Biomedical subjects

D Beroukas

Publications and source records attributed to D Beroukas.

14 recordsLinked to original sources

PubMed2007

Characterisation of a dendritic cell subset in synovial tissue which strongly expresses Jak/STAT transcription factors from patients with rheumatoid arthritis.

OBJECTIVES: To characterise the phenotype of the putative dendritic cells strongly expressing Jak3 and STAT4, which have been previously identified in the synovial tissue of patients with active rheumatoid arthritis (RA). METHODS: Synovial biopsy specimens were obtained at arthroscopy from 30 patients with active RA (42 synovial biopsies). Immunohistological analysis was performed using monoclonal antibodies to detect dendritic cell subsets, including activation markers and cytokines relevant to dendritic cell function. Co-localisation of cell surface markers and cytokines was assessed primarily using sequential sections, with results confirmed by dual immunohistochemistry and immunofluorescence with confocal microscopy. RESULTS: The dendritic cells identified in RA synovial tissue that strongly express Jak3 also strongly express STAT4 and STAT 6 and are correlated with the presence of serum rheumatoid factor. These cells are not confined to a single dendritic cell subset, with cells having phenotypes consistent with both myeloid- and plasmacytoid-type dendritic cells. The activation status of these dendritic cells suggests that they are maturing or mature dendritic cells. These dendritic cells produce IL12 as well as interferon alpha and gamma. CONCLUSIONS: The close correlation of these dendritic cells with the presence of serum rheumatoid factor, a prognostic factor for worse disease outcome, and the strong expression by these cells of components of the Jak/STAT transcription factor pathway suggest a potential therapeutic target for the treatment of RA.

Adult↗

PubMed2006

Changes in synovial tissue Jak-STAT expression in rheumatoid arthritis in response to successful DMARD treatment.

BACKGROUND: Modulation of Jak-STAT signalling may provide an effective therapeutic strategy in inflammatory arthritis (IA). OBJECTIVE: To examine the effect of successful disease-modifying antirheumatic drug (DMARD) treatment on the expression of Jak-STAT in a cohort of patients with active rheumatoid arthritis. METHODS: Synovial tissue biopsy specimens from 16 patients with active rheumatoid arthritis, taken before and after initiation of DMARD treatment, were examined for the presence of janus kinase (Jak)3, signal transducer and activator of transcription (STAT)1, STAT4 and STAT6 expression using immunohistochemistry. RESULTS: Successful treatment with DMARDs results in reduction in STAT1 expression in the lining, and STAT1 and STAT6 in the sublining of rheumatoid arthritis synovial tissue. Although the overall expression of STAT4 and Jak3 was not significantly altered by DMARD treatment, there was a significant reduction in the expression of the STAT4 and Jak3 bright cells, thought to be an activated dendritic cell subpopulation. CONCLUSION: Results show that Jak3, STAT1, STAT4 expression and STAT6 sublining expression decrease in response to successful treatment of rheumatoid arthritis with standard DMARDs. Therefore, altering the expression of these pathways may represent an alternative treatment option, either through promoting up-regulation of inhibitory pathways, or suppressing inflammatory paths.

Antirheumatic Agents↗

PubMed2005

Expression of Jak3, STAT1, STAT4, and STAT6 in inflammatory arthritis: unique Jak3 and STAT4 expression in dendritic cells in seropositive rheumatoid arthritis.

BACKGROUND: Modulation of Jak-STAT signalling may provide an effective therapeutic strategy in inflammatory arthritis. OBJECTIVE: To document Jak-STAT expression in a cohort of patients with active rheumatoid arthritis (RA), spondyloarthritis (SpA), and osteoarthritis (OA) and compare these subsets with normal synovial tissue. METHODS: Synovial tissue biopsy specimens from patients with RA, OA, and SpA and histologically normal tissue (n = 10 in each arthritis group) were examined for the presence of Jak3, STAT1, STAT4, and STAT6 expression using immunohistochemistry. Phenotyping was performed using immunohistochemistry and immunofluorescence. Clinical and serological characteristics of patients with RA expressing Jak3-STAT4 were assessed. RESULTS: STAT1, STAT4, and Jak3 protein expression was generally increased in inflammatory arthritis. In contrast, STAT6 expression was relatively heterogeneous. A subpopulation of CD1a positive dendritic cells unique to seropositive patients with RA was detected. These cells showed intense protein expression for Jak3, STAT4, and STAT6. CONCLUSION: CD1a positive dendritic cells intensely express Jak3, STAT4, and STAT6 in seropositive RA tissue and may be an alternative marker for dendritic cells in their early stages of activation as well as providing a tool for identifying RA at the level of the synovium. Jak3 inhibition may be a potential therapeutic target to prevent dendritic cell maturation in RA. STAT1 expression is increased in inflammatory arthritis, suggesting that its pro-apoptotic and anti-inflammatory effects cannot effectively counteract inflammation. STAT6 expression is heterogeneous in synovium, suggesting a possible homoeostatic role in addition to any anti-inflammatory effects.

