Quantification of human cytomegalovirus DNA in bone marrow transplant recipients by real-time PCR

A real-time PCR assay was developed to quantify human cytomegalovirus (CMV) DNA in peripheral blood leukocytes (PBLs) of bone marrow transplantation patients. Unlike other teams, we quantified CMV and the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene using a plasmid containing both sequences as an external standard. Tenfold serial dilutions of this plasmid yielded overlapping standard curves that allowed the quantification of CMV and GAPDH gene copies in an efficient and accurate manner. Sequential blood samples (164 specimens) were collected from 16 patients. PBLs were tested by the pp65 antigenemia assay and quantitative CMV and GAPDH gene PCRs. CMV DNA was detected by PCR in 13 patients a mean of 15 days prior to the appearance of antigenemia. The administration of anti-CMV drugs led to a rapid decrease in the numbers of viral copies and positive nuclei. Real-time PCR assay results correlated with those of the CMV pp65 antigenemia assay (P < 0.00001). The TaqMan assay may be a useful tool for rapid quantification of CMV infection and for monitoring of CMV reactivation in bone marrow transplantation recipients.

Defective glycosylation and multisystem abnormalities characterize the primary immunodeficiency XMEN disease

X-linked immunodeficiency with magnesium defect, EBV infection, and neoplasia (XMEN) disease are caused by deficiency of the magnesium transporter 1 (MAGT1) gene. We studied 23 patients with XMEN, 8 of whom were EBV naive. We observed lymphadenopathy (LAD), cytopenias, liver disease, cavum septum pellucidum (CSP), and increased CD4-CD8-B220-TCRαβ+ T cells (αβDNTs), in addition to the previously described features of an inverted CD4/CD8 ratio, CD4+ T lymphocytopenia, increased B cells, dysgammaglobulinemia, and decreased expression of the natural killer group 2, member D (NKG2D) receptor. EBV-associated B cell malignancies occurred frequently in EBV-infected patients. We studied patients with XMEN and patients with autoimmune lymphoproliferative syndrome (ALPS) by deep immunophenotyping (32 immune markers) using time-of-flight mass cytometry (CyTOF). Our analysis revealed that the abundance of 2 populations of naive B cells (CD20+CD27-CD22+IgM+HLA-DR+CXCR5+CXCR4++CD10+CD38+ and CD20+CD27-CD22+IgM+HLA-DR+CXCR5+CXCR4+CD10-CD38-) could differentially classify XMEN, ALPS, and healthy individuals. We also performed glycoproteomics analysis on T lymphocytes and show that XMEN disease is a congenital disorder of glycosylation that affects a restricted subset of glycoproteins. Transfection of MAGT1 mRNA enabled us to rescue proteins with defective glycosylation. Together, these data provide new clinical and pathophysiological foundations with important ramifications for the diagnosis and treatment of XMEN disease.

An Update on XMEN Disease

“X-linked immunodeficiency with magnesium defect, Epstein-Barr virus (EBV) infection, and neoplasia” (XMEN) disease is an inborn error of glycosylation and immunity caused by loss of function mutations in the magnesium transporter 1 (MAGT1) gene. It is a multisystem disease that strongly affects certain immune cells. MAGT1 is now confirmed as a non-catalytic subunit of the oligosaccharyltransferase complex and facilitates Asparagine (N)-linked glycosylation of specific substrates, making XMEN a congenital disorder of glycosylation manifesting as a combined immune deficiency. The clinical disease has variable expressivity and impaired glycosylation of key MAGT1-dependent glycoproteins in addition to Mg²⁺ abnormalities can explain some of the immune manifestations. NKG2D, an activating receptor critical for cytotoxic function against EBV, is poorly glycosylated and invariably decreased on CD8⁺ T cells and natural killer (NK) cells from XMEN patients. It is the best biomarker of the disease. The characterization of EBV-naïve XMEN patients has clarified features of the genetic disease that were previously attributed to EBV infection. Extra-immune manifestations, including hepatic and neurological abnormalities have recently been reported. EBV-associated lymphomas remain the main cause of severe morbidity. Unfortunately, treatment options to address the underlying mechanism of disease remain limited and Mg²⁺ supplementation has not proven successful. Here, we review the expanding clinical phenotype and recent advances in glycobiology that have increased our understanding of XMEN disease. We also propose updating XMEN to “X-linked MAGT1 deficiency with increased susceptibility to EBV-infection and N-linked glycosylation defect” in light of these novel findings.

