Frequent altered distribution of peripheral B-lymphocyte subsets in pediatric and adolescent patients with classical Hodgkin lymphoma.

Peripheral lymphopenia is a well-known negative prognostic marker in classical Hodgkin lymphoma (cHL). We characterized the peripheral B-cell compartment in a prospective cohort of 83 pediatric cHL patients. We observed significantly low total B-cell counts (<100 cells/µl) in 31 of 83 patients (37%). More specifically, there was a smaller peripheral IgDhighCD27- naïve B-cell pool among B-cell lymphopenic patients than for non-B-cell lymphopenic patients (p < 0.01). The B-cell count was lower in patients without in situ Epstein Barr Virus (EBV) expression than among those with in situ EBV expression (p = 0.03). Peripheral B-cell lymphopenia was associated with the presence of poor prognostic features, such as advanced lymphoma stage (p < 0.01) and the presence of B symptoms (p = 0.04). Of interest, B-cell lymphopenia resolved in all six studied patients in long-term remission. Our findings support that cHL tumor-associated factors interfere with the distribution of peripheral B-cell subsets.

Assessment of SARS-CoV-2 infection by Reverse transcription-PCR and serology in the Paris area: a cross-sectional study.

BACKGROUND: Several studies indicated that children seem to be less frequently infected with SARS-CoV-2 and are potentially less contagious than adults. To examine the spread of SARS-CoV-2, we combined both Reverse transcription-PCR testing and serology in children in the most affected region in France, Paris, during the COVID-19 epidemic. METHODS: From 14 April 2020 to 12 May 2020, we conducted a cross-sectional, prospective, multicentre study. Healthy controls and pauci-symptomatic children from birth to age 15 years were enrolled by 27 ambulatory paediatricians. A nasopharyngeal swab was taken for detection of SARS-CoV-2 by Reverse transcription-PCR and a microsample of blood for micromethod serology. RESULTS: Among the 605 children, 322 (53.2%) were asymptomatic and 283 (46.8%) were symptomatic. Reverse transcription-PCR and serology results were positive for 11 (1.8%) and 65 (10.7%) children, respectively, with no significant difference between asymptomatic and pauci-symptomatic children. Only three children were Reverse transcription-PCR-positive without any antibody response detected. The frequency of Reverse transcription-PCR SARS-CoV-2 positivity was significantly higher for children with positive than negative serology results (12.3% vs 0.6%, p<0.001). Contact with a person with confirmed COVID-19 increased the odds of Reverse transcription-PCR positivity (OR 7.8, 95% CI 1.5 to 40.7) and serology positivity (OR 15.1, 95% CI 6.6 to 34.6). CONCLUSION: In an area heavily affected by COVID-19, after the peak of the first epidemic wave and during the lockdown, the rate of children with Reverse transcription-PCR SARS-CoV-2 positivity was very low (1.8%), but that of serology positivity was higher (10.7%). Most children with positive Reverse transcription-PCR results also had positive serology results. TRIAL REGISTRATION NUMBER: NCT04318431.

Serum Immunoglobulin Levels in Children with Sickle Cell Disease: A Large Prospective Study.

Over the past 3 decades, the pediatric department of the university Intercommunal Créteil hospital, a referral center for sickle cell disease (SCD), has prospectively evaluated immunoglobulin (Ig) levels in a cohort of 888 children with SCD, including 731 with severe sickle genotypes (HbSS and HbSß0 thalassemia) and 157 with milder genotypes (HbSC and HbSß+ thalassemia). We found consistent sickle genotype differences in levels of IgG and IgA, with increased levels of IgA and IgG in the severe versus milder genotype, from early childhood to late adolescence. Additionally, our results revealed a low serum IgM level, irrespective of sickle genotype. Finally, we found that IgA and IgG levels were significantly increased after therapeutic intensification with hydroxyurea but were stabilized in children receiving a transfusion program. The mechanisms contributing to these changes in Ig levels are unclear as is their clinical significance. We believe they should be further investigated.

T-Lymphocytes Traffic into the Brain across the Blood-CSF Barrier: Evidence Using a Reconstituted Choroid Plexus Epithelium.

An emerging concept of normal brain immune surveillance proposes that recently and moderately activated central memory T lymphocytes enter the central nervous system (CNS) directly into the cerebrospinal fluid (CSF) via the choroid plexus. Within the CSF space, T cells inspect the CNS environment for cognate antigens. This gate of entry into the CNS could also prevail at the initial stage of neuroinflammatory processes. To actually demonstrate T cell migration across the choroidal epithelium forming the blood-CSF barrier, an in vitro model of the rat blood-CSF barrier was established in an "inverse" configuration that enables cell transmigration studies in the basolateral to apical, i.e. blood/stroma to CSF direction. Structural barrier features were evaluated by immunocytochemical analysis of tight junction proteins, functional barrier properties were assessed by measuring the monolayer permeability to sucrose and the active efflux transport of organic anions. The migratory behaviour of activated T cells across the choroidal epithelium was analysed in the presence and absence of chemokines. The migration pathway was examined by confocal microscopy. The inverse rat BCSFB model reproduces the continuous distribution of tight junction proteins at cell margins, the restricted paracellular permeability, and polarized active transport mechanisms, which all contribute to the barrier phenotype in vivo. Using this model, we present experimental evidence of T cell migration across the choroidal epithelium. Cell migration appears to occur via a paracellular route without disrupting the restrictive barrier properties of the epithelial interface. Apical chemokine addition strongly stimulates T cell migration across the choroidal epithelium. The present data provide evidence for the controlled migration of T cells across the blood-CSF barrier into brain. They further indicate that this recruitment route is sensitive to CSF-borne chemokines, extending the relevance of this migration pathway to neuroinflammatory and neuroinfectious disorders which are typified by elevated chemokine levels in CSF.

