Primary immunodeficiency associated with a SAMD9L mutation

Background: SAMD9L is a tumor suppressor involved in regulating the proliferation and maturation of cells, particularly those derived from the bone marrow, and appears to play an important role in cerebellar function. It can be activated in hematopoietic stem cells by type I and type II interferons. It has been hypothesized to act as a critical antiviral gatekeeper regulating interferon dependent demand driven hematopoiesis. Gain of function mutations can present with an immunodeficiency due to transient severe cytopenias during viral infection. Case presentation: We report a 3-year-old boy born full term with a history of severe thrombocytopenia requiring transfusions, developmental delay, ataxia, seizure disorder, and recurrent severe respiratory viral infections. His infectious history was significant for respiratory syncytial virus with shock requiring extracorporeal membrane oxygenation complicated by cerebral infarction and a group A streptococcus empyema, osteomyelitis requiring a left below the knee amputation, and infections with rhinovirus, COVID-19, and parainfluenza requiring hospitalizations for respiratory support. Initial immunologic evaluation was done during his hospitalization for parainfluenza. His full T cell subsets was significant for lymphopenia across all cell lines with CD3 934/microL, CD4 653/microL, CD8 227/microL, CD19 76/microL, and CD1656 61/microL. His mitogen stimulation assay to phytohemagglutinin and pokeweed was normal. Immunoglobulin panel showed a mildly decreased IgM of 25 mg/dL, but normal IgA and IgG. Vaccine titers demonstrated protective titers to 12/22 pneumococcus serotypes, varicella, diphtheria, mumps, rubella, and rubeola. Repeat full T cell subsets 6 weeks later revealed marked improvement in lymphocyte counts with CD3 3083/microL, CD4 2101/microL, CD8 839/microL, CD19 225/microL, and CD1656/microL. A primary immunodeficiency genetic panel was ordered and positive for a heterozygous SAMD9L c.1549T>C (p.Trp517Arg) mutation classified as a variant of unknown significance. Discussion(s): This patient's history of severe viral infections, ataxia, thrombocytopenia, and severe transient lymphopenia during infection is suggestive of a SAM9DL gain of function mutation. Protein modeling done by the laboratory suggests this missense mutation would affect protein structure. The mutation found has been observed in individuals with thrombocytopenia. This case highlights the importance of immunophenotyping both during acute illness and once recovered.Copyright © 2023 Elsevier Inc.

Development of warm autoimmune hemolytic anemia after initiation of Ruxolitinib in a patient with STAT1 gain-of-function mutation

Introduction: STAT1 gain-of-function (GOF) disease is associated with chronic mucocutaneous candidiasis (CMC) and a broad spectrum of infectious, inflammatory, and vascular manifestations. The Janus Kinase inhibitor ruxolitinib has been used successfully for CMC and autoimmune phenomena. We describe a case of warm autoimmune hemolytic anemia (WAIHA) in a patient with STAT1 GOF disease after initiating ruxolitinib. Case report: A 36-year-old man with STAT1 c.850G>A (p.Glu284Lys) mutation presented with CMC as well as recurrent viral and bacterial infections, lymphadenopathy, enteritis, nodular regenerative hyperplasia (NRH) and splenomegaly. Immune workup confirmed a combined immunodeficiency with hypogammaglobulinemia and T-cell lymphopenia. Ruxolitinib was initiated at 5 mg twice daily (due to pre-existing thrombocytopenia) with up titration over 3 months to 20 mg twice daily. He improved with weight gain, increased energy, resolution of chronic anemia, and improved lymphadenopathy and splenomegaly on imaging. Serum CXCL9 only minimally decreased from 4660 pg/ml to 3990 pg/ml. Soon after reaching ruxolitinib 20 mg twice daily, he developed JC viremia, prompting dose reduction to 15 mg BID. Within two weeks, he developed a non-COVID upper respiratory tract infection followed by fatigue, shortness of breath with ambulation, and dark urine. Emergency evaluation revealed warm antibody positive hemolytic anemia with a hemoglobin of 5 g/dL, and worsened thrombocytopenia. He was treated with blood transfusions, pulse steroids, and high-dose IVIG with stabilization but continued hemolysis. Due to the JC viremia, there was concern to give rituximab with increased PML risk. Bone marrow showed trilineage hematopoiesis, a mild increase in megakaryocytes and RBC precursors, and a loss of B-cell progenitors with retention of mature B cells. His B and T lymphocyte numbers had increased since prior to ruxolitinib, with a predominance of Tfh1-cells (58.7% of total Tfh-cells). He was started on sirolimus with a slow taper of prednisone with continued stable hemoglobin and platelets, and resolution of hemolysis after 3 months. Conclusion(s): To our knowledge, this is the first case of a STAT1 GOF patient developing WAIHA while receiving ruxolitinib therapy. Treatment choices were complicated by the risks of PML. Sirolimus combined with ruxolitinib allowed wean of corticosteroid and subsequent resolution of hemolysis.Copyright © 2023 Elsevier Inc.

