Brief report: first identification of H4 histamine receptor in healthy salivary glands and in focal sialadenitis in Sjögren's syndrome.

OBJECTIVE: The conventional H(1) and H(2) histamine receptors have >10,000-fold lower avidity for histamine than H(4) histamine receptor, which has been implicated in autoimmune diseases. This study was undertaken to compare H(4) histamine receptor levels in the salivary glands (SGs) of healthy controls with those in the SGs of patients with primary Sjögren's syndrome (SS). METHODS: H(4) histamine receptor messenger RNA (mRNA) was analyzed using real-time quantitative polymerase chain reaction, and the receptor protein was examined using immunostaining. Effects of the H(4) histamine receptor agonist ST-1006 on cytokine synthesis by human SG (HSG) cells were analyzed using xMAP technology and enzyme-linked immunosorbent assay. RESULTS: Healthy SGs contained H(4) histamine receptor mRNA. The receptor protein was localized to the acinar and ductal epithelial cells. H(4) histamine receptor agonist stimulated HSG cells to produce the cytokines interleukin-8 and vascular endothelial growth factor. SS patients had low H(4) histamine receptor levels. CONCLUSION: H(1) and H(2) histamine receptor antagonists are not effective in the treatment of autoimmune diseases. However, such antagonists do not affect the newly discovered H(4) histamine receptor. Dendritic cells and lymphocytes are nonprofessional histamine-producing cells, which produce histamine at 100-1,000-fold lower rates than mast cells do. Saliva contains only 0.31-12.4 ng/ml histamine, which is too low to stimulate H(1) or H(2) histamine receptor, but stimulates H(4) histamine receptor half maximally. Our findings show that H(4) histamine receptor is strongly expressed in tubuloacinar SG cells, which emphasizes the role of these cells in the pathogenesis of SS.

T lymphocytes are targets for platelet- and trophoblast-derived microvesicles during pregnancy.

Microvesicles (MVs) can derive from several cell types and their membranes contain cell surface elements. Their role is increasingly recognized in cell-to-cell communication, as they act as both paracrine and remote messengers, occurring in circulating form as well as in plasma. Successful pregnancy requires a series of interactions between the maternal immune system and the implanted fetus, such that the semi-allograft will not be rejected. These interactions occur at the materno-placental interface and/or at a systemic level. In the present study we identified for the first time the in vivo plasma pattern of the MVs of third-trimester, healthy pregnant women, their cellular origin, and their target cells using flow cytometry and confocal laser microscopy. We searched for the cellular target molecules of thrombocyte-derived MVs with the help of neutralizing antibodies. We examined the in vitro effects of MVs on STAT3 phosphorylation of primary lymphocytes and Jurkat cells. We found that both placental trophoblast-derived and maternal thrombocyte-derived MVs bind to circulating peripheral T lymphocytes, but not to B lymphocytes or NK cells. We were able to show that the P-selectin (CD62P)-PSGL-1 (CD162) interaction is one mechanism binding platelet-derived MVs to T cells. We were also able to demonstrate that MV-lymphocyte interactions induce STAT3 phosphorylation in T cells. Our findings indicate that both thrombocyte- and trophoblast-derived MVs may play an important role in the immunomodulation of pregnancy. We suggest that the transfer of different signals via MVs represents a novel form of communication between the placenta and the maternal immune system, and that MVs contribute to the establishment of stable immune tolerance to the semi-allograft fetus.

Monocyte activation drives preservation of membrane thiols by promoting release of oxidised membrane moieties via extracellular vesicles.

The redox state of cellular exofacial molecules is reflected by the amount of available thiols. Furthermore, surface thiols can be considered as indicators of immune cell activation. One group of thiol containing proteins, peroxiredoxins, in particular, have been associated with inflammation. In this study, we assessed surface thiols of the U937 and Thp1 monocyte cell lines and primary monocytes in vitro upon inflammatory stimulation by irreversibly labelling the cells with a fluorescent derivative of maleimide. We also investigated exofacial thiols on circulating blood mononuclear cells in patients with rheumatoid arthritis and healthy controls. When analysing extracellular vesicles, we combined thiol labelling with the use of antibodies to specific CD markers to exclude extracellular vesicle mimicking signals from thiol containing protein aggregates. Furthermore, differential detergent lysis was applied to confirm the vesicular nature of the detected extracellular events in blood plasma. We found an increase in exofacial thiols on monocytes upon in vitro stimulation by LPS or TNF, both in primary monocytes and monocytic cell lines (p<0.0005). At the same time, newly released extracellular vesicles showed a decrease in their exofacial thiols compared with those from unstimulated cells (p<0.05). We also found a significant elevation of surface thiols on circulating monocytes in rheumatoid arthritis patients (p<0.05) and newly released extracellular vesicles of isolated CD14+ cells from rheumatoid arthritis patients had decreased thiol levels compared with healthy subjects (p<0.01). Exofacial peroxiredoxin 1 was demonstrated on the surface of primary and cultured monocytes, and the number of peroxiredoxin 1 positive extracellular vesicles was increased in rheumatoid arthritis blood plasma (p<0.05). Furthermore, an overoxidised form of peroxiredoxin was detected in extracellular vesicle-enriched preparations from blood plasma. Our data show that cell surface thiols play a protective role and reflect oxidative stress resistance state in activated immune cells. Furthermore, they support a role of extracellular vesicles in the redox regulation of human monocytes, possibly representing an antioxidant mechanism.

