Daratumumab for delayed RBC engraftment following major ABO mismatched haploidentical bone marrow transplantation

BACKGROUND

Recent case reports have described the efficacy of daratumumab to treat refractory pure red cell aplasia (PRCA) following major ABO mismatched allogeneic hematopoietic stem cell transplantation (HSCT). In this report, we describe the use of daratumumab as a first-line agent for treatment of delayed red blood cell (RBC) engraftment following a major ABO mismatched pediatric HSCT and provide a review of the literature.

STUDY DESIGN AND MATERIALS

We report on a 14-year-old with DOCK8 deficiency who underwent a myeloablative, haploidentical bone marrow transplant from her major ABO mismatched sister (recipient O+, donor A+) for treatment of her primary immunodeficiency. Despite achieving full donor chimerism, she had delayed RBC engraftment requiring ongoing transfusions. Due to iron deposition, symptomatic anemia, and persistence of anti-A iso-hemagglutinins despite discontinuation of immunosuppression, treatment for delayed RBC engraftment with the CD38-targeted monoclonal antibody daratumumab was selected as a less immunosuppressive agent that could more selectively target iso-hemagglutinin producing plasma cells without causing broad B-cell aplasia.

RESULTS

Clinical effect with daratumumab was demonstrated by reduced iso-hemagglutinin titer, increased reticulocytosis, normalization of her hemoglobin, and transfusion independence. In the 11-month follow-up period to date, no additional transfusions or immunosuppression have been necessary, despite persistence of low-level anti-A iso-hemagglutinin.

CONCLUSION

Our experience suggests that daratumumab was an effective first-line therapy for delayed RBC engraftment and that earlier consideration for daratumumab in treatment of delayed RBC engraftment may be warranted.

Immune Reconstitution Inflammatory Syndrome as a Posttransplantation Complication in Primary Immunodeficiency With Disseminated Mycobacterium avium

Patients with primary immunodeficiencies undergoing allogeneic hematopoietic cell transplantation (HCT) for difficult-to-control infections can experience immune reconstitution inflammatory syndrome (IRIS) following engraftment. In 3 patients with post-HCT IRIS related to mycobacterial infection, in vitro data demonstrate the emergence of pathogen-specific immune responses and a concomitant rise in plasma inflammatory markers.

An Unusual Pattern of Premature Cervical Spine Degeneration in STAT3-LOF

Loss of function mutations in STAT3 (STAT3-LOF; autosomal dominant hyper-IgE (Job's) syndrome) are associated with a variety of musculoskeletal manifestations, including scoliosis, osteoporosis, and minimal trauma fractures. This retrospective magnetic resonance (MR) imaging study sought to characterize an unusual pattern of cervical spine degeneration among a cohort of STAT3-LOF patients. Cervical spine MR images of the STAT3-LOF cohort (n = 38) were assessed for a variety of degenerative changes and compared to age-matched groups of controls (n = 42) without known immune or musculoskeletal abnormalities. A unique pattern of premature cervical spine degeneration was identified among the STAT3-LOF cohort which included straightening and eventual reversal of the normal cervical lordosis, mainly due to multi-level spondylolisthesis, as well as early development of spinal canal narrowing, cord compression, and myelomalacia. Cervical spine degeneration in the STAT3-LOF cohort was significantly worse than controls in both the 30-45 and 45 + age groups. Moderate to severe degenerative changes were present after age 30, and markedly worsened over time in several cases. Bone mineral density (BMD) had a moderate negative correlation with cervical degeneration severity and a strong negative correlation with age among STAT3-LOF participants. Cervical degeneration in STAT3-LOF appears to be progressive and could result in cord compromise if left unaddressed. Focused history and physical examination for signs of neurologic compromise as well as periodic MR imaging are thus recommended for the evaluation of premature cervical spine degeneration in STAT3-LOF patients after age 30 so that timely surgical interventions may be considered to prevent spinal cord damage and permanent neurological deficits.

