Immune cell subsets at birth may help to predict risk of late-onset sepsis and necrotizing enterocolitis in preterm infants

Detection of an intestinal cell DNA methylation signature in blood samples from neonates with necrotizing enterocolitis

BACKGROUND

Necrotizing enterocolitis (NEC) is an often fatal intestinal injury that primarily affects preterm infants for which screening tools are lacking. We performed a pilot analysis of DNA methylation in peripheral blood samples from preterm infants with and without NEC to identify potential NEC biomarkers.

METHODS

Peripheral blood samples were collected from infants at NEC diagnosis (n = 15) or from preterm controls (n = 13). Targeted genome-wide analysis was performed to identify DNA methylation differences between cases and controls.

RESULTS

Broad differences between NEC cases and controls were identified in distinct genomic elements. Differences between surgical NEC cases and controls were frequently associated with inflammation. Deconvolution analysis to identify cell type-specific DNA signatures revealed increases in ileal, vascular endothelial, and cardiomyocyte cell type proportions and decreases in colonic and neuronal cell type proportions in blood from NEC cases relative to controls.

CONCLUSIONS

We identified marked differences in DNA methylation of peripheral blood samples from preterm infants with and without NEC. Increased ileal cell-specific methylation signatures in the blood of infants with NEC relative to controls, with a marked increase seen in surgical cases, provides rationale for further analysis of intestinal DNA methylation signatures as biomarkers of NEC.

Addition of CD14 improves discrimination of lymphocytes in the TBNK phenotyping panel

Peripheral blood lymphocyte phenotyping panels typically include CD45 for discrimination of the lymphocyte population, and fluorophore-conjugated monoclonal antibodies to identify T, B, and Natural Killer (NK) cells. While CD45 combined with side scatter is generally sufficient to clearly distinguish lymphocytes from monocytes in the majority of peripheral blood samples, it is challenging to accurately gate lymphocytes in samples from patients with monocytosis or significant lymphopenia, or from very young infants. Addition of a monocyte marker to lymphocyte phenotyping panels for monocyte exclusion has previously been evaluated for improved discrimination of lymphocytes, albeit largely in healthy donor adult samples. Here we evaluate the effect of the addition of CD14 to a standard lymphocyte phenotyping panel on total lymphocyte, T, B, and NK cell percentages in a predominantly pediatric population of patients under evaluation chiefly for immunodeficiency, immune-depletion, or immune reconstitution. Addition of CD14 to the standard lymphocyte phenotyping improved discrimination of lymphocytes from monocytes, resulted in decreased NK cell percentages, likely because CD16+ and/or CD56+ monocytes were included in the CD56+CD16+ NK cell gate with conventional gating, and although less significant, resulted in an increased percentage of B cells, since relatively larger B cells were likely gated out by more restrictive light scatter gating used with the conventional gating approach. The change in NK and B cell percentages were more pronounced in samples from patients below a year of age, and in patients who were relatively lymphopenic. These data suggest that addition of CD14 to conventional lymphocyte phenotyping panels that utilize CD45 versus side scatter gating results in significant improvement in the accuracy of lymphocyte gating, and accurate quantification of NK and B cells particularly in samples from infants and lymphopenic individuals.

Increased Expression of Anaphylatoxin C5a-Receptor-1 in Neutrophils and Natural Killer Cells of Preterm Infants

Preterm infants are susceptible to infection and their defense against pathogens relies largely on innate immunity. The role of the complement system for the immunological vulnerability of preterm infants is less understood. Anaphylatoxin C5a and its receptors C5aR1 and -2 are known to be involved in sepsis pathogenesis, with C5aR1 mainly exerting pro-inflammatory effects. Our explorative study aimed to determine age-dependent changes in the expression of C5aR1 and C5aR2 in neonatal immune cell subsets. Via flow cytometry, we analyzed the expression pattern of C5a receptors on immune cells isolated from peripheral blood of preterm infants (n = 32) compared to those of their mothers (n = 25). Term infants and healthy adults served as controls. Preterm infants had a higher intracellular expression of C5aR1 on neutrophils than control individuals. We also found a higher expression of C5aR1 on NK cells, particularly on the cytotoxic CD56^dim subset and the CD56^- subset. Immune phenotyping of other leukocyte subpopulations revealed no gestational-age-related differences for the expression of and C5aR2. Elevated expression of C5aR1 on neutrophils and NK cells in preterm infants may contribute to the phenomenon of "immunoparalysis" caused by complement activation or to sustained hyper-inflammatory states. Further functional analyses are needed to elucidate the underlying mechanisms.

Probiotics to improve the gut microbiome in premature infants: are we there yet?

