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In utero haematopoietic stem cell transplantation. Experiences in mice, sheep and humans.

Early prenatal diagnosis and in utero therapy of certain fetal diseases have the potential to reduce fetal morbidity and mortality. The intrauterine transplantation of stem cells provides in some instances a therapeutic option before definitive organ failure occurs. Clinical experiences show that certain diseases, such as immune deficiencies or inborn errors of metabolism, can be successfully treated using stem cells derived from bone marrow. However, a remaining problem is the low level of engraftment that can be achieved. Efforts are made in animal models to optimise the graft and study the recipient's microenvironment to increase long-term engraftment levels. Our experiments in mice show similar early homing of allogeneic and xenogeneic stem cells and reasonable early engraftment of allogeneic murine fetal liver cells (17.1% donor cells in peripheral blood 4 weeks after transplantation), whereas xenogeneic HSC are rapidly diminished due to missing self-renewal and low differentiation capacities in the host's microenvironment. Allogeneic murine fetal liver cells have very good longterm engraftment (49.9% donor cells in peripheral blood 16 weeks after transplantation). Compared to the rodents, the sheep model has the advantage of body size and gestation comparable to the human fetus. Here, ultrasound-guided injection techniques significantly decreased fetal loss rates. In contrast to the murine in utero model, the repopulation capacities of allogeneic ovine fetal liver cells are lower (0.112% donor cells in peripheral blood 3 weeks after transplantation). The effect of MHC on engraftment levels seems to be marginal, since no differences could be observed between autologous and allogeneic transplantation (0.117% donor cells vs 0.112% donor cells in peripheral blood 1 to 2 weeks after transplantation). Further research is needed to study optimal timing and graft composition as well as immunological aspects of in utero transplantation.

Animals↗

Bone marrow transplantation in major histocompatibility complex class II deficiency: a single-center study of 19 patients.

Major histocompatibility complex (MHC) class II deficiency (bare lymphocyte syndrome) is a rare inborn error of the immune system characterized by impaired antigen presentation and combined immunodeficiency. It causes severe and unremitting infections leading to progressive liver and lung dysfunctions and death during childhood. As in other combined immunodeficiency disorders, bone marrow transplantation (BMT) is considered the treatment of choice for MHC class II deficiency. We analyzed the files of 19 patients who have undergone BMT in our center. Of the 7 patients who underwent HLA-identical BMT, 3 died in the immediate posttransplant period of severe viral infections, whereas the remaining 4 were cured, with recovery of normal immune functions. Of the 12 patients who underwent HLA-haplo-identical BMT, 3 were cured, 1 was improved by partial engraftment, 7 died of infectious complications due to graft failure or rejection, and 1 is still immunodeficient because of engraftment failure. A favorable outcome in the HLA-non-identical BMT group was associated with an age of less than 2 years at the time of transplantation. All the patients with stable long-term engraftment had persistently low CD4 counts after transplantation (105 to 650/microL at last follow up), but no clear susceptibility to opportunistic infections despite persisting MHC class II deficiency on thymic epithelium and other nonhematopoietic cells. We conclude that HLA-identical and -haploidentical BMT can cure MHC class II deficiency, although the success rate of haploidentical BMT is lower than that in other combined immunodeficiency syndromes. HLA-haploidentical BMT should preferably be performed in the first 2 years of life, before the acquisition of chronic virus carriage and sequelae of infections.

Bone Marrow Transplantation↗

Gene therapy for inborn and acquired immune deficiency disorders.

Gene therapy has been under development as a way to correct inborn errors for over 20 years. Immune deficiencies are favorable candidates for gene therapy because of the potential selective advantage of genetically corrected cells in these conditions. Gene therapy for immune deficiencies has been the only application to show incontrovertible benefit in clinical trials to date. Despite the success in treating the underlying disease, there have been two cases of insertional oncogenesis reported in one of these early phase trials. Gene therapy approaches and clinical trials for several inborn as well as acquired immune deficiencies will be reviewed.

Acquired Immunodeficiency Syndrome↗

Inborn errors of IL-12/23- and IFN-gamma-mediated immunity: molecular, cellular, and clinical features.