Migration-induced cell shattering due to DOCK8 deficiency causes a type 2-biased helper T cell response

Mutations that impact immune cell migration and result in immune deficiency illustrate the importance of cell movement in host defense. In humans, loss-of-function mutations in DOCK8, a guanine exchange factor involved in hematopoietic cell migration, lead to immunodeficiency and, paradoxically, allergic disease. Here, we demonstrate that, like humans, Dock8-/- mice have a profound type 2 CD4+ helper T (TH2) cell bias upon pulmonary infection with Cryptococcus neoformans and other non-TH2 stimuli. We found that recruited Dock8-/-CX3CR1+ mononuclear phagocytes are exquisitely sensitive to migration-induced cell shattering, releasing interleukin (IL)-1β that drives granulocyte-macrophage colony-stimulating factor (GM-CSF) production by CD4+ T cells. Blocking IL-1β, GM-CSF or caspase activation eliminated the type-2 skew in mice lacking Dock8. Notably, treatment of infected wild-type mice with apoptotic cells significantly increased GM-CSF production and TH2 cell differentiation. This reveals an important role for cell death in driving type 2 signals during infection, which may have implications for understanding the etiology of type 2 CD4+ T cell responses in allergic disease.

Tissue specific diversification, virulence and immune response to Mycobacterium bovis BCG in a patient with an IFN-γ R1 deficiency

Summary: We characterized Mycobacterium bovis BCG isolates found in lung and brain samples from a previously vaccinated patient with IFNγR1 deficiency. The isolates collected displayed distinct genomic and phenotypic features consistent with host adaptation and associated changes in antibiotic susceptibility and virulence traits. Background: We report a case of a patient with partial recessive IFNγR1 deficiency who developed disseminated BCG infection after neonatal vaccination (BCG-vaccine). Distinct M. bovis BCG-vaccine derived clinical strains were recovered from the patient's lungs and brain. Methods: BCG strains were phenotypically (growth, antibiotic susceptibility, lipid) and genetically (whole genome sequencing) characterized. Mycobacteria cell infection models were used to assess apoptosis, necrosis, cytokine release, autophagy, and JAK-STAT signaling. Results: Clinical isolates BCG-brain and BCG-lung showed distinct Rv0667 rpoB mutations conferring high- and low-level rifampin resistance; the latter displayed clofazimine resistance through Rv0678 gene (MarR-like transcriptional regulator) mutations. BCG-brain and BCG-lung showed mutations in fadA2, fadE5, and mymA operon genes, respectively. Lipid profiles revealed reduced levels of PDIM in BCG-brain and BCG-lung and increased TAGs and Mycolic acid components in BCG-lung, compared to parent BCG-vaccine. In vitro infected cells showed that the BCG-lung induced a higher cytokine release, necrosis, and cell-associated bacterial load effect when compared to BCG-brain; conversely, both strains inhibited apoptosis and altered JAK-STAT signaling. Conclusions: During a chronic-disseminated BCG infection, BCG strains can evolve independently at different sites likely due to particular microenvironment features leading to differential antibiotic resistance, virulence traits resulting in dissimilar responses in different host tissues.

Characterization of the clinical and immunologic phenotype and management of 157 individuals with 56 distinct heterozygous NFKB1 mutations

BACKGROUND

An increasing number of NFKB1 variants are being identified in patients with heterogeneous immunologic phenotypes.

OBJECTIVE

To characterize the clinical and cellular phenotype as well as the management of patients with heterozygous NFKB1 mutations.

METHODS

In a worldwide collaborative effort, we evaluated 231 individuals harboring 105 distinct heterozygous NFKB1 variants. To provide evidence for pathogenicity, each variant was assessed in silico; in addition, 32 variants were assessed by functional in vitro testing of nuclear factor of kappa light polypeptide gene enhancer in B cells (NF-κB) signaling.

RESULTS

We classified 56 of the 105 distinct NFKB1 variants in 157 individuals from 68 unrelated families as pathogenic. Incomplete clinical penetrance (70%) and age-dependent severity of NFKB1-related phenotypes were observed. The phenotype included hypogammaglobulinemia (88.9%), reduced switched memory B cells (60.3%), and respiratory (83%) and gastrointestinal (28.6%) infections, thus characterizing the disorder as primary immunodeficiency. However, the high frequency of autoimmunity (57.4%), lymphoproliferation (52.4%), noninfectious enteropathy (23.1%), opportunistic infections (15.7%), autoinflammation (29.6%), and malignancy (16.8%) identified NF-κB1-related disease as an inborn error of immunity with immune dysregulation, rather than a mere primary immunodeficiency. Current treatment includes immunoglobulin replacement and immunosuppressive agents.

