Vitamin D supplementation during pregnancy: Effect on the neonatal immune system in a randomized controlled trial

BACKGROUND

Programming of the immune system during fetal development can influence asthma-related risk factors and outcomes in later life. Vitamin D is a well-recognized immune modulator, and deficiency of this nutrient during pregnancy is hypothesized to influence disease development in offspring.

OBJECTIVE

We sought to investigate the effect on neonatal immunity of maternal supplementation with 4400 IU/d vitamin D₃ during the second and third trimesters of pregnancy by using a subset of cord blood samples from a randomized, double-blind, placebo-controlled clinical trial (the Vitamin D Antenatal Asthma Reduction Trial).

METHODS

Cord blood samples from neonates born to mothers supplemented with 4400 IU/d (n = 26) or 400 IU/d (n = 25) of vitamin D₃ were analyzed for immune cell composition by flow cytometry, Toll-like receptor (TLR) expression by quantitative PCR, and cytokine secretion after stimulation with mitogenic, TLR, and T-cell stimuli by cytometric bead array. Responsiveness to the glucocorticoid dexamethasone was determined.

RESULTS

Supplementation of mothers with 4400 IU of vitamin D₃ resulted in an enhanced broad-spectrum proinflammatory cytokine response of cord blood mononuclear cells to innate and mitogenic stimuli (P = .0009), with an average 1.7- to 2.1-fold increase in levels of several proinflammatory cytokines (GM-CSF, IFN-γ, IL-1β, IL-6, and IL-8) across stimuli, a higher gene expression level of TLR2 (P = .02) and TLR9 (P = .02), a greater than 4-fold increase in IL-17A (P = .03) production after polyclonal T-cell stimulation, and an enhanced IL-10 response of cord blood mononuclear cells to dexamethasone treatment in culture (P = .018).

CONCLUSION

Vitamin D exposure during fetal development influences the immune system of the neonate, which can contribute to protection from asthma-related, including infectious, outcomes in early life.

Inhibiting lung lining fluid glutathione metabolism with GGsTop as a novel treatment for asthma

Asthma is characterized by airway inflammation. Inflammation is associated with oxidant stress. Airway epithelial cells are shielded from this stress by a thin layer of lung lining fluid (LLF) which contains an abundance of the antioxidant glutathione. LLF glutathione metabolism is regulated by γ-glutamyl transferase (GGT). Loss of LLF GGT activity in the mutant GGT^enu1 mouse causes an increase in baseline LLF glutathione content which is magnified in an IL-13 model of allergic airway inflammation and protective against asthma. Normal mice are susceptible to asthma in this model but can be protected with acivicin, a GGT inhibitor. GGT is a target to treat asthma but acivicin toxicity limits clinical use. GGsTop is a novel GGT inhibitor. GGsTop inhibits LLF GGT activity only when delivered through the airway. In the IL-13 model, mice treated with IL-13 and GGsTop exhibit a lung inflammatory response similar to that of mice treated with IL-13 alone. But mice treated with IL-13 and GGsTop show attenuation of methacholine-stimulated airway hyper-reactivity, inhibition of Muc5ac and Muc5b gene induction, decreased airway epithelial cell mucous accumulation and a fourfold increase in LLF glutathione content compared to mice treated with IL-13 alone. Mice treated with GGsTop alone are no different from that of mice treated with saline alone, and show no signs of toxicity. GGsTop could represent a valuable pharmacological tool to inhibit LLF GGT activity in pulmonary disease models. The associated increase in LLF glutathione can protect lung airway epithelial cells against oxidant injury associated with inflammation in asthma.

CCR4+T cell recruitment to the skin in mycosis fungoides: potential contributions by thymic stromal lymphopoietin and interleukin-16

Mycosis fungoides (MF) is characterized by skin accumulation of CCR4+CCR7- effector memory T cells; however the mechanism for their recruitment is not clearly identified. Thymic Stromal Lymphopoietin (TSLP) is a keratinocyte-derived cytokine that triggers Th2 immunity and is associated with T cell recruitment to the skin in atopic dermatitis. Interleukin-16 (IL-16) is a chemoattractant and growth factor for CD4+T cells. We hypothesized that TSLP and IL-16 could contribute to recruitment of malignant T cells in MF. We found elevated TSLP and IL-16 in very early stage patients' plasma and skin biopsies, prior to elevation in CCL22. Both TSLP and IL-16 induced migratory responses of CCR4+TSLPR+CD4+CCR7-CD31+cells, characteristic of malignant T cells in the skin. Co-stimulation also resulted in significant proliferative responses. We conclude that TSLP and IL-16, expressed at early stages of disease, function to recruit malignant T cells to the skin and contribute to their enhanced proliferation.

