Liver receptor homolog-1 (NR5a2) regulates CD95/Fas ligand transcription and associated T-cell effector functions

Blocking the LRH-1/LCN2 axis by ML-180, an LRH-1 inverse agonist, ameliorates osteoarthritis via inhibiting the MAPK pathway

Osteoarthritis (OA) is a chronic and degenerative disease marked by inflammation and extracellular matrix (ECM) degeneration, contributing to synovial inflammation and cartilage destruction. Accumulating evidence has demonstrated that Liver receptor homolog-1 (LRH-1), an orphan nuclear receptor, mediates inflammatory response. However, there is a lack of evidence regarding the regulatory role of LRH-1 in OA pathogenesis. In this study, we confirmed that chondrocytes expressed LRH-1, and observed its upregulation in both IL-1β-treated chondrocytes and cartilage of destabilization of the medial meniscus (DMM)-operated mice. Overexpression of LRH-1 promoted inflammation and dysregulation of ECM metabolism in IL-1β-induced chondrocytes, reversed by inhibition of LRH-1 with ML-180 or gene silencing to protect chondrocytes. Moreover, ML-180 treatment in vivo improved the deteriorated OA phenotypes in mouse models, alleviating OA development. Mechanistically, RNA sequencing revealed that Lipocalin-2 (LCN2), a member of the lipocalin family associated with inflammation, is located downstream of LRH-1 and is positively regulated by it. Furthermore, the LRH-1/LCN2 axis mainly relied on activating the mitogen-activated protein kinase (MAPK) signaling pathway to promote inflammation and dysregulation of ECM metabolism, ultimately damaging chondrocytes. Our findings demonstrate that LRH-1 positively modulates LCN2,activating the MAPK pathway, indicating that targeting the LRH-1/LCN2/MAPK axis may represent a potential therapeutic strategy for OA.

Role of Protein Regulators of Cholesterol Homeostasis in Immune Modulation and Cancer Pathophysiology

Cholesterol metabolism and homeostasis have emerged as important factors governing various aspects of cancer biology. Clinical associations between circulating cholesterol and poor prognosis or use of cholesterol-lowering medication and improved prognosis have been noted for several different solid tumors. Mechanistically, cholesterol has many different direct and indirect effects on cancer cells themselves but is also critically involved in shaping the function of other cells of the tumor microenvironment, especially immune cells. There are 2 major feedback loops regulating cholesterol homeostasis. Here we highlight the major proteins involved in the so-called oxysterol-bile acid feedback loop and discuss how each has been implicated in cancer biology. We focus on roles within the immune system with implications for cancer. Given that many of these proteins are enzymes or nuclear receptors, both of which are amenable to small molecule intervention, we posit that this axis may represent a promising area for therapeutic intervention.

LRH-1/NR5A2 targets mitochondrial dynamics to reprogram type 1 diabetes macrophages and dendritic cells into an immune tolerance phenotype

BACKGROUND

The complex aetiology of type 1 diabetes (T1D), characterised by a detrimental cross-talk between the immune system and insulin-producing beta cells, has hindered the development of effective disease-modifying therapies. The discovery that the pharmacological activation of LRH-1/NR5A2 can reverse hyperglycaemia in mouse models of T1D by attenuating the autoimmune attack coupled to beta cell survival/regeneration prompted us to investigate whether immune tolerisation could be translated to individuals with T1D by LRH-1/NR5A2 activation and improve islet survival.

METHODS

Peripheral blood mononuclear cells (PBMCs) were isolated from individuals with and without T1D and derived into various immune cells, including macrophages and dendritic cells. Cell subpopulations were then treated or not with BL001, a pharmacological agonist of LRH-1/NR5A2, and processed for: (1) Cell surface marker profiling, (2) cytokine secretome profiling, (3) autologous T-cell proliferation, (4) RNAseq and (5) proteomic analysis. BL001-target gene expression levels were confirmed by quantitative PCR. Mitochondrial function was evaluated through the measurement of oxygen consumption rate using a Seahorse XF analyser. Co-cultures of PBMCs and iPSCs-derived islet organoids were performed to assess the impact of BL001 on beta cell viability.

