Cord Blood T Cells Expressing High and Low PKCζ Levels Develop into Cells with a Propensity to Display Th1 and Th9 Cytokine Profiles, Respectively

Protein Kinase C Isozyme Immaturity/Deficiency in Cord Blood Monocytes and Neutrophils

Reduced/deficient expression of Protein Kinase C (PKC)ζ in Cord blood (CB) T cells is associated with allergy development in children and a propensity to maintain an immature T-helper (Th)2 cytokine profile. In addition, other PKC isozymes are also low in CBTCs. Since previous studies have reported that cord blood/neonatal monocyte and neutrophil functions are significantly lower than cells from adults, it was of interest to see if the CBTC PKC levels were reflected in CB monocytes and neutrophils. Compared to adult blood, CB expresses low levels of PKCα, β2, ε, θ, μ, ζ and λ/ι in monocytes and PKCα, β2, η, θ, μ, ζ and λ/ι in neutrophils. The T-cell PKCζ levels were positively correlated with levels in CB monocytes but not in neutrophils. However, neither the monocytes nor the neutrophil PKCζ were associated with T-cell development towards a Th1 or Th2 cytokine propensity, based on the production of interferon-gamma and interleukin-4 in response to phytohemagglutinin and phorbol myristate acetate. The results demonstrate that some newborn babies display a deficiency in PKC isozymes in monocytes and neutrophils, as reported for T cells. However, unlike T cells, the PKCζ levels of the phagocytes did not correlate with regulation of development towards a Th1 or Th2 cytokine phenotype.

PKCζ activation promotes maturation of cord blood T cells towards a Th1 IFN-γ propensity

A significant number of babies present transiently with low protein kinase C zeta (PKCζ) levels in cord blood T cells (CBTC), associated with reduced ability to transition from a neonatal Th2 to a mature Th1 cytokine bias, leading to a higher risk of developing allergic sensitisation, compared to neonates whose T cells have 'normal' PKCζ levels. However, the importance of PKCζ signalling in regulating their differentiation from a Th2 to a Th1 cytokine phenotype propensity remains undefined. To define the role of PKCζ signalling in the regulation of CBTC differentiation from a Th2 to a Th1cytokine phenotype we have developed a neonatal T cell maturation model which enables the cells to develop to CD45RA- /CD45RO+ T cells while maintaining the Th2 immature cytokine bias, despite having normal levels of PKCζ. The immature cells were treated with phytohaemagglutinin, but in addition with phorbol 12-myristate 13-acetate (PMA), an agonist which does not activate PKCζ. This was compared to development in CBTC in which the cells were transfected to express constitutively active PKCζ. The lack of PKCζ activation by PMA was monitored by western blot for phospho-PKCζ and translocation from cell cytosol to the membrane by confocal microscopy. The findings demonstrate that PMA fails to activate PKCζ in CBTC. The data show that CBTC matured under the influence of the PKC stimulator, PMA, maintain a Th2 cytokine bias, characterised by robust IL-4 and minimal interferon gamma production (IFN-γ), and lack of expression of transcriptional factor, T-bet. This was also reflected in the production of a range of other Th2/Th1 cytokines. Interestingly, introduction of a constitutively active PKCζ mutant into CBTC promoted development towards a Th1 profile with high IFN-γ production. The findings demonstrate that PKCζ signalling is essential for the immature neonatal T cells to transition from a Th2 to a Th1 cytokine production bias.

Black Ginseng Extract Exerts Potentially Anti-Asthmatic Activity by Inhibiting the Protein Kinase Cθ-Mediated IL-4/STAT6 Signaling Pathway

Asthma is a chronic inflammatory lung disease that causes respiratory difficulties. Black ginseng extract (BGE) has preventative effects on respiratory inflammatory diseases such as asthma. However, the pharmacological mechanisms behind the anti-asthmatic activity of BGE remain unknown. To investigate the anti-asthmatic mechanism of BGE, phorbol 12-myristate 13-acetate plus ionomycin (PMA/Iono)-stimulated mouse EL4 cells and ovalbumin (OVA)-induced mice with allergic airway inflammation were used. Immune cells (eosinophils/macrophages), interleukin (IL)-4, -5, -13, and serum immunoglobulin E (IgE) levels were measured using an enzyme-linked immunosorbent assay. Inflammatory cell recruitment and mucus secretion in the lung tissue were estimated. Protein expression was analyzed via Western blotting, including that of inducible nitric oxide synthase (iNOS) and the activation of protein kinase C theta (PKCθ) and its downstream signaling molecules. BGE decreased T helper (Th)2 cytokines, serum IgE, mucus secretion, and iNOS expression in mice with allergic airway inflammation, thereby providing a protective effect. Moreover, BGE and its major ginsenosides inhibited the production of Th2 cytokines in PMA/Iono-stimulated EL4 cells. In EL4 cells, these outcomes were accompanied by the inactivation of PKCθ and its downstream transcription factors, such as nuclear factor of activated T cells (NFAT), nuclear factor kappa B (NF-κB), activator of transcription 6 (STAT6), and GATA binding protein 3 (GATA3), which are involved in allergic airway inflammation. BGE also inhibited the activation of PKCθ and the abovementioned transcriptional factors in the lung tissue of mice with allergic airway inflammation. These results highlight the potential of BGE as a useful therapeutic and preventative agent for allergic airway inflammatory diseases such as allergic asthma.