Les expériences de gain-de-fonction des virus pathogènes émergents1

Résumé Dans la nature, des virus adaptés à la transmission circulent dans les espèces animales (chauves-souris, oiseaux, rongeurs, primates, etc.). Le franchissement de la barrière des espèces peut se faire par contamination d'autres espèces animales, dont l'homme. Des manipulations génétiques ont été réalisées sur des virus sauvages pour faciliter le passage interespèces et augmenter la virulence virale. Le but était d'identifier les gènes critiques pour la pathogénicité. Ces manipulations ont été réalisées sur des agents pathogènes potentiellement épidémiques, comme Myxovirus influenzae de la grippe aviaire et les coronavirus des épidémies de SRAS et de MERS. Ces expériences dangereuses ont fait l'objet d'un moratoire aux États-Unis (2014-2017). Trois ans après l'émergence du Covid-19, l'origine du SARS-CoV2 d'emblée très contagieux reste un mystère. Il existe deux scénarios pour expliquer son émergence. Les partisans de l'origine naturelle avancent que le virus de la chauve-souris aurait pu infecter directement l'homme, se propageant silencieusement à un faible niveau chez l'homme pendant des années, sans éliminer l'existence d'hôtes intermédiaires non détectés. Cela n'explique pas l'origine à Wuhan, loin des réservoirs naturels de virus. Le site furin serait apparu spontanément à partir d'autres coronavirus. Le scénario alternatif est celui d'un accident de laboratoire à Wuhan, après des expériences de gain-de-fonction à partir d'un SARS-like CoV, voire même la survenue d'une contamination humaine par un virus CoV sauvage recuilli sur le terrain, lors de cultures cellulaires ou des tests sur les animaux à Wuhan. Summary In nature, viruses are well-adapted to transmission in wild animal species (bats, birds, rodents, primates...). The crossing of the species barrier can be done by contamination of other animal species, including humans. Genetic manipulations have been carried out on wild viruses to facilitate interspecies passage and increase viral virulence. The aim was to identify genes critical for pathogenicity. These manipulations have been performed on potentially epidemic pathogens, such as Myxovirus influenzae from avian influenza and coronaviruses from the SARS and MERS epidemics. These dangerous experiments were placed under a moratorium in the United States (2014-2017). Three years after the emergence of Covid-19, the origin of the highly contagious SARS-CoV2 remains a mystery. There are two scenarios to explain its emergence. Proponents of the natural origin argue that the bat virus could have directly infected humans, spreading silently at a low level in humans for years, without eliminating the possibility of undetected intermediate hosts. The furin site would have appeared spontaneously from other coronaviruses. However, this does not explain the specific origin in Wuhan, far from natural virus reservoirs. The alternative scenario is that of a laboratory accident in Wuhan, after gain-of-function experiments with an SARS-like CoV, or even the occurrence of human contamination by a wild CoV virus collected in the field, during cell cultures or animal tests in Wuhan.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Mediates Transforming Growth Factor Beta (TGF-b) Hijacking and Immune Dysregulation Through A Novel Gain of Function Mutation in Its Nonstructural 15 (NSP15) Protein

