Control of the expression of a class II major histocompatibility gene (HLA-DR) in various human cell types: down-regulation by IL-1 but not by IL-6, prostaglandin E2, or glucocorticoids

Monocyte human leukocyte antigen-DR expression-a tool to distinguish intestinal bacterial infections from inflammatory bowel disease?

BACKGROUND

We sought to determine the quantitative expression of human leukocyte antigen-DR (HLA-DR) on monocytes in patients with acute intestinal bacterial infections and inflammatory bowel disease (IBD).

METHODS

The quantitative expression of HLA-DR on monocytes was determined by fluorescence-activated cell sorting analysis in patients with IBD, patients with acute intestinal bacterial infections (bact.), and healthy subjects (contr.).

RESULTS

The quantitative expression of HLA-DR in patients with bact. (n = 20; 90,000 molecules per monocyte; confidence interval [CI], 79,000-102,000) was significantly higher than that in patients with ulcerative colitis (n = 40, 30,000; CI, 30,000-38,000; P < 0.0001), Crohn disease (n = 80, 31,000; CI, 32,000-39,000; P < 0.0001), or in contr. (n = 28, 39,000; CI, 36,000-46,000; P < 0.0001). In patients with ulcerative colitis and Crohn disease, HLA-DR expression was significantly decreased, as compared with contr. (P < 0.05 and P < 0.01, respectively). With a cutoff point of 50,000, HLA-DR showed a sensitivity of 95% and a specificity of 92% in discriminating between bact. and active IBD.

CONCLUSION

The quantitative measurement of HLA-DR expression could serve as a valuable tool to discriminate between bact. and active IBD.

Ameliorative Effects of a Polyphenolic Fraction of Cinnamomum zeylanicum L. Bark in Animal Models of Inflammation and Arthritis

Cinnamon bark (Cinnamomum zeylanicum Syn C. verum, family: Lauraceae) is one of the oldest traditional medicines for inflammatory- and pain-related disorders. The objective of the present study was to evaluate the efficacy of the polyphenol fraction from Cinnamomum zeylanicum bark (CPP) in animal models of inflammation and rheumatoid arthritis. Dose-response studies of CPP (50, 100, and 200 mg/kg) used in a separate set of in vivo experiments were conducted in acute (carrageenan-induced rat paw edema), subacute (cotton pellet-induced granuloma), and sub-chronic (AIA, adjuvant-induced established polyarthrtis) models of inflammation in rats and the acetic acid-induced writhing model of pain in mice. Effects of CPP on cytokine (IL-2, IL-4, and IFNγ) release from Concanavalin (ConA)-stimulated lymphocytes were also evaluated in vitro. CPP showed a strong and dose-dependent reduction in paw volume, weight loss reversal effects against carrageenan-induced paw edema, and cotton pellet-induced granuloma models in rats. CPP (200 mg/kg p.o. for 10 days) showed a significant reduction in elevated serum TNF-α concentration without causing gastric ulcerogenicity in the AIA model in rats. CPP also demonstrated mild analgesic effects during acute treatment as evidenced by the reduction in the writhing and paw withdrawal threshold of the inflamed rat paw during the acetic acid-induced writhing model and Randall-Selitto test. CPP was found to inhibit cytokine (IL-2, IL-4, and IFNγ) release from ConA-stimulated lymphocytes in vitro. In conclusion, CPP demonstrated prominent action in animal models of inflammation and arthritis and therefore can be considered as a potential anti-rheumatic agent with disease-modifying action.

Immunoparalysis after multiple trauma

The immunological sequelae following multiple trauma constitute an ongoing challenge in critical care management. The overall immune response to multiple trauma is a multilevel complex interdependently involving neurohormonal, cellular and haemodynamic factors. Immunoparalysis is characterised by a reduced capacity to present antigens via downregulated HLA-DR and an unbalanced monocyte-T cell interaction. Trauma-induced death of functionally conducive immune cells in the early recovery phase is significant in the emergence of posttraumatic multiple organ dysfunction or failure. Novel findings may contribute to more appropriate immunomonitoring and improved treatment. We must consider the preservation and support of immune function as the ultimate therapeutic goal, which may override the current strategy of simply antagonising excessive pro- or anti-inflammatory immune responses of the severely injured person. This review focuses on the injury-induced conduct of key immune effector cells and associated effects promoting immunoparalysis after multiple trauma.

