Tu-Anh Tran

Background: IgA vasculitis (IgAV) is the most common systemic vasculitis in children, and its prognosis is largely determined by renal involvement (IgAV nephritis). No routine blood test identifies IgAV or stratifies the risk of nephritis, although aberrant O-glycosylation of the IgA1 hinge region is central to its pathogenesis. We developed a mass-spectrometry assay to profile IgA1 hinge O-glycoforms and define signatures of disease activity and renal involvement. Methods: IgA was affinity-purified from 5 µL of plasma from 91 children (27 with acute IgAV, 26 in remission, and 38 age-matched healthy controls; 24 with and 29 without nephritis), trypsin-digested, and hinge-region O-glycopeptides were quantified by LC-MS. Sixty-nine glycoforms were normalized to a total-IgA1 tryptic peptide. Duplicate measurements showed good analytical repeatability, with a median coefficient of variation of 6%. Groups were compared using Mann–Whitney and Kruskal–Wallis tests (Benjamini– Hochberg FDR). Discrimination was assessed by ROC analysis and cross-validated logistic regression panels. Results: Acute IgAV showed broad remodeling of the hinge glycoform profile (35 glycoforms differed with excellent discrimination (AUC 0.93–0.95) for the best ones), with an increase in low-sialylated, agalactosylated species and a decrease in complex sialylated species. The profile was normalized in remission (no glycoform differed from the controls). Two distinct renal patterns emerged: disease-associated glycoforms already altered without nephritis and renal-specific glycoforms altered only in nephritis (H2N2S1, H3N3S5, H3N4S4, and H4N4S3). A four-marker panel discriminated nephritis among IgAV children with a cross-validated AUC of 0.86 (IC 95 % 0.75–0.94). Conclusions: A single mass-spectrometry assay, from a small blood volume, captures an IgAV-associated IgA1 hinge O-glycoform signature that normalizes in remission, together with a distinct renal involvement associated signature. These findings identify candidate IgA1 O-glycoform signatures associated with IgAV activity and documented renal involvement. Prospective longitudinal studies are required to determine whether the renal-associated panel can predict subsequent nephritis.

Background and objectives: Henoch–Schönlein purpura (HSP) is the most common immunoglobulin A-mediated systemic vasculitis in childhood. We studied immune dysregulation in HSP by analyzing regulatory T (Treg), T helper 3 (Th3), and regulatory B cell (Breg) subpopulations that might intervene in immune activation, IgA production, and HSP clinical manifestations. Methods: This prospective study included 3 groups of children: 30 HSP on acute phase, 30 HSP on remission, and 40 healthy controls (HCs) matched on age. Treg, Breg, and Th3 were analyzed by flow cytometry. Serum immunoglobulin and cytokine levels were quantified by ELISA and Luminex. Results: Treg frequencies were higher in acute HSP than in remitting HSP and HCs (6.53% [4.24; 9.21] vs. 4.33% [3.6; 5.66], p = 0.002, and vs. 4.45% [3.01; 6.6], p = 0.003, respectively). Activated Th3 cells (FoxP3 + Th3 cells) tend to be more abundant in HSP than in HCs (78.43% [50.62; 80.84] vs. 43.30% [40.20; 49.32], p = 0.135). Serum IgA, IL-17, and latency-associated peptide (a marker of the anti-inflammatory cytokine TGF-beta production) were significantly and inflammatory cytokines TNF-alpha, IL-1-beta, and IL-6 were non-significantly higher in HSP than HCs. Bregs were identical between the groups, but, in patients with renal impairment, Breg percentage was lower compared to those without. Treg removal in PBMC culture resulted in an increase in IgA production in HSP proving a negative regulatory role of Tregs on IgA production. Conclusions: In pediatric HSP, immune activation persists in spite of an increase in Th3 and Tregs. Th3 could be involved in IgA hyperproduction, inefficiently downregulated by Tregs. Lack of Bregs appears linked to renal impairment.