Rationale: The COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has killed millions via the acute respiratory distress syndrome (ARDS). The early immune suppression of SARS-CoV-2 then subsequent inflammation suggests an unusual ability to cause immune dysregulation. Host transforming growth factor beta (TGF-β) is an immunesuppressing and profibrotic cytokine frequently “hijacked” by microbes to evade immune detection. We discovered a KRFK domain (a potent activating motif for latent TGF-β) in the SARS-CoV-2 nonstructural 15 (NSP15) protein. We hypothesized that this NSP15 protein causes immune dysregulation by activation of latent TGF-β and subsequent activation of immunosuppressive Tregulatory (Treg) cells, and that substantial TGF-β is present in the lungs of COVID-19 ARDS patients. Methods: We evaluated TGF-β1 concentrations in endotracheal aspirates (ETA) of 27 COVID-19 ARDS patients by ELISA. We produced recombinant SARS-CoV-2 NSP15 protein in E. coli and tested its ability to activate latent TGF-β1 using in vitro assays. TGF-β inhibitors were assessed for their ability to block effects. We obtained blood mononuclear cells from healthy subjects and isolated Tregs to assess their activation state via intracellular smad-2 phosphorylation (pSMAD2) using flow cytometry. Results: The KRFK domain was present in all SARS-CoV-2 variants. High concentrations of both active and total TGF-β1 were detected in ETA of COVID-19 ARDS patients (150 +/- 34 pg/ml active;1,819 +/- 304 pg/ml total) in a range previously shown to affect T cell function. NSP15 at 2.4 nM increased activation of latent TGF-β 12-fold (P < .001 vs. vehicle), compared to an 11% activation with the positive control thrombospondin-1 (TSP1;10 nM) (Figure). TGF-β receptor inhibitors blocked NSP15 effects on latent TGF-β activation and intracellular TGF-β1 signaling in a bioassay by over 95% (p<.01). At tested concentrations (25, 50, 100 nM) NSP15 increased Treg pSMAD2 levels via activation of latent TGF-β1, exceeding levels seen in Tregs stimulated with 400 pM of active TGF-β1 (+ control) (pSMAD2 + cells: vehicle 1.1%, active TGF-β1 43%, NSP15/latent TGF-β1 49-56%). Conclusions: High concentrations of active and total TGF-β1 are present in the lungs of COVID-19 ARDS patients, suggesting SARS-CoV-2 uses host TGF-β hijacking as a mechanism for immune evasion. The NSP15 protein of SARSCoV- 2 potently activates latent TGF-β, leading to Treg activation. TGF-β inhibitors are potent inhibitors of these NSP15 effects. A strategy to block NSP15-mediated effects with TGF-β inhibitors is an innovative therapy worthy of testing in animal models of COVID-19.

MINIMAL CHANGE DISEASE SECONDARY TO SARS-COV-2 (COVID-19) INFECTION: A REPORT OF 2 CASES AND REVIEW OF RELATED LITERATURE