Regulation of cellular processes by interleukin-16 in homeostasis and cancer

Interleukin-16 (IL-16) is generated as a precursor molecule that is cleaved by caspase-3 to produce a pro-IL-16 molecule that functions as a regulator of T cell growth, and a secreted peptide that functions as a CD4 and/or CD9 ligand for induction of cell motility and activation. IL-16 has been predominantly studied as a contributing factor in the orchestration of an immune response; however, more recently IL-16 bioactivity has been closely associated with the progression of a number of different cancers. While the association between IL-16 plasma levels and tumor progression has been reported for many types of cancer, the mechanism for IL-16 involvement has been partially elucidated for three of the cancer types, cutaneous T cell lymphoma (CTCL), multiple myeloma (MM), and breast cancer. The mechanism for promoting cell growth is different in each of these cancers and involves a sequence mutation in the pro-molecule facilitating decreased p27(KIP1) levels in CTCL; over expression of the secreted IL-16 molecule to induce proliferation in CTCL T cells, and plasma cells in MM; and increased secreted IL-16 acting to recruit CD4+ pro-tumor macrophages in breast cancer. This article will review the cellular process for generating IL-16, the biological activities for both the pro- and secreted forms of the protein, and then the mechanism by which these forms contribute to cancer progression. As a soluble cytokine the ability to reduce or eliminate IL-16 synthesis through siRNA approaches or bioactivity through the use of neutralizing antibody treatment may represent a novel therapeutic approach.

Comparison of the etiology of viral respiratory illnesses in inner-city and suburban infants

Background. The risk of developing childhood asthma has been linked to the severity and etiology of viral respiratory illnesses in early childhood. Since inner-city infants have unique environmental exposures, we hypothesized that patterns of respiratory viral infections would also be distinct.

Methods. We compared the viral etiology of respiratory illnesses in 2 groups: a cohort of 515 infants from 4 inner-city areas and a cohort of 285 infants from mainly suburban Madison, Wisconsin. Nasal secretions were sampled during periods of respiratory illness and at 1 year of age and were analyzed for viral pathogens by multiplex polymerase chain reaction.

Results. Overall, inner-city infants had lower rates of viral detection. Considering specific viruses, sick urban infants had lower rates of detectable rhinovirus or respiratory syncytial virus infection and higher rates of adenovirus infection. Every urban site had a higher proportion of adenovirus-positive samples associated with illnesses (10%–21%), compared with Madison (6%).

Conclusions. These findings provide evidence that inner-city babies have different patterns of viral respiratory illnesses than babies who grow up in a more suburban location. These findings raise important questions about the etiology of virus-negative illnesses in urban infants and the possibility of long-term consequences of early life infections with adenovirus in this population.

Potential role of TSLP and IL-16 for migration and proliferation in Mycosis Fungoides T cells (161.15)

Mycosis Fungoides is a cutaneous T cell lymphoma disease characterized by CCR4+ T cells in skin plaques. While CCL22/CCR4 has been implicated, the mechanism for recruitment and expansion is not well understood. We have now identified elevated levels of IL-16 and thymic stromal lymphopoietin (TSLP) in the sera and skin of MF patients and investigated the potential role of these cytokines. Sera levels showed a stage-dependent increase of TSLP (3 fold versus control), and consistently, stage independent, elevated IL-16 levels. The source appears to be the skin, as both were positive compared with staining of normal skin. MF T cells expressed higher levels of TSLP receptor and expression correlated with CCR4 expression. In vitro migration studies indicated a 210% and 230% increase in migration to IL-16 and TSLP respectively. Pre-treatment of IL-16 prior to TSLP induced migration increased the migratory response to 280%, suggesting an additive effect. Addressing T cell proliferation, we determined that TSLP and IL-16 separately had minimal effects on proliferation however in combination proliferation increased 3 fold versus stimulated control T cells. Taken together our findings indicate the potential role of IL-16 and TSLP to recruit and expand MF T cells at sites of plaque formation in MF. Co-expression of TSLPR and CCR4 suggests a possible mechanism that at least in part would account for the prevalence of CCR4+ T cells in the skin of MF.

