Leukocyte Activation Patterns in Hospitalized Children: Comparing SARS-CoV-2, Bacterial Infections, and Inflammatory Pathologies.

In adults, monocytes and neutrophils play important roles in the hyper-inflammatory responses' characteristic of severe forms of SARS-CoV-2 infection. We assessed leukocyte activation in 55 children attending the emergency department for acute fever between March 2020 and September 2021. The following markers were analyzed by flow cytometry: CD169 and HLA-DR on monocytes, CD64 and CD16 on neutrophils, CD38 on lymphocytes TCD8. Fifteen of the children had SARS-CoV-2 infection, 15 had bacterial infections, 15 had inflammatory diseases. We observed overexpression of CD169 on monocytes and CD38 on lymphocytes T in all patients with a diagnosis of SARS-CoV-2, while overexpression of CD64 on neutrophils was observed with bacterial infections and inflammatory diseases. There was a decrease in the expression of HLA-DR on monocytes in the bacterial infection and inflammatory pathology groups. Leukocyte analysis identifies distinct activation patterns in children during SARS-CoV-2 infections, bacterial infections, and inflammatory diseases.

Airway epithelial type-2 alarmin profiles: Blood eosinophil counts remain in memory.

Epithelial cytokines are involved in the orchestration of T1/T2 inflammatory patterns. We question the persistence of this trait in air-liquid interface (ALI) epithelial cultures and whether this local orientation can be related to systemic patterns (e.g., blood eosinophil counts [BECs]). We investigated alarmin release related to high versus low T2 phenotypes associated with chronic airway diseases. ALIs were reconstituted from 32 control, 40 chronic obstructive pulmonary disease, and 20 asthmatic patients. Interleukin-8 (IL-8; a T1-cytokine), IL-25, IL-33, and thymic stromal lymphopoietin (T2-alarmins) concentrations were assessed in subnatants at steady state and used to explain blood neutrophil and eosinophil counts. IL-25 and IL-8 levels were highest in asthma ALI-subnatants, whereas IL-33 was sparsely detected. Thymic stromal lymphopoietin levels were similar among groups. All asthma cell cultures were T1-high/T2-high, while chronic obstructive pulmonary disease and controls tended to be mixed. BECs were independently explained by both disease and in-culture T2-alarmin levels, irrespective of the T2-alarmin considered. The epithelial ALI-T2 signature was more frequently high in patients with a BEC > 300/mm3 . Despite removal from an in vivo environment for ≥2 months, ALIs release disease-specific cytokine "cocktails" into their subnatants, suggesting continued persistence of alarmin orientation in differentiated cell line environments.

Severe Acute Respiratory Syndrome Coronavirus 2 Nucleocapsid Antigen in Urine of Hospitalized Patients With Coronavirus Disease 2019.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleocapsid antigen (N-Ag) can be detected in the blood of patients with coronavirus disease 2019 (COVID-19). We used a highly sensitive and specific assay to explore the presence of N-Ag in urine during the course of COVID-19 and its relationship with the severity of disease. METHODS: We studied urinary and plasma N-Ag using a highly sensitive immunoassay in 82 patients with SARS-CoV-2 infection proved by polymerase chain reaction. RESULTS: In the first and second weeks of COVID-19, hospitalized patients tested positive for urinary N-Ag (81.25% and 71.79%, respectively) and plasma N-Ag (93.75% and 94.87%, respectively). High urinary N-Ag levels were associated with the absence of SARS-CoV-2 nucleocapsid antibodies, admission in intensive care units, high C-reactive protein levels, lymphopenia, eosinopenia, and high lactate dehydrogenase levels. Higher accuracy was observed for urinary N-Ag as a predictor of severe COVID-19 than for plasma N-Ag. CONCLUSIONS: Our study demonstrates that N-Ag is present in the urine of patients hospitalized in the early phase of COVID-19. As a direct marker of SARS-CoV-2, urinary N-Ag reflects the dissemination of viral compounds in the body. Urinary N-Ag may be a useful marker for disease severity in SARS-CoV-2 infections.