Mendelian susceptibility to mycobacterial diseases confers predisposition to clinical disease caused by weakly virulent mycobacterial species in otherwise healthy individuals. Since 1996, disease-causing mutations have been found in five autosomal genes (IFNGR1, IFNGR2, STAT1, IL12B, IL12BR1) and one X-linked gene (NEMO). These genes display a high degree of allelic heterogeneity, defining at least 13 disorders. Although genetically different, these conditions are immunologically related, as all result in impaired IL-12/23-IFN-gamma-mediated immunity. These disorders were initially thought to be rare, but have now been diagnosed in over 220 patients from over 43 countries worldwide. We review here the molecular, cellular, and clinical features of patients with inborn errors of the IL-12/23-IFN-gamma circuit.

Animals↗

Defective RNA Polymerase III sensing of mitochondrial DNA in pulmonary epithelial cells impairs type I IFN immunity to SARS-CoV-2.

The clinical spectrum of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection ranges from asymptomatic cases to critical COVID-19 pneumonia. To investigate the role of host genetics in susceptibility to critical COVID-19 and identify pathophysiological mechanisms and pathways, we analyzed whole-exome and whole-genome sequencing data from the COVID Human Genetic Effort. We identified 10 rare, monoallelic predicted loss-of-function variants in 18 patients in POLR3A and POLR3C encoding two subunits of RNA polymerase III (POL III), a nuclear multisubunit enzyme, which has been implicated in cytosolic DNA sensing. These variants were deleterious for expression of full-length POLR3A and POLR3C proteins. We demonstrate that human pulmonary A549-hACE2 cells with reduced POLR3A or POLR3C expression exhibit impaired type I IFN responses to transfected mitochondrial DNA (mtDNA) or SARS-CoV-2 infection, together with increased viral replication. Mechanistically, we show that SARS-CoV-2 induces cellular mtDNA release via oligomerization of the mitochondrial voltage-dependent anion channel under virus-induced oxidative stress, enabling POL III-mtDNA interaction. These findings establish POL III as a sensor of endogenous mtDNA released during viral infection and indicate that autosomal dominant POL III haploinsufficiency may predispose individuals to critical COVID-19.

Humans↗

Genetic Landscape and Mitochondrial Metabolic Dysregulation in Patients Suffering From Severe Long COVID.

Long COVID represents a significant global health challenge with an unclear etiology. Alongside accumulating evidence of mitochondrial dysfunction in patients with acute SARS-CoV-2 infection, a symptomatic overlap exists between long COVID and mitochondrial disorders. However, the genetic underpinnings of mitochondrial dysfunction in long COVID have not been previously explored. We employed whole genome sequencing to analyze 13 patients with severe long COVID to identify genetic defects related to mitochondrial function. We performed extracellular bioenergetics flux analysis on peripheral blood mononuclear cells and proteomics to evaluate cellular bioenergetics and compared the results to those of healthy controls. Our investigation identified 10 variants classified as pathogenic or likely pathogenic and 83 variants of unknown significance affecting a wide range of mitochondria-associated biological functions. Bioenergetics flux analysis in peripheral blood mononuclear cells revealed an altered ATP production rate in four long COVID patients compared to healthy controls. This study presents initial evidence of a potential underlying genetic predisposition to mitochondrial dysfunction in long COVID while demonstrating altered cellular energy capacity in a subset of these patients. These findings open avenues for further research into the role of mitochondrial dysfunction and pathology in patients suffering from long COVID and may pave the way for targeted therapeutic strategies aimed at mitigating mitochondrial dysfunction.

Humans↗

Radioimmunoassay determination of decreased amounts of alpha-L-fucosidase protein in fucosidosis.

Purified human liver alpha-L-fucosidase (EC 3.2.1.51) has been radioiodinated by a chloramine-T procedure to a specific activity of 3.7 . 10(6) dpm/micrograms protein without altering its apparent Michaelis constant for the 4-methylumbelliferyl substrate. This 125I-labeled alpha-L-fucosidase has been used in development of a competitive binding radioimmunoassay for alpha-L-fucosidase which can detect 1-2 ng of enzyme protein and has been employed to quantify the amount of alpha-L-fucosidase protein in the liver and spleen from a patient with fucosidosis. Less than 1% of the normal amount of alpha-L-fucosidase protein is present suggesting that normal amounts of catalytically inactive alpha-L-fucosidase are not found in this disease.