Resistance of hypogonadic patients with mutated GnRH receptor genes to pulsatile GnRH administration

We have studied a kindred with three siblings with isolated hypogonadotropic hypogonadism caused by compound heterozygote mutations in the GnRH receptor gene. The disorder was transmitted as an autosomal recessive trait. The R262Q mutation in intracellular loop 3 of the receptor was associated with a mutation in the third transmembrane domain of the receptor, A129D, that has never been described before. This A129D mutation results in a complete loss of function, indicated by the lack of inositol triphosphate (TP3) 3 production by transfected Chinese hamster ovary (CHO) cells after GnRH stimulation. The two brothers had microphallus and bilateral cryptorchidism and were referred for lack of puberty, whereas their sister had primary amenorrhea and a complete lack of puberty. Their basal gonadotropin concentrations were below the reference range, and their endogenous LH secretory patterns were abnormal, with a low-normal frequency of small pulses or no apparent LH pulse. Pulsatile GnRH administration (10 microg/pulse every 90 min for 40 h) resulted in increased mean LH without any significant changes in testosterone levels in the two brothers, whereas the LH secretory profile of their sister remained apulsatile. Larger pulses of exogenous GnRH (20 microg every 90 min for 24 h) caused the sister to produce recognizable low amplitude LH pulses. The concentrations of free alpha-subunit significantly increased in all patients during the pulsatile GnRH administration. Thus, these hypogonadal patients are partially resistant to pulsatile GnRH administration, suggesting that they should be treated with gonadotropins to induce spermatogenesis or ovulation rather than with pulsatile GnRH.

Functional importance of transmembrane helix 6 Trp(279) and exoloop 3 Val(299) of rat gonadotropin-releasing hormone receptor

Previous studies have established that the interaction of gonadotropin-releasing hormone (GnRH) with its receptor (GnRHR) would require partial entry of the N- and C-terminal regions of ligand into the transmembrane core. The functional significance of the conserved aromatic residue Trp(279) present in the transmembrane helix 6, and Val(299) located in exoloop 3 of the rat GnRHR was investigated by mutagenesis followed by expression in Chinese hamster ovary-K1 cells. Compared with wild-type, substitution of Trp(279) with Ser or Arg resulted in a marked reduction or total abolition, respectively, of ligand binding and, in both cases, abrogation of GnRH-induced inositol phosphate production. A total absence of functionality was observed when Val(299) was simply replaced with Ala. Mention should be made that an expression of all mutated and wild-type receptor proteins was observed. Interestingly, the double mutant [Trp(279)Arg/Val(299)Ala]GnRHR restored B(max) to wild type (504 +/- 43 versus 541 +/- 41 fmol/mg protein), but with a diminished affinity (4.95 +/- 1.05 versus 0.94 +/- 0.35 nM), and GnRH failed to induce inositol phosphate. No influence of the mutations was seen on internalization of the receptor. The three-dimensional model of GnRH binding to the rat GnRHR was built predicting that Trp(279) is buried at 20 A in the transmembrane core of the receptor, directly in contact with Trp(3) of GnRH. In contrast, Val(299) is located in a region that cannot be precisely defined at the extracellular end of transmembrane helix 7. Although models cannot provide any clue concerning the observed interactivity between the two distal residues, altogether these data reveal the functional importance of both GnRHR Trp(279) and Val(299) and suggest that Trp(279), interacting with GnRH Trp(3), represents the bottom of the binding pocket.