Loss of nuclear Pro-IL-16 imparts resistance to apoptosis in CTCL T cells (47.5)

Cutaneous T-cell Lymphoma (CTCL) is a rare type of non-Hodgkin’s lymphomas characterized by increased T cell proliferation and decreased apoptotic responses. We have reported on the loss of nuclear Pro-IL-16 in CTCL T cells due to a mutation restricting nuclear translocation, which results in dysregulation of Skp2 and p27kip1, and promotes hyper-proliferative state. We have now investigated the relationship between the loss of nuclear Pro-IL-16 and apoptosis. RT-PCR analysis of a panel of apoptosis-related genes was conducted using T cells obtained from IL-16 knock out and wild type control mice. The IL-16 null cells demonstrated a significant reduction in pro-apoptotic genes such as Bax, Bcl10, Bcl2110, and caspases 7, 8 and 9, with an increase in expression of anti-apoptotic genes such as Bag1, Tsc22d3 and Pim2. Annexin V staining of these cells indicated a 43% reduction in the apoptotic response to CD3/CD28 stimulation in the knock-out cells. To confirm the anti-apoptotic effect of nuclear Pro-IL-16, human CTCL-derived T cell line (HUT 78) was transfected to express normal full-length IL-16. Based on Annexin V staining, the apoptotic response increased by 35% in cells, expressing normal IL-16. These studies indicate that loss of nuclear Pro-IL-16 in abnormal T cells correlates not only with increased cell proliferation, but with a decrease in apoptosis as well.

Loss of nuclear pro-IL-16 facilitates cell cycle progression in human cutaneous T cell lymphoma

Cutaneous T cell lymphomas (CTCLs) represent a heterogeneous group of non-Hodgkin lymphomas that affect the skin. The pathogenesis of these conditions is poorly understood. For example, the signaling mechanisms contributing to the dysregulated growth of the neoplastic T cells are not well defined. Here, we demonstrate that loss of nuclear localization of pro-IL-16 facilitates CTCL cell proliferation by causing a decrease in expression of the cyclin dependent-kinase inhibitor p27Kip1. The decrease in p27Kip1 expression was directly attributable to an increase in expression of S-phase kinase-associated protein 2 (Skp2). Regulation of Skp2 is in part attributed to the nuclear presence of the scaffold protein pro-IL-16. T cells isolated from 11 patients with advanced CTCL, but not those from healthy controls or patients with T cell acute lymphocytic leukemia (T-ALL), demonstrated reduction in nuclear pro-IL-16 levels. Sequence analysis identified the presence of mutations in the 5' end of the PDZ1 region of pro-IL-16, a domain required for association of pro-IL-16 with the nuclear chaperone HSC70 (also known as HSPA8). HSC70 knockdown led to loss of nuclear translocation by pro-IL-16 and subsequent increases in Skp2 levels and decreases in p27Kip1 levels, which ultimately enhanced T cell proliferation. Thus, our data indicate that advanced CTCL cell growth is facilitated, at least in part, by mutations in the scaffold protein pro-IL-16, which directly regulates Skp2 synthesis.

A genome-wide association study of plasma total IgE concentrations in the Framingham Heart Study

BACKGROUND

Atopy and plasma IgE concentration are genetically complex traits, and the specific genetic risk factors that lead to IgE dysregulation and clinical atopy are an area of active investigation.

OBJECTIVE

We sought to ascertain the genetic risk factors that lead to IgE dysregulation.

METHODS

A genome-wide association study (GWAS) was performed in 6819 participants from the Framingham Heart Study (FHS). Seventy of the top single nucleotide polymorphisms (SNPs) were selected based on P values and linkage disequilibrium among neighboring SNPs and evaluated in a meta-analysis with 5 independent populations from the Cooperative Health Research in the Region of Augsburg cohort, the British 1958 Birth Cohort, and the Childhood Asthma Management Program cohort.

RESULTS

Thirteen SNPs located in the region of 3 genes, FCER1A, signal transducer and activator of transcription 6 (STAT6), and IL13, were found to have genome-wide significance in the FHS cohort GWAS. The most significant SNPs from the 3 regions were rs2251746 (FCER1A, P = 2.11 × 10(-12)), rs1059513 (STAT6, P = 2.87 × 10(-8)), and rs1295686 (IL13, P = 3.55 × 10(-8)). Four additional gene regions, HLA-G, HLA-DQA2, HLA-A, and Duffy blood group, chemokine receptor (DARC), reached genome-wide statistical significance in a meta-analysis combining the FHS and replication cohorts, although the DARC association did not appear independent of SNPs in the nearby FCER1A gene.

CONCLUSION

This GWAS of the FHS cohort has identified genetic loci in HLA genes that might have a role in the pathogenesis of IgE dysregulation and atopy. It also confirmed the association of the known susceptibility loci FCER1A, STAT6, and IL13 for the dysregulation of total IgE.