CONCLUSIONS

We present a comprehensive clinical overview of the NF-κB1-related phenotype, which includes immunodeficiency, autoimmunity, autoinflammation, and cancer. Because of its multisystem involvement, clinicians from each and every medical discipline need to be made aware of this autosomal-dominant disease. Hematopoietic stem cell transplantation and NF-κB1 pathway-targeted therapeutic strategies should be considered in the future.

Coronavirus disease 2019 in patients with inborn errors of immunity: An international study

BACKGROUND

There is uncertainty about the impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in individuals with rare inborn errors of immunity (IEI), a population at risk of developing severe coronavirus disease 2019. This is relevant not only for these patients but also for the general population, because studies of IEIs can unveil key requirements for host defense.

OBJECTIVE

We sought to describe the presentation, manifestations, and outcome of SARS-CoV-2 infection in IEI to inform physicians and enhance understanding of host defense against SARS-CoV-2.

METHODS

An invitation to participate in a retrospective study was distributed globally to scientific, medical, and patient societies involved in the care and advocacy for patients with IEI.

RESULTS

We gathered information on 94 patients with IEI with SARS-CoV-2 infection. Their median age was 25 to 34 years. Fifty-three patients (56%) suffered from primary antibody deficiency, 9 (9.6%) had immune dysregulation syndrome, 6 (6.4%) a phagocyte defect, 7 (7.4%) an autoinflammatory disorder, 14 (15%) a combined immunodeficiency, 3 (3%) an innate immune defect, and 2 (2%) bone marrow failure. Ten were asymptomatic, 25 were treated as outpatients, 28 required admission without intensive care or ventilation, 13 required noninvasive ventilation or oxygen administration, 18 were admitted to intensive care units, 12 required invasive ventilation, and 3 required extracorporeal membrane oxygenation. Nine patients (7 adults and 2 children) died.

CONCLUSIONS

This study demonstrates that (1) more than 30% of patients with IEI had mild coronavirus disease 2019 (COVID-19) and (2) risk factors predisposing to severe disease/mortality in the general population also seemed to affect patients with IEI, including more younger patients. Further studies will identify pathways that are associated with increased risk of severe disease and are nonredundant or redundant for protection against SARS-CoV-2.

STAT3 modulates reprogramming efficiency of human somatic cells; insights from autosomal dominant Hyper IgE syndrome caused by STAT3 mutations

Human induced pluripotent stem cell (iPSC) technology has opened exciting opportunities for stem-cell-based therapy. However, its wide adoption is precluded by several challenges including low reprogramming efficiency and potential for malignant transformation. Better understanding of the molecular mechanisms of the changes that cells undergo during reprograming is needed to improve iPSCs generation efficiency and to increase confidence for their clinical use safety. Here, we find that dominant negative mutations in STAT3 in patients with autosomal-dominant hyper IgE (Job's) syndrome (AD-HIES) result in greatly reduced reprograming efficiency of primary skin fibroblasts derived from skin biopsies. Analysis of normal skin fibroblasts revealed upregulation and phosphorylation of endogenous signal transducer and activator of transcription 3 (STAT3) and its binding to the NANOG promoter following transduction with OKSM factors. This coincided with upregulation of NANOG and appearance of cells expressing pluripotency markers. Upregulation of NANOG and number of pluripotent cells were greatly reduced throughout the reprograming process of AD-HIES fibroblasts that was restored by over-expression of functional STAT3. NANOGP8, the human-specific NANOG retrogene that is often expressed in human cancers, was also induced during reprogramming, to very low but detectable levels, in a STAT3-dependent manner. Our study revealed the critical role of endogenous STAT3 in facilitating reprogramming of human somatic cells.

Hematopoietic Stem Cell Transplantation and Vasculopathy Associated With STAT3-Dominant-Negative Hyper-IgE Syndrome

Dominant negative mutations in the transcription-factor STAT3 underlie the rare primary immunodeficiency Job's syndrome. Allogeneic Hematopoietic Stem Cell Transplantation (HSCT) has shown promise in correction of the underlying immunological defect, with one report suggesting HSCT can prevent development of wider connective tissue complications. Here, we report the case of a 26 year old male who developed an acute ST-elevation myocardial infarction due to coronary artery ectasia and thrombosis, occurring despite pediatric allogeneic HSCT for STAT3-HIES and a predicted 10-year conventional cardiovascular risk of 0.1%. Vasculopathy associated with STAT3-HIES may persist or arise following HSCT and can precipitate life-threatening complications. This has implications for counseling and vascular surveillance, and highlights the need for further studies to determine the risk, pathogenesis, and optimal management of the vasculopathy associated with STAT3-HIES.

