The effects of the glucocorticoids prednisolone, deflazacort and beclomethasone-dipropionate on the RM 3/1 macrophage in human peripheral blood

Alterations of CD163 expression in the complications of diabetes: A systematic review

AIMS

Diabetes mellitus is a state of chronic low-grade inflammation. Scavenger receptor CD163, expressed on monocyte/macrophage cells with anti-inflammatory functions, has been observed in diabetes complications. This review aimed to systematically survey human studies published until 31st January 2022 for CD163 expression, in particular diabetes complications and additionally to investigate whether CD163 may be implicated as a biomarker of, and mediator in, the progression of diabetes complications.

METHODS

A systematic literature search undertaken in Scopus, Embase and Medline established 79 papers of relevance. Data extraction and assessment followed the PRISMA workflow.

RESULTS

Based on specific criteria, 11 studies totalling 821 participants were included in this review. CD163 was quantified in various forms including soluble, cell surface, and mRNA measures. This review found that soluble CD163 was upregulated in diabetes complications in various local body fluids and systemically in plasma or serum and therefore implicated in the progression of those complications. CD163+ cells and mRNA were variably expressed across diabetes complications.

CONCLUSIONS

CD163 was altered in series of diabetes complications and the circulating sCD163 has potential utility as an inflammation biomarker. The variable expression of CD163 on cell surfaces and its mRNA across different diabetes complications warrants further systematic investigation.

Severe COVID-19 Recovery Is Associated with Timely Acquisition of a Myeloid Cell Immune-Regulatory Phenotype

After more than one year since the COVID-19 outbreak, patients with severe disease still constitute the bottleneck of the pandemic management. Aberrant inflammatory responses, ranging from cytokine storm to immune-suppression, were described in COVID-19 and no treatment was demonstrated to change the prognosis significantly. Therefore, there is an urgent need for understanding the underlying pathogenic mechanisms to guide therapeutic interventions. This study was designed to assess myeloid cell activation and phenotype leading to recovery in patients surviving severe COVID-19. We evaluated longitudinally patients with COVID-19 related respiratory insufficiency, stratified according to the need of intensive care unit admission (ICU, n = 11, and No-ICU, n = 9), and age and sex matched healthy controls (HCs, n = 11), by flow cytometry and a wide array of serum inflammatory/immune-regulatory mediators. All patients featured systemic immune-regulatory myeloid cell phenotype as assessed by both unsupervised and supervised analysis of circulating monocyte and dendritic cell subsets. Specifically, we observed a reduction of CD14lowCD16+ monocytes, and reduced expression of CD80, CD86, and Slan. Moreover, mDCs, pDCs, and basophils were significantly reduced, in comparison to healthy subjects. Contemporaneously, both monocytes and DCs showed increased expression of CD163, CD204, CD206, and PD-L1 immune-regulatory markers. The expansion of M2-like monocytes was significantly higher at admission in patients featuring detectable SARS-CoV-2 plasma viral load and it was positively correlated with the levels of specific antibodies. In No-ICU patients, we observed a peak of the alterations at admission and a progressive regression to a phenotype similar to HCs at discharge. Interestingly, in ICU patients, the expression of immuno-suppressive markers progressively increased until discharge. Notably, an increase of M2-like HLA-DRhighPD-L1+ cells in CD14++CD16− monocytes and in dendritic cell subsets was observed at ICU discharge. Furthermore, IFN-γ and IL-12p40 showed a decline over time in ICU patients, while high values of IL1RA and IL-10 were maintained. In conclusion, these results support that timely acquisition of a myeloid cell immune-regulatory phenotype might contribute to recovery in severe systemic SARS-CoV-2 infection and suggest that therapeutic agents favoring an innate immune system regulatory shift may represent the best strategy to be implemented at this stage.

More Than Suppression: Glucocorticoid Action on Monocytes and Macrophages

Uncontrolled inflammation is a leading cause of many clinically relevant diseases. Current therapeutic strategies focus mainly on immunosuppression rather than on the mechanisms of inflammatory resolution. Glucocorticoids (GCs) are still the most widely used anti-inflammatory drugs. GCs affect most immune cells but there is growing evidence for cell type specific mechanisms. Different subtypes of monocytes and macrophages play a pivotal role both in generation as well as resolution of inflammation. Activation of these cells by microbial products or endogenous danger signals results in production of pro-inflammatory mediators and initiation of an inflammatory response. GCs efficiently inhibit these processes by down-regulating pro-inflammatory mediators from macrophages and monocytes. On the other hand, GCs act on “naïve” monocytes and macrophages and induce anti-inflammatory mediators and differentiation of anti-inflammatory phenotypes. GC-induced anti-inflammatory monocytes have an increased ability to migrate toward inflammatory stimuli. They remove endo- and exogenous danger signals by an increased phagocytic capacity, produce anti-inflammatory mediators and limit T-cell activation. Thus, GCs limit amplification of inflammation by repressing pro-inflammatory macrophage activation and additionally induce anti-inflammatory monocyte and macrophage populations actively promoting resolution of inflammation. Further investigation of these mechanisms should lead to the development of novel therapeutic strategies to modulate undesirable inflammation with fewer side effects via induction of inflammatory resolution rather than non-specific immunosuppression.

Increase in plasma and surface CD163 levels in patients undergoing coronary artery bypass graft surgery

Although haptoglobin polymorphism has been shown to be a genetic risk factor in coronary artery disease, its mechanisms of action are incompletely defined. Recently, a macrophage scavenger receptor for the uptake of haptoglobin-hemoglobin (Hp-Hb) complexes was cloned and designated CD163. Macrophage expression of CD163 is increased by glucocorticoids, IL-10 and IL-6. To better understand the in vivo response of CD163 to an inflammatory stimulus and glucocorticoid treatment, we studied 18 patients who underwent elective coronary artery bypass graft (CABG) surgery with cardiopulmonary bypass (CPB). We report a rapid increase in plasma levels of soluble CD163 by 1 h post-declamping the aorta during CABG surgery with CPB. Furthermore, we demonstrate significant increases in monocyte CD163 on post-operative day 1; 14-fold for patients pre-treated with methylprednisolone and 3-fold for those who did not receive exogenous glucocorticoids. These findings show CD163 to be rapidly mobilized in response to systemic inflammatory stimuli and to be affected significantly by glucocorticoids in vivo. The proposed role of CD163 as a Hp-Hb scavenger and anti-inflammatory molecule, in conjunction with the results of this study, make CD163 an intriguing target for potential manipulation of the acute response to inflammation.

Development of an ELISA to measure soluble CD163 in biological fluids

CD163 is a monocyte/macrophage restricted transmembrane glycoprotein and a member of the scavenger receptor cysteine-rich (SRCR) family of proteins. SRCR proteins are typically associated with the immune system. The regulation of CD163 by cytokines and glucocorticoids suggests that it plays a role in inflammatory processes. While CD163 is expressed as a membrane-bound protein, it has been shown to be actively shed from the surface of monocytes in a protease-dependent fashion when cells are stimulated with a phorbol ester. To better elucidate the function and biological importance of CD163, we have developed a solid-phase sandwich enzyme linked immunosorbant assay (ELISA) for the detection of soluble CD163 in biological fluids. This assay has good repeatability both within and between runs (coefficients of variation (CVs) of 3.2% and 7.1% or better, respectively). While detection of CD163 was inhibited by ethylenediamine tetraacetic acid (EDTA), CD163 immunoreactivity was not altered by the addition of heparin or hemoglobin. This report details the development of this novel assay for soluble CD163 and provides the first evidence of CD163 immunoreactivity in normal plasma and serum samples.