Molecular cloning, differential expression and 3D structural analysis of the MHC class-II beta chain from sea bass (Dicentrarchus labrax L.)

The major histocompatibility complex class I and II molecules (MHC-I and MHC-II) play a pivotal role in vertebrate immune response to antigenic peptides. In this paper we report the cloning and sequencing of the MHC class II beta chain from sea bass (Dicentrarchus labrax L.). The six obtained cDNA sequences (designated as Dila-DAB) code for 250 amino acids, with a predicted 21 amino acid signal peptide and contain a 28bp 5'-UTR and a 478bp 3'-UTR. A multiple alignment of the predicted translation of the Dila-DAB sequences was assembled together with other fish and mammalian sequences and it showed the conservation of most amino acid residues characteristic of the MHC class II beta chain structure. The highest basal Dila-DAB expression was found in gills, followed by gut and thymus, lower mRNA levels were found in spleen, peripheral blood leucocytes (PBL) and liver. Stimulation of head kidney leukocytes with LPS for 4h showed very little difference in the Dila-DAB expression, but after 24h the Dila-DAB level decreased to a large extent and the difference was statistically significant. Stimulation of head kidney leukocytes with different concentrations of rIL-1beta (ranging from 0 to 100ng/ml) resulted in a dose-dependent reduction of the Dila-DAB expression. Moreover, two 3D Dila-DAB*0101 homology models were obtained based on crystallographic mouse MHC-II structures complexed with D10 T-cell antigen receptor or human CD4; features and differences between the models were evaluated and discussed. Taken together these results are of interest as MHC-II structure and function, molecular polymorphism and differential gene expression are in correlation with disease resistance to virus and bacteria in teleost fish.

Monocyte Human Leukocyte Antigen–DR Transcriptional Downregulation by Cortisol during Septic Shock

Monocyte deactivation has been identified as a major factor of immunosuppression in sepsis and is associated with a loss of surface human leukocyte antigen-DR (HLA-DR) expression on circulating monocytes. Using flow cytometry, quantitative reverse transcription-polymerase chain reaction, we investigated this phenomenon in septic patients. We confirmed the early loss of monocyte HLA-DR expression in all infected patients and demonstrated that this persistent lowered expression at Day 6 correlated with severity scores, secondary infection, and death. This phenomenon occurred at a transcriptional level via a decrease in the class II transactivator A (CIITA) transcription. Furthermore, these abnormalities correlated with the high cortisol levels observed in sepsis and not with those of other putative factors such as catecholamines or interleukin-10. Finally, in vitro studies evidenced that glucocorticoids decrease HLA-DR expression at a transcriptional level via a decrease in CIITA mRNA levels, mainly by down modulating its isoforms I and III. We conclude that in human sepsis, the loss of HLA-DR expression on circulating monocytes is associated with a poor outcome. We suggest that the high endogenous cortisol level observed in septic shock may be a possible new factor involved in the loss of HLA-DR expression on monocytes via its effect on HLA-DR and CIITA transcription.

Evidence of recurrent atypical meningioma with rhabdoid transformation and expression of pyrogenic cytokines in a child presenting with a marked acute-phase response: case report and review of the literature