RESULTS

LRH-1/NR5A2 activation induced a genetic and immunometabolic reprogramming of T1D immune cells, marked by reduced pro-inflammatory markers and cytokine secretion, along with enhanced mitohormesis in pro-inflammatory M1 macrophages and mitochondrial turnover in mature dendritic cells. These changes induced a shift from a pro-inflammatory to an anti-inflammatory/tolerogenic state, resulting in the inhibition of CD4+ and CD8+ T-cell proliferation. BL001 treatment also increased CD4+/CD25+/FoxP3+ regulatory T-cells and Th2 cells within PBMCs while decreasing CD8+ T-cell proliferation. Additionally, BL001 alleviated PBMC-induced apoptosis and maintained insulin expression in human iPSC-derived islet organoids.

CONCLUSION

These findings demonstrate the potential of LRH-1/NR5A2 activation to modulate immune responses and support beta cell viability in T1D, suggesting a new therapeutic approach.

KEY POINTS

LRH-1/NR5A2 activation in inflammatory cells of individuals with type 1 diabetes (T1D) reduces pro-inflammatory cell surface markers and cytokine release. LRH-1/NR5A2 promotes a mitohormesis-induced immuno-resistant phenotype to pro-inflammatory macrophages. Mature dendritic cells acquire a tolerogenic phenotype via LRH-1/NR5A2-stimulated mitochondria turnover. LRH-1/NR5A2 agonistic activation expands a CD4+/CD25+/FoxP3+ T-cell subpopulation. Pharmacological activation of LRH-1/NR5A2 improves the survival iPSC-islets-like organoids co-cultured with PBMCs from individuals with T1D.

4-1BB-encoding CAR causes cell death via sequestration of the ubiquitin-modifying enzyme A20

CD28 and 4-1BB costimulatory endodomains included in chimeric antigen receptor (CAR) molecules play a critical role in promoting sustained antitumor activity of CAR-T cells. However, the molecular events associated with the ectopic and constitutive display of either CD28 or 4-1BB in CAR-T cells have been only partially explored. In the current study, we demonstrated that 4-1BB incorporated within the CAR leads to cell cluster formation and cell death in the forms of both apoptosis and necroptosis in the absence of CAR tonic signaling. Mechanistic studies illustrate that 4-1BB sequesters A20 to the cell membrane in a TRAF-dependent manner causing A20 functional deficiency that in turn leads to NF-κB hyperactivity, cell aggregation via ICAM-1 overexpression, and cell death including necroptosis via RIPK1/RIPK3/MLKL pathway. Genetic modulations obtained by either overexpressing A20 or releasing A20 from 4-1BB by deleting the TRAF-binding motifs of 4-1BB rescue cell cluster formation and cell death and enhance the antitumor ability of 4-1BB-costimulated CAR-T cells.

Liver receptor homolog-1 (NR5A2) orchestrates hepatic inflammation and TNF-induced cell death

The nuclear receptor liver receptor homolog-1 (LRH-1) has been shown to promote apoptosis resistance in various tissues and disease contexts; however, its role in liver cell death remains unexplored. Hepatocyte-specific deletion of LRH-1 causes mild steatosis and inflammation but unexpectedly shields female mice from tumor necrosis factor (TNF)-induced hepatocyte apoptosis and associated hepatitis. LRH-1-deficient hepatocytes show markedly attenuated estrogen receptor alpha and elevated nuclear factor κB (NF-κB) activity, while LRH-1 overexpression inhibits NF-κB activity. This inhibition relies on direct physical interaction of LRH-1's ligand-binding domain and the Rel homology domain of NF-κB subunit RelA. Mechanistically, increased transcription of anti-apoptotic NF-κB target genes and the proteasomal degradation of pro-apoptotic BCL-2 interacting mediator of cell death prevent mitochondrial apoptosis and ultimately protect mice from TNF-induced liver damage. Collectively, our study emphasizes LRH-1 as a critical, sex-dependent regulator of cell death and inflammation in the healthy and diseased liver.

Regulation of the Intestinal Extra-Adrenal Steroidogenic Pathway Component LRH-1 by Glucocorticoids in Ulcerative Colitis