Th17 CD4+ T-Cell as a Preferential Target for HIV Reservoirs.

Among CD4+ T-cells, T helper 17 (Th17) cells play a sentinel role in the defense against bacterial/fungal pathogens at mucosal barriers. However, Th17 cells are also highly susceptible to HIV-1 infection and are rapidly depleted from gut mucosal sites, causing an imbalance of the Th17/Treg ratio and impairing cytokines production. Consequently, damage to the gut mucosal barrier leads to an enhanced microbial translocation and systemic inflammation, a hallmark of HIV-1 disease progression. Th17 cells' expression of mucosal homing receptors (CCR6 and α4ß7), as well as HIV receptors and co-receptors (CD4, α4ß7, CCR5, and CXCR4), contributes to susceptibility to HIV infection. The up-regulation of numerous intracellular factors facilitating HIV production, alongside the downregulation of factors inhibiting HIV, helps to explain the frequency of HIV DNA within Th17 cells. Th17 cells harbor long-lived viral reservoirs in people living with HIV (PLWH) receiving antiretroviral therapy (ART). Moreover, cell longevity and the proliferation of a fraction of Th17 CD4 T cells allow HIV reservoirs to be maintained in ART patients.

Diagnosis value of SARS-CoV-2 antigen/antibody combined testing using rapid diagnostic tests at hospital admission.

The implementation of rapid diagnostic tests (RDTs) may enhance the efficiency of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) testing, as RDTs are widely accessible and easy to use. The aim of this study was to evaluate the performance of a diagnosis strategy based on a combination of antigen and immunoglobulin M (IgM) or immunoglobulin G (IgG) serological RDTs. Plasma and nasopharyngeal samples were collected between 14 March and 11 April 2020 at hospital admission from 45 patients with reverse transcription polymerase chain reaction (RT-PCR) confirmed COVID-19 and 20 negative controls. SARS-CoV-2 antigen (Ag) was assessed in nasopharyngeal swabs using the Coris Respi-Strip. For IgM/IgG detection, SureScreen Diagnostics and Szybio Biotech RDTs were used in addition to laboratory assays (Abbott Alinity i SARS-CoV-2 IgG and Theradiag COVID-19 IgM enzyme-linked immunosorbent assay). Using the Ag RDT, 13 out of 45 (29.0%) specimens tested positive, the sensitivity was 87.0% for cycle threshold (Ct ) values ≤25% and 0% for Ct values greater than 25. IgG detection was associated with high Ct values and the amount of time after the onset of symptoms. The profile of isolated IgM on RDTs was more frequently observed during the first and second week after the onset of symptoms. The combination of Ag and IgM/IgG RDTs enabled the detection of up to 84.0% of COVID-19 confirmed cases at hospital admission. Antigen and antibody-based RDTs showed suboptimal performances when used alone. However when used in combination, they are able to identify most COVID-19 patients admitted in an emergency department.

Monocyte CD169 Expression as a Biomarker in the Early Diagnosis of Coronavirus Disease 2019.

We assessed the expression of CD169, a type I interferon-inducible receptor, on monocytes (monocyte CD169 [mCD169]) in 53 adult patients admitted to the hospital during the coronavirus disease 2019 (COVID-19) outbreak for a suspicion of severe acute respiratory syndrome coronavirus 2 infection. Monocyte CD169 was strongly overexpressed in 30 of 32 (93.7%) confirmed COVID-19 cases, compared with 3 of 21 (14.3%) patients in whom the diagnosis of COVID-19 was finally ruled out. Monocyte CD169 was associated with the plasma interferon-alpha level and thrombocytopenia. Monocyte CD169 testing may be helpful for the rapid triage of suspected COVID-19 patients during an outbreak.

The CD133+ Stem/Progenitor-Like Cell Subset Is Increased in Human Milk and Peripheral Blood of HIV-Positive Women.

