Biallelic PI4KA Mutations Disrupt B-Cell Metabolism and Cause B-Cell Lymphopenia and Hypogammaglobulinemia.

PURPOSE: PI4KA-related disorder is a highly clinically variable condition characterized by neurological (limb spasticity, developmental delay, intellectual disability, seizures, ataxia, nystagmus) and gastrointestinal (inflammatory bowel disease and multiple intestinal atresia) manifestations. Although features consistent with immunodeficiency (autoimmunity/autoinflammation and recurrent infections) have been reported in a subset of patients, the burden of B-cell deficiency and hypogammaglobulinemia has not been extensively investigated. We sought to describe the clinical presentation and manifestations of patients with PI4KA-related disorder and to investigate the metabolic consequences of biallelic PI4KA variants in B cells. METHODS: Clinical data from patients with PI4KA variants were obtained. Multi-omics analyses combining transcriptome, proteome, lipidome and metabolome analyses in conjunction with functional assays were performed in EBV-transformed B cells. RESULTS: Clinical and laboratory data of 13 patients were collected. Recurrent infections (7/13), autoimmune/autoinflammatory manifestations (5/13), B-cell deficiency (8/13) and hypogammaglobulinemia (8/13) were frequently observed. Patients' B cells frequently showed increased transitional and decreased switched memory B-cell subsets. Pathway analyses based on differentially expressed transcripts and proteins confirmed the central role of PI4KA in B cell differentiation with altered B-cell receptor (BCR) complex and signalling. By altering lipids production and tricarboxylic acid cycle regulation, and causing increased endoplasmic reticulum stress, biallelic PI4KA mutations disrupt B cell metabolism inducing mitochondrial dysfunction. As a result, B cells show hyperactive PI3K/mTOR pathway, increased autophagy and deranged cytoskeleton organization. CONCLUSION: By altering lipid metabolism and TCA cycle, impairing mitochondrial activity, hyperactivating mTOR pathway and increasing autophagy, PI4KA-related disorder causes a syndromic inborn error of immunity presenting with B-cell deficiency and hypogammaglobulinemia.

A Nationwide Study of GATA2 Deficiency in Italy Reveals Novel Symptoms and Genotype-phenotype Association.

GATA2 deficiency is a rare disorder encompassing a broadly variable phenotype and its clinical picture is continuously evolving. Since it was first described in 2011, up to 500 patients have been reported. Here, we describe a cohort of 31 Italian patients (26 families) with molecular diagnosis of GATA2 deficiency. Patients were recruited contacting all the Italian Association of Pediatric Hematology and Oncology (AIEOP) centers, the Hematology Department in their institution and Italian societies involved in the field of vascular anomalies, otorhinolaryngology, dermatology, infectious and respiratory diseases. Median age at the time of first manifestation, molecular diagnosis and last follow-up visit was 12.5 (age-range, 2-52 years), 18 (age-range, 7-64 years) and 22 years (age-range, 3-64), respectively. Infections (39%), hematological malignancies (23%) and undefined cytopenia (16%) were the most frequent symptoms at the onset of the disease. The majority of patients (55%) underwent hematopoietic stem cell transplantation. During the follow-up rarer manifestations emerged. The clinical penetrance was highly variable, with the coexistence of severely affected pediatric patients and asymptomatic adults in the same pedigree. Two individuals remained asymptomatic at the last follow-up visit. Our study highlights new (pilonidal cyst/sacrococcygeal fistula, cholangiocarcinoma and gastric adenocarcinoma) phenotypes and show that lymphedema may be associated with null/regulatory mutations. Countrywide studies providing long prospective follow-up are essential to unveil the exact burden of rarer manifestations and the natural history in GATA2 deficiency.

Antibody Deficiency in Patients with Biallelic KARS1 Mutations.

Biallelic KARS1 mutations cause KARS-related diseases, a rare syndromic condition encompassing central and peripheral nervous system impairment, heart and liver disease, and deafness. KARS1 encodes the t-RNA synthase of lysine, an aminoacyl-tRNA synthetase, involved in different physiological mechanisms (such as angiogenesis, post-translational modifications, translation initiation, autophagy and mitochondrial function). Although patients with immune-hematological abnormalities have been individually described, results have not been collectively discussed and functional studies investigating how KARS1 mutations affect B cells have not been performed. Here, we describe one patient with severe developmental delay, sensoneurinal deafness, acute disseminated encephalomyelitis, hypogammaglobulinemia and recurrent infections. Pathogenic biallelic KARS1 variants (Phe291Val/ Pro499Leu) were associated with impaired B cell metabolism (decreased mitochondrial numbers and activity). All published cases of KARS-related diseases were identified. The corresponding authors and researchers involved in the diagnosis of inborn errors of immunity or genetic syndromes were contacted to obtain up-to-date clinical and immunological information. Seventeen patients with KARS-related diseases were identified. Recurrent/severe infections (9/17) and B cell abnormalities (either B cell lymphopenia [3/9], hypogammaglobulinemia [either IgG, IgA or IgM; 6/15] or impaired vaccine responses [4/7]) were frequently reported. Immunoglobulin replacement therapy was given in five patients. Full immunological assessment is warranted in these patients, who may require detailed investigation and specific supportive treatment.

Pediatric immune myelofibrosis (PedIMF) as a novel and distinct clinical pathological entity.

