in vitro stimulated lymphocyte cultures. It is not known whether these neuropeptides effect the B cell directly, or if they significantly alter humoral immune responses to pathogens. We have previously shown that granulomas derived from schistosome-infected mice contain immunoglobulin secreting B cells (ISC) as well as eosinophils that secrete substance P (SP) and vasoactive intestinal peptide (VIP). It therefore seemed plausible that B cells derived from infected animals might respond to these neuropeptides, and that such responses might effect immunoregulatory signals. In this study, we addressed these issues in the murine Schistosoma mansoni model, at the level of immunoglobulin secretion in single B cells. Spontaneous ISC were observed in both splenic and granuloma cell preparations. The addition of SP resulted in a dose-dependent reduction in the number and size of plaques (a 50% reduction was observed at 10(-9) M). This effect was blocked with SP antagonists. Similar results were observed in T cell-depleted cell cultures. VIP had no effect on ISC number or plaque size. We conclude that SP, but not VIP, decreases spontaneous ISC number and Ig secretion in short-term cultures of spleen and granuloma cells. SP appears to exert its effects at the level of single B cells through a receptor-mediated mechanism and may thus play an immunoregulatory role in schistosomiasis.

Animals↗
PubMed1991

Granulomas in murine schistosomiasis mansoni contain vasoactive intestinal peptide-responsive lymphocytes.

Granulomas develop around schistosome ova in murine Schistosoma mansoni. These granulomas have eosinophils that produce VIP. It is possible that VIP participates in immunoregulation. VIP-mediated effects usually operate through a cAMP-dependent mechanism. To identify VIP-responsive inflammatory cells in murine schistosomiasis, inflammatory cells were exposed to VIP and assessed for adenylate cyclase activation and VIP binding. VIP increased adenylate cyclase activity in splenic lymphocytes from both normal and infected mice. In each case, the half-maximal stimulation was at about 5 x 10(-8) M. [125I]VIP bound to splenic lymphocytes specifically, with a Kd of 10(-8) M. This suggested that maximal adenylate cyclase activation requires full receptor occupancy. The receptor was highly specific for VIP. Hormone analogs, that are VIP receptor antagonists in some tissues, were only weak agonists of the lymphocyte VIP receptor. Granuloma cells also bound VIP and responded with adenylate cyclase activation in a manner similar to that of spleen cells. Both splenic T and B lymphocytes responded to VIP. Deletion experiments, using anti-Thy 1.2, suggested that most of the responsive granuloma cells were T lymphocytes. Thus, VIP alters cAMP metabolism in granuloma T cells through a receptor-coupled mechanism similar to that observed for spleen cells. Binding studies on mouse intestinal epithelial cells suggested that their VIP receptor is functionally and possibly structurally different from the VIP receptor on mouse lymphocytes. Additional experiments suggested that VIP and other neuropeptides are unlikely to alter the granulomatous response through a primary interaction with the granuloma macrophages.

Adenylyl Cyclases↗
PubMed1991

Substance P does not alter interleukin-1 expression by splenic or granuloma macrophages in murine schistosomiasis.

Substance P (SP) is an undecapeptide with neurotransmitter and immunoregulatory properties. In murine schistosomiasis, ova naturally induce liver and intestinal granulomas. These granulomas contain macrophages, and eosinophils that produce SP. A report showed that human blood monocytes isolated by adherence release interleukin-1 (IL-1) in response to SP (Lotz et al. (1989) Science 241, 1218). IL-1 is important for initiation of hypersensitivity granulomas. Therefore, it was determined whether SP modulates granuloma macrophage IL-1 production in murine schistosomiasis. Macrophages were obtained from lung and liver granulomas, and from spleens of infected mice. A thymocyte proliferation assay measured IL-1 activity in culture supernatants. Total RNA, extracted from macrophages, was assayed for IL-1 alpha and beta mRNA by Northern blotting using cDNA probes. In response to lipopolysaccharide (LPS), splenic macrophages and macrophages from young lung granulomas released appreciable IL-1. Macrophages from liver granulomas, that were lesions older than the lung granulomas, were unresponsive to LPS with regard to IL-1 secretion. Yet, granuloma macrophages spontaneously expressed IL-1 alpha and beta mRNA. LPS enhanced IL-1 mRNA expression in both splenic and granuloma macrophages. Exposure of macrophages from all sources to SP did not alter IL-1 secretion or gene expression. Similarly, the responsiveness of macrophages to LPS was not affected by concomitant exposure to SP. It is concluded that, in the murine system, SP does not directly influence splenic or granuloma macrophage IL-1 secretion or gene expression. Also, it appears that macrophage secretion of IL-1 is rapidly down-regulated following granuloma elicitation.