Regulation of cGAS and STING signaling during inflammation and infection

Stimulator of interferon genes (STING) is a sensor of cyclic dinucleotides including cyclic GMP-AMP, which is produced by cyclic GMP-AMP synthase (cGAS) in response to cytosolic DNA. The cGAS-STING signaling pathway regulates both innate and adaptive immune responses, as well as fundamental cellular functions such as autophagy, senescence, and apoptosis. Mutations leading to constitutive activation of STING cause devastating human diseases. Thus, the cGAS-STING pathway is of great interest because of its role in diverse cellular processes and because of the potential therapeutic implications of targeting cGAS and STING. Here, we review molecular and cellular mechanisms of STING signaling, and we propose a framework for understanding the immunological and other cellular functions of STING in the context of disease.

Multiple elements in the distal part of the 1.2 kb 5'-flanking region of the rat GnRH receptor gene regulate gonadotrope-specific expression conferred by proximal domain

Several lines of evidence indicate that the number of GnRH receptors (GnRH-R) and therefore, gonadotrope responsiveness to GnRH, is highly dependent upon the level of GnRH-R mRNA. To explore this aspect of regulation, we have isolated a 3.3 kb fragment encompassing the promoter region of the rat GnRH-R gene. Primer extension and RNase protection assays allowed the identification of five major transcriptional start sites located within the 110 bp region upstream of the translation start codon. Transfection experiments using the CAT reporter gene demonstrated that the 1261 bp 5' flanking region is required to direct high efficient expression in the gonadotrope-derived alphaT3-1 cell line thus contrasting with mouse in which the only 500 bp proximal sequence appeared to be sufficient. Another difference between rat and mouse was apparent in the 183 bp region of the rat promoter which induced a 3-fold stimulation of thymidine kinase promoter activity in both alphaT3-1 and CHO cells. Subsequent deletion analysis of the region residing between -1261 and -519 revealed the presence of multiple regulatory domains that contributed to the cell-specific activity. However, despite this efficiency in the context of the wild-type promoter, they failed to induce the activity of the minimal thymidine kinase (TK) promoter in the absence of the proximal 600 bp promoter region. Accordingly, a composite TK promoter containing the entire 1.2 kb promoter induced a 10-fold increase in the activity of the TK promoter in alphaT3-1 cells. Taken together these data suggest that distal regulatory regions are critical and require cooperation with proximal specific-promoter elements for activating basal R-GnRH gene expression in gonadotrope cells.

A Double-Blind, Placebo-Controlled, Crossover Study of Magnesium Supplementation in Patients with XMEN Disease

X-linked MAGT1 deficiency with increased susceptibility to Epstein-Barr virus (EBV) infection and N-linked glycosylation defect (XMEN) disease is an inborn error of immunity caused by loss-of-function mutations in the magnesium transporter 1 (MAGT1) gene. The original studies of XMEN patients focused on impaired magnesium regulation, leading to decreased EBV-cytotoxicity and the loss of surface expression of the activating receptor "natural killer group 2D" (NKG2D) on CD8+ T cells and NK cells. In vitro studies showed that supraphysiological supplementation of magnesium rescued these defects. Observational studies in 2 patients suggested oral magnesium supplementation could decrease EBV viremia. Hence, we performed a randomized, double-blind, placebo-controlled, crossover study in 2 parts. In part 1, patients received either oral magnesium L-threonate (MLT) or placebo for 12 weeks followed by 12 weeks of the other treatment. Part 2 began with 3 days of high-dose intravenous (IV) magnesium sulfate (MgSO4) followed by open-label MLT for 24 weeks. One EBV-infected and 3 EBV-naïve patients completed part 1. One EBV-naïve patient was removed from part 2 of the study due to asymptomatic elevation of liver enzymes during IV MgSO4. No change in EBV or NKG2D status was observed. In vitro magnesium supplementation experiments in cells from 14 XMEN patients failed to significantly rescue NKG2D expression and the clinical trial was stopped. Although small, this study indicates magnesium supplementation is unlikely to be an effective therapeutic option in XMEN disease.