Faster T-cell development following gene therapy compared with haploidentical HSCT in the treatment of SCID-X1.

During the last decade, gene therapy via ex vivo gene transfer into autologous hematopoietic stem cells has emerged as a convincing therapy for severe combined immunodeficiency caused by ILR2G mutation (SCID-X1) despite the occurrence of genotoxicity caused by the integration of first-generation retroviral vectors. However, the place of gene therapy among the therapeutic armamentarium remains to be defined. We retrospectively analyze and compare clinical outcomes and immune reconstitution in 13 consecutive SCID-X1 patients having undergone haploidentical hematopoietic stem cell transplantation (HSCT) and 14 SCID-X1 patients treated with gene therapy over the same period at a single center level: the Necker Children's Hospital (Paris, France). Our results show a clear advantage in terms of T-cell development of gene therapy over HSCT with a mismatched donor. Patients treated with gene therapy display a faster T-cell reconstitution and a better long-term thymic output. Interestingly, this advantage of gene therapy vs haploidentical HSCT seems to be independent of the existence of clinical graft-versus-host disease in the latter condition. If data of safety are confirmed over the long term, gene therapy for SCID-X1 appears to be an equal, if not superior, alternative to haploidentical HSCT.

p52 Activation in monomorphic B-cell posttransplant lymphoproliferative disorder/diffuse large B-cell lymphoma without BAFF-R expression.

Posttransplantation lymphoproliferative disorders (PTLD) are associated with Epstein-Barr virus (EBV) and activate the NF-κB pathway. B-cell activating factor (BAFF) modulates cell growth and survival in non-Hodgkin's lymphomas. However, there are few studies of EBV, BAFF/BAFF-R signaling, and NF-κB1 and NF-κB2 pathway activation in PTLD. Diffuse large B-cell lymphomas (DLBCL) in two different clinical contexts, immunocompetent patients (DLBCL/IC; n = 30) or posttransplantation solid-organ recipients (DLBCL/PTLD; n = 21), were characterized histogenically as germinal center (GC) or non-germinal center (NGC). Expression of BAFF, BAFF-R, and NF-κB proteins p50 and p52 and the presence or absence of EBV were compared in these clinical contexts. Regardless of the GC or NGC pattern of DLBCL, BAFF-R was expressed in 37% of DLBCL/IC but in only 4.8% of DLBCL/PTLD. p52 was expressed in DLBCL/PTLD/NGC (12 of 19 cases) as compared with DLBCL/IC/NGC (0 of 18 cases). This pattern might be related to the presence of EBV and latent membrane protein 1 because p52 expression was observed primarily in EBV-positive DLBCL/PTLD cases expressing latent membrane protein 1. Thus, the activation profile or NGC pattern of DLBCL/PTLD was not associated with BAFF/BAFF-R expression, whereas nuclear p52 related to NF-κB2 pathway activation might be linked to EBV.

Changes in blood B cell phenotypes and Epstein-Barr virus load in chronically human immunodeficiency virus­infected patients before and after antiretroviral therapy.

BACKGROUND: Switched and nonswitched memory B cells, which usually constitute the main reservoirs of Epstein­Barr virus (EBV), are rapidly depleted in patients with chronic human immunodeficiency virus (HIV) infection. Because the EBV load is frequently increased in these patients, other B cell reservoirs might participate in EBV persistence. METHODS: We examined the combined expression of CD27, SIgD/G/M, CD38, CD10, CD5, CXCR5, CD62L, CD44, and CXCR3 on B cells from healthy donors (n = 30) and from HIV type 1-infected patients (n = 23) at diagnosis and after highly active antiretroviral therapy. The plasma HIV load and the DNA EBV load in peripheral blood mononuclear cells were assessed. RESULTS: Increased frequencies of CD38+SIgD+CD10+ B cells were found in patients with an EBV load >10(3)copies per 10(6)peripheral blood mononuclear cells and a strong depletion of memory B cells. This phenotype resembles that of transitional B cell subsets. Elevated percentages of these B cells were still found in 2 patients showing no decrease in EBV load after highly active antiretroviral therapy. CONCLUSIONS: Because transitional-like B cells persist concomitantly with high EBV load after highly active antiretroviral therapy, we suggest that this population might be an alternative EBV reservoir in patients with chronic HIV infection who have strongly reduced numbers of memory B cells. The consequences of EBV infection of immature B cells are discussed with regard to B cell maturation and a higher prevalence of B cell lymphoma in HIV­infected patients.

