Antiinflammatory effects of dexamethasone are partly dependent on induction of dual specificity phosphatase 1

Chronic TNF exposure induces glucocorticoid-like immunosuppression in the alveolar macrophages of aged mice that enhances their susceptibility to pneumonia

Chronic low-grade inflammation, particularly elevated tumor necrosis factor (TNF) levels, occurs due to advanced age and is associated with greater susceptibility to infection. One reason for this is age-dependent macrophage dysfunction (ADMD). Herein, we use the adoptive transfer of alveolar macrophages (AM) from aged mice into the airway of young mice to show that inherent age-related defects in AM were sufficient to increase the susceptibility to Streptococcus pneumoniae, a Gram-positive bacterium and the leading cause of community-acquired pneumonia. MAPK phosphorylation arrays using AM lysates from young and aged wild-type (WT) and TNF knockout (KO) mice revealed multilevel TNF-mediated suppression of kinase activity in aged mice. RNAseq analyses of AM validated the suppression of MAPK signaling as a consequence of TNF during aging. Two regulatory phosphatases that suppress MAPK signaling, Dusp1 and Ptprs, were confirmed to be upregulated with age and as a result of TNF exposure both ex vivo and in vitro. Dusp1 is known to be responsible for glucocorticoid-mediated immune suppression, and dexamethasone treatment increased Dusp1 and Ptprs expression in cells and recapitulated the ADMD phenotype. In young mice, treatment with dexamethasone increased the levels of Dusp1 and Ptprs and their susceptibility to infection. TNF-neutralizing antibody reduced Dusp1 and Ptprs levels in AM from aged mice and reduced pneumonia severity following bacterial challenge. We conclude that chronic exposure to TNF increases the expression of the glucocorticoid-associated MAPK signaling suppressors, Dusp1 and Ptprs, which inhibits AM activation and increases susceptibility to bacterial pneumonia in older adults.

The glucocorticoid dexamethasone alleviates allergic inflammation through a mitogen-activated protein kinase phosphatase-1-dependent mechanism in mice

Glucocorticoids are widely used in the treatment of allergic and inflammatory diseases. Glucocorticoids have a widespread action on gene expression resulting in their pharmacological actions and also an array of adverse effects which limit their clinical use. It remains, however, to be studied which target gene effects are essential for the anti-allergic activity of glucocorticoids. Mitogen-activated protein kinase phosphatase-1 (MKP-1) inhibits proinflammatory signalling by suppressing the activity of mitogen activated protein kinase (MAP kinase) pathways. MKP-1 is one of the anti-inflammatory genes whose expression is enhanced by glucocorticoids. In the present study, we aimed to investigate the role of MKP-1 in the therapeutic effects of the glucocorticoid dexamethasone in acute allergic reaction. The effects of dexamethasone were studied in wild-type and MKP-1 deficient mice. The mice were first sensitized to ovalbumin, and the allergic reaction was then induced by a subcutaneous ovalbumin injection in the hind paw. Inflammatory edema was quantified with plethysmometer and expression of inflammatory factors was measured by quantitative reverse transcription polymerase chain reaction (RT-PCR). Dexamethasone reduced the ovalbumin-induced paw edema at 1.5, 3 and 6 h time points in wild-type mice by 70%, 95% and 89%, respectively. The effect was largely abolished in MKP-1 deficient mice. Furthermore, dexamethasone significantly attenuated the expression of ovalbumin-induced inflammatory factors cyclooxygenase-2 (COX-2); inducible nitric oxide synthase (iNOS); interleukins (IL) 1β, 6 and 13; C-C motif chemokine 11 (CCL-11); tumour necrosis factor (TNF) and thymic stromal lymphopoietin (TSLP) in wild-type mice by more than 40%. In contrast, in MKP-1 deficient mice dexamethasone had no effect or even enhanced the expression of these inflammatory factors. The results suggest that dexamethasone alleviates allergic inflammation through an MKP-1-dependent mechanism. The results also demonstrate MKP-1 as an important conveyor of the favourable glucocorticoid effects in ovalbumin-induced type I allergic reaction. Together with previous findings, the present study supports the concept of MKP-1 enhancing compounds as potential novel anti-inflammatory and anti-allergic drugs.

5α-Tetrahydrocorticosterone: A topical anti-inflammatory glucocorticoid with an improved therapeutic index in a murine model of dermatitis

BACKGROUND AND PURPOSE

Glucocorticoids are powerful anti-inflammatory drugs, but are associated with many side-effects. Topical application in atopic dermatitis leads to skin thinning, metabolic changes, and adrenal suppression. 5α-Tetrahydrocorticosterone (5αTHB) is a potential selective anti-inflammatory with reduced metabolic effects. Here, the efficacy and side-effect profile of 5αTHB were compared with hydrocortisone in preclinical models of irritant dermatitis.

EXPERIMENTAL APPROACH

Acute irritant dermatitis was invoked in ear skin of male C57BL/6 mice with a single topical application of croton oil. Inflammation was assessed as oedema via ear weight following treatment with 5αTHB and hydrocortisone. Side-effects of 5αTHB and hydrocortisone were assessed following chronic topical steroid treatment (28 days) to non-irritated skin. Skin thinning was quantified longitudinally by caliper measurements and summarily by qPCR for transcripts for genes involved in extracellular matrix homeostasis; systemic effects of topical steroid administration also were assessed. Clearance of 5αTHB and hydrocortisone were measured following intravenous and oral administration.

KEY RESULTS

5αTHB suppressed ear swelling in mice, with ED50 similar to hydrocortisone (23 μg vs. 13 μg). Chronic application of 5αTHB did not cause skin thinning, adrenal atrophy, weight loss, thymic involution, or raised insulin levels, all of which were observed with topical hydrocortisone. Transcripts for genes involved in collagen synthesis and stability were adversely affected by all doses of hydrocortisone, but only by the highest dose of 5αTHB (8× ED50 ). 5αTHB was rapidly cleared from the systemic circulation.

CONCLUSIONS AND IMPLICATIONS

Topical 5αTHB has potential to treat inflammatory skin conditions, particularly in areas of delicate skin.

Comparison of intravitreal preservative-free triamcinolone versus posterior sub-tenon triamcinolone acetonide injection for bevacizumab-resistant diabetic macular edema

BACKGROUND

Triamcinolone acetonide (TA) is administered as an intravitreal or posterior sub-Tenon's capsule injection, as treatment for diabetic macular edema (DME). The intravitreal use of TA is limited because commercially available triamcinolone acetonide contains benzyl alcohol, a neurotoxic preservative. Few studies have compared effects of preservative-free intravitreal TA (IVTA) and posterior sub-Tenon capsule TA (STTA) injections for DME. Thus, herein, we compared the effectiveness of preservative-free IVTA and STTA for treatment of bevacizumab-resistant DME.

METHODS

In this retrospective cohort study, bevacizumab-resistant DME was defined as a lack of response to at least three consecutive intravitreal bevacizumab (IVB) injections. Changes in mean central macula thickness (CMT), best-corrected visual acuity (BCVA), and intraocular pressure (IOP) between IVTA and STTA groups were compared at baseline and at 1, 2, and 3 months after treatment.

RESULTS

Forty eyes from 40 patients were included in this study. In the IVTA group, the mean CMT improved significantly from 400.2 ± 144.42 μm at baseline to 288.35 ± 151.74 μm at 3 months after treatment (p = 0.01). Similarly, in the STTA group, the mean CMT improved significantly from 446.65 ± 120.74 μm at baseline to 382.9 ± 113.58 μm at 3 months after treatment (p = 0.009). The mean BCVA of the IVTA group also showed improvement, decreasing from 0.75 ± 0.55 logarithm of the minimum angle of resolution (logMAR) at baseline to 0.625 ± 0.50 logMAR at 3 months after treatment (p = 0.089). Similarly, the mean BCVA of the STTA group improved, from 0.6 ± 0.36 logMAR at baseline to 0.54 ± 0.35 logMAR at 3 months after treatment (p = 0.094).

CONCLUSION

Given that IVTA and STTA demonstrated statistically equivalent anatomical and functional effects in patients with bevacizumab-resistant DME, the less invasive STTA may be considered the preferred treatment approach for the management of bevacizumab-resistant DME.

TRIAL REGISTRATION

Retrospectively registered.