Myelofibrosis is a rare myeloproliferative disorder. The detailed descriptions of myelofibrosis in children and adolescents is limited to a few case series and case reports describing fewer than 100 patients, thus suggesting the extreme rarity of this condition prior to adulthood. Though pediatric patients rarely present the typical features and outcomes usually observed in older people, pediatric myelofibrosis is not considered an independent entity. Here we aim to describe patients with pediatric myelofibrosis, showing different clinical and pathological features when compared to the World Health Organization 2016 Primary Myelofibrosis classification. We retrospectively collected and analyzed 14 consecutive pediatric myelofibrosis diagnosed in our Pediatric hematology outpatient clinic over a six-year period. According to clinical data and bone marrow biopsy findings, patients were classified into three subgroups: adult-like myelofibrosis, pediatric immune myelofibrosis, idiopathic myelofibrosis. Pediatric Immune Myelofibrosis was the predominant subgroup in our cohort (7/14). Pediatric Immune Myelofibrosis is characterized by peculiar bone marrow features (i.e., T lymphocyte infiltration) and a milder course compared to the other patients Pediatric Immune Myelofibrosis is a novel and distinct pathological entity. We suggest to carefully consider Pediatric Immune Myelofibrosis in case of bone marrow biopsies showing myelofibrosis that do not fulfill WHO criteria.

Abnormal B-Cell Maturation and Increased Transitional B Cells in CBL Syndrome.

CBL syndrome is a Noonan-like RASopathy with heterogeneous clinical phenotype and predisposition to juvenile myelomonocytic leukemia (JMML). Here we describe two patients with identical germline CBL mutation and clinical and immune-hematological overlapping features with autoimmune lymphoproliferative syndrome (ALPS) and B-cell expansion with NF-κB and T-cell anergy (BENTA) syndrome. Increased immature/transitional B cells can be depicted in CBL syndrome, ALPS, and BENTA. Nonetheless, our patients here described showed peculiar B-cell phenotype due to increased immature/transitional CD34+ B cells. This feature differentiates CBL syndrome from BENTA, pointing toward an abnormal proliferation of B-cell early precursors.

A review of current knowledge on Pollution, Cigarette Smoking and COVID-19 diffusion and their relationship with inflammation.

Coronavirus disease (COVID-19) is an infectious disease caused by the newly discovered coronavirus, Sars-Cov-2. This infection can cause mild to very severe respiratory and systemic illness mainly related with a cytokine storm. The epidemiology of COVID-19 is under continuous evolution, and studies are ongoing aiming at identifying the possible factors facilitating the diffusion of this infection. It is documented that air pollution and smoking are a leading cause of human morbidity and mortality globally, and can increase the risk of many diseases, including respiratory diseases. Overall, a linear relationship between exposure to atmospheric pollutants and diffusion of the Sars-Cov2 virus seems to exist. However, this correlation, cannot be regarded as a cause-effect relationship.  The available data show that air pollution is responsible for inflammation and hyper-activation of innate immunity that are associated with the worst outcomes of covid-19 but do not allow to conclude that atmospheric particulate is responsible for increased contagion. As to smoking, nicotine activation of nicotinic receptors leads to enhanced protease activation, apoptosis and inflammatory signaling through the same pathways (Renin-angiotensin system (RAS) and angiotensin-converting enzyme 2 (ACE2)) used by the virus increasing the inflammatory/destructive action of the virus itself. The increase in non-communicable diseases and of chronic inflammatory diseases is in line with environmental pollution, related climate changes, and with an augmented susceptibility to infectious diseases with increased contagiousness and morbidity. Restrictive measures to limit environmental pollution are needed worldwide as this represents a threat for human health.

[Pathogenicity island region of clinical and environmental strains of Vibrio parahaemolyticus, isolated in Chile]. / Isla de patogenicidad de Vibrio parahaemolyticus en cepas chilenas clínicas y ambientales.

BACKGROUND: Most clinical isolates of Vibrio parahaemolyticus produce a major virulence factor known as the thermostable direct hemolysin (TDH). TDH is encoded by the tdh gene which is located in a genomic pathogenicity island (PAI). Most environmental isolates are described as tdh negative. AIM: To assess if environmental strains lack the full pathogenicity island or if only the tdh gene is deleted. MATERIAL AND METHODS: Thirty eight clinical and 66 environmental strains of Vibrio parahaemolyticus were studied. PAI was characterized by polymerase chain reaction (PCR). The presence of tdhA and tdhS genes, was determined by Southern blot. RESULTS: Fifty three environmental strains (80%) lacked a full PAI when compared with clinical strains. In environmental strains, Southern blot and sequence analysis showed that a genetic region of 80 kilobase pairs including genes from VPA1310 to VPA1396 was missing. CONCLUSIONS: These results highlight the genetic dynamism of Vibrio parahaemolyticus pathogenecity island region and suggest that new pathogenic strains could appear by horizontal transfer of the island between toxigenic and non-toxigenic strains.

Isla de patogenicidad de Vibrio parahaemolyticus en cepas chilenas clínicas y ambientales / Pathogenicity island region of clinical and environmental strains of Vibrio parahaemolyticus, isolated in Chile

Background: Most clinical isolates of Vibrio parahaemolyticus produce a major virulence factor known as the thermostable direct hemolysin (TDH). TDH is encoded by the tdh gene which is located in a genomic pathogenicity island (PAI). Most environmental isolates are described as tdh negative. Aim: To assess if environmental strains lack the full pathogenicity island or if only the tdh gene is deleted. Material and methods: Thirty eight clinical and 66 environmental strains of Vibrio parahaemolyticus were studied. PAI was characterized by polymerase chain reaction (PCR). The presence of tdhA and tdhS genes, was determined by Southern blot. Results: Fifty three environmental strains (80%) lacked a full PAI when compared with clinical strains. In environmental strains, Southern blot and sequence analysis showed that a genetic región of 80 kilobase pairs including genes from VPA1310 to VPA1396 was missing. Conclusions: These results highlight the genetic dynamism of Vibrio parahaemolyticus pathogenecity island región and suggest that new pathogenic strains could appear by horizontal transfer of the island between toxigenic and non-toxigenic strains.