The Child with Elevated IgE and Infection Susceptibility

PURPOSE OF REVIEW

Over the last 13 years, the genetic etiologies have been determined for multiple conditions causing elevated serum IgE, infection susceptibilities, and variable other features. In this review, we discuss the clinical presentation, laboratory features, and genetics of these diseases caused by mutations in STAT3, DOCK8, PGM3, IL6ST, ZNF341, IL6R, IL6ST, CARD11, and CARD14, with particular focus given to STAT3LOF and DOCK8 deficiency.

RECENT FINDINGS

Defining the phenotype of each of these syndromes with high IgE and infection susceptibility shows that some have a pronounced connective tissue phenotype such as STAT3LOF and IL6ST deficiency, some have worse viral susceptibility such as DOCK8 deficiency and heterozygous LOF CARD11, and some have more severe allergy and eczema such as LOF CARD14. Studying these distinct but overlapping monogenic diseases will allow a better understanding of more common disease processes such as allergy, eczema, infection susceptibility, scoliosis, and aneurysm.

An autocrine Vitamin D-driven Th1 shutdown program can be exploited for COVID-19

Pro-inflammatory immune responses are necessary for effective pathogen clearance, but cause severe tissue damage if not shut down in a timely manner ^1,2 . Excessive complement and IFN-γ-associated responses are known drivers of immunopathogenesis ³ and are among the most highly induced immune programs in hyper-inflammatory SARS-CoV2 lung infection ⁴ . The molecular mechanisms that govern orderly shutdown and retraction of these responses remain poorly understood. Here, we show that complement triggers contraction of IFN-γ producing CD4 ⁺ T helper (Th) 1 cell responses by inducing expression of the vitamin D (VitD) receptor (VDR) and CYP27B1, the enzyme that activates VitD, permitting T cells to both activate and respond to VitD. VitD then initiates the transition from pro-inflammatory IFN-γ ⁺ Th1 cells to suppressive IL-10 ⁺ Th1 cells. This process is primed by dynamic changes in the epigenetic landscape of CD4 ⁺ T cells, generating superenhancers and recruiting c-JUN and BACH2, a key immunoregulatory transcription factor ^5-7 . Accordingly, cells in psoriatic skin treated with VitD increased BACH2 expression, and BACH2 haplo-insufficient CD4 ⁺ T cells were defective in IL-10 production. As proof-of-concept, we show that CD4 ⁺ T cells in the bronchoalveolar lavage fluid (BALF) of patients with COVID-19 are Th1-skewed and that VDR is among the top regulators of genes induced by SARS-CoV2. Importantly, genes normally down-regulated by VitD were de-repressed in CD4 ⁺ BALF T cells of COVID-19, indicating that the VitD-driven shutdown program is impaired in this setting. The active metabolite of VitD, alfacalcidol, and cortico-steroids were among the top predicted pharmaceuticals that could normalize SARS-CoV2 induced genes. These data indicate that adjunct therapy with VitD in the context of other immunomodulatory drugs may be a beneficial strategy to dampen hyperinflammation in severe COVID-19.

Dominant-negative mutations in human IL6ST underlie hyper-IgE syndrome

Autosomal dominant hyper-IgE syndrome (AD-HIES) is typically caused by dominant-negative (DN) STAT3 mutations. Patients suffer from cold staphylococcal lesions and mucocutaneous candidiasis, severe allergy, and skeletal abnormalities. We report 12 patients from 8 unrelated kindreds with AD-HIES due to DN IL6ST mutations. We identified seven different truncating mutations, one of which was recurrent. The mutant alleles encode GP130 receptors bearing the transmembrane domain but lacking both the recycling motif and all four STAT3-recruiting tyrosine residues. Upon overexpression, the mutant proteins accumulate at the cell surface and are loss of function and DN for cellular responses to IL-6, IL-11, LIF, and OSM. Moreover, the patients' heterozygous leukocytes and fibroblasts respond poorly to IL-6 and IL-11. Consistently, patients with STAT3 and IL6ST mutations display infectious and allergic manifestations of IL-6R deficiency, and some of the skeletal abnormalities of IL-11R deficiency. DN STAT3 and IL6ST mutations thus appear to underlie clinical phenocopies through impairment of the IL-6 and IL-11 response pathways.