Critical implication of transmembrane Phe310, possibly in conjunction with Trp279, in the rat gonadotropin-releasing hormone receptor activation

The GnRH-R belongs to the superfamily of heptahelical GPCRs. A three-dimensional model of GnRH binding to its receptor predicted that Trp3 was the most deeply buried residue, potentially allowing it to interact with both Trp279, a highly conserved residue in the TMH 6 of GPCRs, and Phe310, present essentially in TMH 7 of GnRH-Rs. Replacement of Phe310 with Leu, the most common positional residue in GPCRs, induced a slightly decreased Bmax (1.6-fold) and affinity (3.8-fold); in addition, IP production was completely abolished. Similarly, replacement of Trp279 with Ser depressed the Bmax by 5.2-fold, the affinity by 2.3-fold, and totally abrogated IP production. The effect of the double mutation was not additive on binding, since the Bmax was reduced to the level of the Phe310Leu mutant, although the Kd was restored to a value not significantly different from that of the wild-type. The double mutant was also unable to induce IP production. Unexpectedly, no influence of any single or double substitution was noted on receptor internalization. These data provide evidence for the crucial role of Phe310, possibly in conjunction with Trp279, on GnRH transduction and suggest that the conformation for phospholipase C activation may not be required for GnRH-R internalization.

A new compound heterozygous mutation of the gonadotropin-releasing hormone receptor (L314X, Q106R) in a woman with complete hypogonadotropic hypogonadism: chronic estrogen administration amplifies the gonadotropin defect

We describe a woman with complete hypogonadotropic hypogonadism and a new compound heterozygous mutation of the GnRH receptor (GnRHR) gene. A null mutation L314X leading to a partial deletion of the seventh transmembrane domain of the GnRHR is associated with a Q106R mutation previously described. L314X mutant receptor shows neither measurable binding nor inositol phosphate production when transfected in CHO-K1 cells compared to the wild-type receptor. The disease is transmitted as an autosomal recessive trait, as shown by pedigree analysis. Heterozygous patients with GnRHR mutations had normal pubertal development and fertility. The present study shows an absence of LH and FSH response to pulsatile GnRH administration (20 microg/pulse, sc, every 90 min). However, GnRH triggered free alpha-subunit (FAS) pulses of small amplitude, demonstrating partial resistance to pharmacological doses of GnRH. FSH, LH, and FAS concentrations were evaluated under chronic estrogen treatment and repeat administration of GnRH. Not only were plasma FSH, LH, and FAS concentrations decreased, but FAS responsiveness was reduced. This new case emphasizes the implication of the GnRH receptor mutations in the etiology of idiopathic hypogonadotropic hypogonadism. We also have evidence for a direct negative estrogen effect on gonadotropin secretion at the pituitary level, dependent on the GnRHR signaling pathway.

GIMAP6 regulates autophagy, immune competence, and inflammation in mice and humans

Inborn errors of immunity (IEIs) unveil regulatory pathways of human immunity. We describe a new IEI caused by mutations in the GTPase of the immune-associated protein 6 (GIMAP6) gene in patients with infections, lymphoproliferation, autoimmunity, and multiorgan vasculitis. Patients and Gimap6^−/− mice show defects in autophagy, redox regulation, and polyunsaturated fatty acid (PUFA)–containing lipids. We find that GIMAP6 complexes with GABARAPL2 and GIMAP7 to regulate GTPase activity. Also, GIMAP6 is induced by IFN-γ and plays a critical role in antibacterial immunity. Finally, we observed that Gimap6^−/− mice died prematurely from microangiopathic glomerulosclerosis most likely due to GIMAP6 deficiency in kidney endothelial cells.