Genetic defects in the ability to deliver effective perforin have been reported in patients with hemophagocytic lymphohistiocytosis. We tested the hypothesis that a primary perforin deficiency might also be causal in severe SARS-CoV-2 infection. We recruited 54 volunteers confirmed as being SARS-CoV-2–infected by RT-PCR and admitted to intensive care units or non–intensive care units and age- and sex-matched healthy controls. Compared with healthy controls, the percentage of perforin-expressing CD3−CD56+ NK cells quantified by flow cytometry was low in COVID-19 patients (69.9 ± 17.7 versus 78.6 ± 14.6%, p = 0.026). There was no correlation between the proportions of perforin-positive NK cells and T8 lymphocytes. Moreover, the frequency of NK cells producing perforin was neither linked to disease severity nor predictive of death. Although IL-6 is known to downregulate perforin production in NK cells, we did not find any link between perforin expression and IL-6 plasma level. However, we unveiled a negative correlation between the degranulation marker CD107a and perforin expression in NK cells (r = −0.488, p = 10−4). PRF1 gene expression and the frequency of NK cells harboring perforin were normal in patients 1 y after acute SARS-CoV-2 infection. A primary perforin defect does not seem to be a driver of COVID-19 because NK perforin expression is 1) linked neither to T8 perforin expression nor to disease severity, 2) inversely correlated with NK degranulation, and 3) normalized at distance from acute infection. Thus, the cause of low frequency of perforin-positive NK cells appears, rather, to be consumption.

Since the initial spread of severe acute respiratory syndrome coronavirus 2 infection, several viral variants have emerged and represent a major challenge for immune control, particularly in the context of vaccination. We evaluated the quantity, quality, and persistence of immunoglobulin G (IgG) and IgA in individuals who received two or three doses of messenger RNA (mRNA) vaccines, compared with previously infected vaccinated individuals. We show that three doses of mRNA vaccine were required to match the humoral responses of preinfected vaccinees. Given the importance of antibody-dependent cell-mediated immunity against viral infections, we also measured the capacity of IgG to recognize spike variants expressed on the cell surface and found that cross-reactivity was also strongly improved by repeated vaccination. Last, we report low levels of CXCL13, a surrogate marker of germinal center activation and formation, in vaccinees both after two and three doses compared with preinfected individuals, providing a potential explanation for the short duration and low quality of Ig induced.

Laura Poujade, Guillaume Sarrabay, Renaud Cezar, Quentin Samaran, Pierre Corbeau, Didier Bessis, Tu-Anh Tran; Lenalidomide for treatment of refractory aphthosis

Background: The natural history of immunoglobulin (Ig) E-mediated diseases in preterm infants is still elusive. We aimed at developing a non-invasive tool for detecting specific IgE (sIgE) and eosinophil-derived neurotoxin (EDN) in neonatal fecal samples and evaluating its predictive value for the development of IgE-mediated diseases during the first year of life. Methods: We developed a stool extraction protocol, followed by freeze-drying and solubilization. The sIgEs were investigated in neonatal fecal samples from 21 preterm infants with a 300-allergen multiplex and confirmed by a capillary Western blot with a nano-immunoassay. EDN concentration was used to investigate the local eosinophilic component. Results: The multiplexed allergen assay detected sIgE in all of the samples. A Western blot was used to confirm the results. The frequency and levels of sIgE in the neonatal fecal samples differed between the infants who developed IgE-mediated diseases and the controls. Allergen specificity was associated with the development of cow’s milk allergy (CMA) and asthma. The development of CMA was predicted by the sIgE response to milk proteins (sensitivity was 88%; specificity was 78%). The EDN levels predicted the development of IgE-mediated diseases (sensitivity was 100%; specificity was 75%). Conclusion: The non-invasive investigation of neonatal fecal sIgE is a promising tool for predicting the subsequent development of IgE-mediated diseases. Clinical Implications: The non-invasive sIgE and EDN profiling of neonatal fecal samples from preterm infants can predict the development of IgE-mediated diseases.

