The glucocorticoid receptor in recipient cells keeps cytokine secretion in acute graft-versus-host disease at bay

Environmental signals perceived by the brain abate pro-metastatic monocytes by dampening glucocorticoids receptor signaling

While positive social-behavioral factors predict longer survival in cancer patients, the underlying mechanisms are unknown. Since tumor metastasis are the major cancer mortality factor, we investigated how an enriched environment (EE) conductive to enhanced sensory, cognitive and motor stimulation impact metastatic progression in lungs following intravasation in the circulation. We find that mice housed in EE exhibited reduced number of lung metastatic foci compared to control mice housed in a standard environment (SE). Compared to SE mice, EE mice increased lung inflammation as early as 4 days after circulating tumor cells extravasation. The impact of environmental signals on lung metastasis is independent of adrenergic receptors signaling. By contrast, we find that serum corticosterone levels are lower in EE mice and that glucocorticoid receptor (GR) antagonist reduces the number of lung metastasis in SE mice. In addition, the difference of the number of lung metastasis between SE and EE mice is abolished when inflammatory monocytes are rendered deficient in GR signaling. This decreased GR signaling in inflammatory monocytes of SE mice results in an exacerbated inflammatory profile in the lung. Our study shows that not only EE reduces late stages of metastatic progression in lungs but disclose a novel anti-tumor mechanism whereby GR-dependent reprogramming of inflammatory monocytes can inhibit metastatic progression in lungs. Moreover, while inflammatory monocytes have been shown to promote cancer progression, they also have an anti-tumor effect, suggesting that their role is more complex than currently thought.

Ruxolitinib-corticosteroid as first-line therapy for newly diagnosed high-risk acute graft versus host disease: study protocol for a multicenter, randomized, phase II controlled trial

BACKGROUND

The response rate of the first-line therapy with corticosteroid for acute graft versus host disease (aGVHD) is about 50%, and steroid-refractory disease is associated with high mortality. The improved response rate to the first-line therapy of newly diagnosed aGVHD patients would result in therapeutic benefits. Ruxolitinib, a selective Janus kinase (JAK) 1/2 inhibitor, has been approved for the treatment of steroid-refractory acute GVHD. The addition of ruxolitinib to the first-line therapy may improve the efficacy of corticosteroids.

METHODS

This investigator-initiated, open-label, multicenter, prospective randomized, and controlled two-arm phase II study compares the efficacy and safety of ruxolitinib combined with 1 mg/kg methylprednisolone versus 2 mg/kg methylprednisolone alone in newly diagnosed aGVHD patients. Patients with intermediate or high-risk aGVHD, as defined by the Minnesota aGVHD high-risk score and biomarker algorithm, are eligible for this study. A total of 198 patients will be randomized at a 1:1 ratio and assigned a GVHD risk (intermediate versus high risk) and disease status before transplantation (complete remission versus no complete remission). The primary endpoint is the overall response rate on day 28, which is defined as an improvement of at least one stage in the severity of aGVHD in one organ without deterioration in any other organ or disappearance of any GVHD signs from all organs without requiring new systemic immunosuppressive treatment. The secondary objectives consist of response time, response duration, overall survival, disease-free survival, non-relapse mortality, failure-free survival, and changes in serum levels of proinflammatory cytokines and GVHD-related biomarkers.

DISCUSSION

This open-label, multicenter, two-arm randomized trial will evaluate whether the addition of ruxolitinib combined with corticosteroid is superior to corticosteroid alone in newly diagnosed high-risk aGVHD.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04061876 (version number: 2019.5.18). Registered on July 16, 2019.

