SURF1 deficiency causes demyelinating Charcot-Marie-Tooth disease

Objective: To investigate whether mutations in the SURF1 gene are a cause of Charcot-Marie-Tooth (CMT) disease. Methods: We describe 2 patients from a consanguineous family with demyelinating autosomal recessive CMT disease (CMT4) associated with the homozygous splice site mutation c.107-2A>G in the SURF1 gene, encoding an assembly factor of the mitochondrial respiratory chain complex IV. This observation led us to hypothesize that mutations in SURF1 might be an unrecognized cause of CMT4, and we investigated SURF1 in a total of 40 unrelated patients with CMT4 after exclusion of mutations in known CMT4 genes. The functional impact of c.107-2A>G on splicing, amount of SURF1 protein, and on complex IV activity and assembly was analyzed. Results: Another patient with CMT4 was found to harbor 2 additional SURF1 mutations. All 3 patients with SURF1-associated CMT4 presented with severe childhood-onset neuropathy, motor nerve conduction velocities G mutation produced no normally spliced transcript, leading to SURF1 absence. However, complex IV remained partially functional in muscle and fibroblasts. Conclusions: We found SURF1 mutations in 5% of families (2/41) presenting with CMT4. SURF1 should be systematically screened in patients with childhood-onset severe demyelinating neuropathy and additional features such as lactic acidosis, brain MRI abnormalities, and cerebellar ataxia developing years after polyneuropathy

Germline C1GALT1C1 mutation causes a multisystem chaperonopathy

Mutations in genes encoding molecular chaperones can lead to chaperonopathies, but none have so far been identified causing congenital disorders of glycosylation. Here we identified two maternal half-brothers with a novel chaperonopathy, causing impaired protein O-glycosylation. The patients have a decreased activity of T-synthase (C1GALT1), an enzyme that exclusively synthesizes the T-antigen, a ubiquitous O-glycan core structure and precursor for all extended O-glycans. The T-synthase function is dependent on its specific molecular chaperone Cosmc, which is encoded by X-chromosomal C1GALT1C1. Both patients carry the hemizygous variant c.59C>A (p.Ala20Asp; A20D-Cosmc) in C1GALT1C1. They exhibit developmental delay, immunodeficiency, short stature, thrombocytopenia, and acute kidney injury (AKI) resembling atypical hemolytic uremic syndrome. Their heterozygous mother and maternal grandmother show an attenuated phenotype with skewed X-inactivation in blood. AKI in the male patients proved fully responsive to treatment with the complement inhibitor Eculizumab. This germline variant occurs within the transmembrane domain of Cosmc, resulting in dramatically reduced expression of the Cosmc protein. Although A20D-Cosmc is functional, its decreased expression, though in a cell or tissue-specific manner, causes a large reduction of T-synthase protein and activity, which accordingly leads to expression of varied amounts of pathological Tn-antigen (GalNAcα1-O-Ser/Thr/Tyr) on multiple glycoproteins. Transient transfection of patient lymphoblastoid cells with wild-type C1GALT1C1 partially rescued the T-synthase and glycosylation defect. Interestingly, all four affected individuals have high levels of galactose-deficient IgA1 in sera. These results demonstrate that the A20D-Cosmc mutation defines a novel O-glycan chaperonopathy and causes the altered O-glycosylation status in these patients

Contribution of Aggregation Promoting Factor (APF) to maintenance of cell shape in Lactobacillus gasseri 4B2

Aggregation-promoting factor (APF) was originally described as a protein involved in the conjugation and autoaggregation of Lactobacillus gasseri 4B2, whose corresponding apf gene was cloned and sequenced. In this report, we identified and sequenced an additional apf gene located in the region upstream of the previously published one. Inactivation of both apf genes was unsuccessful, indicating that APF function may be essential for the cell. Overproduction of APF proteins caused drastic alteration in the cell shape of this strain. These cells were irregular, twisted, enlarged, and tightly bound in unbreakable clumps of chains. Down-regulation of APF synthesis was achieved by cloning of the apf2 promoter region on a high-copy-number plasmid, which recruited a putative apf activator. As a consequence, the shape of the corresponding recombinant cells was elongated (filamentous) and cell division sites were no longer visible. None of the induced changes in APF production levels was clearly correlated with modifications of the aggregation phenotype. This report shows, for the first time, that APF proteins are mainly critical for L. gasseri 4B2 cell shape maintenanc

A pharmacodynamic model of ganciclovir antiviral effect and toxicity for lymphoblastoid cells suggests a new dosing regimen to treat cytomegalovirus infection

