Formation of Mycobacterium abscessus colonies in cellular culture in an in vitro infection model.

Mycobacterium abscessus is one of the most important nontuberculous mycobacteria that cause lung diseases. In vitro infection models developed to analyze the immune response are frequently based on the addition of mycobacteria to mononuclear cells or neutrophils from peripheral blood. An important requirement of these assays is that most cells phagocytose mycobacteria, only accomplished by using large multiplicities of infection (1 or more bacteria per cell) which may not adequately reflect the inhalation of a few mycobacteria by the host. We propose modifications that try to mimic some of the conditions in which immune cells deal with mycobacteria. For the preparation of the inoculum mycobacteria are grown in solid media followed by preparation to a single cell suspension. Multiplicities of infection (number of bacteria per cell) are below 0.01. Serum-free cellular media is used to allow the growth of M. abscessus. After several days of incubation Bacterial Colonies in Cellular Culture (BCCC) develop, which are enumerated directly under an inverted microscope. These colonies may represent biofilm formation during chronic infections. •Low multiplicity of infection (below 0.01 bacteria per cell) reflects more realistically conditions encountered by immune cells in the lungs.•The surface of mycobacteria prepared for infection assays that are grown in solid media are less affected than that of mycobacteria grown in liquid media with detergents.•Colony formation in the infected cells may reflect the aggregation and biofilm formation in the lungs during chronic infection.

Genetic profile of a large Spanish cohort with hypercalcemia.

Introduction: The disorders in the metabolism of calcium can present with manifestations that strongly suggest their diagnosis; however, most of the time, the symptoms with which they are expressed are nonspecific or present only as a laboratory finding, usually hypercalcemia. Because many of these disorders have a genetic etiology, in the present study, we sequenced a selection of 55 genes encoding the principal proteins involved in the regulation of calcium metabolism. Methods: A cohort of 79 patients with hypercalcemia were analyzed by next-generation sequencing. Results: The 30% of our cohort presented one pathogenic or likely pathogenic variant in genes associated with hypercalcemia. We confirmed the clinical diagnosis of 17 patients with hypocalciuric hypercalcemia (pathogenic or likely pathogenic variants in the CASR and AP2S1 genes), one patient with neonatal hyperparathyroidism (homozygous pathogenic variant in the CASR gene), and another patient with infantile hypercalcemia (two pathogenic variants in compound heterozygous state in the CYP24A1 gene). However, we also found variants in genes associated with primary hyperparathyroidism (GCM2), renal hypophosphatemia with or without rickets (SLC34A1, SLC34A3, SLC9A3R1, VDR, and CYP27B1), DiGeorge syndrome (TBX1 and NEBL), and hypophosphatasia (ALPL). Our genetic study revealed 11 novel variants. Conclusions: Our study demonstrates the importance of genetic analysis through massive sequencing to obtain a clinical diagnosis of certainty. The identification of patients with a genetic cause is important for the appropriate treatment and identification of family members at risk of the disease.

Genotypic variability in patients with clinical diagnosis of Bartter syndrome type 3.

Bartter syndrome (BS) is a salt-losing hereditary tubulopathy characterized by hypokalemic metabolic alkalosis with secondary hyperaldosteronism. Confirmatory molecular diagnosis may be difficult due to genetic heterogeneity and overlapping of clinical symptoms. The aim of our study was to describe the different molecular findings in patients with a clinical diagnosis of classic BS. We included 27 patients (26 families) with no identified pathogenic variants in CLCNKB. We used a customized Ion AmpliSeq Next-Generation Sequencing panel including 44 genes related to renal tubulopathies. We detected pathogenic or likely pathogenic variants in 12 patients (44%), reaching a conclusive genetic diagnosis. Variants in SLC12A3 were found in 6 (Gitelman syndrome). Median age at diagnosis was 14.6 years (range 0.1-31), with no history of prematurity or polyhydramnios. Serum magnesium level was low in 2 patients (33%) but urinary calcium excretion was normal or low in all, with no nephrocalcinosis. Variants in SLC12A1 were found in 3 (BS type 1); and in KCNJ1 in 1 (BS type 2). These patients had a history of polyhydramnios in 3 (75%), and the mean gestational age was 34.2 weeks (SD 1.7). The median age at diagnosis was 1.8 years (range 0.1-6). Chronic kidney disease and nephrocalcinosis were present in 1 (25%) and 3 (75%) patients, respectively. A variant in CLCN5 was found in one patient (Dent disease), and in NR3C2 in another patient (Geller syndrome). Genetic diagnosis of BS is heterogeneous as different tubulopathies can present with a similar clinical picture. The use of gene panels in these diseases becomes more efficient than the study gene by gene with Sanger sequencing.