Children presenting with acute systemic illnesses that lack specific clinical or serological defining features may be diagnosed as having a chronic infection, an atypical systemic vasculitis or a connective tissue disease, but often turn out to have occult neoplasias. Cytokines have been implicated in causing many of the systemic effects in such cases. In this study, we describe the case of a 9-year-old boy presenting at an interval of 18 months with a marked acute-phase response due to a recurrent atypical meningioma with rhabdoid transformation of the tentorium cerebelli. Resection of the recurrent tumor was curative. We evaluated in detail the local and systemic production of cytokines released by the primary and the recurrent tumor. Blood and CSF samples were taken pre-, intra-, and postoperatively, and the production of IL-6, IL-1beta, and TNF-alpha was measured by enzyme-linked immunosorbent assays (ELISA). The level of IL-6 in CSF was about 150-fold increased before tumor resection, normalizing postoperatively. On the contrary, the levels of IL-1beta and TNF-alpha in CSF and of IL-6, IL-1beta, and TNF-alpha in serum were pre-, intra-, and postoperatively within normal limits. Cytokine production was also evaluated immunohistochemically, and confirmed strong IL-6 and TNF-alpha expression in the primary and the recurrent tumor, while expression of IL-1beta was lacking. The scattered MHC class II- and leukocyte common antigen (LCA)-expressing inflammatory cells, which were infiltrating exclusively the tumoral stroma, had no detectable cytokine immunoreactivity. We conclude that chronic IL-6 and TNF-alpha production by the tumor cells in this patient was responsible for the severe systemic illness with which he presented.

CD9 and HLA-DR expression by crevicular epithelial cells and polymorphonuclear neutrophils in periodontal disease

BACKGROUND, AIMS

The composition of gingival crevicular fluid (GCF) is likely to reflect inflammatory modifications that take place in the gingiva during periodontal diseases.

METHOD

In this study, GCF was collected at 3 different sites from 23 periodontal patients. The sites were assessed to be healthy, presenting gingivitis or periodontitis. 10 healthy individuals without any form of periodontal disease formed the control group and were sampled at one site each. The cell content of GCF was collected using Durapore Millipore strips, and 2 types of cells were studied: epithelial cells (EC) and polymorphonuclear neutrophils (PMN). The expression of CD9 and HLA-DR within or on the surface of these cells was studied in immunofluorescence on cytospin smears.

RESULTS

Both CD9 and HLA-DR expression on EC differed significantly from control subjects, and the latter decreased according to the severity of the pathology. None of the PMN found in controls expressed CD9 or HLA-DR. However, in periodontal patients, the expression of HLA-DR within PMNs was detectable and increased according to the severity of lesions. CD9 expression on PMNs also increased with inflammation.

CONCLUSION

This study shows that clinically healthy sites of periodontal patients already present signs of immunological activation characterised by a down modulation of HLA-DR expression on EC and an upregulation of these 2 molecules in PMN.

Inflammatory molecule release by beta-amyloid-treated T98G astrocytoma cells: role of prostaglandins and modulation by paracetamol

Deposition of beta-amyloid in the brain triggers an inflammatory response which accompanies the neuropathologic events of Alzheimer's disease and contributes to the destruction of brain tissue. The present study shows that beta-amyloid can stimulate human astrocytoma cells (T98G) to secrete the proinflammatory factors interleukin-6 and prostaglandins. Furthermore, prostaglandins can stimulate T98G to secrete interleukin-6, which in turn triggers the formation of additional prostaglandins. Prostaglandins are, therefore, a key element in the induction and maintenance of a state of chronic inflammation in the brain which may exacerbate the fundamental pathology in Alzheimer patients. Paracetamol (0.01-1000 microM), an unusual analgesic/antipyretic drug which acts preferentially by reducing prostaglandin production within the central nervous system, and indomethacin (0.001-10 microM) caused a clear dose-dependent reduction of prostaglandin E2 production by stimulated T98G cells whereas interleukin-6 release was not affected. These data provide further evidence of the involvement of non-steroidal anti-inflammatory drugs in the inflammatory processes that can be generated by glial cells in intact brain.