Carbohydrate Metabolism, Inborn Errors↗

The potential impacts of human genetics on virus emergence.

Human monogenic traits can confer resistance to viral infection in exposed individuals or predisposition to severe disease in infected individuals. Enhanced susceptibility can be driven directly by mutations in genes essential for control of the virus or indirectly via the production of autoantibodies against components of host defense. While the impact of viruses on individuals carrying these genotypes permitted their identification and has been amply studied, little is known about the impact of these human genotypes on the natural history of viruses, including not only persisting but also emerging viruses. We envisage several scenarios, including the possibility that genetically susceptible individuals serve as patient zeros, superspreaders, or mutation incubators, or that genetically resistant individuals even permit the selection of new viral mutants. Viruses are continually shared between individuals and even host species, where they can benefit from adaption to new environments. Current human viruses, as well as novel viruses from animal reservoirs, will continue to threaten the human population. Improvements in the scale of human genomic sequencing and analysis will permit testing hypotheses about the impact of human genetics on the origin and trajectory of viral infections, including future pandemics, which may ultimately help to prevent or curtail impending outbreaks.

Humans↗

[Hepatic complications of bone marrow transplantation].

Bone marrow transplantation has become an accepted procedure for the treatment of severe aplastic anemia, hematologic malignancies (particularly lymphoma and leukemia) and certain inborn errors of metabolism and immunity. However, numerous complications follow bone marrow transplantation. Liver disease is a very common and complex complication after human transplantation. The major complications are: veno-occlusive disease, graft-versus-host disease acute and/or chronic. In this decade, the results of bone marrow transplantation will enhance.

Bone Marrow Transplantation↗

An Update on Inborn Errors of V(D)J Recombination.

V(D)J recombination is the fundamental process by which developing T and B lymphocytes generate diverse antigen receptors, enabling adaptive immunity. This tightly regulated program operates exclusively in lymphoid precursors during G1 phase and depends on the lymphocyte-specific RAG1-RAG2 recombinase to introduce programmed DNA double-strand breaks at recombination signal sequences, followed by repair through the classical nonhomologous end joining (c-NHEJ) pathway. Disruption of any step in this molecular choreography compromises antigen receptor diversity and underlies a spectrum of inborn errors of immunity (IEIs), ranging from severe combined immunodeficiency (SCID) to immune dysregulation with autoimmunity and granulomatous disease. In this review, we place disorders of V(D)J recombination within the broader framework of T-cell development, detailing the temporal waves of recombinase activity, chromatin accessibility, and DNA damage responses that guide thymocyte differentiation. We discuss pathogenic variants affecting the cleavage phase [RAG1, RAG2, and the recently identified RAG cochaperone NudC domain-containing 3 (NUDCD3)], end processing (ARTEMIS), ligation and repair (LIG4, XLF, XRCC4, PRKDC), and genome surveillance pathways (ATM, MRN complex, RNF168), highlighting genotype-phenotype correlations and mechanisms driving immune deficiency and dysregulation. We briefly review recent diagnostic advances, including newborn screening using T-cell receptor excision circles, repertoire sequencing, and functional assays, alongside current therapeutic strategies. Finally, we outline key unanswered questions and argue that continued integration of clinical observation with molecular discovery is essential to improve outcomes and deepen understanding of adaptive immune development.

Humans↗

Chronic liver disease: current concepts of disease mechanisms.

Optimal management of chronic liver disease requires an understanding of aetiological factors or conditions initiating and sustaining tissue damage. Injury may derive initially from toxin or xenobiotic exposure (direct, biotransformation adducts, hypersensitivity responses or immune-mediated mechanisms), infectious organisms, inborn errors of metabolism, or pathological accumulations of transition metals (iron or copper), endotoxins or membranocytolytic bile acids. Secondarily, cells and mediators associated with inflammation, pathological expression of major histocompatibility foci on hepatocytes and biliary epithelia, aberrant initiation of apoptosis, modification of the extracellular matrix, and depletion of natural antioxidants can each play pivotal roles. Cholestatic liver injury derived from extrahepatic mechanical obstruction or intrahepatic cholestasis (many causes) can induce membrane damage subsequent to accumulation of membranocytolytic bile acids, copper retention, and membrane peroxidation. This paper reviews contemporary issues of chronic hepatocellular injury and hepatic fibrosis with the aim of broadening the clinical perspective of treatment strategies.