Environmental and molecular control of tissue-specific ionocyte differentiation in zebrafish

Organisms adjust their physiology to cope with environmental fluctuations and maintain fitness. These adaptations occur via genetic changes over multiple generations or through acclimation, a set of reversible phenotypic changes that confer resilience to the individual. Aquatic organisms are subject to dramatic seasonal fluctuations in water salinity, which can affect the function of lateral line mechanosensory hair cells. To maintain hair cell function when salinity decreases, ion-regulating cells, Neuromast-associated ionocytes (Nm ionocytes), increase in number and invade lateral line neuromasts. How environmental changes trigger this adaptive differentiation of Nm ionocytes and how these cells are specified is still unknown. Here, we identify Nm ionocyte progenitors as foxi3a/foxi3b-expressing skin cells and show that their differentiation is associated with sequential activation of different Notch pathway components, which control ionocyte survival. We demonstrate that new Nm ionocytes are rapidly specified by absolute salinity levels, independently of stress response pathways. We further show that Nm ionocyte differentiation is selectively triggered by depletion of specific ions, such as Ca2+ and Na+/Cl-, but not by low K+ levels, and is independent of media osmolarity. Finally, we demonstrate that hair cell activity plays a role in Nm ionocyte recruitment and that systemic factors are not necessary for Nm ionocyte induction. In summary, we have identified how environmental changes activate a signaling cascade that triggers basal skin cell progenitors to differentiate into Nm ionocytes and invade lateral line organs. This adaptive behavior is an example of physiological plasticity that may prove essential for survival in changing climates.

Global analysis of the abundance of AU-rich mRNAs in response to glucocorticoid treatment

Glucocorticoids (GC) like dexamethasone (Dex) are potent anti-inflammatory agents with diverse cellular functions including the potentiation of the activity of AU-rich elements (AREs). AREs are cis-acting instability sequence elements located in the 3'UTRs of many inflammatory mediator mRNAs. Here, available RNA-seq data were used to investigate the effect of GCs on the ARE-mRNA-transcriptome. At a global scale, ARE-mRNAs had a tendency to be downregulated after GC-treatment of the A549 lung cancer cell-line, but with notable cases of upregulation. mRNA stability experiments indicated that not only the downregulated, but also the upregulated ARE-mRNAs are destabilized by Dex-treatment. Several of the most upregulated ARE-mRNAs code for anti-inflammatory mediators including the established GC targets DUSP1 and ZFP36; both code for proteins that target ARE-containing mRNAs for destruction. GCs are widely used in the treatment of COVID-19 patients; we show that ARE-mRNAs are more likely to regulate in opposite directions between Dex-treatment and SARS-CoV-2 infections compared to non-ARE mRNAs. The effect of GC treatment on ARE-mRNA abundance was also investigated in blood monocytes of COVID-19 patients. The results were heterogeneous; however, in agreement with in vitro observations, ZFP36 and DUSP1 were often amongst the most differentially expressed mRNAs. The results of this study propose a universal destabilization of ARE-mRNAs by GCs, but a diverse overall outcome in vitro likely due to induced transcription or due to the heterogeneity of COVID-19 patient's responses in vivo.

Cellular Immunobiology and Molecular Mechanisms in Alloimmunity-Pathways of Immunosuppression

Current maintenance immunosuppression commonly comprises a synergistic combination of tacrolimus as calcineurin inhibitor (CNI), mycophenolic acid, and glucocorticoids. Therapy is often individualized by steroid withdrawal or addition of belatacept or inhibitors of the mechanistic target of rapamycin. This review provides a comprehensive overview of their mode of action, focusing on the cellular immune system. The main pharmacological action of CNIs is suppression of the interleukin-2 pathway that leads to inhibition of T cell activation. Mycophenolic acid inhibits the purine pathway and subsequently diminishes T and B cell proliferation but also exerts a variety of effects on almost all immune cells, including inhibition of plasma cell activity. Glucocorticoids exert complex regulation via genomic and nongenomic mechanisms, acting mainly by downregulating proinflammatory cytokine signatures and cell signaling. Belatacept is potent in inhibiting B/T cell interaction, preventing formation of antibodies; however, it lacks the potency of CNIs in preventing T cell-mediated rejections. Mechanistic target of rapamycin inhibitors have strong antiproliferative activity on all cell types interfering with multiple metabolic pathways, partly explaining poor tolerability, whereas their superior effector T cell function might explain their benefits in the case of viral infections. Over the past decades, clinical and experimental studies provided a good overview on the underlying mechanisms of immunosuppressants. However, more data are needed to delineate the interaction between innate and adaptive immunity to better achieve tolerance and control of rejection. A better and more comprehensive understanding of the mechanistic reasons for failure of immunosuppressants, including individual risk/benefit assessments, may permit improved patient stratification.

Dual-Specificity Phosphatases in Regulation of Tumor-Associated Macrophage Activity

The regulation of protein kinases by dephosphorylation is a key mechanism that defines the activity of immune cells. A balanced process of the phosphorylation/dephosphorylation of key protein kinases by dual-specificity phosphatases is required for the realization of the antitumor immune response. The family of dual-specificity phosphatases is represented by several isoforms found in both resting and activated macrophages. The main substrate of dual-specificity phosphatases are three components of mitogen-activated kinase signaling cascades: the extracellular signal-regulated kinase ERK1/2, p38, and Janus kinase family. The results of the study of model tumor-associated macrophages supported the assumption of the crucial role of dual-specificity phosphatases in the formation and determination of the outcome of the immune response against tumor cells through the selective suppression of mitogen-activated kinase signaling cascades. Since mitogen-activated kinases mostly activate the production of pro-inflammatory mediators and the antitumor function of macrophages, the excess activity of dual-specificity phosphatases suppresses the ability of tumor-associated macrophages to activate the antitumor immune response. Nowadays, the fundamental research in tumor immunology is focused on the search for novel molecular targets to activate the antitumor immune response. However, to date, dual-specificity phosphatases received limited discussion as key targets of the immune system to activate the antitumor immune response. This review discusses the importance of dual-specificity phosphatases as key regulators of the tumor-associated macrophage function.

Research progress of glucocorticoid resistance in chronic rhinosinusitis with nasal polyps: A review

Chronic rhinosinusitis with nasal polyps (CRSwNP) is one of the common chronic inflammatory diseases in otolaryngology. Glucocorticoid (GC) acts as the first-line drug for the treatment of CRSwNP in clinical practice, and they play an irreplaceable role in reducing nasal mucosal inflammation and restoring the normal physiological function of the nasal mucosa. However, many patients are still insensitive to GC treatment, known as GC resistance, which leads to poor control of the disease, and the underlying mechanisms are still not fully elucidated. This article provides a comprehensive overview of the research progress of GC resistance of patients with CRSwNP in recent years.

Effectiveness of carbonic anhydrase inhibitor loaded nanoparticles in the treatment of diabetic retinopathy

Diabetic Retinopathy (DRP) is a disease consisting of all the structural and functional changes that develop in the retinal layer of the eye due to diabetes. DRP is the most important cause of blindness between the ages of 20-74 in the world, and the most successful standard treatment option in the treatment of DRP is intravitreal injections. To synthesize acetazolamide loaded nanoparticles to be applied intravitreal treatment of DRP and to examine thein vitroefficacy of the nanoparticles. ACZ loaded PHBV nanoparticles (PHBV-ACZ NPs) formulations were prepared. Nanoparticles with a particle size of 253.20 ± 0.55 nm. A DRP model was established and characterized in HRMEC cells. The effect of the nanoparticles on permeability has been investigated and carrier proteins in BRB due to the development of DRP has been investigated. To establish thein vitroDRP model, HRMEC was stimulated with Recombinant human 165 Vascular Endothelial Growth Factor (VEGF), thereby temporarily reducing the expression levels of endothelial junction proteins, increasing the number of intercellular spaces in the monolayers of HRMECs. It was determined that after the cells were exposed to Carbonic anhydrase inhibitors (CAI) loaded nanoparticles, permeability decreased and protein expression increased.

p38 MAPK signaling in chronic obstructive pulmonary disease pathogenesis and inhibitor therapeutics

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is characterized by persistent respiratory symptoms and airflow limitation due to airway and/or alveolar remodeling. Although the abnormalities are primarily prompted by chronic exposure to inhaled irritants, maladjusted and self-reinforcing immune responses are significant contributors to the development and progression of the disease. The p38 isoforms are regarded as pivotal hub proteins that regulate immune and inflammatory responses in both healthy and disease states. As a result, their inhibition has been the subject of numerous recent studies exploring their therapeutic potential in COPD.