Expansion of the Human Phenotype Ontology (HPO) knowledge base and resources

The Human Phenotype Ontology (HPO)—a standardized vocabulary of phenotypic abnormalities associated with 7000+ diseases—is used by thousands of researchers, clinicians, informaticians and electronic health record systems around the world. Its detailed descriptions of clinical abnormalities and computable disease definitions have made HPO the de facto standard for deep phenotyping in the field of rare disease. The HPO’s interoperability with other ontologies has enabled it to be used to improve diagnostic accuracy by incorporating model organism data. It also plays a key role in the popular Exomiser tool, which identifies potential disease-causing variants from whole-exome or whole-genome sequencing data. Since the HPO was first introduced in 2008, its users have become both more numerous and more diverse. To meet these emerging needs, the project has added new content, language translations, mappings and computational tooling, as well as integrations with external community data. The HPO continues to collaborate with clinical adopters to improve specific areas of the ontology and extend standardized disease descriptions. The newly redesigned HPO website (www.human-phenotype-ontology.org) simplifies browsing terms and exploring clinical features, diseases, and human genes.

Prospective Study of a Novel, Radiation-Free, Reduced-Intensity Bone Marrow Transplantation Platform for Primary Immunodeficiency Diseases

Allogeneic blood or marrow transplantation (BMT) is a potentially curative therapy for patients with primary immunodeficiency (PID). Safe and effective reduced-intensity conditioning (RIC) approaches that are associated with low toxicity, use alternative donors, and afford good immune reconstitution are needed to advance the field. Twenty PID patients, ranging in age from 4 to 58 years, were treated on a prospective clinical trial of a novel, radiation-free and serotherapy-free RIC, T-cell-replete BMT approach using pentostatin, low-dose cyclophosphamide, and busulfan for conditioning with post-transplantation cyclophosphamide-based graft-versus-host-disease (GVHD) prophylaxis. This was a high-risk cohort with a median hematopoietic cell transplantation comorbidity index of 3. With median follow-up of survivors of 1.9 years, 1-year overall survival was 90% and grade III to IV acute GVHD-free, graft-failure-free survival was 80% at day +180. Graft failure incidence was 10%. Split chimerism was frequently observed at early post-BMT timepoints, with a lower percentage of donor T cells, which gradually increased by day +60. The cumulative incidences of grade II to IV and grade III to IV acute GVHD (aGVHD) were 15% and 5%, respectively. All aGVHD was steroid responsive. No patients developed chronic GVHD. Few significant organ toxicities were observed. Evidence of phenotype reversal was observed for all engrafted patients, even those with significantly mixed chimerism (n = 2) or with unknown underlying genetic defect (n = 3). All 6 patients with pre-BMT malignancies or lymphoproliferative disorders remain in remission. Most patients have discontinued immunoglobulin replacement. All survivors are off immunosuppression for GVHD prophylaxis or treatment. This novel RIC BMT approach for patients with PID has yielded promising results, even for high-risk patients.

An Update on Syndromes with a Hyper-IgE Phenotype

Improvement in genetic testing has allowed specific delineation of several distinct clinical causes characterized by the hyperimmunoglobulin E (IgE) phenotype of eczema, recurrent infections, and elevated serum IgE. Mutations in STAT3, DOCK8, PGM3, ERBIN, IL6ST, and CARD11 cause clinical phenotypes that can present in this manner. This article focuses on loss of function STAT3 mutations causing autosomal-dominant hyper-IgE syndrome and dedicator of cytokinesis 8 deficiency, with discussion of other more recently described diseases.