Occupational exposure to ambient electromagnetic fields of technical operational personnel working for a mobile telephone operator

In order to investigate the exposure of operational personnel to radiofrequency electromagnetic fields when working for a mobile telephone operator, exposimeters were used to make individual records on 23 Technical Operations personnel (mobile telephone maintenance staff) and also on 22 Other Workers. The exposure densities, to which each of the 45 subjects was subjected, were quantified using 229 exposure indicators. Cluster analysis techniques were applied to the data, in an attempt to show that they would re-emerge as belonging to one of the two groups, i.e. the Technical Operational Personnel group or the Other Workers group. This exploratory investigation has shown that the cluster analysis does not reveal a sufficiently reliable emergence of the two groups, even though certain exposure indicators were significantly different for the two groups. In addition, the use of a Learning Group method does not lead to the discovery of a predictive law that could identify the Technical Operational Personnel as a sub-group within the overall group.

Transient dark photovoltaic spatial solitons and induced guiding in slab LiNbO(3) waveguides

Dark photorefractive photovoltaic spatial solitons are demonstrated at 532 nm in nominally undoped and slightly Fe-doped LiNbO(3) planar optical waveguides. The spatial solitons are observed in a transient regime before transverse modulation instability occurs. Their widths are intensity independent as predicted by theory. Meanwhile, excited mode distribution and Fe-doping concentration are shown to influence soliton width. The guiding properties of soliton-induced waveguides are also presented.

Prime Editor Gene Therapy and TREX1 Mosaicism in Retinal Vasculopathy with Cerebral Leukoencephalopathy

TREX1 mutations underlie a variety of human diseases, including retinal vasculopathy with cerebral leukoencephalopathy (RVCL or RVCL-S), a catastrophic adult-onset vasculopathy that is often confused with multiple sclerosis, systemic vasculitis, or systemic lupus erythematosus. Patients with RVCL develop brain, retinal, liver, and kidney disease around age 35-55, leading to premature death in 100% of patients expressing an autosomal dominant C-terminally truncated form of TREX1. We previously demonstrated that RVCL is characterized by high levels of DNA damage, premature cellular senescence, and risk of early-onset breast cancer before age 45. Here, we report human TREX1 mosaicism causing organ-limited RVCL in the retina, as well as a gene therapy to synthetically create TREX1 mosaicism as a potential treatment for RVCL. In our patient with organ-limited disease, the mosaic TREX1 mutant allele underwent germline transmission to 3 children, who developed severe multi-organ disease at ~ age 40, unlike their mosaic parent, who has organ-limited disease at age 74. Additionally, we describe our TREX1 prime editor gene therapy that corrects the most common RVCL-causing TREX1 variant in cell culture and in mice. Thus, TREX1 mosaicism causes organ-limited RVCL with a normal lifespan, suggesting that a gene therapy to create TREX1 mosaicism in adults may someday become useful as a treatment for patients with RVCL.

GIMAP5 deficiency reveals a mammalian ceramide-driven longevity assurance pathway

Preserving cells in a functional, non-senescent state is a major goal for extending human healthspans. Model organisms reveal that longevity and senescence are genetically controlled, but how genes control longevity in different mammalian tissues is unknown. Here, we report a new human genetic disease that causes cell senescence, liver and immune dysfunction, and early mortality that results from deficiency of GIMAP5, an evolutionarily conserved GTPase selectively expressed in lymphocytes and endothelial cells. We show that GIMAP5 restricts the pathological accumulation of long-chain ceramides (CERs), thereby regulating longevity. GIMAP5 controls CER abundance by interacting with protein kinase CK2 (CK2), attenuating its ability to activate CER synthases. Inhibition of CK2 and CER synthase rescues GIMAP5-deficient T cells by preventing CER overaccumulation and cell deterioration. Thus, GIMAP5 controls longevity assurance pathways crucial for immune function and healthspan in mammals.