Bi-allelic pathogenic variants in ITGA8 cause slowly progressive renal disease of unknown etiology.

Integrin Subunit Alpha 8 gene (ITGA8) encodes an integrin chain that is known to be critical in the early stage of the kidney development. Bi-allelic pathogenic variants in ITGA8 are associated with bilateral renal agenesis, as well as anomalies involving urogenital system. Here, we report two unrelated patients presenting with slowly progressing chronic kidney disease associated with bilateral renal hypodysplasia carrying homozygous loss of function variants in the ITGA8 gene. These results broaden the clinical and genotypic spectrum of ITGA8 defects, revealing the high and unexpected degree of phenotypic heterogeneity of this autosomal recessive disease. Our study emphasizes the usefulness of Next-Generation Sequencing in unraveling the genetic cause of chronic kidney disease of unknown etiology, and raises the question of genetic modifiers involved in the variation of the phenotypes associated with autosomal recessive ITGA8 pathogenic variants.

Long-term health-related quality of life in patients on home mechanical ventilation.

BACKGROUND: It is fundamental to optimize and retain health-related quality of life (HRQoL) in the long term in patients with home mechanical ventilation (HMV). Therefore, this study aimed to evaluate the evolution of the HRQoL in patients already established on HMV across a period of 5 years and whether the HRQoL is associated with mortality. METHODS: This was a 5-year longitudinal cohort study conducted in an Outpatient Ventilation Clinic. Consecutive patients on HMV for at least 30 days responded to the Severe Respiratory Insufficiency (SRI) questionnaire at inclusion and again at 5 years. RESULTS: A total of 104 patients were included (male 56.7%, median age 69 [P25;P75] [61;77] years). Almost half of the patients had COPD (49.0%). Patients were on HMV for a median of 43.5 [22;85.5] months, with overall good adherence (median 8 [6;9] daily hours). Fifty-seven (54.8%) patients were alive at 5 years. In surviving patients, the only difference with statistical significance was in the attendant symptoms and sleep subscale, with patients scoring 7.1 [-4.5;25] points higher in the final questionnaire (p = 0.002). Survivors had significantly better scores in the SRI at inclusion than deceased patients (median 59.6 [49.2;71.7] vs 48.7 [38.4;63.2]; p = 0.004). CONCLUSIONS: These results shows that HRQoL remains stable in surviving patients with HMV at five years. It also suggests that SRI can be of important prognostic value and help predict the terminal phase of the disease course in patients with long-term HMV.

Patients experience regarding home mechanical ventilation in an outpatient setting.

BACKGROUND: The patient's experience of treatment is a cornerstone of high-quality healthcare, along with clinical safety and effectiveness. We aimed to evaluate the patients' perspectives regarding home mechanical ventilation (HMV) follow up in an outpatient setting and ascertain differences between patients that started HMV in the outpatient setting compared to other settings. METHODS: This cross-sectional study was conducted with patients with chronic respiratory failure under HMV in the Outpatient Ventilation Clinic. Patients filled in a patient experience questionnaire and the S3-NIV questionnaire. RESULTS: The study included 235 patients (127, 54% male), median 70 [25-75 percentiles 64-76] years) and about half were adapted to HMV in the outpatient setting (117, 49.8%). Patients had a daily ventilator usage of 8.0 [6.0-10.0] hours and have been on ventilator for a median of 35.0 [12.0-66.0] months. Patients reported an overall good experience regarding education at initiation (209 [88.9%] considered the information given was enough), short time to adaptation [104 (44.3%) felt adapted after some hours], with perceived benefits (171 [72.8%] reported less shortness of breath, 158 (67.2%) improved quality of life and 150 (63.8%) less tiredness). Benefits overcame the treatment side-effects (158 [67.2%] reported mucosal dryness, 109 (46.4%) mask sores and 96 (40.9%) leaks). There was no difference in terms of reported health gains, side effects or time to adaptation between adaptation settings, but patients starting HMV in the outpatient setting reported better communication and education at adaptation. CONCLUSIONS: Outpatient setting was perceived as a positive experience, both in HMV initiation and follow up, with good patient-physician communication leading to significant health reported gains, improvement of health status and well-being and good treatment adherence.