Human milk is a significant source of different CD133+ and/or CD34+ stem/progenitor-like cell subsets in healthy women but their cell distribution and percentages in this compartment of HIV-positive women have not been explored. To date, a decrease of CD34+ hematopoietic stem and progenitor cell frequencies in peripheral blood and bone marrow of HIV-positive patients has been reported. Herein, human milk and peripheral blood samples were collected between day 2-15 post-partum from HIV-positive and HIV-negative women, and cells were stained with stem cell markers and analyzed by flow cytometry. We report that the median percentage of CD45+/highCD34-CD133+ cell subset from milk and blood was significantly higher in HIV-positive than in HIV-negative women. The percentage of CD45dimCD34-CD133+ cell subset from blood was significantly higher in HIV-positive than HIV-negative women. Moreover, percentages of CD45dimCD34+, CD45dimCD34+CD133-, and CD45+highCD34+CD133- cell subsets from blood were significantly lower in HIV-positive than HIV-negative women. The CD133+ stem/progenitor-like cell subsets are increased in early human milk and blood of HIV-positive women and are differentially distributed to CD34+ cell subset frequencies which are decreased in blood.

Large Stem/Progenitor-Like Cell Subsets can Also be Identified in the CD45- and CD45+/High Populations in Early Human Milk.

BACKGROUND: Stem/progenitor cells have been identified in human milk. However, characterization and percentages of cell subsets in human milk using hematopoietic stem and progenitor cell markers according to the differential expression of CD45, i.e., as CD45dim/+ (mainly hematopoietic stem/progenitor cells) and CD45- (mainly non-hematopoietic stem/progenitor cells), have not been assessed to date. RESEARCH AIM: To characterize stem/progenitor-like cell phenotypes in human milk and to report the percentages of these cells at two different lactation stages compared to peripheral blood. METHODS: Human milk samples paired with peripheral blood samples (N = 10) were analyzed by flow cytometry using CD45, CD34, CD133, CD38, and lineage-negative markers. The percentage of cell subsets was analyzed in colostrum (Day 3 postpartum) and transitional milk (Day 5/6 postpartum) and compared with the peripheral blood counterpart. RESULTS: The percentage of CD45-CD34+ cells was predominant in both colostrum and transitional milk. The percentage of CD45+/highCD133+ cells was high in colostrum while the percentage of CD45-CD133+ cells was high in transitional milk. Furthermore, the median percentages of the CD45-CD34+, CD45-CD133+, and CD45dimCD133+ cell subsets were higher in colostrum than its peripheral blood counterpart (0.11% vs. 0.002%; 0.17% vs. 0.0005%; 0.09% vs. 0.05%, p = .04, respectively); also CD45-CD34-CD133+ and CD45dimCD34-CD133+ cell subsets were higher in colostrum than peripheral blood (1.32% vs. 0.0% and 2.4% vs. 0.06%, p = .04), respectively). CONCLUSION: Early human milk is an abundant reservoir of hematopoietic stem/progenitor-like cells in the CD45+/high population and non-hematopoietic stem/progenitor-like cells in the CD45- population.

Discrepancy of Serological and Molecular Patterns of Circulating Epstein-Barr Virus Reactivation in Primary Sjögren's Syndrome.