Ulcerative colitis (UC) is an inflammatory bowel disease (IBD) and can be treated with glucocorticoids (GC), although some patients are unresponsive to this therapy. The transcription factor LRH-1/NR5A2 is critical to intestinal cortisol production (intestinal steroidogenesis), being reduced in UC patients. However, the relationship between LRH-1 expression and distribution with altered corticosteroid responses is unknown. To address this, we categorized UC patients by their steroid response. Here, we found that steroid-dependent and refractory patients presented reduced glucocorticoid receptor (GR)-mediated intestinal steroidogenesis compared to healthy individuals and responder patients, possibly related to increased colonic mucosa GR isoform beta (GRβ) content and cytoplasmic LRH-1 levels in epithelial and lamina propria cells. Interestingly, an intestinal epithelium-specific GR-induced knockout (GR^iKO) dextran sodium sulfate (DSS)-colitis mice model presented decreased epithelial LRH-1 expression, whilst it increased in the lamina propria compared to DSS-treated control mice. Mechanistically, GR directly induced NR5A2 gene expression in CCD841CoN cells and human colonic organoids. Furthermore, GR bound to two glucocorticoid-response elements within the NR5A2 promoter in dexamethasone-stimulated CCD841CoN cells. We conclude that GR contributes to intestinal steroidogenesis by inducing LRH-1 in epithelial cells, suggesting LRH-1 as a potential marker for glucocorticoid-impaired response in UC. However, further studies with a larger patient cohort will be necessary to confirm role of LRH-1 as a therapeutic biomarker.

More than acinar identity? A novel cystic phenotype suggests broader roles for NR5A2 in pancreatic cancer†

The prognosis for pancreatic ductal adenocarcinoma (PDAC) remains dismal. Multiple genome-wide association studies (GWAS) have implicated the nuclear receptor NR5A2 in modulating PDAC risk, but mechanisms for this association are not understood. NR5A2 is a transcription factor that maintains acinar cell identity, and heterozygous loss of Nr5a2 in mice accelerates oncogenic Kras-driven formation of pancreatic intraepithelial neoplasia (PanIN), a PDAC precursor derived from acinar cells. In a recent issue of The Journal of Pathology, Cobo et al characterize a novel mouse model that uses Ptf1a:Cre to drive oncogenic Kras as well as heterozygous Nr5a2 inactivation. In addition to the expected PanIN lesions, these mice exhibited a surprising phenotype: large pancreatic cystic lesions which have not been previously reported. Comparing expression of oncogenic Kras and heterozygous Nr5a2 in various mouse models reveals several possible explanations for these cystic lesions. Importantly, these differences across mouse models suggest that NR5A2 may contribute to PDAC precursors in ways beyond its previously characterized acinar cell-autonomous role. These observations highlight that pathways implicated by GWAS may have roles in unexpected cell types, and an understanding of these roles will be critical to guide new preventive and treatment strategies for PDAC. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Immune and Nervous Systems Interaction in Endocrine Disruptors Toxicity: The Case of Atrazine

Endocrine disruptors (ED) are natural and anthropogenic chemicals that can interfere with hormonal systems at different levels. As such, ED-induced alterations in hormone functions have been implicated in many diseases and pathological conditions, including adverse developmental, reproductive, neurological, cardiovascular, and immunological effects in mammals. The fact that ED may compete with several endogenous hormones for multiple receptors and pathways is not always fully considered. This results in a complex response that depends on the cellular context in terms of receptors and interacting proteins and, thus, may differ between tissues and circumstances. Microglia, neurons, and other immune cells are potential targets and still underappreciated actors in endocrine disruption. Due to the large scale of this topic, this review is not intended to provide a comprehensive review nor a systematic review of chemicals identified as endocrine disruptors. It focuses on the immune-neuro-endocrine network in ED toxicity and research gaps, using atrazine as an example to highlight this complexity and the interrelationship between the immune, endocrine, and nervous systems, and ED.

Another One Bites the Gut: Nuclear Receptor LRH-1 in Intestinal Regeneration and Cancer

The process of self-renewal in normal intestinal epithelium is characterized by a fine balance between proliferation, differentiation, migration, and cell death. When even one of these aspects escapes the normal control, cellular proliferation and differentiation are impaired, with consequent onset of tumorigenesis. In humans, colorectal cancer (CRC) is the main pathological manifestation of this derangement. Nowadays, CRC is the world's fourth most deadly cancer with a limited survival after treatment. Several conditions can predispose to CRC development, including dietary habits and pre-existing inflammatory bowel diseases. Given their extraordinary ability to interact with DNA, it is widely known that nuclear receptors play a key role in the regulation of intestinal epithelium, orchestrating the expression of a series of genes involved in developmental and homeostatic pathways. In particular, the nuclear receptor Liver Receptor Homolog-1 (LRH-1), highly expressed in the stem cells localized in the crypts, promotes intestine cell proliferation and renewal in both direct and indirect DNA-binding manner. Furthermore, LRH-1 is extensively correlated with diverse intestinal inflammatory pathways. These evidence shed a light in the dynamic intestinal microenvironment in which increased regenerative epithelial cell turnover, mutagenic insults, and chronic DNA damages triggered by factors within an inflammatory cell-rich microenvironment act synergistically to favor cancer onset and progression.