Mycobacterium abscessus Infected Neutrophils as an In Vitro Model for Bronchiectasis. Neutrophils Prevent Mycobacterial Aggregation

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Suitability of transiently expressed antibodies for clinical studies: product quality consistency at different production scales.

Transgenic human monoclonal antibodies derived from humanized mice against different epitopes of the Middle East respiratory syndrome coronavirus (MERS-CoV), and chimeric llama-human bispecific heavy chain-only antibodies targeting the Rift Valley fever virus (RVFV), were produced using a CHO-based transient expression system. Two lead candidates were assessed for each model virus before selecting and progressing one lead molecule. MERS-7.7G6 was used as the model antibody to demonstrate batch-to-batch process consistency and, together with RVFV-107-104, were scaled up to 200 L. Consistent expression titers were obtained in different batches at a 5 L scale for MERS-7.7G6. Although lower expression levels were observed for MERS-7.7G6 and RVFV-107-104 during scale up to 200 L, product quality attributes were consistent at different scales and in different batches. In addition to this, peptide mapping data suggested no detectable sequence variants for any of these candidates. Functional assays demonstrated comparable neutralizing activity for MERS-7.7G6 and RVFV-107-104 generated at different production scales. Similarly, MERS-7.7G6 batches generated at different scales were shown to provide comparable protection in mouse models. Our study demonstrates that a CHO-based transient expression process is capable of generating consistent product quality at different production scales and thereby supports the potential of using transient gene expression to accelerate the manufacturing of early clinical material.

Raoultella ornithinolytica in MALT-type non-Hodgkin Lymphoma.

Raoultella ornithinolytica is a bacterium that belongs to the Enterobacteriaceae family. The most frequently reported infections are gastrointestinal and hepatobiliary. Urinary tract infections are very rarely reported and bloodstream infections are usually reported without an identified source. This bacterium is responsible for an increasing number of infections, especially in immunocompromised patients. The authors describe the first case ever reported of an immunocompromised patient due to non-Hodgkin lymphoma MALT type and corticotherapy, who developed urinary tract infection and subsequently bacteriemia due to this pathogen. LEARNING POINTS: Raoultella ornithinolytica is a virulent pathogen causing community-acquired and hospital-acquired infection, especially in immunocompromised populations.Although most cases of R. ornithinolytica infection are susceptible to standard antibiotic regimens, multi-drug resistant strains have been reported, which may pose a severe risk to the immunocompromised patient.Physicians should be aware that some treatments may increase immunosuppression, thus enabling infection by opportunistic agents such as R. ornithinolytica.

Zoonoses Anticipation and Preparedness Initiative, stakeholders conference, February 4 & 5, 2021.

The Zoonoses Anticipation and Preparedness Initiative (ZAPI) was set up to prepare for future outbreaks and to develop and implement new technologies to accelerate development and manufacturing of vaccines and monoclonal antibodies. To be able to achieve surge capacity, an easy deployment and production at multiple sites is needed. This requires a straightforward manufacturing system with a limited number of steps in upstream and downstream processes, a minimum number of in vitro Quality Control assays, and robust and consistent platforms. Three viruses were selected as prototypes: Middle East Respiratory Syndrome (MERS) coronavirus, Rift Valley fever virus, and Schmallenberg virus. Selected antibodies against the viral surface antigens were manufactured by transient gene expression in Chinese Hamster Ovary (CHO) cells, scaling up to 200 L. For vaccine production, viral antigens were fused to multimeric protein scaffold particles using the SpyCatcher/SpyTag system. In vivo models demonstrated the efficacy of both antibodies and vaccines. The final step in speeding up vaccine (and antibody) development is the regulatory appraisal of new platform technologies. Towards this end, within ZAPI, a Platform Master File (PfMF) was developed, as part of a licensing dossier, to facilitate and accelerate the scientific assessment by avoiding repeated discussion of already accepted platforms. The veterinary PfMF was accepted, whereas the human PfMF is currently under review by the European Medicines Agency, aiming for publication of the guideline by January 2022.