Primary Sjögren's syndrome (pSS) is characterized by B cell hyperactivation, production of autoantibodies and increased risk of B cell lymphomas. Serological profile of Epstein-Barr virus (EBV) reactivation and increase EBV DNA levels in exocrine glands are observed in pSS, but whether these abnormalities are accompanied with disturbed systemic EBV control or have any association with pSS activity remains to be investigated. In this observational study, we initially explored anti-EBV antibodies and cell-free DNA in 395 samples from a cross-sectional plasma collection of pSS patients included in ASSESS French national cohort. Results were assessed in relation with disease activity. Further, to assess cell-associated EBV DNA we organized a case-control study including 20 blood samples from pSS patients followed in University Hospital Center of Montpellier. Results were compared with matched controls. Robust response against EBV early antigen (EA) was observed in pSS patients with anti-SSA/B (Sjögren's syndrome A and B) and anti-SSA autoantibodies compared to anti-SSA/B negatives (P < 0.01 and P = 0.01, respectively). Increased beta-2 microglobulin, kappa and lambda light chains, and immunoglobulin G levels were more frequently observed in anti-EA seropositive pSS subjects compared to anti-EA negative subjects (P < 0.001; P = 0.001; P = 0.003, respectively). Beta-2 microglobulin was independently associated with anti-EA positivity in multivariate analysis (P < 0.001). Plasma cell-free EBV DNA and EBV cellular reservoir was not different between pSS patients and controls. We conclude that serological evidence of EBV reactivation was more frequently observed and more strongly associated with anti-SSA/B status and B cell activation markers in pSS. However, serological profile of EBV reactivation was not accompanied by molecular evidence of systemic EBV reactivation. Our data indicated that EBV infection remains efficiently controlled in the blood of pSS patients.

MAIT cells, TCR γδ+ cells and ILCs cells in human breast milk and blood from HIV infected and uninfected women.

BACKGROUND: Human breast milk cells remain poorly characterized for the presence of unconventional T lymphocytes and innate lymphoid cells (ILCs). METHODS: Early breast milk was collected from eight HIV-uninfected and 11 HIV-infected women 3-12 days after delivery. Mucosal-associated invariant T cells (MAIT cells), TCR γδ cells, and innate lymphoid cells (ILCs) were analyzed in breast milk and paired blood samples. RESULTS: CD161+/TRAV1-2 + MAIT cells were detected in breast milk, accounting for a median (IQR) of 0.08% (0.06-0.16) and 0.17% (0.16-0.31) of CD45+ breast milk cells in HIV-uninfected and HIV-infected women, respectively. A selective compartmentalization of γδ T lymphocytes was observed in breast milk. Median (IQR) frequency of γδ T lymphocytes was 8.95% (8.64-12.14) among breast milk lymphocyte cells compared to 2.54% (1.81-4.10) in blood (P = 0.03) in HIV-uninfected women, and 7.26% (4.22-10.54) in breast milk versus 3.31% (2.54-3.80) in blood (P = 0.004) from HIV-infected women. The proportion of group 1 ILC (ILC1) among total ILCs was higher in breast milk compared to blood in HIV-uninfected women (P = 0.03) and HIV-infected women (P = 0.001). The frequency of ILC2 among total ILCs tends to be lower in breast milk compared to blood in HIV-uninfected women (P = 0.06) and HIV-infected women (P = 0.03). CONCLUSION: Unconventional T cells and ILCs that may be involved in both the protection against infection of the lactating mammary gland and maturation of infant's gut and microbiomes account for a detectable fraction of breast milk cells.

Breastmilk cell trafficking induces microchimerism-mediated immune system maturation in the infant.

Initiating breastfeeding within the first hour of life confers an important benefit in terms of child mortality and severe morbidity. Intestinal permeability to ingested macromolecules and immunoglobulins is limited to the first days of human life. These exchanges cease in the very early post-partum period but may increase beyond the neonatal period in response to local inflammation or introduction of a weaning food. From animal- and limited human-based observations, compelling evidence points out to breastmilk cells also trafficking from mother to infant mucosal tissues and participating to the maternal microchimerism. The precise nature of breastmilk cells that are involved is presently not known but likely includes progenitor/stem cells-representing up to 6% of breastmilk cells-with possible contribution of mature immune cells. Stem cell microchimerism may induce tolerance to non-inherited maternal antigens (NIMAs), breastfeeding generating regulatory T cells (Treg ) that suppress antimaternal immunity. Therefore, in complement to pregnancy-induced microchimerism, breastfeeding-induced microchimerism may be pivotal in infant immune development, intestinal tissue repair/growth and protection against infectious diseases. As a continuum of the gestational period, the neonatal gut may be considered as a temporary, but important developmental extension of the role played by the placenta during intrauterine life; breastmilk playing the role of maternal blood by delivering maternal soluble factors (macromolecules, Ig, cytokines) and immunologically active milk cells. A better understanding of breastfeeding-induced maternal microchimerism would provide further evidence in support of public health messages that reinforce the importance of early initiation of breastfeeding.