Nuclear-mitochondrial crosstalk: On the role of the nuclear receptor liver receptor homolog-1 (NR5A2) in the regulation of mitochondrial metabolism, cell survival, and cancer

Liver receptor homolog-1 (LRH-1, NR5A2) is an orphan nuclear receptor with widespread activities in the regulation of development, stemness, metabolism, steroidogenesis, and proliferation. Many of the LRH-1-regulated processes target the mitochondria and associated activities. While under physiological conditions, a balanced LRH-1 expression and regulation contribute to the maintenance of a physiological equilibrium, deregulation of LRH-1 has been associated with inflammation and cancer. In this review, we discuss the role and mechanism(s) of how LRH-1 regulates metabolic processes, cell survival, and cancer in a nuclear-mitochondrial crosstalk, and evaluate its potential as a pharmacological target.

Time for a paradigm shift in treating type 1 diabetes mellitus: coupling inflammation to islet regeneration

Type 1 diabetes mellitus (T1DM) is an autoimmune disease that targets the destruction of islet beta-cells resulting in insulin deficiency, hyperglycemia and death if untreated. Despite advances in medical devices and longer-acting insulin, there is still no robust therapy to substitute and protect beta-cells that are lost in T1DM. Attempts to refrain from the autoimmune attack have failed to achieve glycemic control in patients highlighting the necessity for a paradigm shift in T1DM treatment. Paradoxically, beta-cells are present in T1DM patients indicating a disturbed equilibrium between the immune attack and beta-cell regeneration reminiscent of unresolved wound healing that under normal circumstances progression towards an anti-inflammatory milieu promotes regeneration. Thus, the ultimate T1DM therapy should concomitantly restore immune self-tolerance and replenish the beta-cell mass similar to wound healing. Recently the agonistic activation of the nuclear receptor LRH-1/NR5A2 was shown to induce immune self-tolerance, increase beta-cell survival and promote regeneration through a mechanism of alpha-to-beta cell phenotypic switch. This trans-regeneration process appears to be facilitated by a pancreatic anti-inflammatory environment induced by LRH-1/NR5A2 activation. Herein, we review the literature on the role of LRH1/NR5A2 in immunity and islet physiology and propose that a cross-talk between these cellular compartments is mandatory to achieve therapeutic benefits.

Pharmacological LRH-1/Nr5a2 inhibition limits pro-inflammatory cytokine production in macrophages and associated experimental hepatitis

Liver receptor homolog-1 (LRH-1, Nr5a2) is an orphan nuclear receptor mainly expressed in tissues of endodermal origin, where its physiological role has been extensively studied. LRH-1 has been implicated in liver cell differentiation and proliferation, as well as glucose, lipid, and bile acid metabolism. In addition, increasing evidence highlights its role in immunoregulatory processes via glucocorticoid synthesis in the intestinal epithelium. Although the direct function of LRH-1 in immune cells is fairly elucidated, a role of LRH-1 in the regulation of macrophage differentiation has been recently reported. In this study, we aimed to investigate the role of LRH-1 in the regulation of pro-inflammatory cytokine production in macrophages. Our data demonstrate that pharmacological inhibition, along with LRH-1 knockdown, significantly reduced the lipopolysaccharide (LPS)-induced production of pro-inflammatory cytokines in the macrophage line RAW 264.7 cells, as well as in primary murine macrophages. This inhibitory effect was found to be independent of defects of LRH-1-regulated cell proliferation or toxic effects of the LRH-1 inhibitors. In contrast, LRH-1 inhibition reduced the mitochondrial ATP production and metabolism of macrophages through downregulation of the LRH-1 targets glucokinase and glutminase-2, and thus impairing the LPS-induced macrophage activation. Interestingly, in vivo pharmacological inhibition of LRH-1 also resulted in reduced tumor necrosis factor (TNF) production and associated decreased liver damage in a macrophage- and TNF-dependent mouse model of hepatitis. Noteworthy, despite hepatocytes expressing high levels of LRH-1, pharmacological inhibition of LRH-1 per se did not cause any obvious liver damage. Therefore, this study proposes LRH-1 as an emerging therapeutic target in the treatment of inflammatory disorders, especially where macrophages and cytokines critically decide the extent of inflammation.

