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Biomedical subjects

R Mirakian

Publications and source records attributed to R Mirakian.

At least 19 recordsLinked to original sources
PubMed2006

Insulin allergy in a patient with Type 2 diabetes successfully treated with continuous subcutaneous insulin infusion.

BACKGROUND: Patients with poor control of Type 2 diabetes on maximum oral hypoglycaemic therapy invariably need insulin therapy. Insulin allergy is uncommon, particularly in patients with Type 2 diabetes. Management of the condition can be difficult, and here we report the case of a patient with Type 2 diabetes and insulin allergy successfully managed with a continuous subcutaneous insulin infusion (CSII). CASE REPORT: A 60-year-old man was referred with insulin allergy. He had poorly controlled Type 2 diabetes (glycated haemoglobin 10.4%), on maximum doses of sulphonylurea and metformin, with osmotic symptoms. He was compliant with diet and tablets. His diabetes was complicated by retinopathy, nephropathy, coronary heart disease, obstructive sleep apnoea, obesity, depression and hypertension. He commenced on twice daily mixed insulin and, shortly after, developed pain, itching and erythema at the injection sites. The sites became indurated and tender, and he had constitutional symptoms. The insulin was changed to other preparations, including short- and long-acting analogues, with similar responses. Triple therapy with rosiglitazone was tried, with no improvement in control. Skin-prick testing confirmed allergy to insulin rather than additives. The patient was reluctant to undergo desensitization. He was commenced on an insulin pump in addition to his oral hypoglycaemics, and achieved fair control (glycated haemoglobin 8.3%) on 88 units of lispro per day, with little or no skin or systemic reaction. CONCLUSION: This is the first case report of insulin allergy in Type 2 diabetes being successfully managed by CSII.

Diabetes Mellitus, Type 2↗
PubMed2002

Methods for detecting apoptosis in thyroid diseases.

Over the last few years, the importance of apoptosis in determining the fate of thyrocytes in autoimmune thyroid disease has been the topic of intense investigation. It is now clear that thyrocytes from patients with Hashimoto's thyroiditis are destroyed as a result of an apoptotic process. However, there is no general consensus on whether the intrathyroidal lymphocytes or the thyrocytes themselves are responsible for their death. The use of a wide range of techniques has contributed to the assessment of this process both in situ on thyroid sections and in vitro on thyroid cell preparations. The apoptosis field of research is rapidly evolving and as the pathways to cell death become unravelled, novel methods will emerge. As each technique offers some advantage, it is critical to know the most suitable method for a specific study. Equally, each method also has intrinsic limitations. Thus, to achieve reliable results, it is necessary to use more than one technique per study. In addition, techniques related to the measurement of the expression of pro-apoptotic and anti-apoptotic genes have been contributing to the study of the susceptibility of the cells to apoptosis and/or to their ability to kill themselves or neighbouring cells. In this review we will focus on the most relevant techniques.

Animals↗
PubMed2001

Thyrocyte targets and effectors of autoimmunity: a role for death receptors?

In Hashimoto's thyroiditis, thyrocytes die by apoptosis. Whether this is the result of impaired antiapoptotic gene expression or hyperexpression of proapoptotic signals or other mechanisms is not fully established. Following the suggestion that thyrocytes from Hashimoto's glands die by a fratricidal killing mediated by Fas/Fas ligand, we have investigated whether thyroid cells from different clinical conditions are able to kill Fas-expressing target cells. We have studied whether this effector ability was mediated by Fas/Fas ligand, perforin or other death receptors/ligands, i.e., tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)/tumor necrosis factor-related apoptosis-inducing ligand receptor (TRAIL-R). We have confirmed that thyroid preparations can kill Fas-expressing HUT78 targets through apoptosis. Cell death was only partially dependent on Fas/Fas ligand but it was trypsin-sensitive. Blocking perforin did not affect Fas-expressing target killing while caspase inhibitors had a consistent although limited effect. Thyroid cells were not sensitive to TRAIL/TRAIL-R. We have also found that both thyrocytes and lymphocytes from Graves' disease thyroids were effective at killing autologous and heterologous Fas-expressing targets. Conversely, killing of these targets could be shown only with lymphocytes (but not with thyrocytes) from Hashimoto's glands. In Hashimoto's thyroiditis, thyrocytes were poorly functional while lymphocytes were able to operate as effectors. It is envisaged that thyrocyte death in Hashimoto's would result from autologous thyrocyte killing perpetrated by lymphocytes. Death receptors/ligands would appear to play a role. However, a caspase-independent mechanism may also coexist and contribute to cell death in Hashimoto's thyroiditis.

