MO469: GPR124—A Driver of Fibrotic Kidney Diseases

BACKGROUND AND AIMS

Renal fibrosis is a central feature of chronic kidney disease (CKD), and the severity of CKD correlates with the magnitude of renal fibrosis. Despite the causative role attributed to fibrosis in CKD progression, there is still no treatment available that directly targets renal fibrosis.

Upon kidney injury, embryonic signalling pathways are activated, promoting the repair and regeneration of injured tissue. Maladaptive repair mechanisms have been associated with the development of renal fibrosis and sustained activation of Wnt/β-catenin signalling contributes to CKD progression. GPR124 (ADGRA2 gene), has been identified as a potential fibrotic mediator through its upregulation in pericytes during pericyte to myofibroblast transition. GPR124 has been identified to function as a co-receptor for Wnt7 mediating canonical Wnt signaling in endothelial cells. We observed elevated GPR124 expression in mouse kidneys after chronic ischaemia reperfusion injury (cIRI). To further explore the role of GPR124 in CKD progression, we have studied its correlation with disease severity in human NURTuRE kidney biopsies [1]. We have also looked at GPR124 therapeutic potential in mouse cIRI. Given its potential disease relevance, we set out to develop inhibitory GPR124 antibodies as novel therapeutics to treat renal fibrosis.

METHOD

Diagnostic FFPE kidney cortex biopsy samples from 497 NURTuRE patients were subjected to bulk RNA-Seq. Library preparation with Illumina Enrichment Tagmentation technology was followed by sequencing and alignment of paired-end reads to the reference genome GRCh38/ENSEMBL 97 and quantification. Monoclonal Anti-GPR124 antibodies were generated against the extracellular domain of human GPR124. Top candidates were selected by FACS binding and further characterized in a TCF/LEF luciferase assay for the inhibition of Wnt7 signaling. One hu/ms cross-reactive candidate was studied in a 14-day IRI mouse model to assess its anti-fibrotic effect in vivo. Mice were exposed to 30-min unilateral renal ischaemia, followed by 14 days recovery. Kidneys were studied for gene expression by RT-PCR. Animals were divided into sham (n = 5), control IRI (no antibody, n = 12) and treated groups (each n = 12). The antibody was administered before ischemia and during the recovery phase in two doses [50 mg/kg and 150 mg/kg].

RESULTS

CONCLUSION

NURTuRE provides us with a unique opportunity to assess relevance of a potential target candidate gene in kidney disease patients. The potential of GPR124 as a therapeutic target was highlighted by the upregulation of expression levels along disease severity and biological pathway analysis, where our data supports a potential role in extracellular matrix reorganization. The administration of GPR124 antibodies and inhibition of the GPR124-mediated Wnt signaling in vivo inhibited the development of ischaemia-induced fibrosis in the mouse kidney. The results strongly support a role for GPR124 in human kidney disease progression, through inhibition of fibrosis, and its potential as a future clinical target.

A dual role for hepatocyte-intrinsic canonical NF-κB signaling in virus control

BACKGROUND & AIMS

Hepatic innate immune control of viral infections has largely been attributed to Kupffer cells, the liver-resident macrophages. However, hepatocytes, the parenchymal cells of the liver, also possess potent immunological functions in addition to their known metabolic functions. Owing to their abundance in the liver and known immunological functions, we aimed to investigate the direct antiviral mechanisms employed by hepatocytes.

METHODS

Using lymphocytic choriomeningitis virus (LCMV) as a model of liver infection, we first assessed the role of myeloid cells by depletion prior to infection. We investigated the role of hepatocyte-intrinsic innate immune signaling by infecting mice lacking canonical NF-κB signaling (Ikkβ^ΔHep) specifically in hepatocytes. In addition, mice lacking hepatocyte-specific interferon-α/β signaling-(Ifnar^ΔHep), or interferon-α/β signaling in myeloid cells-(Ifnar^ΔMyel) were infected.

RESULTS

Here, we demonstrate that LCMV activates NF-κB signaling in hepatocytes. LCMV-triggered NF-κB activation in hepatocytes did not depend on Kupffer cells or TNFR1 signaling but rather on Toll-like receptor signaling. LCMV-infected Ikkβ^ΔHep livers displayed strongly elevated viral titers due to LCMV accumulation within hepatocytes, reduced interferon-stimulated gene (ISG) expression, delayed intrahepatic immune cell influx and delayed intrahepatic LCMV-specific CD8⁺ T cell responses. Notably, viral clearance and ISG expression were also reduced in LCMV-infected primary hepatocytes lacking IKKβ, demonstrating a hepatocyte-intrinsic effect. Similar to livers of Ikkβ^ΔHep mice, enhanced hepatocytic LCMV accumulation was observed in livers of Ifnar^ΔHep mice, whereas Ifnar^ΔMyel mice were able to control LCMV infection. Hepatocytic NF-κB signaling was also required for efficient ISG induction in HDV-infected dHepaRG cells and interferon-α/β-mediated inhibition of HBV replication in vitro.

