Inhibition of interleukin-12 expression in diltiazem-treated dendritic cells through the reduction of nuclear factor-κB transcriptional activity

Immunomodulatory properties of antihypertensive drugs and digitalis glycosides

INTRODUCTION

The role of chronic inflammatory process in the pathogenesis or exacerbation of hypertension has been already acknowledged.

AREAS COVERED

Therefore, one can speculate that hypotensive drugs may exert some of their therapeutic effects due to immunomodulatory properties. So far, this assumption has been tested in different studies, and the resulting knowledge is summarized in the current review article that is dedicated to different groups of antihypertensives, namely calcium channel blockers, beta blockers, as well as other less commonly used medications, such as hydralazine, agonists of alfa-2 receptor, diazoxide, doxazosin, aliskiren, and sodium nitroprusside. Articles were found in the Pubmed database by entering the name of a specific drug (or group of drugs) together with the words: immunology, cellular response, humoral response, inflammation, interleukin. The 2000-2021 range was used to search for all drugs except propranolol (1980-2021) and calcium blockers (1990-2021).

EXPERT OPINION

Observed decrease in serum/plasma concentration of proinflammatory cytokines, and CRP along with lower expression of adhesion molecules on immune cells strongly suggest that these drugs possess immunomodulatory properties, which seems to be crucial in the medical practice, especially in the therapy of hypertensive patients with other accompanying inflammatory-based diseases, such as type II diabetes, developed metabolic syndrome, allergies or autoimmunity.

Early expression of tumor necrosis factor α and nuclear factor kappa B after Descemet stripping endothelial keratoplasty in rabbits

PURPOSE

To investigate immune rejection after Descemet stripping endothelial keratoplasty (DSEK) compared with that after penetrating keratoplasty (PKP) in New Zealand rabbit eyes and to identify the relationship between tumor necrosis factor alpha (TNF-α) and nuclear factor kappa B (NFκB) and evaluate their involvement in graft rejection.

METHODS

Sixty-nine New Zealand rabbits were divided into 3 groups: group A comprised the control group, which did not undergo either of the procedures; group B underwent DSEK; and group C underwent PKP. Twenty-three Chinese rabbits (46 eyes) were used as donors. The corneal transparency, graft placement, and anterior chamber were observed for 28 days. Blood serum, aqueous humor, and corneal samples were obtained on days 7, 14, 21, and 28 after the procedures. TNF-α levels were measured weekly by double-antibody enzyme-linked immunosorbent assay. NFκB in the cornea was checked by immunofluorescence.

RESULTS

There were no graft rejections in group B. Group C showed a 50% rejection frequency with an increase in both the TNF-α concentrations and NFκB expression observed at 7 days and peak levels observed at 28 days after PKP. TNF-α concentrations did not differ significantly (P > 0.05) between groups B and A. NFκB expression was slightly increased at 7 days and returned to normal levels by day 14 after DSEK.

CONCLUSION

Rabbits with DSEK had a lower rejection rate than rabbits with PKP. NFκB and TNF-α may contribute to the early rejection of corneal allografts.

Diltiazem induces regulatory T cells in vitro by modulating human dendritic cell maturation

Diltiazem is a calcium channel antagonist that has been commonly associated with currently used immunosuppressants to prevent acute graft rejection in humans. In this study, we examined the possibility that diltiazem may affect human dendritic cell (DC) functions in response to lipopolysaccharide (LPS) stimulation and may induce the generation of DC with the capacity to generate CD4(+) regulatory T cells (Tregs). Blood monocytes were cultured in the presence of diltiazem at the beginning of their differentiation process into DC. Monocyte-derived DCs were stimulated with LPS, and DCs differentiated in the presence of diltiazem showed a decreased interleukin (IL)-12 production and an enhanced IL-10 production. When cultured with CD4(+) CD45RA(+) they were able to enhance the CD4(+) Foxp3(+) T-cell population and to induce slowly proliferating T cells, which showed a significant increase of transforming growth factor (TGF)-β production. These T cells suppress proliferation of activated autologous T cells, and we show that this effect is attributable to soluble factors, primarily to TGF-β. Blockade of TGF-β by specific monoclonal antibodies reversed this inhibitory effect. Herein, we provide new evidence that diltiazem-conditioned monocyte-derived DC induce T cells which acquire a regulatory phenotype and activity similar to those described for Tregs.