Background: Little is known about the natural history of immunoglobulin (Ig) E-mediated diseases in preterm infants, further hampered by the lack of noninvasive investigations. We aimed at developing a non-invasive tool for the study of IgE and eosinophil-derived neurotoxin (EDN) in neonatal fecal samples and evaluating its predictive value for the development of IgE-mediated diseases (cow’s milk allergy, asthma, or atopic dermatitis) during the first year of life. Methods: We developed a stool extraction protocol, followed by freeze-drying and solubilization. sIgE responses were investigated in neonatal fecal samples from 21 preterm infants with a 300-allergen multiplex containing whole and molecular allergens and confirmed by capillary Western blot with nano-immunoassay. The local eosinophilic component was investigated by measuring the concentration of EDN. Results: The multiplexed allergen assay detected sIgE in all samples. Confirmation was obtained with Western blot. Frequency and levels of sIgE in neonatal fecal samples differed between infants who developed IgE-mediated diseases and controls. Neonatal fecal sIgE directed to milk proteins predicted later development of cow’s milk allergy (specificity 88%, sensitivity 78%). Allergen specificity of neonatal fecal sIgE was associated with later development of cow’s milk allergy and asthma. Neonatal fecal EDN levels predicted the development of IgE-mediated diseases (sensitivity 100%, specificity 75%). Conclusion: Non-invasive investigation of neonatal fecal sIgE is a promising tool for the prediction of subsequent development of IgE-mediated diseases.

Background: Preterm birth is a major cause of morbidity and mortality in infants and children. Non-invasive methods for screening the neonatal immune status are lacking. Archaea, a prokaryotic life domain, comprise methanogenic species that are part of the neonatal human microbiota and contribute to early immune imprinting. However, they have not yet been characterized in preterm neonates. Objective: To characterize the gut immunological and methanogenic Archaeal (MA) signature in preterm neonates, using the presence or absence of atopic conditions at the age of one year as a clinical endpoint. Methods: Meconium and stool were collected from preterm neonates and used to develop a standardized stool preparation method for the assessment of mediators and cytokines and characterize the qPCR kinetics of gut MA. Analysis addressed the relationship between immunological biomarkers, Archaea abundance, and atopic disease at age one. Results: Immunoglobulin E, tryptase, calprotectin, EDN, cytokines, and MA were detectable in the meconium and later samples. Atopic conditions at age of one year were positively associated with neonatal EDN, IL-1β, IL-10, IL-6, and MA abundance. The latter was negatively associated with neonatal EDN, IL-1β, and IL-6. Conclusions: We report a non-invasive method for establishing a gut immunological and Archaeal signature in preterm neonates, predictive of atopic diseases at the age of one year.

Background: Preterm birth is a major cause of morbidity and mortality in infants and children. Non-invasive methods for screening the neonatal immune status are lacking. Archaea, a prokaryotic life domain, comprise methanogenic species that are part of the neonatal human microbiota and contribute to early immune imprinting. However, they have not yet been characterized in preterm neonates. Objective: To characterize the gut immunological and methanogenic Archaeal (MA) signature in preterm neonates, using the presence or absence of atopic conditions at the age of 1 year as a clinical endpoint. Methods: Meconium and stool were collected from preterm neonates and used to develop a standardized stool preparation method for the assessment of mediators and cytokines and characterize the qPCR kinetics of gut MA. Analysis addressed the relationship between immunological biomarkers, Archaea abundance, and atopic disease at age 1. Results: Immunoglobulin E, tryptase, calprotectin, EDN, cytokines, and MA were detectable in the meconium and later samples. Atopic conditions at age 1 year were positively associated with neonatal EDN, IL-1β, IL-10, IL-6, and MA abundance. The latter was negatively associated with neonatal EDN, IL-1β and IL-6. Conclusion: We report a non-invasive method for establishing a gut immunological and Archaeal signature in preterm neonates, predictive of atopic diseases at the age of 1 year