MAIN BODY

We performed a systematic search based on the PRISMA guidelines to find relevant studies about P38 signaling in COPD patients. We searched the PubMed and Google Scholar databases and used "P38" AND "COPD" Mesh Terms. We applied the following inclusion criteria: (1) human, animal, ex vivo and in vitro studies; (2) original research articles; (3) published in English; and (4) focused on P38 signaling in COPD pathogenesis, progression, or treatment. We screened the titles and abstracts of the retrieved studies and assessed the full texts of the eligible studies for quality and relevance. We extracted the following data from each study: authors, year, country, sample size, study design, cell type, intervention, outcome, and main findings. We classified the studies according to the role of different cells and treatments in P38 signaling in COPD.

CONCLUSION

While targeting p38 MAPK has demonstrated some therapeutic potential in COPD, its efficacy is limited. Nevertheless, combining p38 MAPK inhibitors with other anti-inflammatory steroids appears to be a promising treatment choice. Clinical trials testing various p38 MAPK inhibitors have produced mixed results, with some showing improvement in lung function and reduction in exacerbations in COPD patients. Despite these mixed results, research on p38 MAPK inhibitors is still a major area of study to develop new and more effective therapies for COPD. As our understanding of COPD evolves, we may gain a better understanding of how to utilize p38 MAPK inhibitors to treat this disease. Video Abstract.

Dexamethasone impairs the expression of antimicrobial mediators in lipopolysaccharide-activated primary macrophages by inhibiting both expression and function of interferon β

Glucocorticoids potently inhibit expression of many inflammatory mediators, and have been widely used to treat both acute and chronic inflammatory diseases for more than seventy years. However, they can have several unwanted effects, amongst which immunosuppression is one of the most common. Here we used microarrays and proteomic approaches to characterise the effect of dexamethasone (a synthetic glucocorticoid) on the responses of primary mouse macrophages to a potent pro-inflammatory agonist, lipopolysaccharide (LPS). Gene ontology analysis revealed that dexamethasone strongly impaired the lipopolysaccharide-induced antimicrobial response, which is thought to be driven by an autocrine feedback loop involving the type I interferon IFNβ. Indeed, dexamethasone strongly and dose-dependently inhibited the expression of IFNβ by LPS-activated macrophages. Unbiased proteomic data also revealed an inhibitory effect of dexamethasone on the IFNβ-dependent program of gene expression, with strong down-regulation of several interferon-induced antimicrobial factors. Surprisingly, dexamethasone also inhibited the expression of several antimicrobial genes in response to direct stimulation of macrophages with IFNβ. We tested a number of hypotheses based on previous publications, but found that no single mechanism could account for more than a small fraction of the broad suppressive impact of dexamethasone on macrophage type I interferon signaling, underlining the complexity of this pathway. Preliminary experiments indicated that dexamethasone exerted similar inhibitory effects on primary human monocyte-derived or alveolar macrophages.

QbD driven targeted pulmonary delivery of dexamethasone-loaded chitosan microspheres: Biodistribution and pharmacokinetic study

Inhaling drugs, on the other hand, is limited mainly by the natural mechanisms of the respiratory system, which push drug particles out of the lungs or make them inefficient once they are there. Because of this, many ways have been found to work around the problems with drug transport through the lungs. Researchers have made polymeric microparticles (MP) and nanoparticles as a possible way to get drugs into the lungs. They showed that the drug could be trapped in large amounts and retained in the lungs for a long time, with as little contact as possible with the bloodstream. MP were formulated in this study to get dexamethasone (DMC) into the pulmonary area. The Box-Behnken design optimized microspheres preparation to meet the pulmonary delivery prerequisites. Optimized formulation was figured out based on the desirability approach. The mass median aerodynamic diameter (MMAD) of the optimized formula (O-DMC-MP) was 8.46 ± 1.45 µm, and the fine particle fraction (FPF) was 77.69 ± 1.26%. This showed that it made suitable drug delivery system, which could make it possible for MP to settle deeply in the lung space after being breathed in. With the first burst of drug release, it was seen that drug release could last up to 16 h. Also, there was no clear sign that the optimized formulation was toxic to the alveoli basal epithelial cells in the lungs, as supported by cytotoxic studies in HUVEC, A549, and H1299 cell lines. Most importantly, loading DMC inside MP cuts the amount of drug into the bloodstream compared to plain DMC, as evident from biodistribution studies. Stability tests have shown that the product can stay the same over time at both the storage conditions. Using chitosan DMC-MP can be a better therapeutic formulation to treat acute respiratory distress syndrome (ARDS).

Dexamethasone attenuates interferon-related cytokine hyperresponsiveness in COVID-19 patients

Background

Dexamethasone improves the survival of COVID-19 patients in need of supplemental oxygen therapy. Although its broad immunosuppressive effects are well-described, the immunological mechanisms modulated by dexamethasone in patients hospitalized with COVID-19 remain to be elucidated.

Objective

We combined functional immunological assays and an omics-based approach to investigate the in vitro and in vivo effects of dexamethasone in the plasma and peripheral blood mononuclear cells (PBMCs) of COVID-19 patients.

Methods

Hospitalized COVID-19 patients eligible for dexamethasone therapy were recruited from the general care ward between February and July, 2021. Whole blood transcriptomic and targeted plasma proteomic analyses were performed before and after starting dexamethasone treatment. PBMCs were isolated from healthy individuals and COVID-19 patients and stimulated with inactivated SARS-CoV-2 ex vivo in the presence or absence of dexamethasone and transcriptome and cytokine responses were assessed.

Results

Dexamethasone efficiently inhibited SARS-CoV-2-induced in vitro expression of chemokines and cytokines in PBMCs at the transcriptional and protein level. Dexamethasone treatment in COVID-19 patients resulted in down-regulation of genes related to type I and II interferon (IFN) signaling in whole blood immune cells. In addition, dexamethasone attenuated circulating concentrations of secreted interferon-stimulating gene 15 (ISG15) and pro-inflammatory cytokines and chemokines correlating with disease severity and lethal outcomes, such as tumor necrosis factor (TNF), interleukin-6 (IL-6), chemokine ligand 2 (CCL2), C-X-C motif ligand 8 (CXCL8), and C-X-C motif chemokine ligand 10 (CXCL10). In PBMCs from COVID-19 patients that were stimulated ex vivo with multiple pathogens or Toll-like receptor (TLR) ligands, dexamethasone efficiently inhibited cytokine responses.

Conclusion

We describe the anti-inflammatory impact of dexamethasone on the pathways contributing to cytokine hyperresponsiveness observed in severe manifestations of COVID-19, including type I/II IFN signaling. Dexamethasone could have adverse effects in COVID-19 patients with mild symptoms by inhibiting IFN responses in early stages of the disease, whereas it exhibits beneficial effects in patients with severe clinical phenotypes by efficiently diminishing cytokine hyperresponsiveness.

Epigallocatechin-3-gallate in combination with corticosteroids mitigates heat stress-induced acute kidney injury through modulating heat shock protein 70 and toll-like receptor 4-dependent pathways

Recently, recurrent heat stress (HS) and dehydration have been exhibited to give rise to kidney disease epidemic in hot regions. The current study was carried out to estimate a possible renoprotective effect of dexamethasone (Dexa) and epigallocatechin-3-gallate (EGCG) as a heat shock protein (HSP)-70 inhibitor on HS-induced nephropathy. In total, five groups of rats were used: control group, HS group (exposed to heat for 40 min), Dexa+HS group (rats were injected with Dexa i.p.15 mg/kg/day for 3 days followed by HS), EGCG+HS group (rats received EGCG 100 mg/kg/day, orally, for 7 days followed by HS), and EGCG+ Dexa +HS group (rats received EGCG 100 mg/kg/day, orally, for 7 days and injected Dexa as described along the last 3 days followed by HS). Kidney sections were stained with H&E and scored for tubular injury. A marked increase in creatinine, urea, malondialdehyde (MDA), monocyte chemoattractant protein (MCP)-1, HSP-70, nuclear factor kappa B (NF-κB), toll-like receptor 4 (TLR-4) and Caspase-3 expression was observed after HS induction (p < 0.001). Treatment with EGCG combined with Dexa notably reduced tubular injury, MCP-1, HSP-70, NF-κB, and TLR-4 levels (p < 0.001). Moreover, it increased IL-10, antioxidant capacity and Bcl-2 expression levels in the kidney (p < 0.001). This renoprotective impact might be attributed to anti-inflammatory, antioxidant, and anti-apoptotic mechanisms besides interfering with TLR-4-mediated NF-κB activation pathway.