Insights into immunity from clinical and basic science studies of DOCK8 immunodeficiency syndrome

DOCK8 immunodeficiency syndrome (DIDS) is a progressive combined immunodeficiency that can be distinguished from other combined immunodeficiencies or hyperimmunoglobulinemia E syndromes in featuring (a) profound susceptibility to virus infections of the skin, with associated skin cancers, and (b) severe food allergies. The DOCK8 locus has many repetitive sequence elements that predispose to the generation of large germline deletions as well as recombination-mediated somatic DNA repair. Residual DOCK8 protein contributes to the variable disease phenotype. The severe virus infections of the skin, and probably also VZV-associated vasculopathy, reflect an important function of DOCK8, which is normally required to maintain lymphocyte shape integrity as the cells migrate through dense tissues. Loss of DOCK8 also causes immune deficits through other mechanisms including a milder generalized cell survival defect and skewing of T helper cell subsets. Recent work has uncovered the roles for DOCK8 in dendritic cell responses that can also help explain the virus susceptibility, as well as in regulatory T cells that might help explain autoimmunity in a minority of patients. Fortunately, hematopoietic stem cell transplantation cures the eczema and infection susceptibility of DIDS, but not necessarily the other disease manifestations including food allergies.

The Changing Paradigm of Management of Liver Abscesses in Chronic Granulomatous Disease

Background

Chronic granulomatous disease (CGD) is a rare genetic disorder causing recurrent infections. More than one-quarter of patients develop hepatic abscesses and liver dysfunction. Recent reports suggest that disease-modifying treatment with corticosteroids is effective for these abscesses. Comparison of corticosteroid therapy to traditional invasive treatments has not been performed.

Methods

Records of 268 patients with CGD treated at the National Institutes of Health from 1980 to 2014 were reviewed. Patients with liver involvement and complete records were included. We recorded residual reactive oxygen intermediate (ROI) production by neutrophils, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase germline mutation status, laboratory values, imaging characteristics, time to repeat hepatic interventions, and overall survival among 3 treatment cohorts: open liver surgery (OS), percutaneous liver-directed interventional radiology therapy (IR), and high-dose corticosteroid management (CM).

Results

Eighty-eight of 268 patients with CGD suffered liver involvement. Twenty-six patients with a median follow-up of 15.5 years (8.5-32.9 years of follow-up) had complete records and underwent 100 standard interventions (42 IR and 58 OS). Eight patients received a treatment with high-dose corticosteroids only. There were no differences in NADPH genotype, size, or number of abscesses between patients treated with OS, IR, or CM. Time to repeat intervention was extended in OS compared with IR (18.8 vs 9.5 months, P = .04) and further increased in CM alone (median time to recurrence not met). Impaired macrophage and neutrophil function measured by ROI production correlated with shorter time to repeat intervention (r = 0.6, P = .0019).

Conclusions

Treatment of CGD-associated liver abscesses with corticosteroids was associated with fewer subsequent hepatic interventions and improved outcome compared to invasive treatments.

Generation of human induced pluripotent stem cell lines (NIHTVBi011-A, NIHTVBi012-A, NIHTVBi013-A) from autosomal dominant Hyper IgE syndrome (AD-HIES) patients carrying STAT3 mutation

Autosomal dominant Hyper IgE syndrome (AD-HIES), a rare immune deficiency affecting fewer than one per million people, is caused by heterozygous deleterious mutations in STAT3. STAT3 signaling plays crucial roles in basic cellular functions affecting broad aspects of cellular homeostasis. Accordingly, in addition to immunological deficits, patients experience severe multisystem non-immunological features. Human induced pluripotent stem cells (hiPSC) are well established as in vivo disease models for various human pathologies. We describe the generation of iPSC from three AD-HIES patients. These iPSCs express pluripotency markers, differentiate into three germ layers, have normal karyotype and similar genome identity to parental cells.

A dysbiotic microbiome triggers TH17 cells to mediate oral mucosal immunopathology in mice and humans

Periodontitis is one of the most common human inflammatory diseases, yet the mechanisms that drive immunopathology and could be therapeutically targeted are not well defined. Here, we demonstrate an expansion of resident memory T helper 17 (T_H17) cells in human periodontitis. Phenocopying humans, T_H17 cells expanded in murine experimental periodontitis through local proliferation. Unlike homeostatic oral T_H17 cells, which accumulate in a commensal-independent and interleukin-6 (IL-6)-dependent manner, periodontitis-associated expansion of T_H17 cells was dependent on the local dysbiotic microbiome and required both IL-6 and IL-23. T_H17 cells and associated neutrophil accumulation were necessary for inflammatory tissue destruction in experimental periodontitis. Genetic or pharmacological inhibition of T_H17 cell differentiation conferred protection from immunopathology. Studies in a unique patient population with a genetic defect in T_H17 cell differentiation established human relevance for our murine experimental studies. In the oral cavity, human T_H17 cell defects were associated with diminished periodontal inflammation and bone loss, despite increased prevalence of recurrent oral fungal infections. Our study highlights distinct functions of T_H17 cells in oral immunity and inflammation and paves the way to a new targeted therapeutic approach for the treatment of periodontitis.