Combination use of immune complexes and a Ca2(+) channel blocker azelnidipine enhances interleukin-12 p40 secretion without T helper type 17 cytokine secretion in human monocyte-derived dendritic cells

Immune complexes (ICs) improve the capacity of priming specific CD8(+) cytotoxic T cell responses of dendritic cells (DCs). ICs induce phosphorylation of mitogen-activated protein kinases (MAPK) and calcium influx, although the precise regulating mechanism still remains unclear. In the present study, we investigated the effect of a Ca2(+) channel blocker on the phosphorylation of p38 MAPK and extracellular signal-regulated kinase (ERK) in immature monocyte-derived DCs stimulated with lipopolysaccharide (LPS) or LPS-ICs, and the production of interleukin (IL)-12 family members (p40, p70, IL-23), T helper type 17 (Th17) cytokines (IL-6 and IL-23), tumour necrosis factor (TNF)-alpha and IL-10 were also investigated. In comparison with LPS stimulation, LPS-ICs stimulation enhanced p38 MAPK phosphorylation significantly, which was associated with an increase in IL-12 p40 monomer/homodimer secretion. LPS-ICs also enhanced TNF-alpha and IL-6 secretion, but suppressed IL-23 secretion. The use of azelnidipine (Aze), a long-acting L-type Ca2(+) channel blocker with a high lipid solubility, suppressed p38 MAPK phosphorylation stimulated with LPS or LPS-ICs, but surprisingly enhanced IL-12 p40 monomer/homodimer secretion stimulated with LPS-ICs. This IL-12 p40 secretion-enhancing effect was not accompanied by IL-10 or IL-23 production, but was associated with ERK phosphorylation. The use of Aze did not affect IL-12 p70 production. These results suggest that the use of Aze enhances ICs-mediated IL-12 p40 secretion without additional IL-23 secretion. Therefore, the use of Aze and ICs could be a new therapeutic approach to immunomolecular therapy, as it does not cause Th17 differentiation which induces autoimmunity or reduces anti-tumour immunity.

Sensitization to TLR7 agonist in IFN-beta-preactivated dendritic cells

TLRs interact with a growing list of pathogen-derived products and these interactions drive the activation of innate and adaptive immune responses. Dendritic cells (DC) play a key role in these events expressing a heterogeneous repertoire of TLRs. We have previously demonstrated the production of type I IFNs in DC following bacterial infections and TLR triggering. In this study, we sought to characterize the transcriptome specifically induced in human DC by IFN-beta production stimulated upon LPS treatment. To this aim, by using cDNA microarrays, we compared the transcriptome of DC following LPS treatment in the absence or presence of neutralizing anti-type I IFN Abs. Interestingly, we found that the expression of TLR7 was induced during LPS-induced maturation of DC in a type I IFN-dependent manner. The induction of TLR7 in maturing DC was mainly a consequence of the transcriptional activity of IRF-1, whose binding site was located within TLR7 promoter. Moreover, we also demonstrated that "priming" of immature DC, that usually express TLR8 but not TLR7, with exogenous IFN-beta induced a functionally active TLR7. In fact, treatment with the TLR7-specific ligand 3M-001 up-regulated the expression of CD83, CD86, and CD38 in IFN-beta-primed DC but not in immature DC. Therefore, a robust enhancement in proinflammatory as well as regulatory cytokines was observed. These data suggest that TLR4-mediated type I IFN release activates specific transcription programs in DC amplifying the expression of pathogen sensors to correctly and combinatorially respond to a bacterial as well as viral infection.

Introduction to NF-kappaB: players, pathways, perspectives

This article serves as an introduction to the collection of reviews on nuclear factor-kappaB (NF-kappaB). It provides an overview of the discovery and current status of NF-kappaB as a research topic. Described are the structures, activities and regulation of the proteins in the NF-kappaB family of transcription factors. NF-kappaB signaling is primarily regulated by inhibitor kappaB (IkappaB) proteins and the IkappaB kinase complex through two major pathways: the canonical and non-canonical NF-kappaB pathways. The organization and focus of articles included in the following reviews are described, as well as likely future areas of research interest on NF-kappaB.

Somatostatin inhibits dendritic cell responsiveness to Helicobacter pylori

Somatostatin is a regulatory peptide found in abundance in the stomach. We have previously shown that somatostatin is required for IL-4-mediated resolution of Helicobacter pylori gastritis. In the current study, we hypothesize that somatostatin acts directly on antigen-presenting cells in the stomach to lessen the severity of gastritis. To test this hypothesis, we first show that CD11c+ dendritic cells are present in the infected tissue of mice with H. pylori-induced gastritis. Pretreatment of bone marrow-derived dendritic cells with somatostatin results in decreased IL-12 production, and lower splenocyte proliferation induced by H. pylori-stimulated dendritic cells. Furthermore, octreotide, a somatostatin analogue, is more potent than somatostatin in suppressing IL-12 release by H. pylori-stimulated dendritic cells through an NF-kappaB-independent pathway. In addition, IL-4 stimulates somatostatin secretion from dendritic cells. In conclusion, somatostatin inhibits dendritic cell activation by H. pylori; a possible mechanism by which IL-4 mediates resolution of gastritis. We suggest that octreotide may be effective in treating immune-mediated diseases of the stomach.