In bone marrow transplantation, the efficacy of ganciclovir in cytomegalovirus (CMV) disease treatment or prophylaxis remains partial. Because its hematological toxicity is dose limiting, optimization of the dosing schedule is required to increase its therapeutic index. The goal of our study was to describe the influence of the ganciclovir concentration and duration of exposure on cell survival and antiviral efficacy. The study was carried out in vitro on cultures of lymphoblastoid cells infected or not with the CMV AD169 reference strain and exposed to ganciclovir at different concentrations for 1, 2, 7, or 14 days. The data were analyzed by a mathematical model that allowed a quantitative characterization of ganciclovir pharmacodynamics and its variability. Simulations of the model were undertaken to determine the optimal concentration profile for maximizing the ganciclovir therapeutic index. Ganciclovir had very little toxic and antiviral effect, even at 20 mg liter(−1), when the duration of exposure was ≤7 days. A biologically significant effect was observed only with a 14-day exposure. Complete inhibition of viral replication was obtained at 20 mg liter(−1). The utility function, assuming equal weights for antiviral effect and toxicity, showed that maximal utility was reached around 10 mg liter(−1). The optimal ganciclovir concentration profile consisted of maintaining the concentration at 20 mg liter(−1) at the intervals 0 to 2 days and 7.58 to 9.58 days and a null concentration at other times. This optimal profile could be obtained by intravenous (i.v.) ganciclovir at 10 mg/kg of body weight twice daily (b.i.d.) at days 1, 2, 8.5, and 9.5 in stem cell transplant patients with normal renal function

Effect of whey-based culture supernatant of Lactobacillus acidophilus (johnsonii) La1 on Helicobacter pylori infection in humans

BACKGROUND: Specific strains of Lactobacillus acidophilus are known to inhibit intestinal cell adhesion and invasion by enterovirulent bacteria. As L. acidophilus can survive transiently in the human stomach, it may downregulate Helicobacter pylori infection. METHODS: The ability of L. acidophilus (johnsonii) La1 supernatant to interfere with H. pylori bacterial growth, urease activity, and adhesion to epithelial cells was tested in vitro. Its effect on H. pylori infection in volunteers was monitored in a randomized, double-blind, controlled clinical trial, using a drinkable, whey-based, La1 culture supernatant. H. pylori infected volunteers were treated 14 days with 50 ml of La1 supernatant four times a day combined with either omeprazole 20 mg four times a day or with placebo. Infection was assessed by breath test, endoscopy, and biopsy sampling, performed at inclusion, immediately at the end of the treatment (breath test only), and 4 weeks after the end of the treatment. RESULTS: La1 supernatant inhibited H. pylori growth in vitro, regardless of previous binding of H. pylori to epithelial cells. In 20 subjects (8 females, 12 males, mean age 33.1 years) a marked decrease in breath test values was observed immediately after treatment with La1 supernatant, both in the omeprazole and in the placebo group (median 12.3 vs. 28.8 and 9.4 vs. 20.4, respectively; p < 0.03). In both treatment groups, breath test values remained low 6 weeks after treatment (omeprazole treated 19.2, placebo treated 8. 3; p < 0.03 vs. pretreatment), but the persistence of H. pylori infection was confirmed in gastric biopsies. CONCLUSION: La1 culture supernatant shown to be effective in vitro has a partial, acid-independent long-term suppressive effect on H. pylori in humans

DNASE1L3 deficiency, new phenotypes, and evidence for a transient type I IFN signaling

Background: Deoxyribonuclease 1 like 3 (DNASE1L3) is a secreted enzyme that has been shown to digest the extracellular chromatin derived from apoptotic bodies, and DNASE1L3 pathogenic variants have been associated with a lupus phenotype. It is unclear whether interferon signaling is sustained in DNASE1L3 deficiency in humans. Objectives: To explore interferon signaling in DNASE1L3 deficient patients. To depict the characteristic features of DNASE1L3 deficiencies in human. Methods: We identified, characterized, and analyzed five new patients carrying biallelic DNASE1L3 variations. Whole or targeted exome and/or Sanger sequencing was performed to detect pathogenic variations in five juvenile systemic erythematosus lupus (jSLE) patients. We measured interferon-stimulated gene (ISG) expression in all patients. We performed a systematic review of all published cases available from its first description in 2011 to March 24th 2022. Results: We identified five new patients carrying biallelic DNASE1L3 pathogenic variations, including three previously unreported mutations. Contrary to canonical type I interferonopathies, we noticed a transient increase of ISGs in blood, which returned to normal with disease remission. Disease in one patient was characterized by lupus nephritis and skin lesions, while four others exhibited hypocomplementemic urticarial vasculitis syndrome. The fourth patient presented also with early-onset inflammatory bowel disease. Reviewing previous reports, we identified 35 additional patients with DNASE1L3 deficiency which was associated with a significant risk of lupus nephritis and a poor outcome together with the presence of anti-neutrophil cytoplasmic antibodies (ANCA). Lung lesions were reported in 6/35 patients. Conclusions: DNASE1L3 deficiencies are associated with a broad phenotype including frequently lupus nephritis and hypocomplementemic urticarial vasculitis with positive ANCA and rarely, alveolar hemorrhages and inflammatory bowel disease. This report shows that interferon production is transient contrary to anomalies of intracellular DNA sensing and signaling observed in Aicardi-Goutières syndrome or STING-associated vasculitis in infancy (SAVI)

