Case Report: Altered NK Cell Compartment and Reduced CXCR4 Chemotactic Response of B Lymphocytes in an Immunodeficient Patient With HPV-Related Disease

the study of inborn errors of immunity (IEI) provides unique opportunities to elucidate the microbiome and pathogenic mechanisms related to severe viral infection. several immunological and genetic anomalies may contribute to the susceptibility to develop human papillomavirus (HPV) pathogenesis. they include different acquired immunodeficiencies, EVER1-2 or CIB1 mutations underlying epidermodysplasia verruciformis (EV) syndrome and multiple IEI. whereas EV syndrome patients are specifically unable to control infections with beta HPV, individuals with IEI show broader infectious and immune phenotypes. the WHIM (warts, hypogammaglobulinemia, infection, and myelokathexis) syndrome caused by gain-of-CXCR4-function mutation manifests by HPV-induced extensive cutaneous warts but also anogenital lesions that eventually progress to dysplasia. Here we report alterations of B and NK cells in a female patient suffering from cutaneous and mucosal HPV-induced lesions due to an as-yet unidentified genetic defect. despite no detected mutations in CXCR4, B but not NK cells displayed a defective CXCR4-dependent chemotactic response toward CXCL12. In addition, NK cells showed an abnormal distribution with an expanded CD56(bright) cell subset and defective cytotoxicity of CD56(dim) cells. our observations extend the clinical and immunological spectrum of IEI associated with selective susceptibility toward HPV pathogenesis, thus providing new insight on the immune control of HPV infection and potential host susceptibility factors

Case Report: Crossing a rugged road in a primary immune regulatory disorder

over the last decades, Inborn errors of immunity (IEI) characterized by an immune dysregulatory picture, isolated or combined with infections, have been increasingly identified and referred as primary immune regulatory disorders (PIRD). PIRD diagnosis may be difficult due to heterogeneity of time onset, sequence of clinical manifestations and laboratory abnormalities. moreover, the dissection of a PIRD vs. a secondary immunodeficiency (SID) might be a real challenge since the same indications for immunosuppressant treatments might represent per se a PIRD clinical expression. here we report a female patient with a history of recurrent respiratory and urinary tract infections since early infancy and a diagnosis of rheumatoid arthritis in adulthood. after poor response to several biologicals she was treated with rituximab and sent to immunology referral for a severe hypogammaglobulinemia. clinical and immunological features matched a diagnosis of common variable immunodeficiency and when IgG replacement therapy and antibiotic prophylaxis were added a good infectious control was obtained. hh next generation sequencing analysis has revealed a novel heterozygous VUS in the IKBKB gene (c.1465A > G; p.Ser489Gly). functional analysis has shown a reduced capacity of B lymphocytes and CD4 positive T cells in inducing I kappa B alpha degradation, with negative impact on NF-kB pathway. due to recurrent infections attributed to a common condition in childhood and to an exclusive autoimmunity-centered approach in adulthood, both diagnosis and suitable treatment strategies have suffered a significant delay. to reduce the diagnostic delay, pediatricians, general practitioners and specialists should be aware of IEI and the challenges to differentiate them from SID. furthermore, genetic characterization and functional analysis may contribute to a personalized approach, in a perspective of targeted or semi-targeted therapy

The Evolutionary Scenario of Pediatric Unclassified Primary Antibody Deficiency to Adulthood

background: unclassified primary antibody deficiency (unPAD) is a relatively novel inborn error of immunity (IEI) condition that can vary with time to more defined entities. since long-term follow-up (FU) studies are scarce, we aimed to provide insight into the evolutionary clinical and immunological scenario of unPAD children to adulthood and identification of biomarkers of primary immune deficiency (PID) persistence. methods: a total of 23 pediatric unPAD patients underwent clinical and immunological FU for a mean time of 14 years (range 3-32 years, median 16 years). results: UnPAD diagnosis may change over time. at the last FU, 10/23 (44%) children matched the diagnosis of transient hypogammaglobulinemia of infancy and 13/23 (56%) suffered from a persistent PID. In detail, an unPAD condition was confirmed in 7/23 (30%) patients, whereas 3/23 (13%), 2/23 (9%), and 1/23 (4%) were reclassified as common variable immunodeficiency, selective IgA deficiency, and isolated IgM deficiency, respectively. Low IgA, low specific antibody response to pneumococcus, and lower respiratory tract infections at diagnosis were independently associated with IEI persistence. conclusions: long-term monitoring of unPAD patients is required to define their outcome and possible evolution towards a definitive IEI diagnosis