Mechanisms underlying corticosteroid resistance in patients with asthma: a review of current knowledge

INTRODUCTION

Corticosteroids are the most cost-effective anti-inflammatory drugs available for the treatment of asthma. Despite their effectiveness, several asthmatic patients have corticosteroid resistance or insensitivity and exhibit a poor response. Corticosteroid insensitivity implies a poor prognosis due to challenges in finding alternative therapeutic options for asthma.

AREAS COVERED

In this review, we describe asthma phenotypes and endotypes, as well as their differential responsiveness to corticosteroids. In addition, we describe the mechanism of action of corticosteroids underlying their regulation of the expression of glucocorticoid receptors (GRs) and their anti-inflammatory effects. Furthermore, we summarize the mechanistic evidence underlying corticosteroid-insensitive asthma, which is mainly related to changes in GR gene expression, structure, and post-transcriptional modifications. Finally, various pharmacological strategies designed to reverse corticosteroid insensitivity are discussed.

EXPERT OPINION

Corticosteroid insensitivity is influenced by the asthma phenotype, endotype, and severity, and serves as an indication for biological therapy. The molecular mechanisms underlying corticosteroid-insensitive asthma have been used to develop targeted therapeutic strategies. However, the lack of clinical trials prevents the clinical application of these treatments.

Drug Repurposing for Targeting Myeloid-Derived Suppressor-Cell-Generated Immunosuppression in Ovarian Cancer: A Literature Review of Potential Candidates

The lethality of patients with ovarian cancer (OC) remains high. Current treatment strategies often do not lead to the desired outcome due to the development of therapy resistance, resulting in high relapse rates. Additionally, clinical trials testing immunotherapy against OC have failed to reach significant results to date. The OC tumor microenvironment and specifically myeloid-derived suppressor cells (MDSC) are known to generate immunosuppression and inhibit the anti-tumor immune response following immunotherapy treatment. Our review aims to characterize potential candidate treatments to target MDSC in OC through drug-repurposing. A literature search identified repurposable compounds with evidence of their suppressing the effect of MDSC. A total of seventeen compounds were withheld, of which four were considered the most promising. Lurbinectedin, metformin, celecoxib, and 5-azacytidine have reported preclinical effects on MDSC and clinical evidence in OC. They have all been approved for a different indication, characterizing them as the most promising candidates for repurposing to treat patients with OC.

p38 MAPK and MKP-1 control the glycolytic program via the bifunctional glycolysis regulator PFKFB3 during sepsis

Hyperlactatemia often occurs in critically ill patients during severe sepsis/septic shock and is a powerful predictor of mortality. Lactate is the end product of glycolysis. While hypoxia due to inadequate oxygen delivery may result in anaerobic glycolysis, sepsis also enhances glycolysis under hyperdynamic circulation with adequate oxygen delivery. However, the molecular mechanisms involved are not fully understood. Mitogen-activated protein kinase (MAPK) families regulate many aspects of the immune response during microbial infections. MAPK phosphatase (MKP)-1 serves as a feedback control mechanism for p38 and JNK MAPK activities via dephosphorylation. Here, we found that mice deficient in Mkp-1 exhibited substantially enhanced expression and phosphorylation of 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase (PFKFB) 3, a key enzyme that regulates glycolysis following systemic Escherichia coli infection. Enhanced PFKFB3 expression was observed in a variety of tissues and cell types, including hepatocytes, macrophages, and epithelial cells. In bone marrow-derived macrophages, Pfkfb3 was robustly induced by both E. coli and lipopolysaccharide, and Mkp-1 deficiency enhanced PFKFB3 expression with no effect on Pfkfb3 mRNA stability. PFKFB3 induction was correlated with lactate production in both WT and Mkp-1-/- bone marrow-derived macrophage following lipopolysaccharide stimulation. Furthermore, we determined that a PFKFB3 inhibitor markedly attenuated lactate production, highlighting the critical role of PFKFB3 in the glycolysis program. Finally, pharmacological inhibition of p38 MAPK, but not JNK, substantially attenuated PFKFB3 expression and lactate production. Taken together, our studies suggest a critical role of p38 MAPK and MKP-1 in the regulation of glycolysis during sepsis.

Blockade of neutrophil extracellular traps ameliorates toluene diisocyanate-induced steroid-resistant asthma

BACKGROUND AND PURPOSE

Toluene diisocyanate (TDI)-induced asthma is characterized by mixed inflammation dominated by neutrophils, and is refractory to steroid treatment. Neutrophil extracellular traps (NETs) play an important role in severe asthma, but their role in TDI-induced asthma models is unclear. This study focused on the role and mechanism of NETs in steroid-resistant TDI-induced asthma.

METHODS

Induced sputum was collected from 85 asthmatic patients and 25 healthy controls to detect eDNA. A murine TDI-induced asthma model was prepared, and asthmatic mice were given dexamethasone or DNase I. In vitro, the human bronchial epithelial cell line HBE was stimulated with NETs or TDI-human serum albumin (TDI-HSA).

RESULTS

Asthma patients had higher sputum eDNA compared to healthy subjects. In asthma patients, eDNA was positively correlated with sputum neutrophils, and negatively correlated with FEV1%predicted. Airway inflammation, airway reactivity, Th2 cytokine levels in lymph supernatant, and levels of NETs were significantly increased in the TDI-induced asthmatic mice. These increases were suppressed by DNase I, but not by dexamethasone. Inhibition of NETs improved interleukin (IL)-8 and MKP1 mRNA expression, and reduced phosphorylation of GR-S226 induced by TDI. Inhibition of NETs improved airway epithelial barrier disruption, as well as p38 and ERK signaling pathways in TDI-induced asthmatic mice. In vitro, NETs promoted the expression of IL-8 mRNA in HBE cells, and reduced the expression of MKP1. IL-8 elevation induced by NETs was suppressed by a p38 inhibitor or ERK inhibitor, but not by dexamethasone. Pretreatment with RAGE inhibitor reduced NETs induced p38/ERK phosphorylation and IL-8 levels in HBE cells.

CONCLUSION

Our data suggest that targeting NETs might effectively improved TDI-induced airway inflammation and airway epithelial barrier function. This may potentially be a treatment for patients with steroid-resistance asthma.

Identification of ester-linked ubiquitylation sites during TLR7 signalling increases the number of inter-ubiquitin linkages from 8 to 12

The E3 ligase HOIL-1 forms ester bonds in vitro between ubiquitin and serine/threonine residues in proteins. Here, we exploit UbiSite technology to identify serine and threonine residues undergoing HOIL-1 catalysed ubiquitylation in macrophages stimulated with R848, an activator of the TLR7/8 heterodimer. We identify Thr12, Thr14, Ser20 and Thr22 of ubiquitin as amino acid residues forming ester bonds with the C-terminal carboxylate of another ubiquitin molecule. This increases from 8 to 12 the number of ubiquitin linkage types that are formed in cells. We also identify Ser175 of IRAK4, Ser136, Thr163 and Ser168 of IRAK2 and Thr141 of MyD88 as further sites of HOIL-1-catalysed ubiquitylation together with lysine residues in these proteins that also undergo R848-dependent ubiquitylation. These findings establish that the ubiquitin chains attached to components of myddosomes are initiated by both ester and isopeptide bonds. Ester bond formation takes place within the proline, serine, threonine-rich (PST) domains of IRAK2 and IRAK4 and the intermediate domain of MyD88. The ubiquitin molecules attached to Lys162, Thr163 and Ser168 of IRAK2 are attached to different IRAK2 molecules.

An anti-inflammatory activation sequence governs macrophage transcriptional dynamics during tissue injury in zebrafish

Macrophages are essential for tissue repair and regeneration. Yet, the molecular programs, as well as the timing of their activation during and after tissue injury are poorly defined. Using a high spatio-temporal resolution single cell analysis of macrophages coupled with live imaging after sensory hair cell death in zebrafish, we find that the same population of macrophages transitions through a sequence of three major anti-inflammatory activation states. Macrophages first show a signature of glucocorticoid activation, then IL-10 signaling and finally the induction of oxidative phosphorylation by IL-4/Polyamine signaling. Importantly, loss-of-function of glucocorticoid and IL-10 signaling shows that each step of the sequence is independently activated. Lastly, we show that IL-10 and IL-4 signaling act synergistically to promote synaptogenesis between hair cells and efferent neurons during regeneration. Our results show that macrophages, in addition to a switch from M1 to M2, sequentially and independently transition though three anti-inflammatory pathways in vivo during tissue injury in a regenerating organ.