Antibodies, Blocking↗
PubMed2000

Death of the autoimmune thyrocyte: is it pushed or does it jump?

Programmed cell death or apoptosis is central both in physiology during development and in disease. The mechanism of apoptosis is under the control of antiapoptotic survival genes of the Bcl-2 family and proapoptotic death receptors of the TNF superfamily (Fas, TNFR, TRAILR). Following death signal, the death receptor binds to its own receptor and initiates, through binding of adaptors, a cascade of events mediated by the autoproteolytic activation of specific enzymes called caspases. This enzyme activation is ultimately responsible for the dissembly of basic nuclear and cytoplasmic cell structures leading to cell death. In certain cell systems, antiapoptotic genes of the Bcl-2 family prevent the proapoptotic pathway. One of their roles is to maintain mitochondrial function integrity. In autoimmune destructive thyroiditis high levels of apoptosis have been demonstrated particularly within the destructed follicles near the infiltrated areas in comparison to Graves' disease and non autoimmune glands. In Hashimoto's thyroiditis Fas expression has been found increased on thyrocytes and in vitro can be modulated by proinflammatory cytokines. FasL expression on thyrocytes remains controversial. Thyroid cells from Graves' disease and multinodular glands are known to kill Fas expressing target cells although Hashimoto's thyrocytes are not efficient effector cells. Intrathyroidal lymphocytes from Hashimoto's thyroids maintain functional killer activity. These findings would suggest that intrathyroidal lymphocytes could be responsible for thyrocyte death in vivo. Whether this mechanism is Fas/FasL, TRAIL/TRAILR dependent can not be confirmed as specific blocking reagents were not able to inhibit cell induced death. In Hashimoto's thyroiditis an impairment of Bcl-2 and Bcl-X anitapoptotic genes on thyrocytes has also been detected. Bcl-X expression can be down-regulated in vitro by incubation with cytokines. These findings suggest that thyrocyte death may not exclusively be the result of specific interactions between death receptor and their ligands but it may involve simultaneous impairment of protective genes of the Bcl-2 family. Whether the impairment of the Bcl-2 family is a direct consequence of environmental stimuli or is the result of an intrinsic thyrocyte (mitochondrial?) alteration is as yet not known.

Animals↗
PubMed2000

Transcriptional regulation of the MHC II gene DRA in untransformed human thyrocytes.

MHC class II molecules are heterodimeric, polymorphic transmembrane glycoproteins physiologically expressed on cells of the immune system and pathologically expressed on the affected target cells of autoimmunity. Their function is to present processed peptides to antigen-specific CD4(+) T cells. To understand the molecular mechanism of the regulation of class II genes in autoimmune target cell thyrocytes, we investigated the transcriptional regulation of DRA on untransformed, differentiated human thyroid cells following IFN-gamma stimulation, which is potentially relevant to the inappropriate class II expression found in Graves' disease. Data from this study show that IFN-gamma enhances a promoter Y box binding protein and induces an X box binding protein in untransformed thyrocytes, but not in SV-40-transfected thyrocytes. Initial characterization of the proteins has indicated that the Y box binding protein is approximately 132 kDa in size while the X box binding protein binds to the X2 region and is approximately 116 kDa. The X box binding protein may correspond to poly(ADP-ribose) polymerase, a recently described component of the X2 box binding protein, X2BP. In addition, the signal transducer and activator of transcription 1alpha protein (STAT1alpha) is also induced by IFN-gamma in these cells. These results further suggest that there are differences in class II gene regulation between differentiated cells and transformed cell lines.

Base Sequence↗
PubMed1999

The effect of staphylococcal enterotoxin B on thyrocyte HLA molecule expression.

Microbial superantigens have been implicated in the pathogenesis of human autoimmune diseases. In autoimmune glands, thyrocytes inappropriately express HLA-DR molecules and these cells may function as antigen presenting cells (APC) We studied the effect in vitro of staphylococcal enterotoxin B (SEB) on HLA molecule expression on thyrocytes obtained from autoimmune and non-autoimmune glands by immunofluorescence. HLA class I and class II upregulation could be detected by FACS analysis on thyrocytes. Anti-IFN-gamma neutralizing antibodies markedly affect both class I and class II upregulation on thyrocytes. FRTL5 cells were not responsive to SEB. Similarly, a human thyroid cell strain maintained in culture in a conditioned medium was not induced to express HLA products by SEB stimulation. The addition of autologous intrathyroidal lymphocytes caused reestablishment of the SEB effect.

Cells, Cultured↗
PubMed1999

HLA-DMB expression by thyrocytes: indication of the antigen-processing and possible presenting capability of thyroid cells.