Current Practices in Home Mechanical Ventilation for Chronic Obstructive Pulmonary Disease: A Real-Life Cross-Sectional Multicentric Study.

Purpose: Home mechanical ventilation (HMV) use in chronic obstructive pulmonary disease (COPD) is becoming increasingly widespread. The aim of this study was to provide an accurate description of the current practices and clinical characteristics of COPD patients on HMV in Portugal. Methods: The study was designed as a cross-sectional, multicenter real-life study of COPD patients established on HMV for at least 30 days. Data related to clinical characteristics, adaptation and ventilatory settings were collected. Results: The study included 569 COPD patients on HMV from 15 centers. The majority were male, with a median age of 72 years and a high prevalence of obesity (43.2%) and sleep apnea (45.8%). A high treatment compliance was observed (median 8h/day), 48.7% with inspiratory positive airway pressure ≥20 cmH2O and oronasal masks were the preferred interface (91.7%). There was an equal distribution of patients starting HMV during chronic stable condition and following an exacerbation. Patients in stable condition were initiated in the outpatient setting in 92.3%. Despite the differences in criteria and setting of adaptation and a slightly lower BMI in patients starting HMV following an exacerbation, we found no significant differences regarding age, gender, ventilation pressures, time on HMV, usage, severity of airflow obstruction or current arterial blood gas analysis (ABGs) in relation to patients adapted in stable condition. Conclusion: Patients were highly compliant with the therapy. In agreement with most recent studies and recommendations, there seems to be a move towards higher ventilation pressures, increased use of oronasal masks and an intent to obtain normocapnia. This study shows that chronic hypercapnic and post exacerbation patients do not differ significantly regarding patient characteristics, physiological parameters or ventilatory settings with one exception: chronic hypercapnic patients are more often obese and, subsequently, more frequently present OSA.

Acidosis tubular renal distal hereditaria: correlación genotípica, evolución a largo plazo y nuevas perspectivas terapéuticas / Hereditary distal renal tubular acidosis: Genotypic correlation, evolution to long term, and new therapeutic perspectives

La acidosis tubular renal distal (ATRD) es una enfermedad rara que se debe al fallo del proceso normal de acidificación de la orina a nivel tubular distal y colector. Se caracteriza por una acidosis metabólica hiperclorémica persistente, con anión gap normal en plasma, en presencia de un pH urinario elevado y baja excreción urinaria de amonio. Se han descrito hasta el momento 5 genes cuyas mutaciones dan lugar a ATRD primaria. Las alteraciones de los genes ATP6V1B1 y ATP6V0A4 se heredan de forma recesiva y están asociadas a formas de inicio más precoces y con sordera neurosensorial en muchos casos. Las variantes patogénicas en el gen SLC4A1 se heredan habitualmente de forma dominante y dan lugar a cuadros más leves, con un diagnóstico más tardío y alteraciones electrolíticas menores. Sin embargo, la evolución a nefrocalcinosis y litiasis, y el desarrollo de enfermedad renal crónica a medio-largo plazo se ha descrito de forma similar en estos 3grupos. Por último, se han descrito también formas recesivas de ATRD asociadas a mutaciones en los genes FOXI1 y WDR72. El manejo clínico de la ATRD se basa en sales de bicarbonato o citrato, que no logran corregir en todos los casos las alteraciones metabólicas descritas y, por lo tanto, las consecuencias asociadas a ellas. Recientemente, un nuevo tratamiento basado en sales de bicarbonato y citrato de liberación prolongada ha recibido la denominación de medicamento huérfano en Europa para el tratamiento de la ATRD. (AU)