Isoflavones daidzin and daidzein inhibit lipopolysaccharide-induced inflammation in RAW264.7 macrophages

Background

Inflammation contributes to various diseases and soybeans and legumes are shown to reduce inflammation. However, the bioactive ingredients involved and mechanisms are not completely known. We hypothesized that soy isoflavones daidzin and daidzein exhibit anti-inflammatory effect in lipopolysaccharides (LPS)-stimulated RAW264.7 macrophage cell model and that activation mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-κB) signaling pathways may mediate the effect.

Methods

Cell viability and nitric oxide (NO) level were determined by 3-(4,5)-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and Griess reagent respectively. ELISA kits and Western blotting respectively assessed the generations of pro-inflammatory cytokines and protein expressions of signaling molecules. p65 nuclear translocation was determined by immunofluorescence assay.

Results

The in vitro results showed that both isoflavones did not affect cell viability at the concentrations being tested and significantly reduced levels of NO, pro-inflammatory cytokines such as interleukin (IL)-6 and tumor necrosis factor-α (TNF-α), and inflammatory indicators such as cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) in RAW264.7 cells. Daidzin and daidzein partially suppressed MAPK signaling pathways, reducing the phosphorylation of p38 and ERK; whilst phosphorylation of JNK was mildly but not significantly decreased. For the involvement of NF-κB signaling pathways, daidzin only reduced the phosphorylation of p65 whereas daidzein effectively inhibited the phosphorylation of IKKα/β, IκBα and p65. Daidzin and daidzein inhibited p65 nuclear translocation, comparable with dexamethasone (positive control).

Conclusion

This study supports the anti-inflammatory effects of isoflavones daidzin and daidzein, which were at least partially mediated through inactivation of MAPK and/or NF-κB signaling pathways in macrophages.

Crosstalk between p38 MAPK and GR Signaling

The p38 MAPK is a signaling pathway important for cells to respond to environmental and intracellular stress. Upon activation, the p38 kinase phosphorylates downstream effectors, which control the inflammatory response and coordinate fundamental cellular processes such as proliferation, apoptosis, and differentiation. Dysregulation of this signaling pathway has been linked to inflammatory diseases and cancer. Secretion of glucocorticoids (GCs) is a classical endocrine response to stress. The glucocorticoid receptor (GR) is the primary effector of GCs and plays an important role in the regulation of cell metabolism and immune response by influencing gene expression in response to hormone-dependent activation. Its ligands, the GCs or steroids, in natural or synthetic variation, are used as standard therapy for anti-inflammatory treatment, severe asthma, autoimmune diseases, and several types of cancer. Several years ago, the GR was identified as one of the downstream targets of p38, and, at the same time, it was shown that glucocorticoids could influence p38 signaling. In this review, we discuss the role of the crosstalk between the p38 and GR in the regulation of gene expression in response to steroids and comprehend the importance and potential of this interplay in future clinical applications.

Deciphering the Molecular Signature of Human Hyalocytes in Relation to Other Innate Immune Cell Populations

Purpose

Hyalocytes are the tissue-resident innate immune cell population of the vitreous body with important functions in health and vitreoretinal disease. The purpose of this study is to gain new insights into the biology and function of human hyalocytes in comparison to other innate immune cells.

Methods

The present study applies fluorescence-activated cell sorting and RNA sequencing to compare the transcriptional profiles of human hyalocytes, retinal microglia (rMG) and classical, intermediate, and non-classical monocytes isolated from the same patients. Immunohistochemistry was applied for morphological characterization of human hyalocytes.

Results

Pairwise analysis indicates distinct differences between hyalocytes and monocytes, whereas a high degree of similarity to rMG is apparent, with comparable expression levels of established microglia markers, such as TREM2, P2RY12, and TMEM119. Among the top expressed genes in hyalocytes, SPP1, CD74, and C3, were significantly upregulated when compared with monocytes. Despite the high level of similarity of hyalocytes and rMG, ten highly expressed genes in hyalocytes compared to microglia were identified, among them FOS, DUSP1, and EGR2.

Conclusions

This study reveals a high degree of similarity between hyalocytes and retinal microglia. Nevertheless, hyalocytes exhibit some expression differences that may adapt them to the specific needs of the vitreous and provide the basis for deciphering the multiple roles of this fascinating cell population in health and vitreoretinal diseases.

The impact of calcitriol and estradiol on the SARS-CoV-2 biological activity: a molecular modeling approach

The novel coronavirus disease (COVID-19) is currently a big concern around the world. Recent reports show that the disease severity and mortality of COVID-19 infected patients may vary from gender to gender with a very high risk of death for seniors. In addition, some steroid structures have been reported to affect coronavirus, SARS-CoV-2, function and activity. The entry of SARS-CoV-2 into host cells depends on the binding of coronavirus spike protein to angiotensin converting enzyme-2 (ACE2). Viral main protease is essential for the replication of SARS-CoV-2. It was hypothesized that steroid molecules (e.g., estradiol, progesterone, testosterone, dexamethasone, hydrocortisone, prednisone and calcitriol) could occupy the active site of the protease and could alter the interaction of spike protein with ACE2. Computational data showed that estradiol interacted more strongly with the main protease active site. In the presence of calcitriol, the binding energy of the spike protein to ACE2 was increased, and transferring Apo to Locked S conformer of spike trimer was facilitated. Together, the interaction between spike protein and ACE2 can be disrupted by calcitriol. Potential use of estradiol and calcitriol to reduce virus invasion and replication needs clinical investigation.

SOCS3 Attenuates Dexamethasone-Induced M2 Polarization by Down-Regulation of GILZ via ROS- and p38 MAPK-Dependent Pathways

Suppressors of cytokine signaling (SOCS) have emerged as potential regulators of macrophage function. We have investigated mechanisms of SOCS3 action on type 2 macrophage (M2) differentiation induced by glucocorticoid using human monocytic cell lines and mouse bone marrow-derived macrophages. Treatment of THP1 monocytic cells with dexamethasone (Dex) induced ROS generation and M2 polarization promoting IL-10 and TGF-β production, while suppressing IL-1β, TNF-α and IL-6 production. SOCS3 over-expression reduced, whereas SOCS3 ablation enhanced IL-10 and TGF-β induction with concomitant regulation of ROS. As a mediator of M2 differentiation, glucocorticoid-induced leucine zipper (GILZ) was down-regulated by SOCS3 and up-regulated by shSOCS3. The induction of GILZ and IL-10 by Dex was dependent on ROS and p38 MAPK activity. Importantly, GILZ ablation led to the inhibition of ROS generation and anti-inflammatory cytokine induction by Dex. Moreover, GILZ knock-down negated the up-regulation of IL-10 production induced by shSOCS3 transduction. Our data suggest that SOCS3 targets ROS- and p38-dependent GILZ expression to suppress Dex-induced M2 polarization.

DUSP-1 Induced by PGE2 and PGE1 Attenuates IL-1β-Activated MAPK Signaling, Leading to Suppression of NGF Expression in Human Intervertebral Disc Cells

The molecular mechanism of discogenic low back pain (LBP) involves nonphysiological nerve invasion into a degenerated intervertebral disc (IVD), induced by nerve growth factor (NGF). Selective cyclooxygenase (COX)-2 inhibitors are mainly used in the treatment of LBP, and act by suppressing the inflammatory mediator prostaglandin E₂ (PGE₂), which is induced by inflammatory stimuli, such as interleukin-1β (IL-1β). However, in our previous in vitro study using cultured human IVD cells, we demonstrated that the induction of NGF by IL-1β is augmented by a selective COX-2 inhibitor, and that PGE₂ and PGE₁ suppress NGF expression. Therefore, in this study, to elucidate the mechanism of NGF suppression by PGE₂ and PGE₁, we focused on mitogen-activated protein kinases (MAPKs) and its phosphatase, dual-specificity phosphatase (DUSP)-1. IL-1β-induced NGF expression was altered in human IVD cells by MAPK pathway inhibitors. PGE₂ and PGE₁ enhanced IL-1β-induced DUSP-1 expression, and suppressed the phosphorylation of MAPKs in human IVD cells. In DUSP-1 knockdown cells established using small interfering RNA, IL-1β-induced phosphorylation of MAPKs was enhanced and prolonged, and NGF expression was significantly enhanced. These results suggest that PGE₂ and PGE₁ suppress IL-1β-induced NGF expression by suppression of the MAPK signaling pathway, accompanied by increased DUSP-1 expression.

