Regulation of LFA-3 (CD58) by dexamethasone and retinoic acids in vitro

CD58 Immunobiology at a Glance

The glycoprotein CD58, also known as lymphocyte-function antigen 3 (LFA-3), is a costimulatory receptor distributed on a broad range of human tissue cells. Its natural ligand CD2 is primarily expressed on the surface of T/NK cells. The CD2-CD58 interaction is an important component of the immunological synapse (IS) that induces activation and proliferation of T/NK cells and triggers a series of intracellular signaling in T/NK cells and target cells, respectively, in addition to promoting cell adhesion and recognition. Furthermore, a soluble form of CD58 (sCD58) is also present in cellular supernatant in vitro and in local tissues in vivo. The sCD58 is involved in T/NK cell-mediated immune responses as an immunosuppressive factor by affecting CD2-CD58 interaction. Altered accumulation of sCD58 may lead to immunosuppression of T/NK cells in the tumor microenvironment, allowing sCD58 as a novel immunotherapeutic target. Recently, the crucial roles of costimulatory molecule CD58 in immunomodulation seem to be reattracting the interests of investigators. In particular, the CD2-CD58 interaction is involved in the regulation of antiviral responses, inflammatory responses in autoimmune diseases, immune rejection of transplantation, and immune evasion of tumor cells. In this review, we provide a comprehensive summary of CD58 immunobiology.

Micronutrients Profile in Oral Lichen Planus: a Review Literature

Oral lichen planus (OLP) is a relatively common chronic inflammatory disease. The micronutrients are critical factors in health of oral mucous and proper function of immune system. There have not been any review articles for evaluating trace element levels before and after standard treatments of OLP. The purpose of this study is to provide complete review of the association of micronutrients with OLP. Databases including PubMed, Google Scholar, Scopus, and Embase (Ovid) with keywords of oral lichen planus, OLP, oral disorder, micronutrients, trace element, nutrient element, antioxidant, oxidative stress, malnutrition, and essential trace elements, without time limitation (1900-2019) were searched to collect data on related articles. Total number of 58 original articles including 12 randomized clinical trials, 41 case-control, 4 case reports, and 1 cell line research were reviewed in this study. Lower levels of iron and its associated markers, such as hemoglobin and ferritin, increased levels of TIBC; reduced levels of zinc, calcium, vitamin D, vitamin B12, folic acid, and antioxidants such as vitamins C and E; and increased levels of oxidants and homocysteine, have been reported in OLP patients.

SEM analysis of oral lichen planus before and after treatment with 13 cis-retinoic acid

Cancer of the oral cavity is a frequent worldwide neoplasia, averaging 4% in men and 2% in women. Cancer of the oral cavity is often preceded by particular epithelial lesions, called precancerous lesions. The aim of this study is to evaluate, by SEM microscope analysis, before and after treatment with 0.1% 13-cis-retinoic, the morphostructural variation of the surface of the oral mucous affected by lichen planus in respect to healthy oral mucous. Following topical therapy with 0.1% 13-cis-retinoic acid for 8 weeks, a restoration of the physiological morphostructure was observed by SEM, demonstrating the efficaciousness of the treatment and the SEM analysis for identifying the lesions of oral epithelium.

Structure-function studies of peptides for cell adhesion inhibition: identification of key residues by alanine mutation and peptide-truncation approach

Blockage of the interaction of CD2 with its ligand CD58 is expected to bring out potential therapeutic value for autoimmune diseases and organ transplantation. Three series of peptides (cVL, cIL and cAQ series) were designed from ratCD2 and humanCD2 to modulate CD2-CD58 interaction. To determine the specific segments in parent peptides responsible for inhibitory activity as lead sequence, we generated shorter fragments of the parent peptides and evaluated their biological activity with cell adhesion assay. The structure-activity relationship studies indicated that small cyclic peptides derived from CD2 ligand binding epitopes could mimic native beta-turn structure, and thus modulate CD2-CD58 interaction.

Therapeutic effect of all-trans-retinoic acid (at-RA) on an autoimmune nephritis experimental model: role of the VLA-4 integrin

Background

Mercuric chloride (HgCl₂) induces an autoimmune nephritis in the Brown Norway (BN) rats characterized by anti-glomerular basement membrane antibodies (anti-GBM Ab) deposition, proteinuria and a severe interstitial nephritis, all evident at day 13 of the disease. We assessed the effects of all-trans retinoic acid (at-RA) in this experimental model. At-RA is a vitamin A metabolite which has shown beneficial effects on several nephropathies, even though no clear targets for at-RA were provided.

