Biomedical subjects

M Sadick

Publications and source records attributed to M Sadick.

22 records · Page 2Linked to original sources

PubMed1993

Expression of the cytokine RANTES in human rheumatoid synovial fibroblasts. Differential regulation of RANTES and interleukin-8 genes by inflammatory cytokines.

A chronic inflammatory disease may be characterized by an accumulation of activated leukocytes at the site of inflammation. Since the chemokine RANTES may play an active role in recruiting leukocytes into inflammatory sites, we investigated the ability of cultured human synovial fibroblasts isolated from patients suffering from rheumatoid arthritis to produce this chemokine and compared its regulation to that of the closely related chemokine gene, interleukin-8 (IL-8). In unstimulated synovial fibroblasts, the expression of mRNA for both chemokines was undetectable, but was increased in both a time- and dose-dependent manner upon stimulation with the monokines tumor necrosis factor alpha (TNF alpha) and interleukin-1 beta (IL-1 beta). Preincubation of the cells with cycloheximide "superinduced" the level of IL-8 mRNA stimulated by TNF alpha and IL-1 beta and RANTES mRNA stimulated by IL-1 beta, but decreased the expression of RANTES mRNA in response to TNF alpha. In addition, differential regulation of these genes was noted when synovial fibroblasts were stimulated with a combination of cytokines. IL-4 down-regulated and IFN gamma enhanced the TNF alpha- and IL-1 beta-induced increase in RANTES mRNA, whereas the induction of IL-8 mRNA by TNF alpha or IL-1 beta was inhibited by IFN gamma and augmented by IL-4. Moreover, a combination of TNF alpha and IL-1 beta synergistically induced IL-8 mRNA expression, whereas under the same conditions, the level of expression of RANTES mRNA was less than that induced by TNF alpha alone. These observations were also reflected at the level of chemokine secretion. These studies demonstrate that by expressing the chemokines RANTES and IL-8, synovial fibroblasts may participate in the ongoing inflammatory process in rheumatoid arthritis. In addition, the observation that these chemokine genes are differentially regulated, depending upon the presence of different cytokines, indicates that the type of cellular infiltrate and the progress of the inflammatory disease is likely to depend on the relative levels of stimulatory and inhibitory cytokines.

Arthritis, Rheumatoid↗

PubMed1993

Characterization of the human basophil response to cytokines, growth factors, and histamine releasing factors of the intercrine/chemokine family.

We have tested the histamine releasing properties and priming abilities of a wide range of recombinant or purified cytokines and growth factors on the basophils of 20 subjects (10 atopic and 10 nonatopic). We found that monocyte chemotactic and activating factor/monocyte chemoattractant protein-1 (MCAF/MCP-1), RANTES, human macrophage inflammatory protein-1 alpha and human inflammatory protein-1 beta, Connective tissue activating peptide III and Neutrophil Activating Peptide-2 (NAP-2) cause histamine release from basophils and are all members of the intercrine/chemokine family. MCAF/MCP-1 was as potent as anti-IgE or C5a and it is clearly the major contributor to histamine releasing factor activity. RANTES was the second major histamine releasing factor among the positive cytokines. Both MCAF/MCP-1 and RANTES are present in conditioned mononuclear cell media and can be separated using Mono Q anion exchange chromatography. We also demonstrated that RANTES has unusual chromatographic properties in spite of its isoelectric point of > 9.0 because it is largely found in peak-2 of the Mono Q column rather than peak-1 in which intercrines such as MCAF/MCP-1, IL-8, and connective tissue activating peptide III are found. All other cytokines and growth factors tested were negative, with the exception of IL-3, which caused histamine release in a subpopulation of subjects, and also primed basophils for release by anti-IgE. Other basophil primers for anti-IgE-dependent histamine release were IL-5, mast cell growth factor (c-kit ligand), and insulin-like growth factor II. Using specific neutralizing antibodies we have shown that MCAF/MCP-1, RANTES, and IL-3 contribute significantly to the activity found in mononuclear cell culture supernatants. Granulocyte-macrophage-CSF, IP-10, I-309, IL-7, IL-8, IL-9, IL-10, IL-11, IgE-binding factor, TNF-alpha, TGF-beta 1, fibroblast growth factor, epidermal growth factor, and endothelial cell growth factor were negative for direct histamine release and as primers of basophils. Our results indicate that cytokines belonging to the intercrine/chemokine family are major constituents of the activity known as "histamine releasing factor" found in MNC supernatants.

Animals↗

PubMed1993

Quantitative two-site enzyme-linked immunosorbent assays for inhibin A, activin A and activin B.

We have developed three specific enzyme-linked immunosorbent assay (ELISA) formats which quantitate inhibin A in conditioned media and serum. The assays are sensitive in a range 0.078-5.0 ng/ml and have been characterized in terms of cross-reactivity to inhibin related proteins. The CK:CK assay format recognizes inhibin A, inhibin B and inhibin-related molecules, while the 9A9:CK assay format recognizes inhibin A and inhibin A precursors, but not free alpha-subunit. The 11B5:CK assay appears to recognize only mature 32 kDa inhibin A. Additionally, we have developed separate, specific ELISA formats which quantitate activin A and activin B. The assays have a range of 0.2-50 ng/ml and 0.4-50 ng/ml for activin A and recombinant activin B, respectively. These assays are presently being used to examine the concentration of inhibin A, activin A and activin B in clinical serum samples.

Activins↗

PubMed1992

Tumour necrosis factor alpha restores granulomas and induces parasite egg-laying in schistosome-infected SCID mice.

Schistosomiasis (bilharzia) is a parasitic disease caused by several species of schistosome worms (blood flukes). The key pathogenic event in this disease is the formation of granulomas around schistosome eggs trapped in portal venules of the liver. Granulomas are a distinctive form of chronic inflammation characterized by localized aggregation of activated macrophages around an inciting stimulus. Each granuloma evolves to form a fibrous scar; in schistosomiasis, the result is widespread hepatic fibrosis and portal hypertension. To identify the specific immune signal molecules necessary for granuloma formation, we studied schistosome infections in severe combined immunodeficient (SCID) mice, which have normal macrophages but lack functional B or T lymphocytes. Here we report that the immunoregulatory cytokine tumour necrosis factor alpha is necessary and sufficient to reconstitute granuloma formation in schistosome-infected SCID mice. Moreover, we find that the parasitic worms require tumour necrosis factor alpha for egg-laying and for excretion of eggs from the host. The implication of this latter result is that the parasite has adapted so successfully to its host that it uses a host-derived immunoregulatory protein as a signal for replication and transmission.

Animals↗