Dimerization of the Glucocorticoid Receptor and Its Importance in (Patho)physiology: A Primer

The glucocorticoid receptor (GR) is a very versatile protein that comes in several forms, interacts with many proteins and has multiple functions. Numerous therapies are based on GRs’ actions but the occurrence of side effects and reduced responses to glucocorticoids have motivated scientists to study GRs in great detail. The notion that GRs can perform functions as a monomeric protein, but also as a homodimer has raised questions about the underlying mechanisms, structural aspects of dimerization, influencing factors and biological functions. In this review paper, we are providing an overview of the current knowledge and insights about this important aspect of GR biology.

Characterization of testicular macrophagesubpopulations in mice

Testis is an immune privileged site, a feature that prevents germ cells from eliciting an autoimmune response. Macrophages contribute to this state of tolerance by adopting an immunoregulatory phenotype. Here, we further characterized their features in mice by analyzing surface markers, anatomic localization as well as morphology and function. Testicular macrophages (TMF) were stained for various surface receptors, and MHCII and CD206 were found to be most suitable to discriminate between two subpopulations. Our immunohistochemical analysis further confirmed a predominant localization of CD206+ cells in the interstitial space. Imaging flow cytometry revealed that both subtypes of TMF differed in size and contrast, and to some extent also in their ability to engulf high-molecular dextran. To investigate whether the polarization of the immune system had any influence on the phenotype of TMF, we compared C57BL/6 and BALB/c mice. Importantly, our analysis revealed that the abundance of cells expressing either MHCII or any of the scavenger receptors CD206, CD163 and CD71 differed between both mouse strains. In addition, the presence of the glucocorticoid receptor in macrophages affected the ratio between individual subpopulations, which is consistent with a crucial role of glucocorticoids in macrophage polarization. Collectively, our results indicate that TMF are composed in a variable ratio of distinct subsets with characteristic features, which may shape the immune privilege of the testis also in humans.

Topical neurokinin-1 receptor antagonist Fosaprepitant ameliorates ocular graft-versus-host disease in a preclinical mouse model

PURPOSE

to assess the effect of topical administration of the Neurokin-1 receptor (NK1R) antagonist Fosaprepitant in a pre-clinical model of ocular Graft-versus-Host disease (GVHD).

METHODS

BALB/c mice were pre-conditioned by myeloablative total body irradiation and subjected to allogeneic bone marrow transplantation and mature T cell infusion (BM + T). BM-transplanted mice (BM) were used as controls. Ocular GVHD was specifically assessed by quantifying corneal epithelial damage, tear secretion, blepharitis and phimosis, 3 times/week for 28 days post-transplantation. A group of BM + T mice received Fosaprepitant 10 mg/mL, 6 times/day, topically, from day 7-29 after transplantation. After sacrifice, the expression of NK1R, CD45, CD3, and CXCL10 was quantified in the cornea, conjunctiva, and lacrimal gland by immunohistochemistry.

RESULTS

BM + T mice developed corneal epithelial damage (day 0-29, p < 0.001), blepharitis (day 0-29, p < 0.001), and phimosis (day 0-29, p < 0.01), and experienced decreased tear secretion (day 21, p < 0.01) compared to controls. NK1R was found upregulated in corneal epithelium (p < 0.01) and lacrimal gland (p < 0.01) of BM + T mice. Fosaprepitant administration significantly reduced corneal epithelial damage (p < 0.05), CD45⁺ (p < 0.05) and CD3⁺ (p < 0.01) immune cell infiltration in the cornea and conjunctiva (p < 0.001 and p < 0.001, respectively). In addition, Fosaprepitant reduced the expression of CXCL10 in the cornea (p < 0.05) and in the lacrimal gland (p < 0.05).

CONCLUSIONS

Our results suggest that NK1R represents a novel druggable pathway for the therapy of ocular GVHD.

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.