Intrauterine Growth Restriction Alters the Genome-Wide DNA Methylation Profiles in Small Intestine, Liver and Longissimus Dorsi Muscle of Newborn Piglets

Intrauterine growth restriction (IUGR) remains a major problem in swine production since the associated low birth weight leads to high rates of pre-weaning morbidity and mortality, and permanent retardation of growth and development. The underlying regulatory mechanisms from the aspects of epigenetic modification has received widespread attention. Studies explore the changes in genome wide methylation in small intestine (SI), liver and longissimus dorsi muscle (LDM) between IUGR and normal birth weight (NBW) newborn piglets using a methylated DNA immunoprecipitation-sequencing (MeDIP-Seq) approach. The data demonstrated that methylated peaks were prominently distributed in distal intergenic regions and the quantities of peaks in IUGR piglets were more than that of NBW piglets. IUGR piglets had relatively high methylated level in promoters, introns and coding exons in all the three tissues. Through KEGG pathway analysis of differentially methylated genes found that 33, 54 and 5 differentially methylated genes in small intestine, liver and longissimus dorsi muscle between NBW and IUGR piglets, respectively, which are related to development and differentiation, carbohydrate and energy metabolism, lipid metabolism, protein turnover, immune response, detoxification, oxidative stress and apoptosis pathway. The objective of this review is to assess the impact of differentially methylation status on developmental delay, metabolic disorders and immune deficiency of IUGR piglets.

CXCR3 chemokine receptor guides Trypanosoma cruzi-specific T-cells triggered by DNA/adenovirus ASP2 vaccine to heart tissue after challenge

CD8+ T lymphocytes play an important role in controlling infections by intracellular pathogens. Chemokines and their receptors are crucial for the migration of CD8+ T-lymphocytes, which are the main IFNγ producers and cytotoxic effectors cells. Although the participation of chemokine ligands and receptors has been largely explored in viral infection, much less is known in infection by Trypanosoma cruzi, the causative agent of Chagas disease. After T. cruzi infection, CXCR3 chemokine receptor is highly expressed on the surface of CD8+ T-lymphocytes. Here, we hypothesized that CXCR3 is a key molecule for migration of parasite-specific CD8+ T-cells towards infected tissues, where they may play their effector activities. Using a model of induction of resistance to highly susceptible A/Sn mice using an ASP2-carrying DNA/adenovirus prime-boost strategy, we showed that CXCR3 expression was upregulated on CD8+ T-cells, which selectively migrated towards its ligands CXCL9 and CXCL10. Anti-CXCR3 administration reversed the vaccine-induced resistance to T. cruzi infection in a way associated with hampered cytotoxic activity and increased proapoptotic markers on the H2KK-restricted TEWETGQI-specific CD8+ T-cells. Furthermore, CXCR3 receptor critically guided TEWETGQI-specific effector CD8+ T-cells to the infected heart tissue that express CXCL9 and CXCL10. Overall, our study pointed CXCR3 and its ligands as key molecules to drive T. cruzi-specific effector CD8+ T-cells into the infected heart tissue. The unveiling of the process driving cell migration and colonization of infected tissues by pathogen-specific effector T-cells is a crucial requirement to the development of vaccine strategies.

The orphan nuclear receptor LRH-1/NR5a2 critically regulates T cell functions

LRH-1 (liver receptor homolog-1/NR5a2) is an orphan nuclear receptor, which regulates glucose and lipid metabolism, as well as intestinal inflammation via the transcriptional control of intestinal glucocorticoid synthesis. Predominantly expressed in epithelial cells, its expression and role in immune cells are presently enigmatic. LRH-1 was found to be induced in immature and mature T lymphocytes upon stimulation. T cell-specific deletion of LRH-1 causes a drastic loss of mature peripheral T cells. LRH-1-depleted CD4⁺ T cells exert strongly reduced activation-induced proliferation in vitro and in vivo and fail to mount immune responses against model antigens and to induce experimental intestinal inflammation. Similarly, LRH-1-deficient cytotoxic CD8⁺ T cells fail to control viral infections. This study describes a novel and critical role of LRH-1 in T cell maturation, functions, and immopathologies and proposes LRH-1 as an emerging pharmacological target in the treatment of T cell-mediated inflammatory diseases.