Methods

We separated animals in four different experimental groups (HgCl₂, HgCl₂+at-RA, at-RA and vehicle). From each animal we collected, at days 0 and 13, numerous biological samples: urine, to measure proteinuria by colorimetry; blood to determine VLA-4 expression by flow citometry; renal tissue to study the expression of VCAM-1 by Western blot, the presence of cellular infiltrates by immunohistochemistry, the IgG deposition by immunofluorescence, and the cytokines expression by RT-PCR. Additionally, adhesion assays to VCAM-1 were performed using K562 α4 transfectant cells. ANOVA tests were used for statistical significance estimation.

Results

We found that at-RA significantly decreased the serum levels of anti-GBM and consequently its deposition along the glomerular membrane. At-RA markedly reduced proteinuria as well as the number of cellular infiltrates in the renal interstitium, the levels of TNF-α and IL-1β cytokines and VCAM-1 expression in renal tissue. Moreover, we reported here for the first time in an in vivo model that at-RA reduced, to basal levels, the expression of VLA-4 (α4β1) integrin induced by mercury on peripheral blood leukocytes (PBLs). In addition, using K562 α4 stable transfectant cells, we found that at-RA inhibited VLA-4 dependent cell adhesion to VCAM-1.

Conclusion

Here we demonstrate a therapeutic effect of at-RA on an autoimmune experimental nephritis model in rats. We report a significant reduction of the VLA-4 integrin expression on PBLs as well as the inhibition of the VLA4/VCAM1-dependent leukocyte adhesion by at-RA treatment. Thereby we point out the VLA-4 integrin as a target for at-RA in vivo.

Dexamethasone inhibits apoptosis of human neutrophils induced by reactive oxygen species

Neutrophils are completely differentiated cells that die in tissues a few days after they migrate from the vascular compartment as a consequence of a rigouous apoptotic program. Many of the mediators produced during an inflammatory response delay neutrophil apoptosis allowing a more efficient removal of microorganisms but also favoring the tissue damage by reactive oxygen species (ROS) and lysosomal proteins released by neutrophils. Glucocorticoids delay the apoptosis of neutrophils but the mechanisms are not completely understood. To investigate the inhibition of glucocorticoids on neutrophil apoptosis we have used the glucose/glucose oxidase (G/GO) system as a constant source of hydrogen peroxide. When neutrophils are incubated in the presence of the G/GO system, a significant acceleration of their apoptotic response is observed. Preincubation with 10(-6) M, 10(-7) M, 10(-8) M or 10(-9) M of dexamethasone, negatively modulated the spontaneous and G/GO induced apoptosis of neutrophils. Then the G/GO system is a useful model to simulate the oxidative stress of neutrophils, and that the effect of DXM on neutrophil apoptosis depends, at least in part, on blocking the proapoptotic effect of ROS.

Modulation of leukotriene B4 receptor-1 expression by dexamethasone: potential mechanism for enhanced neutrophil survival

Glucocorticoids can down-regulate many inflammatory and immune responses and constitute a powerful therapeutic tool in a number of diseases. However, they have a somewhat paradoxical effect on neutrophils, in that they prolong their survival. Because leukotriene B(4) (LTB(4)) can also extend neutrophil survival, we proposed that glucocorticoids could prevent neutrophil apoptosis by up-regulating their expression of the high-affinity LTB(4) receptor (BLT1). Here we show that, indeed, dexamethasone (DEX) up-regulates the steady-state levels of BLT1 mRNA in human neutrophils. The effect was time and concentration dependent, being maximal at 4 h and at 10-100 nM DEX. The effect was also dependent on transcriptional activity, whereas BLT1 mRNA stability was not affected. DEX-induced up-regulation of BLT1 expression was prevented by pretreatment with the LTB(4) antagonist LY255283. Moreover, LTB(4) itself up-regulated the expression of BLT1 mRNA. BLT1 protein expression on neutrophils exposed to DEX for 24 h was also up-regulated 2- to 3-fold, and DEX-treated as well as LTB(4)-treated cells showed enhanced responsiveness to LTB(4) in terms of intracellular Ca(2+) mobilization and chemotaxis. Whereas DEX and LTB(4) alone decreased neutrophil apoptosis by approximately 50%, neutrophils treated with both LTB(4) and DEX showed >90% survival at 24 h. Moreover, BLT1 antagonists prevented the increased neutrophil survival induced by DEX as well as by LTB(4). Taken together, our results suggest that DEX-induced up-regulation of BLT1 expression in neutrophils may be one mechanism through which glucocorticoids can prolong neutrophil survival, namely by enhancing cell responses to the antiapoptotic effect of LTB(4).