Adult↗

PubMed2005

Scleroderma in Australian aborigines.

Scleroderma (systemic sclerosis) has not been reported before in Australian Aborigines. We describe in detail a community middle-aged Aboriginal woman whose diffuse scleroderma terminated fatally with a renal crisis. Moreover, we have identified a further five Aboriginal patients on the South Australian Scleroderma Register (two with diffuse, two with limited and one with overlap scleroderma), a number consistent with that expected from the 2001 census data for our state. However, an analysis of all antinuclear antibody (ANA) requests from the Top End of Australia over a 6-year period revealed only two Aborigines with low titre anticentromere antibody (despite frequent occurrence of ANA with other specificities). Neither of these Aborigines had features of scleroderma. In conclusion, scleroderma does occur in indigenous Australians but further studies are needed to confirm the apparent infrequency of centromere-associated limited scleroderma (which is the commonest form of scleroderma in our Caucasian population).

Antibodies, Antinuclear↗

PubMed2001

Subcellular distribution of aquaporin 5 in salivary glands in primary Sjögren's syndrome.

Secretions from salivary and lacrimal glands are reduced in patients with primary Sjögren's syndrome (PSS). Since aquaporin 5 is involved in transport of water and is present in salivary and lacrimal glands, this protein was thought to have a major role in the pathogenesis of PSS. We used indirect immunofluorescence and an immunoperoxidase technique to assess expression and subcellular localisation of aquaporin 5 in patients and controls. Our results suggest that the distribution and density of aquaporin 5 in salivary glands does not differ between patients with PSS and those without. Thus, the role of aquaporin 5 in the pathogenesis of PSS needs to be reassessed and alternative pathogenetic mechanisms investigated.

Animals↗

PubMed2001

Cognate T cell help is sufficient to trigger anti-nuclear autoantibodies in naive mice.

The mechanisms involved in the initiation of anti-nuclear autoantibodies are unknown. In this study, we show that one factor allowing anti-nuclear autoantibodies to develop is the incomplete nature of immune tolerance to many of these proteins. Immune responses in mice toward the ubiquitous nuclear autoantigen La/SS-B are much weaker than responses to the xenoantigen, human La (hLa; 74% identical). However, in transgenic (Tg) mice expressing hLa, the Ab response to this neo-autoantigen was reduced to a level resembling the weak autoimmune response to mouse LA: Partial tolerance to endogenous La autoantigen was restricted to the T compartment because transfer of CD4(+) T cells specific for one or more hLa determinants into mice bearing the hLa transgene was sufficient to elicit production of anti-hLa autoantibodies. Notably, only hLa- specific T cells from non-Tg mice, and not T cells from hLa Tg mice, induced autoantibody production in hLa Tg mice. These findings confirm partial Th tolerance to endogenous La and indicate the existence in normal animals of autoreactive B cells continuously presenting La nuclear AG: Therefore, the B cell compartment is constitutively set to respond to particular nuclear autoantigens, implicating limiting Th responses as a critical checkpoint in the development of anti-nuclear autoantibodies in normal individuals.

Adoptive Transfer↗

PubMed2000

Antibodies to AB blood group antigens mimic anti-salivary duct autoantibodies in patients with limited sicca symptoms.