CONCLUSIONS

Together, these data show that hepatocyte-intrinsic NF-κB is a vital amplifier of interferon-α/β signaling, which is pivotal for strong early ISG responses, immune cell infiltration and hepatic viral clearance.

LAY SUMMARY

Innate immune cells have been ascribed a primary role in controlling viral clearance upon hepatic infections. We identified a novel dual role for NF-κB signaling in infected hepatocytes which was crucial for maximizing interferon responses and initiating adaptive immunity, thereby efficiently controlling hepatic virus replication.

Patient iPSC-Derived Macrophages to Study Inborn Errors of the IFN-γ Responsive Pathway

Interferon γ (IFN-γ) was shown to be a macrophage activating factor already in 1984. Consistently, inborn errors of IFN-γ immunity underlie Mendelian Susceptibility to Mycobacterial Disease (MSMD). MSMD is characterized by genetic predisposition to disease caused by weakly virulent mycobacterial species. Paradoxically, macrophages from patients with MSMD were little tested. Here, we report a disease modeling platform for studying IFN-γ related pathologies using macrophages derived from patient specific induced pluripotent stem cells (iPSCs). We used iPSCs from patients with autosomal recessive complete- and partial IFN-γR2 deficiency, partial IFN-γR1 deficiency and complete STAT1 deficiency. Macrophages from all patient iPSCs showed normal morphology and IFN-γ-independent functionality like phagocytic uptake of bioparticles and internalization of cytokines. For the IFN-γ-dependent functionalities, we observed that the deficiencies played out at various stages of the IFN-γ pathway, with the complete IFN-γR2 and complete STAT1 deficient cells showing the most severe phenotypes, in terms of upregulation of surface markers and induction of downstream targets. Although iPSC-derived macrophages with partial IFN-γR1 and IFN-γR2 deficiency still showed residual induction of downstream targets, they did not reduce the mycobacterial growth when challenged with Bacillus Calmette-Guérin. Taken together, we report a disease modeling platform to study the role of macrophages in patients with inborn errors of IFN-γ immunity.

Delayed onset of smooth muscle cell differentiation leads to hydroureter formation in mice with conditional loss of the zinc finger transcription factor gene Gata2 in the ureteric mesenchyme

The establishment of the peristaltic machinery of the ureter is precisely controlled to cope with the onset of urine production in the fetal kidney. Retinoic acid (RA) has been identified as a signal that maintains the mesenchymal progenitors of the contractile smooth muscle cells (SMCs), while WNTs, SHH, and BMP4 induce their differentiation. How the activity of the underlying signalling pathways is controlled in time, space, and quantity to activate coordinately the SMC programme is poorly understood. Here, we provide evidence that the Zn-finger transcription factor GATA2 is involved in this crosstalk. In mice, Gata2 is expressed in the undifferentiated ureteric mesenchyme under control of RA signalling. Conditional deletion of Gata2 by a Tbx18^cre driver results in hydroureter formation at birth, associated with a loss of differentiated SMCs. Analysis at earlier stages and in explant cultures revealed that SMC differentiation is not abrogated but delayed and that dilated ureters can partially regain peristaltic activity when relieved of urine pressure. Molecular analysis identified increased RA signalling as one factor contributing to the delay in SMC differentiation, possibly caused by reduced direct transcriptional activation of Cyp26a1, which encodes an RA-degrading enzyme. Our study identified GATA2 as a feedback inhibitor of RA signalling important for precise onset of ureteric SMC differentiation, and suggests that in a subset of cases of human congenital ureter dilatations, temporary relief of urine pressure may ameliorate the differentiation status of the SMC coat. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Tolerogenic Transcriptional Signatures of Steady-State and Pathogen-Induced Dendritic Cells