Histamine deficiency induces tissue-specific down-regulation of histamine H2 receptor expression in histidine decarboxylase knockout mice.

Histidine decarboxylase (HDC) is the single enzyme responsible for histamine synthesis. HDC-deficient mice (HDC(-/-)) have no histamine in their tissues when kept on a histamine-free diet. Therefore, the HDC(-/-) mice provide a suitable model to investigate the involvement of histamine in the regulation of histamine receptor expression. Gene expression of H1 and H2 histamine receptors was studied in several organs of HDC(-/-) mice and compared to standard (HDC(+/+)) mice. In many tissues, prolonged absence of histamine induced down-regulation of the H2 receptor subtype. The expression of the H1 receptor was less sensitive to histamine deficiency. Exogenous histamine present in the diet abolished the differences observed in H2 receptor expression. These results suggest that the expression of mouse H2 receptor is under the control of histamine in a tissue-specific manner.

Mice lacking histidine decarboxylase exhibit abnormal mast cells.

Histidine decarboxylase (HDC) synthesizes histamine from histidine in mammals. To evaluate the role of histamine, we generated HDC-deficient mice using a gene targeting method. The mice showed a histamine deficiency and lacked histamine-synthesizing activity from histidine. These HDC-deficient mice are viable and fertile but exhibit a decrease in the numbers of mast cells while the remaining mast cells show an altered morphology and reduced granular content. The amounts of mast cell granular proteases were tremendously reduced. The HDC-deficient mice provide a unique and promising model for studying the role of histamine in a broad range of normal and disease processes.

Interferon-gamma but not granulocyte/macrophage colony-stimulating factor augments proteoglycan presentation by synovial cells and chondrocytes to an autopathogenic T cell hybridoma.

Immunization of BALB/c mice with human cartilage proteoglycan (aggrecan) produces a progressive polyarthritis, similar in many aspects to human rheumatoid arthritis, and autoreactive T cells are necessary for initiation of the disease. To study the immunopathological mechanisms operating in the synovium of arthritic mice, we isolated a proteoglycan (PG)-specific arthritogenic T-cell hybridoma, 5/4E8, and examined the presentation of PG to this T-cell hybridoma by mouse synovial cells and chondrocytes. Both cell types expressed very low levels of major histocompatibility complex (MHC) class II following isolation and culture and were unable to present PG to the hybridoma. However, following stimulation with interferon-gamma (IFN-gamma), both synovial cells and chondrocytes showed a marked increase in MHC class II expression and consequently were able to present PG very effectively. The PG-specific responses of the hybridoma were abrogated by an anti-Ia monoclonal antibody. Granulocyte-macrophage colony-stimulating factor (GM-CSF), one of the most abundant cytokines in the rheumatoid synovium, had no effect on the antigen-presenting capacity of synovial cells and chondrocytes, either on its own or together with IFN gamma.

Inverse regulation of interleukin-6 (IL-6) and IL-6 receptor in histamine deficient histidine decarboxylase-knock-out mice.

Interleukin-6, a multifunctional cytokine upon binding to its receptor on hepatocytes regulates production of acute phase proteins involved in local and systemic inflammation. Gene expression and biosynthesis of IL-6 and its receptor (IL-6 R/gp130) is under complex regulation. Histamine, in addition to its principal role in immediate type hypersensitivity has been described to modulate IL-6 production and expression of IL-6 receptor. In this study, the IL-6 and IL-6 receptor expression was examined in histamine deficient histidine decarboxylase (HDC) knock-out mouse model. Our data suggest that in histamine deficient mice the inducibility of IL-6 is significantly reduced, whilst more IL-6 receptor/gp130 mRNA expresses in the liver than in wild type (HDC(+/+)) mice. These in vivo findings confirm earlier in vitro results and emphasize the efficacy of antihistamines in local IL-6 related processes.

Histidine decarboxylase deficiency in gene knockout mice elevates male sex steroid production.