OBJECTIVE: We evaluated the clinical relevance and pathogenic significance of anti-salivary duct autoantibodies (ASDA) in Sjögren's syndrome (SS) and rheumatoid arthritis (RA) by examining (1) their frequency in healthy controls, patients with sicca symptoms, and patients with various autoimmune and infective disorders; (2) their localization by confocal microscopy; and (3) their tissue distribution and cross reactivity with blood group antigens. METHODS: Indirect immunofluorescence (IF) was performed on commercial cryostat sections of monkey parotid salivary gland. Sections were examined by fluorescence and confocal laser scanning microscopy. Sera giving positive staining on the ducts were tested by IF on a range of monkey tissues and salivary glands from several mammalian species. Blocking experiments were performed with human erythrocytes of different ABO blood groups and AB antigens. RESULTS: We identified 2 distinct ductal staining patterns. The first resembled ASDA described in earlier studies and showed patchy bright staining of the apical (luminal) surfaces of the ducts and staining of apical cytoplasmic vesicles. The other was only observed with anti-mitochondrial antibody positive sera and stained the mitochondrial-rich ductal epithelium in a distinctive punctate pattern. Antibodies staining the apical surface of ducts were detected rarely in patients with antiRo/La autoantibody-positive primary SS (1/76) and RA (1/36) and were found in only 1115 with RA and secondary SS. ASDA were detected in sera from 13/51 (25.5%) of patients referred to our clinic with limited sicca symptoms who were anti-Ro/La antibody-negative and had no typical clinical or laboratory features of classical primary SS. The apical ductal staining pattern was not observed with sera from 63 healthy controls without sicca symptoms or in patients with autoimmune and infective disorders. Twelve of the 13 patients whose sera gave ASDA-like staining were blood group O and one group A. Ductal staining was abolished in all sera after absorption with blood group AB erythrocytes or AB antigen. In 5 patients ductal staining was removed by absorption with B erythrocytes but not with A erythrocytes; in the remainder ductal reactivity was abolished by both A and B erythrocytes. CONCLUSION: ASDA seem to occur rarely in patients with primary SS and RA. However, isotype-switched IgG AB blood group antibodies cross react with primate salivary ducts and may produce false positive ASDA staining. Detection of ASDA may be of value in identifying a subset of patients who present with mild sicca symptoms without other autoimmune features.

ABO Blood-Group System↗

PubMed1997

Quinine-induced hemolytic uremic syndrome.

Although quinine use is very common, hemolytic uremic syndrome (HUS) following exposure to quinine is only a recently reported phenomenon, with the first description published in 1991. Previous reports have concentrated on the nature of the hematological process and in particular characterization of the quinine-induced antibodies involved. We present a case of HUS with a clear temporal and immunological relationship to quinine which demonstrates the pathognomonic renal features of HUS. An indirect antiglobulin test with the patient's serum agglutinated red blood cells only in the presence of quinine. Renal biopsy features included glomerular and arteriolar endothelial swelling, capillary loop thrombi, mesangiolysis, segmental sclerosis and segmental ischemia. Early empiric treatment with plasma exchange and corticosteroids was instituted and this resulted in recovery of renal function to normal.

Biopsy↗

PubMed1993

An organ fragment culture model to study lymphocyte activation in human lymphoid tissue.

We have established and evaluated an organ fragment culture model for the study of human lymphocyte activation and differentiation. Small fragments of tonsillar tissue were cultured on Gelfoam for periods of up to 7 days. Monoclonal antibody in the medium was able to diffuse into the tissue, as demonstrated by subsequent detection of antibody-coated cells. Phytohaemagglutinin added to the culture medium caused activation of T and B cells, as indicated by changes in expression of a number of markers. Antibody against human IgM (added as a F(ab')2 fragment) together with IL-4 caused B cell activation, detectable by an increased expression of CD23 and other markers. Cell viability fell gradually in culture, but useful data could nevertheless be obtained from culture periods up to 7 days. The organ fragment culture provides a model for the study of T and B cell activation which maintains, at least in part, the intercellular interactions and the native microenvironment of lymphoid tissue.

Antibodies, Monoclonal↗

PubMed1992

Video image analysis of AgNOR distribution in the normal and adenomatous colorectum.

The nucleolar organizer regions (AgNORs) have been studied by video image analysis in the normal colorectum and in adenomas arising there. Total AgNOR area was measured in conjunction with the total area of nuclei and expressed as a ratio. AgNORs are found to predominate in the proliferative regions of the normal mucosal crypt, and the ratio of AgNOR to nuclear area proved significantly greater in the normal colon than in the rectum and far greater in colorectal adenomas. Further, there is a significant difference between the ratio in tubular as opposed to villous patterns of adenomatous growth in the colon but not in the rectum. When classified according to their degree of dysplasia, adenomas in the rectum exhibit a significantly higher ratio of AgNOR to nuclear area as the degree of dysplasia increases in severity. This correlation is not shown in the colon.