Animals↗

Congenital hypothyroidism and nonimmune hydrops fetalis: associated?

Hydrops fetalis (HF) consists of an abnormal accumulation of fluid in two or more fetal compartments, including ascites, pleural effusion, pericardial effusion, and skin edema. Almost all observed cases of HF are of the nonimmune type, the causes of which remain undetermined in 15% of patients. We report a newborn infant with nonimmune hydrops fetalis (NIHF) and congenital hypothyroidism. The infant's mother was healthy and there were no malformations of the placenta or umbilical cord. The infant did not show any structural abnormalities of his central nervous, cardiovascular, gastrointestinal, or urinary tract systems, and there was no evidence of anemia, infectious disease, or inborn error of metabolism. An immune-based process was unlikely, because the blood group of the mother and infant was A-positive and results of an indirect Coombs test in the mother and a direct Coombs test in the infant were negative. The patient's condition gradually improved with mechanical ventilation, repeated thoracocentesis, and total parenteral nutrition. By day 5 of age the skin edema, pericardial effusion, and ascites disappeared, but accumulation of significant amounts of chylous pleural fluid persisted. Because of lethargy, FT4 and thyroid-stimulating hormone levels were obtained and showed hypothyroidism. Thyroid hormone supplementation was then started, and within 4 days the infant became more vigorous and was weaned from mechanical ventilation. After 7 days, the chylothorax resolved completely as the serum thyroxine level normalized. No reaccumulation of pleural effusion was noticed. The infant started to gain weight and was discharged from the hospital at 35 days of age. A possible pathophysiologic association between congenital hypothyroidism and NIHF is discussed. NIHF may be caused by lymphatic congestion attributable to an impairment of lymphatic flow and a delayed return of lymph to the vascular compartment. There could be a possibility that because of thyroid hormone deficiency in this patient, there was reduced adrenergic stimulation of the lymphatic system. This could result in a sluggish flow of the lymph with engorgement of the lymphatic system, leakage of lymph into the pleura and the interstitial spaces, and the production of chylothorax with NIHF. Animal studies demonstrate a direct relationship between lymph flow rate or lung liquid clearance and adrenergic receptor activity in the lymphatic system. These observations support our hypothesis that deficient adrenergic activity in congenital hypothyroidism might lead to chylothorax with NIHF in the fetus. We speculate that thyroid hormone may play a role in the regulation of adrenergic receptors in the lymphatic system and lungs, thus modulating both the lymphatic flow rate and lung liquid clearance, and facilitating the resolution of chylothorax. Examination of thyroid functions should be included in the investigation of fetuses and neonates with NIHF of an obscure origin.

Congenital Hypothyroidism↗

Lysosomal storage diseases in non-immune hydrops fetalis pregnancies.

BACKGROUND: At least 20 inborn errors of metabolism may cause hydrops fetalis. Most of these are lysosomal storage diseases. The study proposes a diagnostic flowchart for prenatal diagnosis of non-immune hydrops fetalis. METHODS: This study contains a series of 75 non-immune hydrops fetalis pregnancies. Mucopolysaccharides, oligosaccharides, neuraminic acid and 21 lysosomal enzymes were measured in amniotic fluid and cultured amniotic cells. RESULTS: The study gives reference values for mucopolysaccharides and neuraminic acid at various stages of gestation. Four definite and two probable lysosomal diagnoses were found among the 75 investigated cases (=5.3-8%). Fetal death was found to cause false positive values for mucopolysaccharides in amniotic fluid. In the galactosialidosis case, two novel mutations were found in the cathepsin A gene. CONCLUSIONS: Reference values for mucopolysaccharides and neuraminic acid depend on gestational age. In a relatively high percentage of the hydrops foetalis pregnancies, a lysosomal aetiology is found. This study provides a strategy to diagnose lysosomal diseases in hydrops fetalis pregnancies. Awareness of lysosomal storage diseases causing hydrops fetalis is useful as it gives an opportunity for risk evaluation, genetic counseling to parents and targeted prenatal diagnostics for ensuing pregnancies.