Selective loss of BoLA class I determinants from the lymphocyte surface after acid treatment

Acid treatment of bovine lymphocytes by a buffered solution of 0.263 m citric acid and 0.123 M Na2HPO4 at pH = 3.0, originally described for human and murine lymphocytes, selectively eliminated the antigenicity of MHC (BoLA) class I determinants also from bovine lymphocytes. The viability of acid-treated cell suspension was higher than 90%. The reactivity of acid-treated lymphocytes with BoLA class I typing alloantisera was lost in microcytotoxicity test, while their reactions with cross-reactive anti-HLA class II, anti-BoCD2 and BoCD5 monoclonal antibodies, and with antisera detecting two non-MHC lymphocyte alloantigenic specificities (BoLY w1 and R') remained unchanged in the microcytotoxicity and/or indirect immunofluorescence tests. The results thus show that this approach of modulating cell surface expression of MHC class I determinants may be used in cattle.

Induction of MHC class II antigen expression on human HMC-1 mast cells

Mast cells are not only the primary effector cells of immediate type immune reactions, but they have recently also been considered to contribute to the induction of an immune response. Data on the ability of the cells to express major histocompatibility complex (MHC) antigens and the mechanisms involved are however controversial or unclear. We have therefore studied the expression of MHCI and the induction of MHCII molecules on leukemic HMC-1 mast cells by immunohistochemistry. Cells were incubated for up to 72 h in the presence of IFN gamma, TNF alpha and IL-4, and immunohistochemical staining was done with monoclonal antibodies with specificity for HLA class I heavy chain, HLA-DQ (Tü22), HLA-DR (Tü36) and HLA-DQ, -R and -P (Tü35). All unstimulated mast cells expressed MHC class I, but almost no class II antigens. Incubation with IFN gamma caused a rapid, dose-dependent induction of MHC class II molecules, with Tü35 staining maximally one third of the cells within 24 h at the highest dose tested (100 IU/ml), with decline on extended culture. TNF alpha (2 ng/ml) was less effective but caused more persistent induction with time. IL-4 (200 ng/ml) had hardly any effects at all. Staining with Tü22 and Tü36 was always lower than with Tü35, and additive or even synergistic results were obtained when cells were stimulated with a combination of IFN gamma and TNF alpha. These findings support the concept that mast cells can facultatively participate in immune recognition processes depending on the type of pathological conditions in their microenvironment which allow expression of MHC class II molecules.

A rare mediastinal tumour presenting with systemic effects due to IL-6 and tumour necrosis factor (TNF) production

Patients presenting with prolonged systemic illnesses with no specific clinical or serological defining features may be diagnosed as having atypical systemic vasculitides, but often turn out to have occult malignancies. Cytokines have been implicated in causing many of the systemic effects in such cases. In this study we describe a patient presenting after 2 years of a severe systemic illness with a marked acute phase response, due to an occult mediastinal angiomatoid malignant fibrous histiocytoma. Tumour resection was curative. We evaluated in detail the local and systemic production of cytokines induced by this tumour. Blood samples were taken pre- and post-operatively for cytokine studies. In vitro production of IL-2, IL-2R, IL-1 beta, IL-6 and TNF-alpha by cultured monocytes from the patient, as well as plasma cytokine levels, were measured by ELISA. Tumour cytokine production was also evaluated immunocytochemically, and by in situ hybridization with specific cDNA probes. Plasma IL-2R and IL-6, and IL-6 and TNF-alpha production by peripheral blood monocytes were markedly elevated before tumour resection, normalizing post-operatively. Most tumour cells and infiltrating lymphocytes stained with antibodies to IL-6, IL-6R and TNF-alpha, and expressed HLA class II. IL-6 and TNF-alpha mRNA production in the tumour was confirmed by in situ hybridization studies. We have described the first case of an occult angiomatoid malignant fibrous histiocytoma in the mediastinum. Studies of cytokine expression suggested that chronic TNF, IL-6, and IL-2 production by leucocytes and tumour cells in this patient was responsible for the severe systemic illness with which she presented.