BACKGROUND AND AIMS: The COVID-19 pandemic has brought to the forefront a wide spectrum of renal injuries that included glomerulopathies, some of which were recently highlighted in various case reports. These consist of focal and segmental glomerulosclerosis (FSGS) and minimal change disease (MCD).1 These changes were found among seemingly vulnerable populations such as the African American and Caucasian ethnicities with paucity of reports among other races. We present two cases of biopsy-confirmed MCD secondary to COVID-19 infection among adult Filipino patients. METHODS: Case Report RESULTS: Case 1 A 40-year-old Filipino female with a history of right total mastectomy 2 years prior for a low-grade phyllodes tumor and no other medical comorbidities was admitted due to stillbirth. She was noted to have bipedal edema with a positive COVID-19 RT-PCR swab. Further workup revealed a serum creatinine 1.04 mg/dL, urine RBC 1/HPF and a 24-h urine protein of 9.22 g with hypoalbuminemia and dyslipidemia. Serologic workup was noted to be negative. She was started on Losartan, Atorvastatin, and Furosemide. A kidney biopsy was performed which demonstrated unremarkable light microscopy and immunofluorescence and widespread podocyte-foot process effacement. These biopsy findings were interpreted to be consistent with minimal change disease. She was started on Prednisone at 1 mg/kg/day with continuation of both Losartan and Atorvastatin. Six weeks after, the patient achieved complete remission with resolution of both hypoalbuminemia and dyslipidemia. She also reports no further recurrence of edema. Case 2 A 61-year-old Filipino male with a history of type 2 diabetes mellitus, hypertension, dyslipidemia and mild COVID-19 infection 4 months prior now presented with diarrhea. A routine COVID-19 RT-PCR swab revealed a re-infection. Physical examination noted bipedal edema. Further workup demonstrated a serum creatinine 3.39 mg/dL, urine RBC 2/HPF and urine ACR 2.6 g/g. Serologic tests were negative. He was diagnosed with Nephrotic Syndrome and underwent kidney biopsy. Findings showed an unremarkable light microscopy and immunofluorescence with widespread podocyte-foot process effacement. These findings were found to be consistent with minimal change disease and acute tubular injury. He was started on Prednisone (1 mg/kg/day), Losartan, Furosemide and Atorvastatin. Eight weeks later, the patient achieved complete remission with resolution of edema. CONCLUSION: It is currently suspected that APOL1 risk variants found in reported cases of COVID-19-associated glomerulopathies are underlying toxic gain-of-function mutations that drive kidney disease.2 It is interesting to note that APOL1 renal risk variants are found exclusively in African-derived chromosomes and are rarely found among European or Asian chromosomes.3 Even though an APOL1 genotyping was not performed, our case reports provide the first examples of MCD among individuals without a high-risk genotype (APOL1) by epidemiology and enlarge the literature on MCD in COVID-19. We posit that there may be other underlying predispositions or mechanisms that may be driving glomerulopathy formation among COVID-19 patients aside from their inherent APOL 1 risk. Both of our patients were started on steroid therapy with a tapering regimen and achieved complete remission on subsequent follow-up. Existing reports suggest that most cases of COVID-19-associated MCD will often achieve resolution of AKI and proteinuria with steroid therapy, even in those with high-risk APOL1 genotype, emphasizing the need for an accurate histologic classification.4 (Figure Presented).

STIM1 and ORAI1 mutations leading to tubular aggregate myopathies are sensitive to the Store-operated Ca2+-entry modulators CIC-37 and CIC-39.

Gain-of-function mutations on STIM1 and ORAI1 genes are responsible for an increased store-operated calcium entry, and underlie the characteristic symptoms of three overlapping ultra-rare genetic disorders (i.e tubular aggregate myopathy, Stormorken syndrome, York platelet syndrome) that can be grouped as tubular aggregate myopathies. These mutations lead to a wide spectrum of defects, which usually include muscle weakness and cramps. Negative modulators of store-operated Ca2+-entry targeting wild-type STIM1 and ORAI1 have entered clinical trials for a different array of disorders, including pancreatitis, COVID-19, cancer, and autoimmune disorders and, while efficacy data is awaited, safety data indicates tolerability of this STIM1/ORAI1 mutations are amenable to pharmacological intervention. If this were so, given that there are no approved treatments or clinical trials ongoing for these rare disorders, it could be envisaged that these agents could also rehabilitate tubular aggregate myopathy patients. In the present contribution we characterized the Ca2+-entry patterns induced by eleven STIM1 and three ORAI1 mutations in heterologous systems or in patient-derived cells, i.e. fibroblasts and myotubes, and evaluated the effect of CIC-37 and CIC-39, two novel store-operated calcium entry modulators. Our data show that all STIM1 and ORAI1 gain-of-function mutations tested, with the possible exception of the R304Q STIM1 mutation, are amenable to inhibition, albeit with slightly different sensitivities, paving the way to the development of SOCE modulators in tubular aggregate myopathies.