Amniotic Fluid↗

[Metabolism of non-conjugated pteridines in man].

In the review, we have attempted to show the growing momentum in the area of unconjugated pteridine research. The de novo biosynthetic pathway of tetrahydrobiopterin has been recently clarified. The development of specific assays to measure pteridines in biological fluids has facilitated the acquisition of data on changes in the levels of pteridines during the course of various diseases. Several human inborn errors of its metabolism have been discovered and have become an important resource to elucidate the consequences of tetrahydrobiopterin deficiency. Changes in pteridine metabolism have also been investigated in diseases involving stimulation of cellular mediated immunological processes.

Biopterins↗

Bone marrow transplantation.

Over the last 20 years allogeneic bone marrow transplantation from an HLA-identical sibling donor has become the treatment of choice for a number of human haematological malignancies, severe aplastic anaemia, some congenital diseases of the immune and haemopoietic systems, and some inborn errors of metabolism. Recently, the successful introduction of HLA-matched unrelated donor transplants, convenient T cell depletion technology, combination immunosuppressive therapy to minimise graft-versus-host disease, blood products that are seronegative for cytomegalovirus, effective antiviral agents, and cloned haemopoietic and immune system growth factors have markedly increased the scope of bone marrow transplantation. Additionally, autologous transplantation appears to have promise especially in lymphoma and breast cancer.

Bone Marrow Transplantation↗

[Fatty acids in prevention and therapy in pediatrics].

Fatty acids (FA) are involved in both physiologic and pathologic biochemical pathways. Saturated FA (mainly 12-C and 14-C) are implicated in the development of hypercholesterolemia and early atherogenesis. On the contrary, monounsaturated and polyunsaturated FA (mainly 18:2 n-6 and n-3 very long-chain FA) have been claimed to have hypocholesterolemic and protective effects. In particular, oleic acid (18:1 n-9) seems to lower only the atherogenic fraction of circulating cholesterol (the low-density lipoproteins), leaving immodified the level of the protective fraction (the high-density lipoproteins). Polyunsaturated very long-chain FA have been recently studied for the prevention and therapy of atopic and cutaneous disorders, with conflicting results. In this respect, the 20:4 n-6 acts as proinflammatory agent, while the n-3 very long-chain FA could act as modulators of the immuno-allergic and inflammatory reactions. However, attention must be paid to the high peroxidative potential of the more unsaturated FA. Very recently, VLCFA have been considered for the therapy of some inherited disorders of metabolism. Monounsaturated very long-chain FA have been used in the treatment of x-linked adrenoleukodystrophy. A dietetic deficiency of polyunsaturated very long-chain FA has been observed in treated phenylketonuric children. Some inborn errors of metabolism could represent an useful model for better understanding the biochemistry of FA.

Arteriosclerosis↗

Laser desorption time-of-flight mass spectrometric analysis of transferrin precipitated with antiserum: a unique simple method to identify molecular weight variants.

Serum transferrin precipitated with anti-transferrin serum was analysed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOFMS). The transferrin-antibody complex in the immunoprecipitates was separated into transferrin and IgG in an acidic pH, which is the usual condition of loading on MALDI-TOFMS. Ions of IgG and other minor components were not superimposed on the transferrin ions. Transferrin isoforms with different carbohydrate contents could be identified by this simple method easier than by affinity chromatography requiring the time-consuming preparation of an insolubilized specific antibody. The transferrin isoform with a molecular weight of approximately 2.2 kDa smaller than normal transferrin, which is contained in the serum from patients with carbohydrate-deficient glycoprotein (CDG) syndrome, was identified by this method. In addition to the M(1+) ion detected using sinapinic acid as a matrix, the M(2+) and M(3+) ions of transferrin were clearly detected using alpha-cyano-4-hydroxycinnamic acid as matrix and the molecular weight heterogeneity was identified more clearly in multivalent ions than that in the M(1+) ion. The MALDI-TOF analysis of immunoprecipitates may serve as a simple and sensitive method to identify the molecular weight heterogeneity of various biological materials.

Carbohydrate Metabolism, Inborn Errors↗