Inherited C-terminal TREX1 variants disrupt homology-directed repair to cause senescence and DNA damage phenotypes in Drosophila, mice, and humans

Age-related microangiopathy, also known as small vessel disease (SVD), causes damage to the brain, retina, liver, and kidney. Based on the DNA damage theory of aging, we reasoned that genomic instability may underlie an SVD caused by dominant C-terminal variants in TREX1, the most abundant 3'-5' DNA exonuclease in mammals. C-terminal TREX1 variants cause an adult-onset SVD known as retinal vasculopathy with cerebral leukoencephalopathy (RVCL or RVCL-S). In RVCL, an aberrant, C-terminally truncated TREX1 mislocalizes to the nucleus due to deletion of its ER-anchoring domain. Since RVCL pathology mimics that of radiation injury, we reasoned that nuclear TREX1 would cause DNA damage. Here, we show that RVCL-associated TREX1 variants trigger DNA damage in humans, mice, and Drosophila, and that cells expressing RVCL mutant TREX1 are more vulnerable to DNA damage induced by chemotherapy and cytokines that up-regulate TREX1, leading to depletion of TREX1-high cells in RVCL mice. RVCL-associated TREX1 mutants inhibit homology-directed repair (HDR), causing DNA deletions and vulnerablility to PARP inhibitors. In women with RVCL, we observe early-onset breast cancer, similar to patients with BRCA1/2 variants. Our results provide a mechanistic basis linking aberrant TREX1 activity to the DNA damage theory of aging, premature senescence, and microvascular disease.

A Murine Model of X-Linked Moesin-Associated Immunodeficiency (X-MAID) Reveals Defects in T Cell Homeostasis and Migration

X-linked moesin associated immunodeficiency (X-MAID) is a primary immunodeficiency disease in which patients suffer from profound lymphopenia leading to recurrent infections. The disease is caused by a single point mutation leading to a R171W amino acid change in the protein moesin (moesinR171W). Moesin is a member of the ERM family of proteins, which reversibly link the cortical actin cytoskeleton to the plasma membrane. Here, we describe a novel mouse model with global expression of moesinR171W that recapitulates multiple facets of patient disease, including severe lymphopenia. Further analysis reveals that these mice have diminished numbers of thymocytes and bone marrow precursors. X-MAID mice also exhibit systemic inflammation that is ameliorated by elimination of mature lymphocytes through breeding to a Rag1-deficient background. The few T cells in the periphery of X-MAID mice are highly activated and have mostly lost moesinR171W expression. In contrast, single-positive (SP) thymocytes do not appear activated and retain high expression levels of moesinR171W. Analysis of ex vivo CD4 SP thymocytes reveals defects in chemotactic responses and reduced migration on integrin ligands. While chemokine signaling appears intact, CD4 SP thymocytes from X-MAID mice are unable to polarize and rearrange cytoskeletal elements. This mouse model will be a valuable tool for teasing apart the complexity of the immunodeficiency caused by moesinR171W, and will provide new insights into how the actin cortex regulates lymphocyte function.

ArfGAP2 promotes STING proton channel activity, cytokine transit, and autoinflammation

Stimulator of interferon genes (STING) transmits signals downstream of the cytosolic DNA sensor cyclic guanosine monophosphate-AMP synthase (cGAS), leading to transcriptional upregulation of cytokines. However, components of the STING signaling pathway, such as IRF3 and IFNAR1, are not essential for autoinflammatory disease in STING gain-of-function (STING-associated vasculopathy with onset in infancy [SAVI]) mice. Recent discoveries revealed that STING also functions as a proton channel that deacidifies the Golgi apparatus. Because pH impacts Golgi enzyme activity, protein maturation, and trafficking, we hypothesized that STING proton channel activity influences multiple Golgi functions. Here, we show that STING-mediated proton efflux non-transcriptionally regulates Golgi trafficking of protein cargos. This process requires the Golgi-associated protein ArfGAP2, a cell-type-specific dual regulator of STING-mediated proton efflux and signaling. Deletion of ArfGAP2 in hematopoietic and endothelial cells markedly reduces STING-mediated cytokine and chemokine secretion, immune cell activation, and autoinflammatory pathology in SAVI mice. Thus, ArfGAP2 facilitates STING-mediated signaling and cytokine release in hematopoietic cells, significantly contributing to autoinflammatory disease pathogenesis.