Localized drug delivery graphene bioscaffolds for cotransplantation of islets and mesenchymal stem cells

In the present work, we developed, characterized, and tested an implantable graphene bioscaffold which elutes dexamethasone (Dex) that can accommodate islets and adipose tissue–derived mesenchymal stem cells (AD-MSCs). In vitro studies demonstrated that islets in graphene–0.5 w/v% Dex bioscaffolds had a substantial higher viability and function compared to islets in graphene-alone bioscaffolds or islets cultured alone (P < 0.05). In vivo studies, in which bioscaffolds were transplanted into the epididymal fat pad of diabetic mice, demonstrated that, when islet:AD-MSC units were seeded into graphene–0.5 w/v% Dex bioscaffolds, this resulted in complete restoration of glycemic control immediately after transplantation with these islets also showing a faster response to glucose challenges (P < 0.05). Hence, this combination approach of using a graphene bioscaffold that can be functionalized for local delivery of Dex into the surrounding microenvironment, together with AD-MSC therapy, can significantly improve the survival and function of transplanted islets.

Targeting Macrophage Dysregulation for Viral Infections: Novel Targets for Immunomodulators

A major barrier to human immunodeficiency virus (HIV-1) cure is the latent viral reservoir, which persists despite antiretroviral therapy (ART), including across the non-dividing myeloid reservoir which is found systemically in sanctuary sites across tissues and the central nervous system (CNS). Unlike activated CD4+ T cells that undergo rapid cell death during initial infection (due to rapid viral replication kinetics), viral replication kinetics are delayed in non-dividing myeloid cells, resulting in long-lived survival of infected macrophages and macrophage-like cells. Simultaneously, persistent inflammation in macrophages confers immune dysregulation that is a key driver of co-morbidities including cardiovascular disease (CVD) and neurological deficits in people living with HIV-1 (PLWH). Macrophage activation and dysregulation is also a key driver of disease progression across other viral infections including SARS-CoV-2, influenza, and chikungunya viruses, underscoring the interplay between macrophages and disease progression, pathogenesis, and comorbidity in the viral infection setting. This review discusses the role of macrophages in persistence and pathogenesis of HIV-1 and related comorbidities, SARS-CoV-2 and other viruses. A special focus is given to novel immunomodulatory targets for key events driving myeloid cell dysregulation and reservoir maintenance across a diverse array of viral infections.

Rare variant analysis in eczema identifies exonic variants in DUSP1, NOTCH4 and SLC9A4

Previous genome-wide association studies revealed multiple common variants involved in eczema but the role of rare variants remains to be elucidated. Here, we investigate the role of rare variants in eczema susceptibility. We meta-analyze 21 study populations including 20,016 eczema cases and 380,433 controls. Rare variants are imputed with high accuracy using large population-based reference panels. We identify rare exonic variants in DUSP1, NOTCH4, and SLC9A4 to be associated with eczema. In DUSP1 and NOTCH4 missense variants are predicted to impact conserved functional domains. In addition, five novel common variants at SATB1-AS1/KCNH8, TRIB1/LINC00861, ZBTB1, TBX21/OSBPL7, and CSF2RB are discovered. While genes prioritized based on rare variants are significantly up-regulated in the skin, common variants point to immune cell function. Over 20% of the single nucleotide variant-based heritability is attributable to rare and low-frequency variants. The identified rare/low-frequency variants located in functional protein domains point to promising targets for novel therapeutic approaches to eczema.

Genetic studies of eczema to date have mostly explored common genetic variation. Here, the authors perform a large meta-analysis for common and rare variants and discover 8 loci associated with eczema. Over 20% of the heritability of the condition is attributable to rare variants.

The Role of Glucocorticoids in Inflammatory Diseases

For more than 70 years, glucocorticoids (GCs) have been a powerful and affordable treatment option for inflammatory diseases. However, their benefits do not come without a cost, since GCs also cause side effects. Therefore, strong efforts are being made to improve their therapeutic index. In this review, we illustrate the mechanisms and target cells of GCs in the pathogenesis and treatment of some of the most frequent inflammatory disorders affecting the central nervous system, the gastrointestinal tract, the lung, and the joints, as well as graft-versus-host disease, which often develops after hematopoietic stem cell transplantation. In addition, an overview is provided of novel approaches aimed at improving GC therapy based on chemical modifications or GC delivery using nanoformulations. GCs remain a topic of highly active scientific research despite being one of the oldest class of drugs in medical use.

Cell Type Dependent Suppression of Inflammatory Mediators by Myocardin Related Transcription Factors

Myocardin related transcription factors (MRTFs: MYOCD/myocardin, MRTF-A, and MRTF-B) play a key role in smooth muscle cell differentiation by activating contractile genes. In atherosclerosis, MRTF levels change, and most notable is a fall of MYOCD. Previous work described anti-inflammatory properties of MRTF-A and MYOCD, occurring through RelA binding, suggesting that MYOCD reduction could contribute to vascular inflammation. Recent studies have muddled this picture showing that MRTFs may show both anti- and pro-inflammatory properties, but the basis of these discrepancies remain unclear. Moreover, the impact of MRTFs on inflammatory signaling pathways in tissues relevant to human arterial disease is uncertain. The current work aimed to address these issues. RNA-sequencing after forced expression of myocardin in human coronary artery smooth muscle cells (hCASMCs) showed reduction of pro-inflammatory transcripts, including CCL2, CXCL8, IL6, and IL1B. Side-by-side comparison of MYOCD, MRTF-A, and MRTF-B in hCASMCs, showed that the anti-inflammatory impact was shared among MRTFs. Correlation analyses using human arterial transcriptomic datasets revealed negative correlations between MYOCD, MRTFA, and SRF, on the one hand, and the inflammatory transcripts, on the other. A pro-inflammatory drive from lipopolysaccharide, did not change the size of the suppressive effect of MRTF-A in hCASMCs on either mRNA or protein levels. To examine cell type-dependence, we compared the anti-inflammatory impact in hCASMCs, with that in human bladder SMCs, in endothelial cells, and in monocytes (THP-1 cells). Surprisingly, little anti-inflammatory activity was seen in endothelial cells and monocytes, and in bladder SMCs, MRTF-A was pro-inflammatory. CXCL8, IL6, and IL1B were increased by the MRTF-SRF inhibitor CCG-1423 and by MRTF-A silencing in hCASMCs, but depolymerization of actin, known to inhibit MRTF activity, had no stimulatory effect, an exception being IL1B. Co-immunoprecipitation supported binding of MRTF-A to RelA, supporting sequestration of this important pro-inflammatory mediator as a mechanism. Dexamethasone treatment and silencing of RelA (by 76 ± 1%) however only eliminated a fraction of the MRTF-A effect (≈25%), suggesting mechanisms beyond RelA binding. Indeed, SRF silencing suggested that MRTF-A suppression of IL1B and CXCL8 depends on SRF. This work thus supports an anti-inflammatory impact of MRTF-SRF signaling in hCASMCs and in intact human arteries, but not in several other cell types.

Targeted Redesign of Suramin Analogs for Novel Antimicrobial Lead Development

The emergence of new viral infections and drug-resistant bacteria urgently necessitates expedient therapeutic development. Repurposing and redesign of existing drugs against different targets are one potential way in which to accelerate this process. Suramin was initially developed as a successful antiparasitic drug but has also shown promising antiviral and antibacterial activities. However, due to its high conformational flexibility and negative charge, suramin is considered quite promiscuous toward positively charged sites within nucleic acid binding proteins. Although some suramin analogs have been developed against specific targets, only limited structure-activity relationship studies were performed, and virtual screening has yet to be used to identify more specific inhibitor(s) based on its scaffold. Using available structures, we investigated suramin's target diversity, confirming that suramin preferentially binds to protein pockets that are both positively charged and enriched in aromatic or leucine residues. Further, suramin's high conformational flexibility allows adaptation to structurally diverse binding surfaces. From this platform, we developed a framework for structure- and docking-guided elaboration of suramin analog scaffolds using virtual screening of suramin and heparin analogs against a panel of diverse therapeutically relevant viral and bacterial protein targets. Use of this new framework to design potentially specific suramin analogs is exemplified using the SARS-CoV-2 RNA-dependent RNA polymerase and nucleocapsid protein, identifying leads that might inhibit a wide range of coronaviruses. The approach presented here establishes a computational framework for designing suramin analogs against different bacterial and viral targets and repurposing existing drugs for more specific inhibitory activity.