DNASE1L3 deficiency, new phenotypes and evidence for a transient type I interferon signaling

Introduction: Deoxyribonuclease 1 like 3 (DNASE1L3) is a secreted enzyme that has been shown to digest the extracellular chromatin derived from apoptotic bodies, and DNASE1L3 pathogenic variants have been associated to a lupus phenotype. It is unclear whether interferon signaling is sustained in DNASE1L3 deficiency in humans. Objectives: Here, we report on four patients with pathogenic variations in DNASE1L3, including 2 previously undescribed causal variants, and expand the phenotype from SLE to vasculitis with gut involvement. To explore whether or not the interferon cascade was strongly and sustainably induced, Interferon stimulated genes (ISGs) expression was assessed for each patient. We also review previous reports highlighting the spectrum of DNASE1L3 deficiency. Methods: Identification of disease-causing variants was based on NGS sequencing in 3 out of 4 patients, and for one patient, coding regions of the DNASE1L3 gene were directly sequenced by Sanger sequencing. Type I interferon signature was determined using either quantitative reverse transcription polymerase chain reaction or nanostring technology, and serum IN-α2 concentrations was measured using simoa assay. Results: Disease in one patient was characterized by lupus nephritis and skin lesions, while two others exhibited hypocomplementemic urticarial vasculitis syndrome. The fourth patient presented with early-onset inflammatory bowel disease. Contrary to canonical type-I interferonopathies, we noticed a transient increase of ISGs in blood, which reverted to normal with disease remission. Conclusion: Reviewing previous reports, DNASE1L3-related disease appears to carry a significant risk of lupus nephritis and a poor outcome together with the presence of anti-neutrophil cytoplasmic antibodies (ANCA). DNASE1L3 deficiency may share the pathogenesis with C1q deficiency by affecting efferocytosis, and this report suggests that interferon production is not directly driven by DNASE1L3 pathogenic variants

DNASE1L3 deficiency, new phenotypes, and evidence for a transient type I IFN signaling

peer reviewedBACKGROUND: Deoxyribonuclease 1 like 3 (DNASE1L3) is a secreted enzyme that has been shown to digest the extracellular chromatin derived from apoptotic bodies, and DNASE1L3 pathogenic variants have been associated with a lupus phenotype. It is unclear whether interferon signaling is sustained in DNASE1L3 deficiency in humans. OBJECTIVES: To explore interferon signaling in DNASE1L3 deficient patients. To depict the characteristic features of DNASE1L3 deficiencies in human. METHODS: We identified, characterized, and analyzed five new patients carrying biallelic DNASE1L3 variations. Whole or targeted exome and/or Sanger sequencing was performed to detect pathogenic variations in five juvenile systemic erythematosus lupus (jSLE) patients. We measured interferon-stimulated gene (ISG) expression in all patients. We performed a systematic review of all published cases available from its first description in 2011 to March 24(th) 2022. RESULTS: We identified five new patients carrying biallelic DNASE1L3 pathogenic variations, including three previously unreported mutations. Contrary to canonical type I interferonopathies, we noticed a transient increase of ISGs in blood, which returned to normal with disease remission. Disease in one patient was characterized by lupus nephritis and skin lesions, while four others exhibited hypocomplementemic urticarial vasculitis syndrome. The fourth patient presented also with early-onset inflammatory bowel disease. Reviewing previous reports, we identified 35 additional patients with DNASE1L3 deficiency which was associated with a significant risk of lupus nephritis and a poor outcome together with the presence of anti-neutrophil cytoplasmic antibodies (ANCA). Lung lesions were reported in 6/35 patients. CONCLUSIONS: DNASE1L3 deficiencies are associated with a broad phenotype including frequently lupus nephritis and hypocomplementemic urticarial vasculitis with positive ANCA and rarely, alveolar hemorrhages and inflammatory bowel disease. This report shows that interferon production is transient contrary to anomalies of intracellular DNA sensing and signaling observed in Aicardi-Goutières syndrome or STING-associated vasculitis in infancy (SAVI)