IL-10 signaling in dendritic cells controls IL-1β-mediated IFNγ secretion by human CD4+ T cells: relevance to inflammatory bowel disease

Uncontrolled interferon γ (IFNγ)-mediated T-cell responses to commensal microbiota are a driver of inflammatory bowel disease (IBD). Interleukin-10 (IL-10) is crucial for controlling these T-cell responses, but the precise mechanism of inhibition remains unclear. A better understanding of how IL-10 exerts its suppressive function may allow identification of individuals with suboptimal IL-10 function among the heterogeneous population of IBD patients. Using cells from patients with an IL10RA deficiency or STAT3 mutations, we demonstrate that IL-10 signaling in monocyte-derived dendritic cells (moDCs), but not T cells, is essential for controlling IFNγ-secreting CD4⁺ T cells. Deficiency in IL-10 signaling dramatically increased IL-1β release by moDCs. IL-1β boosted IFNγ secretion by CD4⁺ T cells either directly or indirectly by stimulating moDCs to secrete IL-12. As predicted a signature of IL-10 dysfunction was observed in a subgroup of pediatric IBD patients having higher IL-1β expression in activated immune cells and macroscopically affected intestinal tissue. In agreement, reduced IL10RA expression was detected in peripheral blood mononuclear cells and a subgroup of pediatric IBD patients exhibited diminished IL-10 responsiveness. Our data unveil an important mechanism by which IL-10 controls IFNγ-secreting CD4⁺ T cells in humans and identifies IL-1β as a potential classifier for a subgroup of IBD patients.

STAT1 Gain-of-Function Mutations Cause High Total STAT1 Levels With Normal Dephosphorylation

Signal transducer and activator of transcription (STAT1)1 gain of function (GOF) pathogenic variants have been associated with increased levels of phosphorylated STAT1 and STAT1-dependent cellular responses. Delayed dephosphorylation was proposed as the underlying mechanism leading to the characteristically raised pSTAT1 levels. We examined the levels of STAT1 protein and message as well as rates of STAT1 phosphorylation, dephosphorylation, and degradation associated with STAT1 GOF pathogenic variants. Fresh peripheral blood mononuclear cells (PBMC) from 14 STAT1 GOF patients carrying 10 different pathogenic variants in the coiled-coil, DNA binding, and SH2 domains and healthy donors were used to study STAT1 levels and phosphorylation (pSTAT1) following IFNγ and IFNα stimulation. STAT1 protein levels were measured by flow cytometry and immunoblot. STAT1 mRNA levels were measured using quantitative reverse transcription PCR. STAT1 protein degradation was studied using cycloheximide. Patient IFNγ and IFNα induced peak pSTAT1 was higher than in healthy controls. The velocity of pSTAT1 dephosphorylation after treatment of IFNγ stimulated CD14⁺ monocytes with the Janus Kinase (JAK)-inhibitor ruxolitinib was significantly faster in patient cells. STAT1 protein levels in patient CD14⁺ monocytes and CD3⁺ T cells were higher than in healthy donors. There was a strong and positive correlation between CD14⁺ STAT1 protein levels and peak pSTAT1 levels. Patient fresh PBMC STAT1 mRNA levels were increased at rest and after 16 h of incubation. STAT1 protein degradation was similar in patient and healthy volunteer cells. Patient IFNγ receptors 1 and 2 and JAK2 levels were normal. One patient in our cohort was treated with the oral JAK inhibitor ruxolitinib. Treatment was associated with normalization of both STAT1 protein and peak pSTAT1 levels. After JAK inhibitor treatment was stopped the patient's CD14⁺ monocyte STAT1 protein and peak phosphorylation levels increased proportionally. These findings suggest that patients with STAT1 GOF mutations have higher levels of total STAT1 protein, leading to high levels of pSTAT1 after stimulation, despite rapid STAT1 dephosphorylation and normal degradation.