Distal renal tubular acidosis (DRTA) is a rare disease resulting from a failure in the normal urine acidification process at the distal tubule and collecting duct level. It is characterised by persistent hyperchloremic metabolic acidosis, with a normal anion gap in plasma, in the presence of high urinary pH and low urinary excretion of ammonium. To date, 5 genes whose mutations give rise to primary DRTA have been described. Alterations in the ATP6V1B1 and ATP6V0A4 genes are inherited recessively and are associated with forms of early onset and, in many cases, with neurosensorial deafness. Pathogenic variants in the SLC4A1 gene are habitually inherited dominantly and give rise to milder symptoms, with a later diagnosis and milder electrolytic alterations. Nonetheless, evolution to nephrocalcinosis and lithiasis, and the development of chronic kidney disease in the medium to long term has been described in a similar manner in all 3groups. Lastly, recessive forms of DTRA associated to mutations in the FOXI1 and WDR72 genes have also been described. The clinical management of DTRA is based on bicarbonate or citrate salts, which do not succeed in correcting all cases of the metabolic alterations described and, thus, the consequences associated with them. Recently, a new treatment based on slow-release bicarbonate and citrate salts has received the designation of orphan drug in Europe for the treatment of DTRA. (AU)

Molecular aspects and long-term outcome of patients with primary distal renal tubular acidosis.

BACKGROUND: Primary distal renal tubular acidosis (dRTA) is a rare genetic disorder caused by impaired distal mechanisms of urinary acidification. Most cases are secondary to pathogenic variants in ATP6V0A4, ATP6V1B1, and SLC4A1 genes, which encode transporters regulating acid-base balance in the collecting duct. METHODS: Retrospective study of molecular and clinical data from diagnosis and long-term follow-up (10, 20, and 40±10 years) of 16 patients with primary dRTA diagnosed in childhood. RESULTS: Molecular analyses revealed nine patients had ATP6V0A4 pathogenic variants, five in ATP6V1B1, and two in SLC4A1. A novel intragenic deletion and a common ATP6V0A4 gene variant (c.1691 + 2dupT) in ATP6V0A4 occurred in two-thirds of these patients, suggesting a founder effect. Median age at diagnosis was 3.25 months (IQR 1, 13.5), which was higher in the SLC4A1 group. Median SDS height at diagnosis was -1.02 (IQR -1.79, 0.14). Delayed clinical diagnosis was significantly related to growth failure (P = 0.01). Median SDS height at 20 years follow-up was -1.23 (IQR -1.71, -0.48), and did not significantly improve from diagnosis (P = 0.76). Kidney function declined over time: at last follow-up, 43% had moderate to severe chronic kidney disease (CKD). Adequate metabolic control was not related to CKD development. Incidence of sensorineural hearing loss (SNHL) was high in ATP6V1B1 patients, though not universal. Patients harboring ATP6V0A4 variants also developed SNHL at a high rate (80%) over time. CONCLUSIONS: Patients with dRTA can develop moderate to severe CKD over time with a high frequency despite adequate metabolic control. Early diagnosis ameliorates long-term height prognosis.

Five patients with disorders of calcium metabolism presented with GCM2 gene variants.

The GCM2 gene encodes a transcription factor predominantly expressed in parathyroid cells that is known to be critical for development, proliferation and maintenance of the parathyroid cells. A cohort of 127 Spanish patients with a disorder of calcium metabolism were screened for mutations by Next-Generation Sequencing (NGS). A targeted panel for disorders of calcium and phosphorus metabolism was designed to include 65 genes associated with these disorders. We observed two variants of uncertain significance (p.(Ser487Phe) and p.Asn315Asp), one likely pathogenic (p.Val382Met) and one benign variant (p.Ala393_Gln395dup) in the GCM2 gene in the heterozygous state in five families (two index cases had hypocalcemia and hypoparathyroidism, respectively, and three index cases had primary hyperparathyroidism). Our study shows the utility of NGS in unravelling the genetic origin of some disorders of the calcium and phosphorus metabolism, and confirms the GCM2 gene as an important element for the maintenance of calcium homeostasis. Importantly, a novel variant in the GCM2 gene (p.(Ser487Phe)) has been found in a patient with hypocalcemia.

Hereditary distal renal tubular acidosis: Genotypic correlation, evolution to long term, and new therapeutic perspectives.