Histamine is synthesized in cells by histidine decarboxylase (HDC). HDC-deficient knockout (KO) mice lack functional HDC and histamine in the tissues. In the present study we used this in vivo model for studying the role of HDC deficiency in the regulation of male steroid hormone metabolism. In agreement with earlier studies showing the lack of effects of central histamine on the basal secretion of gonadotrope hormones, we found no difference with in situ hybridization in the expression of GnRH in the hypothalamus of wild type and KO mice. The tissue concentrations of testosterone and several androgenic steroids were significantly elevated in the testes but not in the adrenal glands of HDC-KO mice. In contrast, serum estradiol levels failed to show a significant difference between the two groups. The weight of the testes was significantly smaller in both 7-day-old and adult KO mice. The ultrastructure of the adult testis indicated elevated steroid synthesis with more tightly coiled membranous whorls in Leydig cells. The present results suggest that changes in reproductive functions and sex steroid secretion in male HDC-KO mice are not due to altered hypothalamic GnRH expression but are probably related to definite modifications during fetal development of KO mice reinforced later by the lack of the effect of peripheral histamine. This may provide in vivo evidence that peripheral histamine is an important regulatory factor of male gonadal development during embryogenesis and of sex steroid metabolism later in adulthood.

[Experience with the regeneration and repeated use of dialyzers (1977-1987)]. / Dialysatorok regenerálásával és ismételt felhasználásával szerzett tapasztalatok (1977-1987).

During ten years 59616 haemodialyses were performed with 18139 capillary dialysers on 226 patients being in the final stage of chronic renal insufficiency. With the semi-automatic technique applied blood can be eliminated from the dialyser in 15-20 minutes. Formalin used for desinfection is washed out of the apparatus such a way, that formalin content of the last washing solution ranges between 0-0.1 microgram/ml. Anti-N antibody indicating the presence of formalin could be detected in the serum of 2 patients out of the 120 cases tested. The same dialyser is used repeatedly on one patient, 3.29-times on the average. The regenerated dialyser eliminates compounds of small-and middle molecular weight with the same efficiency up to the 4th repeated use. Ratio of pyrogenic reactions is low, 0.08%. Neither infection or sepsis associated with the regeneration occurred. Rehabilitation degree as well as the survival time of patient corresponded with the average European standard. Because of the "first use syndrome" (allergic symptoms, hypotension, nausea, vomiting, headache, cramps etc.) with 5 patients haemodialysis could be performed only with regenerated dialysers dialyses. From the considerable sums saved by regeneration process 7 satellite dialysing units were established and equipped.

[Light-chain nephropathy]. / A könnyülánc-nephropathia.

The authors deal with the clinicopathology of the renal, alterations in light-chain disease in connection with 6 cases. The disease was recognized by the monotype (in 5 cases kappa, in 1 case lambda) immunoreactivity of the light-chain paraprotein deposited in the basal membranes of the renal tissue. Electron microscopic examinations proved the fine-granulated, electrodense character of the paraprotein. Multiple myeloma was found in 3 cases and plasma cell dyscrasia of non-tumorous characteristic in 3 cases in the background of the deposition. The renal involvement appeared clinically in the picture of proteinuria without nephrosis syndrome and in progressing azotemia. Chronic renal insufficiency developed during some months in 5 patients. Morphologically renal impairment manifested in interstitial fibrosis, tubular atrophy and ateriolar hyalinosis was seen. These were associated with different glomerular alterations, for instance in 3 cases with nodular glomerulosclerosis. In 1 patient with plasma cell dyscrasia of non-tumorous characteristic nodular glomerulosclerosis and semilunar formation was observed in 56% of the glomeruli. In an other patient with myeloma the simultaneous existence of cylinder nephropathy and light-chain nephropathy was demonstrated. Both observations are unusual phenomena in plasma cell dyscrasia.

[The effect of hemodialysis, using acetate and bicarbonate, on erythrocyte deformability]. / Acetátos és bikarbonátos oldattal történö haemodialysis hatása a vörösvérsejt deformálódási képességére.

The red blood cell filtration parameters were examined in 82 patients with chronic renal failure and 50 healthy controls. The most expressed decrease in deformability was observed in uremic patients who had not been haemodialysed; the values nearest to the healthy ones were observed in transplanted patients. The deformability was considerably improved after haemodialysis, especially when acetate-containing dialyzing solution was applied.

[Rhabdomyoma as a first manifestation of childhood tuberous sclerosis]. / Rhabdomyoma mint a gyermekkori sclerosis tuberosa elsö manifesztációja.