The inhibition of interferon-gamma-induced upregulation of HLA-DR expression on cultured human gingival fibroblasts by interleukin-1 beta or tumor necrosis factor-alpha

The purpose of this study was to examine the effect of inflammatory cytokines on IFN-gamma-induced HLA-DR expression on cultured human gingival fibroblasts by flow cytometry. Natural human IFN-gamma, recombinant human interleukin-1 beta (rhIL-1 beta), and rh tumor necrosis factor-alpha (rhTNF-alpha) were used. IFN-gamma-induced upregulation of HLA-DR expression was inhibited by simultaneously adding rhIL-1 beta or rhTNF-alpha (65.9% and 31.4% inhibition, respectively). Both rhIL-1 beta and rhTNF-alpha induced endogenous prostaglandin E2 (PGE2) from gingival fibroblasts, while IFN-gamma did not. The inhibitory effect of rhIL-1 beta or rhTNF-alpha on IFN-gamma-induced upregulation of HLA-DR expression was partially abated in the presence of indomethacin (reductions of 65.9% and 41.7%, respectively). Both rhIL-1 beta- and rhTNF-alpha-induced endogenous PGE2 synthesis were completely inhibited by adding indomethacin (P < 0.001). The addition of exogenous PGE2 inhibited the IFN-gamma-induced HLA-DR expression (P < 0.001). These observations suggest that the MCH class II expression on human gingival fibroblasts are influenced by the cytokine network and indirectly by the cytokine-mediated fibroblast PGE2.

Synergism of glucocorticoids with granulocyte macrophage colony stimulating factor (GM-CSF) but not interferon gamma (IFN-gamma) or interleukin-4 (IL-4) on induction of HLA class II expression on human monocytes

Peripheral blood monocytes from up to 13 normal donors were stimulated with the cytokines interferon gamma (IFN-gamma), interleukin 4 (IL-4) and granulocyte macrophage-colony stimulating factor (GM-CSF) in the presence or absence of dexamethasone (Dex), and the effects on HLA class II (HLA-DR, DP and DQ) expression studied. Dex markedly augmented HLA-DR, DP and DQ levels induced by GM-CSF, in all samples tested. Particularly striking were the effects on HLA-DQ expression, since stimulation with a combination of Dex and GM-CSF induced markedly higher levels of HLA-DQ antigen than stimulation with IFN-gamma. Northern blot analysis of samples treated for 40 hours with Dex and GM-CSF indicated that levels of DR alpha, DP alpha and DQ alpha mRNA were also increased. In contrast, despite variation between individual donors, in general Dex weakly inhibited both constitutive and IFN-gamma- or IL-4-induced HLA-DR expression. Variability in the responsiveness of monocytes purified from individual donors to each cytokine was also observed. GM-CSF was less potent than IFN-gamma and IL-4, enhancing HLA class II expression in only seven of 13 donors tested, whereas in the presence of Dex all donors responded to GM-CSF. The differential effects of glucocorticoids in vitro suggest that these cytokines induce HLA class II expression by different mechanisms.

Autocrine stimulation of interleukin-1 alpha and transforming growth factor alpha production in human keratinocytes and its antagonism by glucocorticoids

Interleukin-1 (IL-1) and transforming growth factor alpha (TGF alpha) mRNA expression was analyzed in cultured normal human keratinocytes. Keratinocytes constititively express IL-1 mRNA when cultured in keratinocyte growth medium but not in Dulbecco's minimal essential medium containing fetal bovine serum, in which the cells differentiate. The predominant form of IL-1 expressed by keratinocytes is IL-1 alpha. Addition of IL-1 alpha to keratinocytes increased IL-1 alpha and TGF alpha mRNA expression in a dose-dependent manner. TGF alpha induced a similar increase in IL-1 alpha and TGF alpha mRNA in keratinocytes. Hydrocortisone decreased the expression of both IL-1 alpha and TGF alpha mRNA in keratinocytes. These findings document an autocrine mechanism by which IL-1 alpha and TGF alpha can stimulate the proliferation of keratinocytes in the skin. It is proposed that this autocrine loop may be hyperactive in psoriasis. Antagonism of the effects of this autocrine loop may be one of the mechanisms by which glucocorticoids exert clinically useful effects in psoriasis and other diseases of the skin.