Case report: Neonatal-onset inflammatory bowel disease due to novel compound heterozygous mutations in DUOX2

Very Early Onset Inflammatory Bowel Disease (VEO-IBD) is potentially associated with genetic disorders of the intestinal epithelial barrier or inborn errors of immunity (IEI). Dual oxidase 2 (DUOX2), an H2O2-producing NADPH oxidase expressed at apical enterocyte membranes, plays a crucial role in innate defense response. Biallelic DUOX2 mutations have been described only in two patients with VEO-IBD to date. We report the case of a 1-month-old female infant who presented persistent high C-reactive protein (CRP) levels from birth and anemia. Positive occult blood and very high calprotectin in the stool were detected and abdominal ultrasound showed thickened last ileal loop. Full endoscopy evaluation revealed important colon stenosis with multiple pseudo-polyploidy formations that resulted refractory to steroid therapy, requiring a partial colic resection. Histological examination of biopsy samples showed morphological features of IBD. Whole Exome Sequencing (WES) disclosed compound heterozygous variants in the DUOX2 gene: the pathogenic c.2524C>T; p.Arg842Ter and the variant of uncertain significance (VUS) c.3175C>T; p.Arg1059Cys. Molecular and functional studies showed the presence of mutant DUOX2 in the intestinal epithelium of the patient, albeit with at least 50% decreased catalytic activity. In conclusion, we describe the third patient to date with compound heterozygous variants of DUOX2, responsible for monogenic neonatal-IBD. This case expands the knowledge about Mendelian causes of VEO-IBD and DUOX2 deficiency. We suggest that DUOX2 should be part of the diagnostic evaluation of patients with suspected monogenic VEO-IBD

Partial T cell defects and expanded CD56bright NK cells in an SCID patient carrying hypomorphic mutation in the IL2RG gene

X-linked severe combined immunodeficiency (X-SCID) caused by full mutation of the IL2RG gene leads to T- B+ NK- phenotype and is usually associated with severe opportunistic infections, diarrhea, and failure to thrive. When IL2RG hypomorphic mutation occurs, diagnosis could be delayed and challenging since only moderate reduction of T and NK cells may be present. Here, we explored phenotypic insights and the impact of the p.R222C hypomorphic mutation (IL2RGR222C ) in distinct cell subsets in an 8-month-old patient with atypical X-SCID. We found reduced CD4+ T cell counts, a decreased frequency of naïve CD4+ and CD8+ T cells, and an expansion of B cells. Ex vivo STAT5 phosphorylation was impaired in CD4+ CD45RO+ T cells, yet compensated by supraphysiological doses of IL-2. Sanger sequencing on purified cell subsets showed a partial reversion of the mutation in total CD3+ cells, specifically in recent thymic emigrants (RTE), effector memory (EM), and CD45RA+ terminally differentiated EM (EMRA) CD4+ T cells. Of note, patient's NK cells had a normal frequency compared to age-matched healthy subjects, but displayed an expansion of CD56bright cells with higher perforin content and cytotoxic potential, associated with accumulation of NK-cell stimulatory cytokines (IL-2, IL-7, IL-15). Overall, this report highlights an alteration in the NK-cell compartment that, together with the high disease-phenotype variability, should be considered in the suspicion of X-SCID with hypomorphic IL2RG mutation

IPINeT Ped-unPAD Study: Goals, Design, and Preliminary Results

background: an unclassified primary antibody deficiency (unPAD) is a widely heterogeneous clinical entity, recently identified within the spectrum of Inborn errors of Immunity (IEIs). since unPAD has been traditionally considered as a mild condition, it has incorrectly received little attention, resulting in the paucity of extensive and comparable studies describing its natural history. to address the gaps in characterizing, understanding, and managing pediatric unPAD patients, the Italian primary Immunodeficiency network (IPINet) Ped-unPAD study has recently been launched. methods: seventeen IPINeT centers have expressed interest to participate, and data collection is still on-going. hereby, we anticipate preliminary key issues emerging from the first 110 enrolled patients, attending three IPINet centers. results: a proportion of unPAD patients have experienced a severe infectious phenotype, which required hospitalization in a quarter of patients and antibiotic prophylaxis or Immunoglobulin replacement therapy in approximately 10% of patients. In this partial cohort, a mean follow-up (FU) of 5 years confirmed unPAD diagnosis in fifty percent of cases, with the remaining being reclassified as the transient hypogammaglobulinemia of Infancy (25%) and other IEIs (25%), such as a common variable Immunodeficiency, selective IgA deficiency, selective IgM deficiency, and IgG3 subclass deficiency. conclusions: despite a phenotype overlap at diagnosis, clinicians should be aware that unPAD is a mutable condition that deserves comprehensive evaluation and long-term monitoring to dissect the final diagnosis for optimal treatment