Expected impact of immunomodulatory agents during pregnancy: A newborn's perspective

The neonatal immune ontogeny begins during pregnancy to ensure that the neonate is well-suited for perinatal life. It prioritizes Th2/M2 and regulatory responses over Th/M1 activity to avoid excessive inflammatory responses and to ensure immune tolerance and homeostasis. Newborns also present increased Th17/Th22 responses providing effective anti-fungal immunity and mucosal protection. Intrauterine exposure to immune modulatory drugs with the placental transfer may influence the natural course of the fetal immune development. The vertical transfer of both biological therapy and small molecules begins during the first trimester through neonatal Fc receptor or placental diffusion, respectively, reaching its maximum transfer potential during the third trimester of pregnancy. Most of the biological therapy have a prolonged half-life in newborn's blood, being detectable in infants up to 12 months after birth (usually 6-9 months). The use of immunomodulators during pregnancy is gaining global interest. Current evidence mainly reports birth-related outcomes without exhaustive analysis of the on-target side effect on the perinatal immune system ontogeny, the infection risk, or the immune dysregulation. The present review will focus on: (1) the main characteristics of the perinatal immune system to understand its specific features and vulnerabilities to immune modulation; (2) the mechanisms of placental transfer of immunomodulators; and (3) the immune changes reported to date in newborns exposed to immunomodulators with emphasis on the current concerns and gaps in knowledge.

NRF2 Protects against Altered Pulmonary T Cell Differentiation in Neonates Following In Utero Ultrafine Particulate Matter Exposure

Early life exposure to particulate matter (PM) air pollution negatively impacts neonatal health. The underlying mechanisms following prenatal exposure, particularly to ultrafine particles (UFP, diameter ≤ 0.1 μm), are not fully understood; To evaluate the role of Nrf2 in response to in utero UFP exposure, we exposed time-mated Nrf2-deficient (Nrf2-/-) or wildtype (WT) mice to filtered air (FA) or 100 μg/m3 ultrafine PM daily throughout pregnancy. Offspring were evaluated for pulmonary immunophenotypes and pulmonary/systemic oxidative stress on postnatal day 5, a timepoint at which we previously demonstrated viral respiratory infection susceptibility; Nrf2-/- offspring exposed to FA had significantly lower average body weights compared to FA-exposed WT pups. Moreover, PM-exposed Nrf2-/- offspring weighed significantly less than PM-exposed WT pups. Notably, PM-exposed Nrf2-/- offspring showed a decreased pulmonary Th1/Th2 ratio, indicating a Th2 bias. Th17 cells were increased in FA-exposed Nrf2-/- neonates yet decreased in PM-exposed Nrf2-/- neonates. Analysis of oxidative stress-related genes in lung and oxidative stress biomarkers in liver tissues did not vary significantly across exposure groups or genotypes. Collectively, these findings indicate that the lack of Nrf2 causes growth inhibitory effects in general and in response to gestational UFP exposure. Prenatal UFP exposure skews CD4+ T lymphocyte differentiation toward Th2 in neonates lacking Nrf2, signifying its importance in maternal exposure and infant immune responses.

Characterization of the Transient Deficiency of PKC Isozyme Levels in Immature Cord Blood T Cells and Its Connection to Anti-Allergic Cytokine Profiles of the Matured Cells

Cord blood T cells (CBTC) from a proportion of newborns express low/deficient levels of some protein kinase C (PKC) isozymes, with low levels of PKCζ correlating with increased risk of developing allergy and associated decrease in interferon-gamma (IFN-γ) producing T cells. Interestingly, these lower levels of PKCζ were increased/normalized by supplementing women during pregnancy with n-3 polyunsaturated fatty acids. However, at present, we have little understanding of the transient nature of the deficiency in the neonate and how PKCζ relates to other PKC isozymes and whether their levels influence maturation into IFN-γ producing T cells. There is also no information on PKCζ isozyme levels in the T cell subpopulations, CD4⁺ and CD8⁺ cells. These issues were addressed in the present study using a classical culture model of neonatal T cell maturation, initiated with phytohaemagglutinin (PHA) and recombinant human interleukin-2 (rhIL-2). Of the isozymes evaluated, PKCζ, β2, δ, μ, ε, θ and λ/ι were low in CBTCs. The PKC isozyme deficiencies were also found in the CD4⁺ and CD8⁺ T cell subset levels of the PKC isozymes correlated between the two subpopulations. Examination of changes in the PKC isozymes in these deficient cells following addition of maturation signals showed a significant increase in expression within the first few hours for PKCζ, β2 and μ, and 1–2 days for PKCδ, ε, θ and λ/ι. Only CBTC PKCζ isozyme levels correlated with cytokine production, with a positive correlation with IFN-γ, interleukin (IL)-2 and tumour necrosis factor-alpha (TNF), and a negative association with IL-9 and IL-10. The findings reinforce the specificity in using CBTC PKCζ levels as a biomarker for risk of allergy development and identify a period in which this can be potentially ‘corrected’ after birth.