TWEAK is expressed at the cell surface of monocytes during multiple sclerosis.

The TNF superfamily ligand, TNF-like weak inducer of apoptosis (TWEAK), regulates cellular responses ranging from proliferation to cell death in a manner highly dependent on the cell type and the microenvironmental context. We have shown previously that treatment of experimental autoimmune encephalomyelitis mice after the priming phase with neutralizing anti-TWEAK antibodies results in a reduction in the severity of the disease and leukocyte infiltration. To further characterize TWEAK/fibroblast growth factor-inducible 14-kDa protein (Fn14) involvement during multiple sclerosis (MS), we evaluated in MS patients and controls: TWEAK and Fn14 expression on PBMC and soluble TWEAK concentration in serum and cerebrospinal fluid (CSF). Thirty-six consecutive patients were enrolled, including 11 patients with relapsing-remitting MS, 11 with a clinical isolated syndrome suggestive of MS (CISSMS), and 14 controls with non-MS diseases. Intracellular TWEAK could be observed in lymphocytes and/or monocytes in all groups of patients. None of the 36 patients displayed TWEAK expression at the cell surface of lymphocytes. In contrast, 12 out of the 36 patients were positive for membrane TWEAK expression on their monocytes. Among these patients, eight were from the CISSMS group. Fn14 was not detected in PBMC. The soluble form of TWEAK is detectable in serum and CSF of patients, and TWEAK concentrations were not statistically different between the disease groups. We demonstrated for the first time that TWEAK is expressed at the cell surface of monocytes during MS, especially in the CISSMS group. Our results support the proposal that TWEAK could be a target for antibody therapy in MS.

Astrocyte reactivity to Fas activation is attenuated in TIMP-1 deficient mice, an in vitro study.

BACKGROUND: Tissue inhibitor of metalloproteinases-1 (TIMP-1) is a multifunctional secreted protein with pleiotropic actions, including the inhibition of matrix metalloproteinases (MMPs), cell death/survival and growth promoting activities. After inflammatory challenge, the levels of TIMP-1 are highly and selectively upregulated in astrocytes among glial cells, but little is know about its role in these neural cells. We investigated the influence of TIMP-1 null mutation in the reactivity of cultured astrocytes to pro-inflammatory stimuli with TNF-alpha and anti-Fas antibody. RESULTS: When compared to WT, mutant astrocytes displayed an overall increased constitutive gelatinase expression and were less responsive to Fas-mediated upregulation of MMP-9, of monocyte chemoattractant protein-1 (MCP-1) and of intercellular cell adhesion molecule-1 (ICAM-1), all markers of astrocyte inflammatory response. In contrast, TNF-alpha treatment induced all these factors similarly regardless of the astrocyte genotype. The incorporation of 3H-thymidin, a marker of cell proliferation, increased in wild-type (WT) astrocytes after treatment with anti-Fas antibody or recombinant TIMP-1 but not in mutant astrocytes. Finally, lymphocyte chemotaxis was differentially regulated by TNF-alpha in WT and TIMP-1 deficient astrocytes. CONCLUSION: We provide evidence that the alteration of the MMP/TIMP balance in astrocytes influences their reactivity to pro-inflammatory stimuli and that Fas activation modulates the expression of members of the MMP/TIMP axis. We hypothesise that the Fas/FasL transduction pathway and the MMP/TIMP system interact in astrocytes to modulate their inflammatory response to environmental stimuli.

Anti-TWEAK monoclonal antibodies reduce immune cell infiltration in the central nervous system and severity of experimental autoimmune encephalomyelitis.

TWEAK is a member of the TNF family, constitutively expressed in the central nervous system (CNS), with pro-inflammatory, proliferative or apoptotic effects depending upon cell types. Its receptor, Fn14, is expressed in CNS by endothelial cells, reactive astrocytes and neurons. We showed that TWEAK and Fn14 mRNA expression increased in spinal cord during experimental autoimmune encephalomyelitis (EAE). We investigated the role of TWEAK during EAE using neutralizing anti-TWEAK antibody in myelin oligodendrocyte glycoprotein (MOG) induced EAE in C57BL/6 mice. We observed a reduction of disease severity and leukocyte infiltration when mice were treated after the priming phase.

TWEAK is expressed by glial cells, induces astrocyte proliferation and increases EAE severity.

TWEAK is a new TNF family member with proinflammatory and proliferative effects on different cell types, mediated by the recently identified Fn14 receptor. TWEAK expression was analyzed on mouse microglial cells and astrocytes. Both cell types express TWEAK mRNA. Astrocytes expressed Fn14 and proliferated in the presence of rTWEAK. TWEAK mRNA is expressed in normal CNS and its steady state level increases in spinal cord during EAE. Finally, EAE severity is enhanced in soluble TWEAK-overexpressing transgenic mice. These results support the contention that TWEAK is involved in CNS inflammation.