Peripheral blood 8 colour flow cytometry monitoring of hairy cell leukaemia allows detection of high-risk patients.

Although purine analogues have significantly improved the outcome of hairy cell leukaemia (HCL) patients, 30-40% relapse, illustrating the need for minimal residual disease (MRD) markers that can aid personalized therapeutic management. Diagnostic samples from 34 HCL patients were used to design an 8-colour flow cytometry (8-FC) tube for blood MRD (B/RD) analysis (188 samples) which was compared to quantitative IGH polymerase chain reaction (Q-PCR) on 83 samples and to qualitative consensus IGH PCR clonality analysis on 165 samples. Despite heterogeneous HCL phenotypes at diagnosis, discrimination from normal B lymphocytes was possible in all cases using a single 8-FC tube, with a robust sensitivity of detection of 10(-4) , comparable to Q-PCR at this level, but preferable in terms of informativeness, simplicity and cost. B/RD assessment of 15 patients achieving haematological complete remission after purine analogues was predictive of a clinically significant relapse risk: with a median follow-up of 95 months; only one of the nine patients with reproducible 8-FC B/RD levels below 10(-4) (B/RD(neg) ) relapsed, compared to 5/6 in the B/RD(pos) group (P = 0.003). These data demonstrate the clinical interest of a robust 8-FC HCL B/RD strategy that could become a surrogate biomarker for therapeutic stratification and new drug assessment, which should be evaluated prospectively.

Effect of a hemiuroid trematode on the hemocyte immune parameters of the cockle Anadara trapezia.

When a trematode parasite penetrates a potential molluscan host, it has to circumvent the host's internal defense system. In molluscs, the primary effector cells of this system are the hemocytes which orchestrate many of the cellular and humoral immune functions. Survival of the parasite can occur only in the absence of a successful immune response, and continued development only if the host is physiologically suitable. This study investigated hemocytic response against asexual stages of a hemiuroid trematode by its host, the marine bivalve Anadara trapezia. Hemocyte characteristic (type, morphology) and function (mortality, phagocytosis and oxidative activity) were analyzed by flow cytometry in parasitized and non-parasitized cockles. A. trapezia possesses two types of hemocytes: amebocytes and erythrocytes. Analysis of histological section showed that there was no host hemocytic response around hemiuroid sporocysts. The infection induced a significant increase of the total circulating hemocytes with a higher proportion of erythrocytes relative to amebocytes, coupled with a lower phagocytosis rate and a statistically non-significant decrease of the intracellular oxidative activity. No significant differences were observed in hemocyte size and complexity, mortality, or phagocytic capacity. Our results indicate that in A. trapezia, hemiuroids modulate the immune response by increasing the number of circulating hemocytes and decreasing phagocytosis.

A novel fluorescent reporter CDy1 enriches for neural stem cells derived from the murine brain.