Adenoma↗

PubMed1990

Synapses, axonal and dendritic patterns of GABA-immunoreactive neurons in human cerebral cortex.

Gamma-aminobutyric acid (GABA) containing neurons were characterized in human association cortex by a combination of Golgi impregnation and immunohistochemistry. Neurons were Golgi impregnated, gold toned, drawn and then classified on the basis of their dendritic and axonal arborization in layers I-VI. An antiserum to GABA was used to determine which of the impregnated neurons were immunopositive. Twenty-four GABA-positive cells were Golgi impregnated: 7 were bitufted with their dendrites predominantly radially oriented, and 17 were multipolar stellate cells. Three of the multipolar cells with large somata in the deep layers showed dendritic patterns similar to previously described basket cells. Nine of the multipolar stellate cells in layers III-VI showed characteristics of 'neurogliaform' neurons (Ramón y Cajal, 1899). The somata and the dendritic field of these cells were spherical, with diameters of about 10-15 microns and 200 microns, respectively. Their dendrites were smooth and slightly beaded. The axon collaterals were densely distributed in and around the dendritic field, in a spherical area with a diameter of at least 300 microns. The thin axon collaterals had only occasional 'en passant' swellings. Contacts between the axons of neurogliaform cells and the distal dendrites of Golgi-impregnated pyramidal cells were observed. Electron microscopic immunocytochemistry revealed that GABA immunopositive nerve terminals formed symmetric synaptic contacts with somata, with GABA immunonegative and immunopositive dendritic shafts and with dendritic spines. The results show that GABAergic neurons are heterogeneous with respect to their dendritic and axonal patterns. In addition to the chandelier and basket cells, which have been shown in animal studies to contain GABA, other cell types, most prominently the neurogliaform cells, terminating on the distal parts of neurons, also contain GABA and may have a inhibitory function. Many of the GABAergic terminals make synapses on dendritic spines and shafts in the human cerebral cortex.

Adolescent↗

PubMed1989

Neuropeptide Y-like immunoreactivity is present in boutons synapsing on vasopressin-containing neurons in rabbit supraoptic nucleus.

Ultrastructural immunocytochemical methods were used to examine the relationship between nerve terminals containing neuropeptide Y-like immunoreactivity and vasopressin-containing neurons in the rabbit supraoptic nucleus. Some boutons containing neuropeptide Y-like immunoreactivity formed synapses on the soma and proximal dendrites of vasopressin-containing neurons.

Animals↗

PubMed1987

Ultrastructural evidence for gamma aminobutyric acid-immunoreactive synapses on somatostatin-immunoreactive perikarya in the periventricular anterior hypothalamus.

Somatostatin-immunoreactive perikarya in the periventricular anterior hypothalamus were demonstrated to be surrounded by gamma aminobutyric acid GABA-immunoreactive nerve terminals, by combining pre-embedding immunocytochemistry for somatostatin and gold labelling post-embedding immunocytochemistry for GABA. Ultrastructural studies revealed that in each 100-nm section, cells immunoreactive for somatostatin (n = 62) were contacted by a mean of 7.6 +/- 0.4 terminal profiles of which 3.0 +/- 0.3 (40%) were GABA-immunoreactive. Most GABA-immunoreactive terminals contained clear rounded vesicles and, where synaptic specializations were well demonstrated, appeared to be symmetric. The finding provides evidence that there is a significant GABA input to somatostatin neurons, an observation strengthening the hypothesis that GABA may inhibit somatostatin neurons, thereby causing increased secretion of growth hormone.

Animals↗

PubMed1985

Identified axo-axonic cells are immunoreactive for GABA in the hippocampus and visual cortex of the cat.

Chandelier or axo-axonic cells (AACs) are specialized interneurons terminating on the axon initial segments of pyramidal neurons. Two AACs have been localized by Golgi impregnation, one in the CA1 region of the hippocampus and one in the visual cortex of cat, for structural analysis and for the identification of their transmitter. They had 323 and 268 terminal bouton rows, respectively, probably making synapses with an equal number of initial segments. The distribution of the dendrites of the hippocampal cell was strikingly similar to that of pyramidal cells suggesting a similar input. Using an antiserum to GABA and postembedding GABA-immunocytochemistry, developed for Golgi-impregnated neurons, both cells were found to be GABA-immunoreactive. The strategic location of their synapses and the presence of GABA in AACs suggest that in normal cortical tissue they play a major role in GABA-mediated inhibition.

Animals↗