Gut microbiome maturation in infants born prematurely is uniquely influenced by the physiological, clinical, and environmental factors surrounding preterm birth and early life, leading to altered patterns of microbial succession relative to term infants during the first months of life. These differences in microbiome composition are implicated in acute clinical conditions that disproportionately affect preterm infants, including necrotizing enterocolitis (NEC) and late-onset sepsis (LOS). Probiotic supplementation initiated early in life is an effective prophylactic measure for preventing NEC, LOS, and other clinical concerns relevant to preterm infants. In parallel, reported benefits of probiotics on the preterm gut microbiome, metabolome, and immune function are beginning to emerge. This review summarizes the current literature on the influence of probiotics on the gut microbiome of preterm infants, outlines potential mechanisms by which these effects are exerted, and highlights important clinical considerations for determining the best practices for probiotic use in premature infants.

Immunoglobulin Profile and Lymphocyte Subsets in Preterm Neonates

Objective

Methods

Results

Conclusion

Electronic Supplementary Material

Dysregulated Mucosal Immunity and Associated Pathogeneses in Preterm Neonates

Many functions of the immune system are impaired in neonates, allowing vulnerability to serious bacterial, viral and fungal infections which would otherwise not be pathogenic to mature individuals. This vulnerability is exacerbated in compromised newborns such as premature neonates and those who have undergone surgery or who require care in an intensive care unit. Higher susceptibility of preterm neonates to infections is associated with delayed immune system maturation, with deficiencies present in both the innate and adaptive immune components. Here, we review recent insights into early life immunity, and highlight features associated with compromised newborns, given the challenges of studying neonatal immunity in compromised neonates due to the transient nature of this period of life, and logistical and ethical obstacles posed by undertaking studies newborns and infants. Finally, we highlight how the unique immunological characteristics of the premature host play key roles in the pathogenesis of diseases that are unique to this population, including necrotizing enterocolitis and the associated sequalae of lung and brain injury.

Multiparameter flow cytometry analysis of leukocyte markers for diagnosis in preterm neonatal sepsis

PURPOSE

Neonatal sepsis is an important public health concern worldwide due to its immediate lethality and long-term morbidity rates, Clinical evaluation and laboratory analyses are indispensable for diagnosis of neonatal sepsis. However, assessing multiple biomarkers in neonates is difficult due to limited blood availability. The aim is to investigate if the neonatal sepsis in preterm could be identified by multiparameter analysis with flow cytometry.

MATERIALS AND METHODS

The expression of activation-related molecules was evaluated by flow cytometry in newborn with or without risk factors for sepsis.

RESULTS

Our analysis revealed that several markers could be useful for sepsis diagnosis, such as CD45RA, CD45RO, or CD71 on T cells; HLA-DR on NKT or classic monocytes, and TREM-1 on non-classic monocytes or neutrophils. However, ROC analysis shows that the expression of CD45RO on T lymphocytes is the only useful biomarker for diagnosis of neonatal late-onset sepsis. Also, decision tree analyses showed that CD45RO plus CD27 could help differentiate the preterm septic neonates from those with risk factors.

CONCLUSIONS

Our study shows a complementary and practical strategy for biomarker assessment in neonatal sepsis.

CD56- CD16+ NK cells from HIV-infected individuals negatively regulate IFN-γ production by autologous CD8+ T cells

The percentage of human CD56^- CD16⁺ NK cells increases during chronic infection with human HIV; however, the biologic role of CD56^- CD16⁺ NK cells in HIV infection is unclear. Our results demonstrate that the percentage of CD56^- CD16⁺ NK cells producing IL-10 and TGF-β was higher than CD56^dim CD16⁺ NK cells. CD56^- CD16⁺ NK cells could inhibit IFN-γ production by autologous CD8⁺ T cells, and this inhibition could be partially reversed by anti-IL-10, anti-TGF-β, or anti-PD-L1 mAbs. CD56^- CD16⁺ NK cells are potential targets for the development of novel immune therapies against HIV infection.

The effects of umblical cord clamping time on lymphocyte subgroups in term and late preterm infants

Aim

To evaluate the effect of umblical cord clamping time on lymphocyte subgroups in term and late preterm infants.

Material and Methods

Seventy-four infants between 34 and 41 weeks of gestation were included in the study. Of these, 37 were umbilical cord clamped immediately after birth and the remaining 37 were clamped after waiting one minute. Babies were divided into two groups as term and preterm. The prenatal, natal, postnatal characteristics of the infants were recorded. Hematologic and lymphocyte subgroups were investigated in cord blood and venous blood at day 7. Lymphocyte subgroups were evaluated using flow cytometry.

Results

With the delay of cord clamping, the leucocytes count and the percentage of CD3+T lymphocytes in cord blood of preterm infants decreased and this decrease continued at day 7. On the contrary, CD19+B lymphocyte levels in the cord blood of preterm infants increased, and this increase continued at day 7. Also, the percentage of CD4+T lymphocytes of preterm infants decreased with the delay of cord clamping at day 7. There was no difference between groups for the rate of sepsis development.