Dendritic cells (DCs) are key directors of tolerogenic and immunogenic immune responses. During the steady state, DCs maintain T cell tolerance to self-antigens by multiple mechanisms including inducing anergy, deletion, and Treg activity. All of these mechanisms help to prevent autoimmune diseases or other hyperreactivities. Different DC subsets contribute to pathogen recognition by expression of different subsets of pattern recognition receptors, including Toll-like receptors or C-type lectins. In addition to the triggering of immune responses in infected hosts, most pathogens have evolved mechanisms for evasion of targeted responses. One such strategy is characterized by adopting the host’s T cell tolerance mechanisms. Understanding these tolerogenic mechanisms is of utmost importance for therapeutic approaches to treat immune pathologies, tumors and infections. Transcriptional profiling has developed into a potent tool for DC subset identification. Here, we review and compile pathogen-induced tolerogenic transcriptional signatures from mRNA profiling data of currently available bacterial- or helminth-induced transcriptional signatures. We compare them with signatures of tolerogenic steady-state DC subtypes to identify common and divergent strategies of pathogen induced immune evasion. Candidate molecules are discussed in detail. Our analysis provides further insights into tolerogenic DC signatures and their exploitation by different pathogens.

Hematopoietic stem cell gene therapy for IFNγR1 deficiency protects mice from mycobacterial infections

Mendelian susceptibility to mycobacterial disease is a rare primary immunodeficiency characterized by severe infections caused by weakly virulent mycobacteria. Biallelic null mutations in genes encoding interferon gamma receptor 1 or 2 (IFNGR1 or IFNGR2) result in a life-threatening disease phenotype in early childhood. Recombinant interferon γ (IFN-γ) therapy is inefficient, and hematopoietic stem cell transplantation has a poor prognosis. Thus, we developed a hematopoietic stem cell (HSC) gene therapy approach using lentiviral vectors that express Ifnγr1 either constitutively or myeloid specifically. Transduction of mouse Ifnγr1-/- HSCs led to stable IFNγR1 expression on macrophages, which rescued their cellular responses to IFN-γ. As a consequence, genetically corrected HSC-derived macrophages were able to suppress T-cell activation and showed restored antimycobacterial activity against Mycobacterium avium and Mycobacterium bovis Bacille Calmette-Guérin (BCG) in vitro. Transplantation of genetically corrected HSCs into Ifnγr1-/- mice before BCG infection prevented manifestations of severe BCG disease and maintained lung and spleen organ integrity, which was accompanied by a reduced mycobacterial burden in lung and spleen and a prolonged overall survival in animals that received a transplant. In summary, we demonstrate an HSC-based gene therapy approach for IFNγR1 deficiency, which protects mice from severe mycobacterial infections, thereby laying the foundation for a new therapeutic intervention in corresponding human patients.

Impaired IFNγ-Signaling and Mycobacterial Clearance in IFNγR1-Deficient Human iPSC-Derived Macrophages

Mendelian susceptibility to mycobacterial disease (MSMD) is caused by inborn errors of interferon gamma (IFNγ) immunity and is characterized by severe infections by weakly virulent mycobacteria. Although IFNγ is the macrophage-activating factor, macrophages from these patients have never been studied. We demonstrate the generation of heterozygous and compound heterozygous (iMSMD-cohet) induced pluripotent stem cells (iPSCs) from a single chimeric patient, who suffered from complete autosomal recessive IFNγR1 deficiency and received bone-marrow transplantation. Loss of IFNγR1 expression had no influence on the macrophage differentiation potential of patient-specific iPSCs. In contrast, lack of IFNγR1 in iMSMD-cohet macrophages abolished IFNγ-dependent phosphorylation of STAT1 and induction of IFNγ-downstream targets such as IRF-1, SOCS-3, and IDO. As a consequence, iMSMD-cohet macrophages show impaired upregulation of HLA-DR and reduced intracellular killing of Bacillus Calmette-Guérin. We provide a disease-modeling platform that might be suited to investigate novel treatment options for MSMD and to gain insights into IFNγ signaling in macrophages.

Tbx18 expression demarcates multipotent precursor populations in the developing urogenital system but is exclusively required within the ureteric mesenchymal lineage to suppress a renal stromal fate