Animals↗
PubMed1991

Isolated hepatic granulomas from mice infected with Schistosoma mansoni contain nerve growth factor.

Nerve growth factor (NGF) is a neurotrophic factor essential for the development and maintenance of specific neuronal cell populations. In addition, NGF has biological effects on inflammatory cells. The aim of this study was to determine whether NGF is present in chronic inflammation, using isolated hepatic granulomas from mice infected with Schistosoma mansoni as the model. The schistosome granuloma is a complex T-cell-mediated immune response to the egg. Intact granulomas were isolated from the livers of infected mice and examined for the presence of NGF. In homogenized granuloma samples, radioimmunoassay and immunoblotting analyses detected an immunoreactive NGF that had the same molecular mass as that of purified murine NGF (13 kDa). Isolated granulomas cultured in vitro released soluble factor(s) with NGF-like neurite-promoting activity in a rat pheochromocytoma (PC12) bioassay. This activity was partially inhibited by a blocking anti-NGF antibody. There were two potential sources of this NGF-like neurite-promoting activity, either the schistosome egg or the host inflammatory response. Since neither isolated eggs nor soluble egg antigen had neurite-promoting activity, the inflammation was the source of this activity. The inability of the anti-NGF antibody to inhibit completely the granuloma-induced neurite outgrowth in the bioassay signifies that NGF is not the only neurotrophic factor present in these granulomas. The presence of NGF within the granulomas may indicate that NGF has a role in the granulomatous response.

Animals↗
PubMed1991

Alterations of the intestinal innervation in mice infected with Schistosoma mansoni.

Schistosomiasis mansoni is a parasitic disease in which granulomas form around schistosome eggs in the liver and intestines. The purpose of this study was to determine the alterations in the intrinsic innervation of the distal ileum and proximal colon resulting from schistosomiasis. Using murine schistosomiasis mansoni, we examined light microscopic preparations stained with osmium-zinc iodide or the dihydronicotinamide adenine dinucleotide: nitro BT oxidoreductase (NADH) method. We also examined specific populations of peptidergic nerves (vasoactive intestinal polypeptide and substance P) using an avidin-biotin complex (ABC) immunohistochemical technique. We found that granulomas focally destroyed the enteric nerves. Occasionally nerves were found within granulomas, particularly at the periphery of the lesions. Nerve cell bodies close to granulomas had altered staining, which included increased staining for vasoactive intestinal polypeptide. The distribution of nerve injury varied between the 2 enteric segments studied. In the distal ileum, the principal injury was to the myenteric plexus; whereas, the submucous and mucosal plexuses were predominantly damaged in the proximal colon. The physiologic significance of this injury to the enteric nerves requires elucidation.

Animals↗
PubMed1990

Detection of vasoactive intestinal peptide and localization of its mRNA within granulomas of murine schistosomiasis.

Schistosomiasis mansoni is a parasitic disease resulting in the deposition of ova predominantly in the liver and intestines. These ova secrete antigens which induce host sensitization and evoke focal granulomas. The granulomas are intricate delayed-hypersensitivity reactions governed by numerous cellular and humoral interactions. They displace or destroy normal tissue. Vasoactive intestinal peptide (VIP) is one of several neuropeptides which exert a broad range of biologic actions that may include modulation of immune responses. In this study, VIP was sought within liver granulomas isolated from Schistosoma mansoni-infected, CBA/J mice. Granuloma extracts contained appreciable amounts of immunoreactive VIP as detected by radioimmunoassay. Immunoreactive VIP was shown, by each of two chromatographic methods, to elute as a single peak coinciding with that of synthetic VIP. In situ hybridization was performed with an oligonucleotide probe complementary to a portion of the nucleotide sequence encoding VIP on preproVIP mRNA (antisense probe). Radiolabeled VIP probe adhered exclusively to granuloma eosinophils and to eosinophils within a peritonitis induced in normal mice by proteose peptone. Hybridization of radiolabeled VIP probe in the presence of unlabeled probe substantially attenuated binding. A sense probe failed to bind. These data suggest that the granulomas contain authentic VIP and that eosinophils express the gene for this molecule.

Animals↗