Conclusion

With the delay of cord clamping, the leucocytes count, the percentage of CD3+T, and CD4+T lymphocytes decreased, and the percentage of CD19+B lymphocytes increased in preterm infants. The delay in cord clamping time in term and preterm infants seems to have no impact on the rate of sepsis development. Larger series of studies are needed to assess the effect of these findings on the development of infection in late preterm infants who have delayed cord clamping.

Pathophysiology of Necrotizing Enterocolitis: An Update

NEC is a devastating disease that, once present, is very difficult to treat. In the absence of an etiologic treatment, preventive measures are required. Advances in decoding the pathophysiology of NEC are being made but a more comprehensive understanding is needed for the targeting of preventative strategies. A better definition of the disease as well as diagnostic criteria are needed to be able to specifically label a disease as NEC. Multiple environmental factors combined with host susceptibility appear to contribute to enhanced risks for developing this disease. Several different proximal pathways are involved, all leading to a common undesired outcome: Intestinal necrosis. The most common form of this disease appears to involve inflammatory pathways that are closely meshed with the intestinal microbiota, where a dysbiosis may result in dysregulated inflammation. The organisms present in the intestinal tract prior to the onset of NEC along with their diversity and functional capabilities are just beginning to be understood. Fulfillment of postulates that support causality for particular microorganisms is needed if bacteriotherapies are to be intelligently applied for the prevention of NEC. Identification of molecular effector pathways that propagate inflammation, understanding of, even incipient role of genetic predisposition and of miRNAs may help solve the puzzle of this disease and may bring the researchers closer to finding a treatment. Despite recent progress, multiple limitations of the current animal models, difficulties related to studies in humans, along with the lack of a "clear" definition will continue to make it a very challenging disease to decipher.

Elevated CD3low double negative T lymphocyte is associated with pneumonia and its severity in pediatric patients

Background

Previous studies have shown that the adaptive immunity function of T cells in disease states correlates with CD3 surface expression closely. During routine assessment of TBNK subsets in peripheral blood of pediatric patients by flow cytometry, we noticed that variable expression levels of CD3 on CD3⁺CD4⁻CD8⁻ double-negative T (DNT) lymphocytes in different patients. The objective of this study was to assess the relationship of CD3 expression levels on DNT cells with disease severity.

Methods

In this prospective study, we investigated the frequencies of circulating CD4⁻CD8⁻ DNT cell subsets with CD3^low or CD3^high phenotype by flow cytometry in 76 pediatric patients with pneumonia, 55 patients with severe pneumonia (SP), and 29 healthy controls (Con).

Results

The numbers of circulating DNT cells were similar in all groups; however, the frequency of CD3^low DNT cell subsets was significantly increased in patients with pneumonia (p < 0.001) and SP (p < 0.001). The elevated CD3^low DNT cell frequency showed a positive correlation with the clinical severity of pneumonia. On sub-group analysis, the frequency of CD3^low DNT cells was only elevated in children with pneumonia aged <5 years, while no association was observed with the causative pathogen of pneumonia.

Conclusions

These findings suggest that CD3 expression levels on DNT cell subsets of peripheral lymphocytes may be a valuable biomarker for evaluation of immune response in pediatric infectious disease. CD3^low DNT cells were elevated in children with pneumonia aged <5 years, which indicates that it may be an important research target in pediatric infectious diseases.

Immunogenicity of amino acids 1-150 of Streptococcus GapC displayed on the surface of Escherichia coli

Streptococcus is one of the main pathogens that cause bovine mastitis. They includes into S.agalactiae, S.dysgalactiae, and S.uberis. The GapC protein is a virulence factor that is expressed on the surface of Streptococcus species. GapC is highly antigenic and immunization with GapC confers cross-protection against all three species. Our previous data showed that amino acids 1-150 of GapC (GapC_1-150) of S. dysgalactiae conferred similar immunoprotection compared to full-length GapC. Thus, the present study aimed to construct a recombinant Escherichia coli XL1-Blue strain that displayed GapC_1-150 on its surface, and to investigate the immunogenicity of the surface-localized GapC_1-150. To do so, the ompA gene of the E. coli XL1-Blue strain was replaced with the lpp'-ompA-gapC1_1-150 or lpp'-ompA genes by λ Red recombination, the former of which fused GapC_1-150 to an Lpp lipoprotein signal peptide and amino acids 1-159 of OmpA; the recombinant strains were named XL1-Blue/LOG76 and XL1-Blue/LO11, respectively. GapC_1-150 was confirmed to localize to the surface of the XL1-Blue/LOG76 strain by an indirect enzyme-linked immunosorbent assay (ELISA), a fluorescence-activated cell sorter analysis, and laser-scanning confocal microscopy. Then, ICR mice were immunized intramuscularly with the XL1-Blue/LOG76 or XL1-Blue/LO11 strains, or recombinant GapC_1-150. The sera of the immunized mice were collected and the anti-GapC_1-150 antibody levels were detected by ELISA. Lymphocytes secreting interleukin (IL)-4 and interferon-γ were detected by an enzyme-linked ImmunoSpot assay, as was the level of IL-17A level in the supernatant of cultured splenic lymphocytes. The mice immunized with the XL1-Blue/LOG76 strain or GapC_1-150 exhibited better cellular and humoral immunity. Lastly, the immunized mice were challenged with S. uberis, S. dysgalactiae, and S. agalactiae strains, and mice that were immunized with the XL1-Blue/LOG76 strain were better protected than those that were immunized with the XL1-Blue/LO11 strain. These results indicate that it is feasible to display GapC_1-150 on the E. coli surface as a vaccine against Streptococcus species.