Distal renal tubular acidosis (DRTA) is a rare disease resulting from a failure in the normal urine acidification process at the distal tubule and collecting duct level. It is characterised by persistent hyperchloremic metabolic acidosis, with a normal anion gap in plasma, in the presence of high urinary pH and low urinary excretion of ammonium. To date, 5 genes whose mutations give rise to primary DRTA have been described. Alterations in the ATP6V1B1 and ATP6V0A4 genes are inherited recessively and are associated with forms of early onset and, in many cases, with neurosensorial deafness. Pathogenic variants in the SLC4A1 gene are habitually inherited dominantly and give rise to milder symptoms, with a later diagnosis and milder electrolytic alterations. Nonetheless, evolution to nephrocalcinosis and lithiasis, and the development of chronic kidney disease in the medium to long term has been described in a similar manner in all 3 groups. Lastly, recessive forms of DTRA associated to mutations in the FOXI1 and WDR72 genes have also been described. The clinical management of DTRA is based on bicarbonate or citrate salts, which do not succeed in correcting all cases of the metabolic alterations described and, thus, the consequences associated with them. Recently, a new treatment based on slow-release bicarbonate and citrate salts has received the designation of orphan drug in Europe for the treatment of DTRA.

Novel variant in the CNNM2 gene associated with dominant hypomagnesemia.

The maintenance of magnesium (Mg2+) homeostasis is essential for human life. The Cystathionine-ß-synthase (CBS)-pair domain divalent metal cation transport mediators (CNNMs) have been described to be involved in maintaining Mg2+ homeostasis. Among these CNNMs, CNNM2 is expressed in the basolateral membrane of the kidney tubules where it is involved in Mg2+ reabsorption. A total of four patients, two of them with a suspected disorder of calcium metabolism, and two patients with a clinical diagnosis of primary tubulopathy were screened for mutations by Next-Generation Sequencing (NGS). We found one novel likely pathogenic variant in the heterozygous state (c.2384C>A; p.(Ser795*)) in the CNNM2 gene in a family with a suspected disorder of calcium metabolism. In this family, hypomagnesemia was indirectly discovered. Moreover, we observed three novel variants of uncertain significance in heterozygous state in the other three patients (c.557G>C; p.(Ser186Thr), c.778A>T; p.(Ile260Phe), and c.1003G>A; p.(Asp335Asn)). Our study shows the utility of Next-Generation Sequencing in unravelling the genetic origin of rare diseases. In clinical practice, serum Mg2+ should be determined in calcium and PTH-related disorders.

Multimeric single-domain antibody complexes protect against bunyavirus infections.

The World Health Organization has included three bunyaviruses posing an increasing threat to human health on the Blueprint list of viruses likely to cause major epidemics and for which no, or insufficient countermeasures exist. Here, we describe a broadly applicable strategy, based on llama-derived single-domain antibodies (VHHs), for the development of bunyavirus biotherapeutics. The method was validated using the zoonotic Rift Valley fever virus (RVFV) and Schmallenberg virus (SBV), an emerging pathogen of ruminants, as model pathogens. VHH building blocks were assembled into highly potent neutralizing complexes using bacterial superglue technology. The multimeric complexes were shown to reduce and prevent virus-induced morbidity and mortality in mice upon prophylactic administration. Bispecific molecules engineered to present two different VHHs fused to an Fc domain were further shown to be effective upon therapeutic administration. The presented VHH-based technology holds great promise for the development of bunyavirus antiviral therapies.

A strategy based on Amplified Fragment Length Polymorphism (AFLP) for routine genotyping of nontuberculous mycobacteria at the clinical laboratory.

The increasing worldwide incidence of mycobacteriosis and the need to achieve improved clinical management makes nontuberculous mycobacteria (NTM) genotyping a useful tool. However, because of technical difficulties, medium size microbiology laboratories do not attempt to compare the genetic patterns that each of their isolates present. We have aimed to optimize a genotyping method with a reduced hands-on experimental time and that requires few technical resources. A strategy based on the Amplified Fragment Length Polymorphism (AFLP) methodology was developed using two rare-cutters enzymes (SacI and BglII). One out of seven primers was sequentially used in each amplification reaction that was analyzed by agarose gel electrophoresis. This approach makes it possible the timely genotyping of a moderate number of strains and its characterization without the need of image analysis software. We have genotyped 28 Mycobacterium intracellulare and 4 M. abscessus. Clinical researchers are encouraged to routinely genotype their NTM isolates.