Two dimensional echocardiography seems to be the best diagnostic tool for diagnosis of cardiac tumors. In our practice using 2 dimensional echocardiography in pediatric patients from 1984 11 cardiac tumors were diagnosed and followed-up. Four of them the cardiac rhabdomyomata (one of them diagnosed in utero) was the first manifestation of tuberous sclerosis. We summarized the follow-up data from our patients with cardiac rhabdomyomata. The detection of cardiac tumor in the fetal or infant period is of outmost importance in the early diagnosis of tuberous sclerosis and suggest careful follow-up and management. To the best of our knowledge no report of tuberous sclerosis based on echocardiographic diagnosis of cardiac rhabdomyomata has been described in our country.

[Serum keratan sulfate studies and their significance in the evaluation of cartilage degradation in degenerative and inflammatory joint diseases]. / Szérum keratán szulfát vizsgálatok és jelentöségük a porcdegradáció megítélésében degeneratív és gyulladásos ízületi betegségekben.

Fragments of high density cartilage proteoglycan (aggrecan) are released during either the normal or pathological turnover of cartilage proteoglycans, which fragments diffuse into the synovial fluids and then appear in the serum. The keratan sulphate (KS; a glycosaminoglycan side chain of aggrecan) is resistant to enzymatic degradation, it has a relatively low clearance and has a "standard" serum level indicating the actual level of cartilage (proteoglycan) breakdown. Using anti-KS monoclonal antibody in ELISA (enzyme-linked immunosorbent assay), we measured serum KS levels in patients with different joint diseases. The highest KS content (595 ng/ml) was measured in the sera of patients with articular chondrocalcinosis (calcium pyrophosphate crystal deposition disease/pseudogout). Slightly lower KS levels were determined in osteoarthrosis (OA; 578 ng/ml) and much less in rheumatoid arthritis (RA; 421 ng/ml). All these patient groups (either with degenerative or inflammatory joint diseases) expressed slightly higher KS levels compared to control blood donors (295 ng/ml). However, there were remarkable variations between these diseased groups, i. e., KS levels in patients with RA were significantly lower than in patients with OA (p < 0.001) and this difference was more pronounced in rheumatoid patients with I-II Steinbrocker stage (370 ng/ml) or in those treated with non-steroid anti-inflammatory drugs (NSAIDs) (382 ng/ml). Keratan sulphate levels in RA patients chronically treated with corticosteroid (460 ng/ml) or auro-thiomalat (473 ng/ml) indicate that these drugs may influence the cartilage metabolism more effectively than the NSAIDs.(ABSTRACT TRUNCATED AT 250 WORDS)

Microencapsulation technology by nature: Cell derived extracellular vesicles with therapeutic potential.

Cell derived extracellular vesicles are submicron structures surrounded by phospholipid bilayer and released by both prokaryotic and eukaryotic cells. The sizes of these vesicles roughly fall into the size ranges of microbes, and they represent efficient delivery platforms targeting complex molecular information to professional antigen presenting cells. Critical roles of these naturally formulated units of information have been described in many physiological and pathological processes. Extracellular vesicles are not only potential biomarkers and possible pathogenic factors in numerous diseases, but they are also considered as emerging therapeutic targets and therapeutic vehicles. Strikingly, current drug delivery systems, designed to convey therapeutic proteins and peptides (such as liposomes), show many similarities to extracellular vesicles. Here we review some aspects of therapeutic implementation of natural, cell-derived extracellular vesicles in human diseases. Exploration of molecular and functional details of extracellular vesicle release and action may provide important lessons for the design of future drug delivery systems.

Infection and autoimmunity: Lessons of animal models.

While the key initiating processes that trigger human autoimmune diseases remain enigmatic, increasing evidences support the concept that microbial stimuli are among major environmental factors eliciting autoimmune diseases in genetically susceptible individuals. Here, we present an overview of evidences obtained through various experimental models of autoimmunity for the role of microbial stimuli in disease development. Disease onset and severity have been compared in numerous models under conventional, specific-pathogen-free and germ-free conditions. The results of these experiments suggest that there is no uniform scheme that could describe the role played by infectious agents in the experimental models of autoimmunity. While some models are dependent, others prove to be completely independent of microbial stimuli. In line with the threshold hypothesis of autoimmune diseases, highly relevant genetic factors or microbial stimuli induce autoimmunity on their own, without requiring further factors. Importantly, recent evidences show that colonization of germ-free animals with certain members of the commensal flora [such as segmented filamentous bacteria (SFB)] may lead to autoimmunity. These data drive attention to the importance of the complex composition of gut flora in maintaining immune homeostasis. The intriguing observation obtained in autoimmune animal models that parasites often confer protection against autoimmune disease development may suggest new therapeutic perspectives of infectious agents in autoimmunity.