Extra-Adrenal Glucocorticoid Synthesis in the Intestinal Mucosa: Between Immune Homeostasis and Immune Escape

Glucocorticoids (GCs) are steroid hormones predominantly produced in the adrenal glands in response to physiological cues and stress. Adrenal GCs mediate potent anti-inflammatory and immunosuppressive functions. Accumulating evidence in the past two decades has demonstrated other extra-adrenal organs and tissues capable of synthesizing GCs. This review discusses the role and regulation of GC synthesis in the intestinal epithelium in the regulation of normal immune homeostasis, inflammatory diseases of the intestinal mucosa, and the development of intestinal tumors.

Comprehensive analysis of differentially expressed profiles of long non-coding RNAs and messenger RNAs in kaolin-induced hydrocephalus

BACKGROUNDS

The pathophysiology of hydrocephalus induced brain damage remains unclear. Long non-coding RNAs (lncRNAs) have been demonstrated to be implicated in many central nervous system diseases. However, the roles of lncRNAs in hydrocephalus injury are poorly understood.

METHODS

The present study depicted the expression profiles of lncRNAs and messenger RNAs (mRNAs) in C57BL/6 mice with kaolin-induced hydrocephalus and saline controls using high-throughput RNA sequencing. Afterward, Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed to identify potential targets that correlated with hydrocephalus. In addition, co-expression networks and cis- and trans-regulation were predicted using bioinformatics methods. Finally, representative lncRNAs and mRNAs were further validation using quantitative real-time polymerase chain reaction.

RESULTS

A total of 1575 lncRNAs and 1168 mRNAs were differentially expressed (DE) in hydrocephalus. GO and KEGG analyses indicated several immune and inflammatory response-associated pathways may be important in the hydrocephalus. Besides, functional enrichment analysis based on co-expression network showed several similar pathways, such as chemokine signaling pathway, phagosome, MAPK signaling pathway and complement and coagulation cascade. Cis-regulation prediction revealed 5 novel lncRNAs might regulate their nearby coding genes, and trans-regulation revealed several lncRNAs participate in pathways regulated by transcription factors, including BPTF, FOXM1, NR5A2, P2RX5, and NR6A1.

CONCLUSIONS

In conclusion, our results provide candidate genes involved in hydrocephalus and suggest a new perspective on the modulation of lncRNAs in hydrocephalus.

Intestinal glucocorticoid synthesis enzymes in pediatric inflammatory bowel disease patients

Inflammatory bowel disease (IBD), such as Crohn's disease and ulcerative colitis are devastating chronic immunopathologies of the intestinal mucosa, which are frequently treated by immunosuppressive glucocorticoids. Endogenous glucocorticoids are not only produced by the adrenal glands, but also by the intestinal epithelium. Local glucocorticoid synthesis critically contributes to the immune homeostasis of the intestinal mucosa. As defective intestinal glucocorticoid synthesis has been associated with the development of IBD, we investigated the expression of steroidogenic enzymes and the key transcriptional regulator Liver Receptor Homolog-1 (LRH-1/NR5A2) in ileal and colonic biopsies human pediatric IBD and control patients. Furthermore, the induction of steroidogenic enzymes and their transcriptional regulation by LRH-1 was investigated in a mouse model of experimental colitis. These analyses revealed that colitis-induced expression of steroidogenic enzymes in the murine colon is dependent on the presence of LRH-1, as intestinal deletion of LRH-1 strongly reduced their colitis-induced expression. Similarly, a strong correlation between the expression of LRH-1 and different steroidogenic enzymes was seen in intestinal biopsies of human pediatric patients. Importantly, reduced expression of hydroxysteroid dehydrogenase 11B1 (HSD11B1) was observed in IBD patients compared to control patients, suggesting that defective local reactivation of glucocorticoids could contribute to the pathogenesis of IBD.

Early activation of CD95 is limited and localized to the cytotoxic synapse

The cytotoxic synapse formed between cytotoxic T lymphocytes or natural killer cells expressing CD95L and target cells with CD95 on their surface is a key pathway for apoptosis induction by the immune system. Despite similarities with the immune synapse in antigen presenting cells, little is known about the role of the spatiotemporal organization of agonistic proteins/receptor interactions for CD95 signaling. Here, we have developed an artificial cytotoxic synapse to examine how mobility and geometry of an anti-CD95 agonistic antibody affect receptor aggregation and mobility, ie the first step of receptor activation. By measuring the distribution, diffusion coefficient, and fraction of immobile CD95 receptor in living cells, we show that at short times, the initial activation of CD95 occurs locally and is limited to the contact region of the cytotoxic synapse. This anisotropic activation of apoptotic signaling supports a role for confined interactions on the efficiency of signal transduction that may have implications for biomedical applications of extrinsic apoptosis induction.