The mammalian urogenital system derives from multipotent progenitor cells of different germinal tissues. The contribution of individual sub-populations to specific components of the mature system, and the spatiotemporal restriction of the respective lineages have remained poorly characterized. Here, we use comparative expression analysis to delineate sub-regions within the developing urogenital system that express the T-box transcription factor gene Tbx18. We show that Tbx18 is transiently expressed in the epithelial lining and the subjacent mesenchyme of the urogenital ridge. At the onset of metanephric development Tbx18 expression occurs in a band of mesenchyme in between the metanephros and the Wolffian duct but is subsequently restricted to the mesenchyme surrounding the distal ureter stalk. Genetic lineage tracing reveals that former Tbx18(+) cells of the urogenital ridge and the metanephric field contribute substantially to the adrenal glands and gonads, to the kidney stroma, the ureteric and the bladder mesenchyme. Loss of Tbx18 does not affect differentiation of the adrenal gland, the gonad, the bladder and the kidney. However, ureter differentiation is severely disturbed as the mesenchymal lineage adopts a stromal rather than a ureteric smooth muscle fate. DiI labeling and tissue recombination experiments show that the restriction of Tbx18 expression to the prospective ureteric mesenchyme does not reflect an active condensation process but is due to a specific loss of Tbx18 expression in the mesenchyme out of range of signals from the ureteric epithelium. These cells either contribute to the renal stroma or undergo apoptosis aiding in severing the ureter from its surrounding tissues. We show that Tbx18-deficient cells do not respond to epithelial signals suggesting that Tbx18 is required to prepattern the ureteric mesenchyme. Our study provides new insights into the molecular diversity of urogenital progenitor cells and helps to understand the specification of the ureteric mesenchymal sub-lineage.

Cutaneous Acanthamoeba in a patient with AIDS: a case study with a review of new therapy; quiz 386

GOAL

To describe the presenting signs of an Acanthamoeba infection.

OBJECTIVES

Upon completion of this activity, dermatologists and general practitioners should be able to: 1. Discuss the clinical presentation of Acanthamoeba infection. 2. Describe the conditions that make a patient susceptible to Acanthamoeba. 3. Outline treatment options for Acanthamoeba infection. CME: This article has been peer reviewed and approved by Michael Fisher, MD, Professor of Medicine, Albert Einstein College of Medicine.

REVIEW DATE

April 2001. This activity has been planned and implemented in accordance with the Essentials and Standards of the Accreditation Council for Continuing Medical Education through the joint sponsorship of Albert Einstein College of Medicine and Quadrant HealthCom, Inc. The Albert Einstein College of Medicine is accredited by the ACCME to provide continuing medical education for physicians. Albert Einstein College of Medicine designates this educational activity for a maximum of 1.0 hour in category 1 credit toward the AMA Physician's Recognition Award. Each physician should claim only those hours of credit that he/she actually spent in the educational activity. This activity has been planned and produced in accordance with ACCME Essentials.

The impact of primary mental health care in a prison system in Brazil

OBJECTIVE

To analyze the impact of a psychiatric service in a prison general hospital that refers prisoners with mental disorders to a separate forensic psychiatric hospital (FPH).

METHOD

Analysis of data on prison population and referrals to the FPH.

RESULTS

Despite a 10.9% increase in the overall prison system population over 3 years, referrals from the prison general hospital with the new psychiatric service to the FPH were reduced by 36.5%, whereas referrals from other prisons increased by 120.4%.

CONCLUSION

Our results demonstrate the efficiency of the new primary health care approach.

Technique and dosimetry of total body irradiations at Ulm

At the University of Ulm total body irradiation before bone marrow transplantation is given in nine fractions within three days. A total dose of 13 Gy is applied via four fields with 8-MV X-rays. Dose to the lung is limited to 10.5 Gy by means of individually shaped blocks. The homogeneity of dose distributions is improved by the use of compensators for the lower extremities and boli in the head and neck region. Dosimetric data for treatment planning are measured by an ionization chamber and thermoluminescence dosimeters in water and perspex phantoms. In vivo measurements of dose distributions (ionization chamber, TLD) during each fraction allow modifications of compensators and boli in the case of deviations from calculated data.

Prevalence of Paget's disease of bone in hospital patients in Jerusalem: an epidemiologic study

Epidemiological studies have revealed the widely varied prevalence of Paget's disease of bone. The highest rates have been found in parts of England. The disease has been reported only infrequently in Jews and no previous studies of prevalence have been performed in the Middle East or Asia. In the present study an age- and sex-standardized rate of 1% was found among Jews, which is similar to that in many southern European populations. No case of Paget's disease of bone was found among Arabs in this study.

Opto-electronic patient positioning

A microprocessor-system is described which utilizes videocameras and a digital image recorder in order to facilitate and to improve the accuracy of patient positioning in radiation therapy.

Calcified mucinous adenocarcinoma of the stomach--the CT appearances

The CT appearances of calcified mucinous adenocarcinoma of the stomach have not been previously reported. This is a rare tumour with a high propensity to calcify, the calcifications typically are small and spiculated. A case is described where the condition was suspected in the plain films of the abdomen and confirmed by CT examination of the stomach.