First Case of Patient With Two Homozygous Mutations in MYD88 and CARD9 Genes Presenting With Pyogenic Bacterial Infections, Elevated IgE, and Persistent EBV Viremia

We described for the first time a female patient with the simultaneous presence of two homozygous mutations in MYD88 and CARD9 genes presenting with pyogenic bacterial infections, elevated IgE, and persistent EBV viremia. In addition to defective TLR/IL1R-signaling, we described novel functional alterations into the myeloid compartment. In particular, we demonstrated a defective production of reactive oxygen species exclusively in monocytes upon E. coli stimulation, the inability of immature mono-derived DCs (iDCs) to differentiate into mature DCs (mDCs) and the incapacity of mono-derived macrophages (MDMs) to resolve BCG infection in vitro. Our data do not provide any evidence for digenic inheritance in our patient, but rather for the association of two monogenic disorders. This case illustrates the importance of using next generation sequencing (NGS) to determine the most accurate and early diagnosis in atypical clinical and immunological phenotypes, and with particular concern in consanguineous families. Indeed, besides the increased susceptibility to recurrent invasive pyogenic bacterial infections due to MYD88 deficiency, the identification of CARD9 mutations underline the risk of developing invasive fungal infections emphasizing the careful monitoring for the occurrence of fungal infection and the opportunity of long-term antifungal prophylaxis

Radiosensitivity in patients affected by ARPC1B deficiency: a new disease trait?

Actin-related protein 2/3 complex subunit 1B (ARPC1B) deficiency is a recently described inborn error of immunity (IEI) presenting with combined immunodeficiency and characterized by recurrent infections and thrombocytopenia. Manifestations of immune dysregulation, including colitis, vasculitis, and severe dermatitis, associated with eosinophilia, hyper-IgA, and hyper-IgE are also described in ARPC1B-deficient patients. To date, hematopoietic stem cell transplantation seems to be the only curative option for patients. ARPC1B is part of the actin-related protein 2/3 complex (Arp2/3) and cooperates with the Wiskott–Aldrich syndrome protein (WASp) in the regulation of the actin cytoskeleton remodeling and in driving double-strand break clustering for homology-directed repair. In this study, we aimed to investigate radiosensitivity (RS) in ARPC1B-deficient patients to assess whether it can be considered an additional disease trait. First, we performed trio-based next-generation-sequencing studies to obtain the ARPC1B molecular diagnosis in our index case characterized by increased RS, and then we confirmed, using three different methods, an increment of radiosensitivity in all enrolled ARPC1B-deficient patients. In particular, higher levels of chromatid-type aberrations and γH2AX foci, with an increased number of cells arrested in the G2/M-phase of the cell cycle, were found in patients’ cells after ionizing radiation exposition and radiomimetic bleomycin treatment. Overall, our data suggest increased radiosensitivity as an additional trait in ARPC1B deficiency and support the necessity to investigate this feature in ARPC1B patients as well as in other IEI with cytoskeleton defects to address specific clinical follow-up and optimize therapeutic interventions

Natural Killer Cells from Patients with Recombinase-Activating Gene and Non-Homologous End Joining Gene Defects Comprise a Higher Frequency of CD56bright NKG2A+++ Cells, and Yet Display Increased Degranulation and Higher Perforin Content.

Mutations of the recombinase Activating Genes 1 and 2 (RAG1, RAG2) in humans are associated with a broad range of phenotypes. For patients with severe clinical presentation, hematopoietic stem cell transplantation (HSCT) represents the only curative treatment, however high rates of graft failure and incomplete immune reconstitution have been observed, especially after unconditioned haploidentical transplantation. Studies in mice have shown that Rag-/- NK cells have a mature phenotype, reduced fitness and increased cytotoxicity. We aimed to analyze NK cell phenotype and function in patients with mutations in RAG and in non-homologous end joining (NHEJ) genes. Here we provide evidence that NK cells from these patients have an immature phenotype, with significant expansion of CD56bright CD16-/int CD57- cells, yet increased degranulation and high perforin content. Correlation was observed between in vitro recombinase activity of the mutant proteins, NK cell abnormalities, and in vivo clinical phenotype. Addition of serotherapy in the conditioning regimen, with the aim of depleting the autologous NK cell compartment, may be important to facilitate engraftment and immune reconstitution in patients with RAG and NHEJ defects treated by HSCT