Expression of HLA class II molecules on thyrocytes is a characteristic feature of autoimmune thyroid disease and may lead the thyroid cells to present autoantigens to CD4+ T lymphocytes. Since HLA-DM is a critical molecule in class II-restricted antigen processing and presentation, we assessed the expression of HLA-DMB, -invariant chain (Ii), class II transactivator (CIITA) and DRA in an untransformed, pure thyrocyte strain HTV-59A. Here we report that both HLA-DMB mRNA and the protein are expressed in thyrocytes and that CIITA expression is enhanced by interferon-gamma (IFN-gamma) treatment and occurs before DMB, Ii and DRA up-regulation, suggesting CIITA expression is a requirement for antigen processing in thyrocytes. These results indicate that thyrocytes are capable of antigen processing and possibly antigen presentation to T cells.

Antigen Presentation↗
PubMed1998

IL-10 expression in thyroid glands: protective or harmful role against thyroid autoimmunity?

IL-10 is a cytokine which not only suppresses cellular immunity but also stimulates the humoral response. In certain animal models of autoimmunity, IL-10 exerts a protective effect against autodestruction. This study was to ascertain whether there could be a role for IL-10 in human autoimmune thyroid disease. Total RNA was extracted from snap-frozen thyroid blocks from surgical specimens. Five 'normal', five multinodular, six Graves and two Hashimoto thyroids (one euthyroid and one hypothyroid) were studied. Approximately 7 microg of total RNA from each gland were reverse transcribed with oligo-dT primers. Pre-plateau semiquantitative polymerase chain reaction (PCR) was performed with specific IL-10 primers. PCR products were run on a 1-5% agarose gel, blotted onto a N-hybond nylon membrane, hybridized with a specific internal probe labelled with gamma-32P-ATP and autoradiographed. Statistical analysis of densitometric values showed significantly higher IL-10 levels in the autoimmune than in the non-autoimmune glands. In situ hybridization and immunohistochemistry showed that the IL-10 message was located within the infiltrating lymphomononuclear cells. Histological analysis revealed that the autoimmune thyroids with the highest IL-10 levels were characterized by relevant degrees of B and T cell infiltration and also exhibited the greatest percentage of spontaneous HLA class II expression on thyrocytes. IL-10 and neutralizing anti-IL-10 antibodies were not able to regulate in vitro spontaneous or interferon-gamma (IFN-gamma)/phytohaemagglutinin (PHA)-induced HLA class II on thyrocytes. We conclude that in active autoimmune thyroiditis, in addition to the well documented production of Th1 cytokines, Th2-related lymphokines can be detected simultaneously. It can be envisaged that in this condition the role of IL-10 might be directed to the stimulation of B cell proliferation and antibody production rather than to the suppression of proinflammatory cytokine release.

Adult↗
PubMed1997

Analysis of apoptosis in relation to tissue destruction associated with Hashimoto's autoimmune thyroiditis.

The level of apoptosis has been investigated in thyroid tissue from eight patients with Graves's disease, one with Hashitoxicosis, three with Hashimoto's thyroiditis, and five patients with multinodular goitre, using flow cytometry and an in situ immunofluorescence technique. Cryostat sections have also been studied for Bcl-2 and APO-1/Fas expression in the thyrocytes and infiltrating lymphocytes, to determine their susceptibility to apoptosis. An increased level of apoptosis was detected in Hashimoto's glands. This was associated with decreased Bcl-2 staining and a patchy APO-1/Fas reactivity on thyrocytes. In addition, APO-1/Fas expression was noted within the germinal centres of lymphoid follicles. It is suggested that the dysregulation of apoptosis-related genes could be an important factor in the progression of destructive thyroid autoimmune disease.

Apoptosis↗
PubMed1996

The immunological features of Peyronie's disease.

PURPOSE: We investigated the immunological features and possible autoimmune basis of Peyronie's disease. MATERIALS AND METHODS: The sera of 100 patients with Peyronie's disease were tested for circulating autoantibodies, including anti-penis antibodies, by indirect immunofluorescence. Antibody deposition and the immunological activity in Peyronie's plaque tissue from patients with early and long-standing disease were also assessed. RESULTS: Circulating anti-penis antibodies were not found in any patient although antinuclear antibodies were present in 24%. Patients with early Peyronie's disease had IgM antibody deposition, marked T lymphocytic and macrocytic infiltration in the sub-tunical space, increased expression of adhesion molecules by endothelial cells and an increased human lymphocyte antigen class 2 expression by the cellular infiltrate, indicating cellular immune activation. CONCLUSIONS: These results show that some of the features of autoimmunity, in particular the cell mediated response, are present in Peyronie's disease.

Autoantibodies↗