Pathogenesis of NEC: Role of the innate and adaptive immune response

Necrotizing enterocolitis (NEC) is a devastating disease in premature infants with high case fatality and significant morbidity among survivors. Immaturity of intestinal host defenses predisposes the premature infant gut to injury. An abnormal bacterial colonization pattern with a deficiency of commensal bacteria may lead to a further breakdown of these host defense mechanisms, predisposing the infant to NEC. Here, we review the role of the innate and adaptive immune system in the pathophysiology of NEC.

Cytotoxic potential of IL-15-activated cytokine-induced killer cells against human neuroblastoma cells

BACKGROUND

Neuroblastoma (NB) is the most common solid extracranial tumor in childhood. Despite advances in therapy, the prognosis is poor and optimized therapies are urgently needed. Therefore, we investigated the antitumor potential of interleukin-15 (IL-15)-activated cytokine-induced killer (CIK) cells against different NB cell lines.

PROCEDURE

CIK cells were generated from peripheral blood mononuclear cells by the stimulation with interferon-γ (IFN-γ), IL-2, OKT-3 and IL-15 over a period of 10-12 days. The cytotoxic activity against NB cells was analyzed by nonradioactive Europium release assay before and after blocking of different receptor-ligand interactions relevant in CIK cell-mediated cytotoxicity.

RESULTS

The final CIK cell products consisted in median of 83% (range: 75.9-91.9%) CD3⁺ CD56^- T cells, 14% (range: 5.2-20.7%) CD3⁺ CD56⁺ NK-like T cells and 2% (range: 0.9-4.8%) CD3^- CD56⁺ NK cells. CIK cells expanded significantly upon ex vivo stimulation with median rates of 22.3-fold for T cells, 58.3-fold for NK-like T cells and 2.5-fold for NK cells. Interestingly, CD25 surface expression increased from less than equal to 1% up to median 79.7%. Cytotoxic activity of CIK cells against NB cells was in median 34.7, 25.9 and 34.8% against the cell lines UKF-NB-3, UKF-NB-4 and SK-N-SH, respectively. In comparison with IL-2-stimulated NK cells, CIK cells showed a significantly higher cytotoxicity. Antibody-mediated blocking of the receptors NKG2D, TRAIL, FasL, DNAM-1, NKp30 and lymphocyte function-associated antigen-1 (LFA-1) significantly reduced lytic activity, indicating that diverse cytotoxic mechanisms might be involved in CIK cell-mediated NB killing.

CONCLUSIONS

Unlike the mechanism reported in other malignancies, NKG2D-mediated cytotoxicity does not constitute the major killing mechanism of CIK cells against NB.

Inflammatory Response in Preterm and Very Preterm Newborns with Sepsis

The response of the adaptive immune system is usually less intense in premature neonates than term neonates. The primary objective of this study was to determine whether immunological parameters vary between preterm (PT) neonates (≥32 weeks of gestational age) and very preterm (VPT) neonates (<32 weeks of gestational age). A cross-sectional study was designed to prospectively follow PT and VPT neonates at risk of developing sepsis. Plasma concentrations of IFN-γ, TNF-α, IL-6, IL-4, and IL-10 were detected using flow cytometry. C-reactive protein (C-RP) and the complex SC5b-9 were detected in the plasma using commercial kits. A total of 83 patients were included. The laboratory results and clinical histories showed that 26 patients had sepsis; 14 were VPT, and 12 were PT. The levels of C-RP, SC5b-9 (innate immune response mediators), and IL-10 or IL-4 (anti-inflammatory cytokines) were elevated during sepsis in both groups. IFN-γ, TNF-α, and IL-6 (proinflammatory cytokines) were differentially elevated only in PT neonates. The VPT neonates with sepsis presented increases in C-RP, SC5b-9, and anti-inflammatory cytokines but not in proinflammatory cytokines, whereas PT neonates showed increases in all studied mediators of inflammation.