A CA repeat polymorphism of the IFN-gamma gene is associated with susceptibility to type 1 diabetes

Recent studies have shown that loci outside the HLA region are involved in determining susceptibility to type 1 diabetes. Polymorphisms in the coding and noncoding regions of the genes encoding cytokines may be involved in modulating the immune response to self and nonself antigens. There is increasing evidence that an imbalance and disruption of the Thl and Th2 T cell subsets play a key role in the development of experimental and clinical type 1 diabetes. The aim of this study was to investigate the frequency of a CA dinucleotide repeat polymorphism in the interferon-gamma (IFN-gamma) gene (IFNG) and a C(-590)T polymorphism of the interleukin-4 (IL-4) gene in 236 Caucasoid patients with type 1 diabetes. There was a highly significant increase in the 3/3 IFNG genotype in the patients compared with normal healthy controls (34.3% vs. 13.5%, p<0.0001) as well as a significant increase in allele 3 of the IFNG locus in the patients compared with controls (51.9% vs. 31.7%, p<0.00001). In contrast, no significant differences were found in the frequency of the C(-590)T IL-4 polymorphism between patients and controls. These results suggest that polymorphisms of the IFNG gene may modify the function of this proinflammatory mediator and the response to pancreatic islet beta cells.

A study of cytokine protein secretion, frequencies of cytokine expressing cells and IFN-G gene polymorphisms in normal individuals

BACKGROUND

Cytokines are major regulators of immune responses, and there is evidence that they play a role in allograft rejection. Before embarking on a detailed study of pretransplant cytokine profiles in renal allograft recipients, we wished to investigate variations in cytokine protein secretion, numbers of cytokine expressing T cells, and cytokine gene polymorphisms in normal volunteers.

METHODS

Twenty normal healthy volunteers were studied. Cytokine protein secretion [interleukin- (IL) 2, IL-4, IL-10, and interferon- (IFN) y] and numbers of cytokine expressing CD3+ T cells (IL-2, IL-4, IL-10, and IFN-gamma) were quantified by means of enzyme-linked immunosorbent assay and two-color flow cytometry respectively. IFN-gamma gene polymorphisms were determined by polymerase chain reaction and autoradio graphy.

RESULTS

Large interindividual variations in both the quantity of IL-2, IL-4, IL-10, and IFN-gamma cytokine protein secreted and numbers of IL-2 and IFN-gamma expressing T cells were demonstrated. However, numbers of IL-4 and IL-10 expressing cells were found to be below detectable limits by flow cytometry. In the case of IFN-gamma, a bi-modal distribution was seen for the quantity of protein secreted. In addition, correlations were observed between IL-2 protein and frequency of IL-2 expressing T cells. However, no relationship was found between IFN-gamma protein levels, numbers of IFN-gamma expressing cells and IFN-gamma gene polymorphisms.

CONCLUSIONS

We have demonstrated large differences in both numbers of T helper 1 cytokine expressing cells and the quantity of T helper 1 and T helper 2 cytokine protein secreted between normal individuals. Although the amount of IL-2 protein secreted appeared to be determined by the frequency of IL-2 expressing cells, this was not the case for IFN-gamma.

Transcription of genes involved in bleaching of a coral reef species Acropora downingi (Wallace, 1999) in response to high temperature

Anthropogenic-induced global warming poses a significant threat to coral reef ecosystems worldwide. However, certain species within the Persian Gulf exhibit remarkable resilience to elevated temperatures compared to their counterparts in other reef systems. To understand the thermal tolerance in Persian Gulf corals and their molecular responses to extreme warm temperatures, Acropora downingi specimens collected from Larak Island were subjected to a heat shock of 34 ± 1 °C. We evaluated coral coloration, bleaching, and mRNA expression of biomarkers related to heat shock proteins (HSPs) such as Hsp70 and Hsp90, oxidative stress markers like Catalase and manganese superoxide dismutase (Cat and Mn-Sod), anti-apoptotic factors exemplified by B-cell lymphoma 2 (Bcl-2), and calcification-related genes including galaxin (Gal) after 24 h and 48 h of thermal shock exposure. Exposure of A. downingi to a 48-h heat shock at 34 °C resulted in noticeable fading of coral coloration compared to the control group. Despite this, the corals demonstrated resilience and did not undergo complete bleaching. Our findings also revealed significant increase of Hsp70, Hsp90, Cat, Mn-Sod, Bcl-2, and Gal mRNA expression after 24 h of thermal stress. However, after 48 h, transcripts for Hsp90, Cat, and Gal were observed to be decreased. These results suggest the pivotal roles played by genes involved in HSP signaling pathways, oxidative stress responses, anti-apoptosis processes, and calcification processes in the Persian Gulf coral's adaptation to thermal stress and its resistance to bleaching.