Neurogenesis occurs continuously in two brain regions of adult mammals, underpinned by a pool of resident neural stem cells (NSCs) that can differentiate into all neural cell types. To advance our understanding of NSC function and to develop therapeutic and diagnostic approaches, it is important to accurately identify and enrich for NSCs. There are no definitive markers for the identification and enrichment of NSCs present in the mouse brain. Recently, a fluorescent rosamine dye, CDy1, has been identified as a label for pluripotency in cultured human embryonic and induced pluripotent stem cells. As similar cellular characteristics may enable the uptake and retention of CDy1 by other stem cell populations, we hypothesized that this dye may also enrich for primary NSCs from the mouse brain. Because the subventricular zone (SVZ) and the hippocampus represent brain regions that are highly enriched for NSCs in adult mammals, we sampled cells from these areas to test this hypothesis. These experiments revealed that CDy1 staining indeed allows for enrichment and selection of all neurosphere-forming cells from both the SVZ and the hippocampus. We next examined the effectiveness of CDy1 to select for NSCs derived from the SVZ of aged animals, where the total pool of NSCs present is significantly lower than in young animals. We found that CDy1 effectively labels the NSCs in adult and aged animals as assessed by the neurosphere assay and reflects the numbers of NSCs present in aged animals. CDy1, therefore, appears to be a novel marker for enrichment of NSCs in primary brain tissue preparations.

Multicentric Castleman disease is associated with polyfunctional effector memory HHV-8-specific CD8+ T cells.

Multicentric Castleman disease (MCD) is a devastating human herpesvirus 8 (HHV-8)-related lymphoproliferative disorder that occurs in immunocompromised persons. To determine the role of immune responses in MCD, we studied the frequency, antigenic repertoire, differentiation, and functional profile of HHV-8-specific CD8(+) T cells in MCD patients and in human immunodeficiency virus-coinfected asymptomatic HHV-8 carriers (AC). Screening CD8(+) T-cell responses with ELISpot interferon-gamma (IFN-gamma) assays using 56 peptides on 6 latent and lytic HHV-8 proteins showed that MCD and AC patients had responses of similar magnitude and antigenic repertoire and identified a new 10-mer human leukocyte antigen B7 CD8 epitope in K15. Intracellular IFN-gamma staining showed significantly more CD45RA(-)CCR7(-)CD27(-) CD8(+)IFN-gamma(+) cells (late phenotype) and significantly fewer CCR7(-)CD27(+)CD45RA(-) cells (early and intermediate phenotype) in MCD than in AC patients. This phenotypic shift was not found for Epstein-Barr virus-specific CD8(+) T cells tested as controls. HHV-8 viral loads were negatively correlated with early and intermediate effector memory cells. HHV-8-specific T cells were polyfunctional (secretion of IFN-gamma, tumor necrosis factor-alpha, macrophage inflammatory protein-1beta, and/or CD107a) in both MCD and AC patients. In conclusion, MCD is not associated with a lack of HHV-8-specific CD8(+) T cells or limitation of their functional profile. Their differentiation increases with HHV-8 viral load. These results offer new insight into the pathophysiology of MCD.

Low T cell responses to human herpesvirus 8 in patients with AIDS-related and classic Kaposi sarcoma.

BACKGROUND: Kaposi sarcoma (KS) occurs mainly in immunocompromised patients and is strongly associated with infection with human herpesvirus 8 (HHV-8; also known as "KS-associated herpesvirus"). We hypothesized that KS is linked to deficiencies in specific anti-HHV-8 T cell immunity. METHODS: We studied asymptomatic HHV-8 carriers coinfected with human immunodeficiency virus (HIV; n = 23) and patients with HIV-related or classic KS (n = 29). We used an interferon- gamma enzyme-linked immunospot assay with 56 specific peptides distributed on 6 HHV-8 proteins (glycoprotein [gp] B, gpH, gp35/37, latent nuclear antigen 1 [LANA-1], K12, and K15) to detect HHV-8-specific T cell responses. RESULTS: We found that patients with KS responded to these peptides less often and had much lower HHV-8-specific T cells counts than did asymptomatic HHV-8 carriers (P = .001 and P = .0004, respectively), regardless of CD4 T cell count or HHV-8 load. The frequency of Epstein-Barr virus-specific T cells was similar in both groups. CONCLUSIONS: Our results suggest that HIV-related and classic KS are associated with a lack of HHV-8-specific T cells. Also, we have described 8 new HHV-8 T cell epitopes in LANA-1, K12, and K15, including 2 CD4 T cell epitopes. These data provide new insight into HHV-8 cellular immunity.