A flow cytometric approach to study glucocorticoid receptor expression in immune cell subpopulations of genetically engineered mice

Glucocorticoids (GCs) constitute one of the most powerful classes of anti-inflammatory agents and are used for the treatment of a plethora of diseases related to autoimmunity, allergy, cancer, and infection. In the last two decades, multiple studies using genetically engineered mice with targeted deletions of the GC receptor (GR) in individual cell types have provided insights into the mechanisms of GCs in the control of the immune system. The characterization of GR expression in these mouse models, however, mostly relied on the analysis of mRNA expression or reporter gene activity. In contrast, approaches directly detecting the GR protein on a cellular level are scarce. Thus, we here used a flow cytometric method to analyze mice in which the GR gene locus was disrupted with the help of a Cre recombinase expressed under the control of either the lck or the lysM promoter. Measuring GR protein expression in immune cell subpopulations unveiled an efficient and highly selective depletion in both strains of knock-out mice in accordance with the expected cellular specificity of the employed promoters for T cells or myeloid cells, respectively. The flow cytometric data were well in line with those from the analysis of GR mRNA expression in magnetically sorted immune cell subpopulations but they could be obtained much more quickly. In summary, our data indicate that flow cytometry is a powerful tool with which to define GR protein content at a single cell level when studying the function of GCs in the immune system.

Immunopathology and biology-based treatment of steroid-refractory graft-versus-host disease

Acute graft-versus-host disease (GVHD) is 1 of the major life-threating complications after allogeneic cell transplantation. Although steroids remain first-line treatment, roughly one-half of patients will develop steroid-refractory GVHD (SR-GVHD), which portends an extremely poor prognosis. Many agents that have shown encouraging response rates in early phase 1/2 trials for prevention and treatment have been unsuccessful in demonstrating a survival advantage when applied in the setting of SR-GVHD. The discovery of novel treatments has been further complicated by the absence of clinically informative animal models that address what may reflect a distinct pathophysiology. Nonetheless, the combined knowledge of established bone marrow transplantation models and recent human trials in SR-GVHD patients are beginning to illuminate novel mechanisms for inhibiting T-cell signaling and promoting tissue tolerance that provide an increased understanding of the underlying biology of SR-GVHD. Here, we discuss recent findings of newly appreciated cellular and molecular mechanisms and provide novel translational opportunities for advancing the effectiveness of treatment in SR-GVHD.

Glucocorticoids delivered by inorganic-organic hybrid nanoparticles mitigate acute graft-versus-host disease and sustain graft-versus-leukemia activity

Glucocorticoids (GCs) are widely used to treat acute graft-versus-host disease (aGvHD) due to their immunosuppressive activity, but they also reduce the beneficial graft-versus-leukemia (GvL) effect of the allogeneic T cells contained in the graft. Here, we tested whether aGvHD therapy could be improved by delivering GCs with the help of inorganic-organic hybrid nanoparticles (IOH-NPs) that preferentially target myeloid cells. IOH-NPs containing the GC betamethasone (BMP-NPs) efficiently reduced morbidity, mortality, and tissue damage in a totally MHC mismatched mouse model of aGvHD. Therapeutic activity was lost in mice lacking the GC receptor (GR) in myeloid cells, confirming the cell type specificity of our approach. BMP-NPs had no relevant systemic activity but suppressed cytokine and chemokine gene expression locally in the small intestine, which presumably explains their mode of action. Most importantly, BMP-NPs delayed the development of an adoptively transferred B cell lymphoma better than the free drug, although the overall incidence was unaffected. Our findings thus suggest that employing IOH-NPs could diminish the risk of relapse associated with GC therapy of aGvHD patients while still allowing to efficiently ameliorate the disease.