Glucocorticoid Resistance: Interference between the Glucocorticoid Receptor and the MAPK Signalling Pathways

Endogenous glucocorticoids (GCs) are steroid hormones that signal in virtually all cell types to modulate tissue homeostasis throughout life. Also, synthetic GC derivatives (pharmacological GCs) constitute the first-line treatment in many chronic inflammatory conditions with unquestionable therapeutic benefits despite the associated adverse effects. GC actions are principally mediated through the GC receptor (GR), a ligand-dependent transcription factor. Despite the ubiquitous expression of GR, imbalances in GC signalling affect tissues differently, and with variable degrees of severity through mechanisms that are not completely deciphered. Congenital or acquired GC hypersensitivity or resistance syndromes can impact responsiveness to endogenous or pharmacological GCs, causing disease or inadequate therapeutic outcomes, respectively. Acquired GC resistance is defined as loss of efficacy or desensitization over time, and arises as a consequence of chronic inflammation, affecting around 30% of GC-treated patients. It represents an important limitation in the management of chronic inflammatory diseases and cancer, and can be due to impairment of multiple mechanisms along the GC signalling pathway. Among them, activation of the mitogen-activated protein kinases (MAPKs) and/or alterations in expression of their regulators, the dual-specific phosphatases (DUSPs), have been identified as common mechanisms of GC resistance. While many of the anti-inflammatory actions of GCs rely on GR-mediated inhibition of MAPKs and/or induction of DUSPs, the GC anti-inflammatory capacity is decreased or lost in conditions of excessive MAPK activation, contributing to disease susceptibility in tissue- and disease- specific manners. Here, we discuss potential strategies to modulate GC responsiveness, with the dual goal of overcoming GC resistance and minimizing the onset and severity of unwanted adverse effects while maintaining therapeutic potential.

Lung Targeted Lipopolymeric Microspheres of Dexamethasone for the Treatment of ARDS

Acute respiratory distress syndrome (ARDS), a catastrophic illness of multifactorial etiology, involves a rapid upsurge in inflammatory cytokines that leads to hypoxemic respiratory failure. Dexamethasone, a synthetic corticosteroid, mitigates the glucocorticoid-receptor-mediated inflammation and accelerates tissue homeostasis towards disease resolution. To minimize non-target organ side effects arising from frequent and chronic use of dexamethasone, we designed biodegradable, lung-targeted microspheres with sustained release profiles. Dexamethasone-loaded lipopolymeric microspheres of PLGA (Poly Lactic-co-Glycolic Acid) and DPPC (Dipalmitoylphosphatidylcholine) stabilized with vitamin E TPGS (D-α-tocopheryl polyethylene glycol succinate) were prepared by a single emulsion technique that had a mean diameter of 8.83 ± 0.32 μm and were spherical in shape as revealed from electron microscopy imaging. Pharmacokinetic and biodistribution patterns studied in the lungs, liver, and spleen of Wistar rats showed high selectivity and targeting efficiency for the lung tissue (re 13.98). As a proof-of-concept, in vivo efficacy of the microspheres was tested in the lipopolysaccharide-induced ARDS model in rats. Inflammation markers such as IL-1β, IL-6, and TNF-α, quantified in the bronchoalveolar lavage fluid indicated major improvement in rats treated with dexamethasone microspheres by intravenous route. Additionally, the microspheres substantially inhibited the protein infiltration, neutrophil accumulation and lipid peroxidation in the lungs of ARDS bearing rats, suggesting a reduction in oxidative stress. Histopathology showed decreased damage to the pulmonary tissue upon treatment with the dexamethasone-loaded microspheres. The multipronged formulation technology approach can thus serve as a potential treatment modality for reducing lung inflammation in ARDS. An improved therapeutic profile would help to reduce the dose, dosing frequency and, eventually, the toxicity.

Glucocorticoid receptor triggers a reversible drug-tolerant dormancy state with acquired therapeutic vulnerabilities in lung cancer

The glucocorticoid receptor (GR) regulates gene expression, governing aspects of homeostasis, but is also involved in cancer. Pharmacological GR activation is frequently used to alleviate therapy-related side-effects. While prior studies have shown GR activation might also have anti-proliferative action on tumours, the underpinnings of glucocorticoid action and its direct effectors in non-lymphoid solid cancers remain elusive. Here, we study the mechanisms of glucocorticoid response, focusing on lung cancer. We show that GR activation induces reversible cancer cell dormancy characterised by anticancer drug tolerance, and activation of growth factor survival signalling accompanied by vulnerability to inhibitors. GR-induced dormancy is dependent on a single GR-target gene, CDKN1C, regulated through chromatin looping of a GR-occupied upstream distal enhancer in a SWI/SNF-dependent fashion. These insights illustrate the importance of GR signalling in non-lymphoid solid cancer biology, particularly in lung cancer, and warrant caution for use of glucocorticoids in treatment of anticancer therapy related side-effects.

Host Directed Therapies for Tuberculous Meningitis

A dysregulated host immune response significantly contributes to morbidity and mortality in tuberculous meningitis (TBM). Effective host directed therapies (HDTs) are critical to improve survival and clinical outcomes. Currently only one HDT, dexamethasone, is proven to improve mortality. However, there is no evidence dexamethasone reduces morbidity, how it reduces mortality is uncertain, and it has no proven benefit in HIV co-infected individuals. Further research on these aspects of its use, as well as alternative HDTs such as aspirin, thalidomide and other immunomodulatory drugs is needed. Based on new knowledge from pathogenesis studies, repurposed therapeutics which act upon small molecule drug targets may also have a role in TBM. Here we review existing literature investigating HDTs in TBM, and propose new rationale for the use of novel and repurposed drugs. We also discuss host variable responses and evidence to support a personalised approach to HDTs in TBM.

Host Directed Therapies for Tuberculous Meningitis

A dysregulated host immune response significantly contributes to morbidity and mortality in tuberculous meningitis (TBM). Effective host directed therapies (HDTs) are critical to improve survival and clinical outcomes. Currently only one HDT, dexamethasone, is proven to improve mortality. However, there is no evidence dexamethasone reduces morbidity, how it reduces mortality is uncertain, and it has no proven benefit in HIV co-infected individuals. Further research on these aspects of its use, as well as alternative HDTs such as aspirin, thalidomide and other immunomodulatory drugs is needed. Based on new knowledge from pathogenesis studies, repurposed therapeutics which act upon small molecule drug targets may also have a role in TBM. Here we review existing literature investigating HDTs in TBM, and propose new rationale for the use of novel and repurposed drugs. We also discuss host variable responses and evidence to support a personalised approach to HDTs in TBM.

Impacts of heat stress on immune responses and oxidative stress in farm animals and nutritional strategies for amelioration

Heat stress is one of the greatest challenges for the global livestock industries as increased environmental temperature and humidity compromises animal production during summer leading to devastating economic consequences. Over the last 30 years, significant developments have been achieved in cooling and provision of shade and shelter to mitigate heat stress reducing some of the losses associated with heat stress in farm animals. However, the recent increase in the incidence of heat waves which are also becoming more severe and lasting longer, due to climate change, further accentuates the problem of heat stress. Economic losses associated with heat stress are both direct due to loss in production and animal life, and indirect due to poorer quality products as a result of poor animal health and welfare. Animal health is affected due to impaired immune responses and increased reactive oxygen species production and/or deficiency of antioxidants during heat stress leading to an imbalance between oxidant and antioxidants and resultant oxidative stress. Research over the last 20 years has achieved partial success in understanding the intricacies of heat stress impacts on oxidative stress and immune responses and developing interventions to ameliorate impacts of heat stress, improving immune responses and farm animal health. This paper reviews the body of knowledge on heat stress impacts on immune response in farm animals. The impacts of heat stress on both cell-mediated and humoral immune responses have been discussed identifying the shift in immune response from cell-mediated towards humoral response, thereby weakening the immune status of the animal. Both species and breed differences have been identified as influencing how heat stress impacts the immune status of farm animals. In addition, crosstalk signaling between the immune system and oxidative stress has been considered and the role of antioxidants as potential nutritional strategies to mitigate heat stress has been discussed.

Drug targets, mechanisms of drug action, and therapeutics against SARS-CoV-2

The recent outbreak of COVID-19 has affected human lives severely. The human-to-human transmission of this viral disease has become deadly due to the unavailability of COVID-19 specific drugs. Here, an overview of various attempts made to design different therapeutic agents against various structural and non-structural proteins of SARS-CoV-2 has been summarized. Emphasis has been made to highlight the mechanisms of drug action and ways to design better inhibitors of these proteins. The roles of anti-oxidants and vitamins in suppressing COVID-19 are also discussed.

Repression of transcription by the glucocorticoid receptor: A parsimonious model for the genomics era

Glucocorticoids are potent anti-inflammatory drugs that are used to treat an extraordinary range of human disease, including COVID-19, underscoring the ongoing importance of understanding their molecular mechanisms. Early studies of GR signaling led to broad acceptance of models in which glucocorticoid receptor (GR) monomers tether repressively to inflammatory transcription factors, thus abrogating inflammatory gene expression. However, newer data challenge this core concept and present an exciting opportunity to reframe our understanding of GR signaling. Here, we present an alternate, two-part model for transcriptional repression by glucocorticoids. First, widespread GR-mediated induction of transcription results in rapid, primary repression of inflammatory gene transcription and associated enhancers through competition-based mechanisms. Second, a subset of GR-induced genes, including targets that are regulated in coordination with inflammatory transcription factors such as NF-κB, exerts secondary repressive effects on inflammatory gene expression. Within this framework, emerging data indicate that the gene set regulated through the cooperative convergence of GR and NF-κB signaling is central to the broad clinical effectiveness of glucocorticoids in terminating inflammation and promoting tissue repair.

COVID-19 and Cancer Comorbidity: Therapeutic Opportunities and Challenges

The coronavirus disease 2019 (COVID-19) is a viral disease caused by a novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that affects the respiratory system of infected individuals. COVID-19 spreads between humans through respiratory droplets produced when an infected person coughs or sneezes. The COVID-19 outbreak originated in Wuhan, China at the end of 2019. As of 29 Sept 2020, over 235 countries, areas or territories across the globe reported a total of 33,441,919 confirmed cases, and 1,003,497 confirmed deaths due to COVID-19. Individuals of all ages are at risk for infection, but in most cases disease severity is associated with age and pre-existing diseases that compromise immunity, like cancer. Numerous reports suggest that people with cancer can be at higher risk of severe illness and related deaths from COVID-19. Therefore, managing cancer care under this pandemic is challenging and requires a collaborative multidisciplinary approach for optimal care of cancer patients in hospital settings. In this comprehensive review, we discuss the impact of the COVID-19 pandemic on cancer patients, their care, and treatment. Further, this review covers the SARS-CoV-2 pandemic, genome characterization, COVID-19 pathophysiology, and associated signaling pathways in cancer, and the choice of anticancer agents as repurposed drugs for treating COVID-19.

Control of immunity by glucocorticoids in health and disease

Animals receive environmental stimuli from neural signals in order to produce hormones that control immune responses. Glucocorticoids (GCs) are a group of steroid hormones produced in the adrenal cortex and well-known mediators for the nervous and immune systems. GC secretion is induced by circadian rhythm and stress, and plasma GC levels are high at the active phase of animals and under stress condition. Clinically, GCs are used for allergies, autoimmunity, and chronic inflammation, because they have strong anti-inflammatory effects and induce the apoptosis of lymphocytes. Glucocorticoid receptor (GR) acts as a transcription factor and represses the expression of inflammatory cytokines, chemokines, and prostaglandins by binding to its motif, glucocorticoid-response element, or to other transcription factors. In mice, GR suppresses the antigen-stimulated inflammation mediated by macrophages, dendritic cells, and epithelial cells, and impairs cytotoxic immune responses by downregulating interferon-γ production and inhibiting the development of type-1 helper T cells, CD8+ T cells, and natural killer cells. These immune inhibitory effects prevent lethality by excessive inflammation, but at the same time increase the susceptibility to infection and cancer. GCs can also activate the immune system. The circadian cycle of GC secretion controls the diurnal oscillations of the distribution and response of T cells, thus supporting T cell maintenance and effective immune protection against infection. Moreover, several reports have shown that GR has the potential to enhance the activities of Th2, Th17, and immunoglobulin-producing B cells. Stress has two different effects on immune responses: immune suppression to cause mortality by infection and cancer, and excessive immune activation to induce chronic inflammation and autoimmune disease. Consistently, stress-induced GCs strongly suppress cell-mediated immunity and cause viral infection and tumor development. They may also enhance the development of pathogenic helper T cells and cause tissue damage through neural and intestinal inflammation. Past studies have reported the positive and negative effects of GCs on the immune system. These opposing properties of GCs may regulate the immune balance between the responsiveness to antigens and excessive inflammation in steady-state and stress conditions.

Efficacy of Dexamethasone for Reducing Edema and Ecchymosis After Rhinoplasty: A Systematic Review and Meta-analysis

BACKGROUND

Rhinoplasty is one of the most challenging cosmetic surgical operations. The procedure has been known to precipitate higher levels of edema and ecchymosis in the periorbital and paranasal regions. The literature recommends the use of corticosteroids such as dexamethasone to alleviate these postoperative morbidities. In this review, we aim to provide a current state of evidence concerning the influence of dexamethasone together with rhinoplasty on intraoperative and postoperative morbidities.

METHODS

A systematic identification of the literature was performed according to PRISMA guidelines on four academic databases: MEDLINE, Scopus, EMBASE and CENTRAL. A meta-analysis compared the influence of dexamethasone and normal saline administered during rhinoplasty on the amount of intraoperative blood loss, postoperative edema and ecchymosis.

RESULTS

Out of 1045 records, ten articles including 374 participants (mean age: 25.8 ± 2.5 years) were included in this review. This systematic review presents a 1b level of evidence supporting the use of dexamethasone during rhinoplasty to reduce the amount of intraoperative blood loss, edema and ecchymosis as compared to normal saline. The meta-analysis reveals beneficial effects for dexamethasone interventions by demonstrating medium to large effect reduction of the amount of intraoperative blood loss (Hedge's g: - 0.69), mean edema score (- 1.09) and mean ecchymosis score (- 1.03) as compared to placebo groups using normal saline.

CONCLUSION

The current systematic review and meta-analysis recommend the administration of dexamethasone with rhinoplasty. The review reports beneficial effects of dexamethasone's administration as compared to normal saline for reducing the amount of intraoperative blood loss, postoperative edema and ecchymosis.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

New insights into the cell- and tissue-specificity of glucocorticoid actions

Glucocorticoids (GCs) are endogenous hormones that are crucial for the homeostasis of the organism and adaptation to the external environment. Because of their anti-inflammatory effects, synthetic GCs are also extensively used in clinical practice. However, almost all cells in the body are sensitive to GC regulation. As a result, these mediators have pleiotropic effects, which may be undesirable or detrimental to human health. Here, we summarize the recent findings that contribute to deciphering the molecular mechanisms downstream of glucocorticoid receptor activation. We also discuss the complex role of GCs in infectious diseases such as sepsis and COVID-19, in which the balance between pathogen elimination and protection against excessive inflammation and immunopathology needs to be tightly regulated. An understanding of the cell type- and context-specific actions of GCs from the molecular to the organismal level would help to optimize their therapeutic use.

Glucocorticoids Promote the Onset of Acute Experimental Colitis and Cancer by Upregulating mTOR Signaling in Intestinal Epithelial Cells

The therapeutic effects of glucocorticoids on colitis and colitis-associated cancer are unclear. In this study, we investigated the therapeutic roles of glucocorticoids in acute experimental ulcerative colitis and colitis-associated cancer in mice and their immunoregulatory mechanisms. Murine acute ulcerative colitis was induced by dextran sulfate sodium (DSS) and treated with dexamethasone (Dex) at different doses. Dex significantly exacerbated the onset and severity of DSS-induced colitis and potentiated mucosal inflammatory macrophage and neutrophil infiltration, as well as cytokine production. Furthermore, under inflammatory conditions, the expression of the glucocorticoid receptor (GR) did not change significantly, while mammalian target of rapamycin (mTOR) signaling was higher in colonic epithelial cells than in colonic immune cells. The deletion of mTOR in intestinal epithelial cells, but not that in myeloid immune cells, in mice significantly ameliorated the severe course of colitis caused by Dex, including weight loss, clinical score, colon length, pathological damage, inflammatory cell infiltration and pro-inflammatory cytokine production. These data suggest that mTOR signaling in intestinal epithelial cells, mainly mTORC1, plays a critical role in the Dex-induced exacerbation of acute colitis and colitis-associated cancer. Thus, these pieces of evidence indicate that glucocorticoid-induced mTOR signaling in epithelial cells is required in the early stages of acute ulcerative colitis by modulating the dynamics of innate immune cell recruitment and activation.