Glucocorticoid resistance of allogeneic T cells alters the gene expression profile in the inflamed small intestine of mice suffering from acute graft-versus-host disease

Glucocorticoids (GCs) play an important role in controlling acute graft-versus-host disease (aGvHD), a frequent complication of allogeneic hematopoietic stem cell transplantation. The anti-inflammatory activity of GCs is mainly ascribed to the modulation of T cells and macrophages, for which reason a genetically induced GC resistance of either of these cell types causes aggravated aGvHD. Since only a few genes are currently known that are differentially regulated under these conditions, we analyzed the expression of 54 candidate genes in the inflamed small intestine of mice suffering from aGvHD when either allogeneic T cells or host myeloid cells were GC resistant using a microfluidic dynamic array platform for high-throughput quantitative PCR. The majority of genes categorized as cytokines (e.g. Il2, Il6), chemokines (e.g. Ccl2, Cxcl1), cell surface receptors (e.g. Fasl, Ctla4) and intracellular molecules (e.g. Dusp1, Arg1) were upregulated in mice transplanted with GC resistant allogeneic T cells. Moreover, the expression of several genes linked to energy metabolism (e.g. Glut1) was altered. Surprisingly, mice harboring GC resistant myeloid cells showed almost no changes in gene expression despite their fatal disease course after aGvHD induction. To identify additional genes in the inflamed small intestine that were affected by a GC resistance of allogeneic T cells, we performed an RNAseq analysis, which uncovered more than 500 differentially expressed transcripts (e.g. Cxcr6, Glut3, Otc, Aoc1, Il1r1, Sphk1) that were enriched for biological processes associated with inflammation and tissue disassembly. The changes in gene expression could be confirmed during full-blown disease but hardly any of them in the preclinical phase using high-throughput quantitative PCR. Further analysis of some of these genes revealed a highly selective expression pattern in T cells, intestinal epithelial cells and macrophages, which correlated with their regulation during disease progression. Collectively, we identified an altered gene expression profile caused by GC resistance of transplanted allogeneic T cells, which could help to define new targets for aGvHD therapy.

GR Dimerization and the Impact of GR Dimerization on GR Protein Stability and Half-Life

Pharmacologically, glucocorticoids, which mediate their effects via the glucocorticoid receptor (GR), are a most effective therapy for inflammatory diseases despite the fact that chronic use causes side-effects and acquired GC resistance. The design of drugs with fewer side-effects and less potential for the development of resistance is therefore considered crucial for improved therapy. Dimerization of the GR is an integral step in glucocorticoid signaling and has been identified as a possible molecular site to target for drug development of anti-inflammatory drugs with an improved therapeutic index. Most of the current understanding regarding the role of GR dimerization in GC signaling derives for dimerization deficient mutants, although the role of ligands biased toward monomerization has also been described. Even though designing for loss of dimerization has mostly been applied for reduction of side-effect profile, designing for loss of dimerization may also be a fruitful strategy for the development of GC drugs with less potential to develop GC resistance. GC-induced resistance affects up to 30% of users and is due to a reduction in the GR functional pool. Several molecular mechanisms of GC-mediated reductions in GR pool have been described, one of which is the autologous down-regulation of GR density by the ubiquitin-proteasome-system (UPS). Loss of GR dimerization prevents autologous down-regulation of the receptor through modulation of interactions with components of the UPS and post-translational modifications (PTMs), such as phosphorylation, which prime the GR for degradation. Rational design of conformationally biased ligands that select for a monomeric GR conformation, which increases GC sensitivity through improving GR protein stability and increasing half-life, may be a productive avenue to explore. However, potential drawbacks to this approach should be considered as well as the advantages and disadvantages in chronic vs. acute treatment regimes.

Defining the role of glucocorticoids in inflammation

An established body of knowledge and clinical practice has argued in favor of the use of glucocorticoids in various chronic inflammatory and autoimmune diseases. However, the very well-known adverse effects associated with their treatment hampers continuation of therapy with glucocorticoids. Analyses of the molecular mechanisms underlying the actions of glucocorticoids have led to the discovery of several mediators that add complexity and diversity to the puzzling world of these hormones and anti-inflammatory drugs. Such mediators hold great promise as alternative pharmacologic tools to be used as anti-inflammatory drugs with the same properties as glucocorticoids, but avoiding their metabolic side effects. This review summarizes findings about the molecular targets and mediators of glucocorticoid function.