Longitudinal relationship of early life immunomodulatory T cell phenotype and function to development of allergic sensitization in an urban cohort

BACKGROUND

Immunomodulatory T cells are thought to influence development of allergy and asthma, but early life longitudinal data on their phenotype and function are lacking.

OBJECTIVES

As part of the Urban Environment and Childhood Asthma (URECA) study, we investigated the development of immunomodulatory T cell phenotype and function, and characterized their relation to allergic disease progression from birth through to 2 years of age.

METHODS

Immunomodulatory T cell phenotype and function in cord blood mononuclear cells (CBMC) and peripheral blood mononuclear cells (PBMC) at 1 and 2 years of age were characterized by analysing CD25(bright) and FoxP3(+) expression, proliferative responses and cytokine production. The relation of immunomodulatory T cell characteristics to allergic sensitization and disease at 1- and 2-years of age was investigated.

RESULTS

The proportion of CD4(+)CD25(bright) and CD4(+)CD25(+)FoxP3(+)T cells (n = 114, 83, 82 at birth, 1- and 2-years respectively) increased significantly, whereas there were no significant changes in the suppressive function of CD25(+)T cells (n = 78, 71, 81 at birth, 1- and 2-years respectively). Birth immunomodulatory T cell characteristics were not related to subsequent allergic sensitization or disease. However, increases in the numbers of CD4(+)CD25(bright) cells and their ability to suppress lymphoproliferative responses at 1 year of age were associated with reduced allergic sensitization at 1 (P = 0.03) and 2 (P = 0.02) years of age. Production of the anti-inflammatory cytokine IL-10 by CD25(+)T cells appeared to mediate this protective suppressive function. In contrast, by 2 years of age, we observed the emergence of a positive association of CD4(+)CD25(+) FoxP3(+) T cell numbers with allergic sensitization (P = 0.05) and eczema (P = 0.02).

CONCLUSIONS AND CLINICAL RELEVANCE

These findings suggest that the relationship between immunomodulatory T cell subsets, allergic sensitization and eczema is developmentally regulated. In the first year of life, CD4(+)CD25(+) IL-10 producing T cells are associated with a reduced incidence of allergic sensitization. Once allergic sensitization or eczema is established, CD4(+)CD25(+)FoxP3(+)T-reg cells expand to potentially counteract the allergic inflammatory response. Understanding the relationship between development of immunoregulatory T cells and early onset atopy could lead to new preventive strategies for allergic diseases.

A homologous form of human interleukin 16 is implicated in microglia recruitment following nervous system injury in leech Hirudo medicinalis

In contrast to mammals, the medicinal leech Hirudo medicinalis can completely repair its central nervous system (CNS) after injury. This invertebrate model offers unique opportunities to study the molecular and cellular basis of the CNS repair processes. When the leech CNS is injured, microglial cells migrate and accumulate at the site of lesion, a phenomenon known to be essential for the usual sprouting of injured axons. In the present study, we demonstrate that a new molecule, designated HmIL-16, having functional homologies with human interleukin-16 (IL-16), has chemotactic activity on leech microglial cells as observed using a gradient of human IL-16. Preincubation of microglial cells either with an anti-human IL-16 antibody or with anti-HmIL-16 antibody significantly reduced microglia migration induced by leech-conditioned medium. Functional homology was demonstrated further by the ability of HmIL-16 to promote human CD4+ T cell migration which was inhibited by antibody against human IL-16, an IL-16 antagonist peptide or soluble CD4. Immunohistochemistry of leech CNS indicates that HmIL-16 protein present in the neurons is rapidly transported and stored along the axonal processes to promote the recruitment of microglial cells to the injured axons. To our knowledge, this is the first identification of a functional interleukin-16 homologue in invertebrate CNS. The ability of HmIL-16 to recruit microglial cells to sites of CNS injury suggests a role for HmIL-16 in the crosstalk between neurons and microglia in the leech CNS repair.

Interleukin-16 as a marker of Sézary syndrome onset and stage

INTRODUCTION

Sézary syndrome is one of the most common forms of cutaneous T cell lymphoma (CTCL). It is characterized by skin infiltration of malignant T cells. We examined interleukin-16, a potent T cell chemoattractant and cell-cycle regulator, as a prospective marker of disease onset and stage.

METHODS

The correlation of total intracellular interleukin-16 and surface CD26 was studied by flow cytometry. Confocal microscopy was performed to determine localization of interleukin-16 at different stages of the disease. The levels of interleukin-16 in plasma and culture supernatants were examined by enzyme-linked immunoassay. Additionally, lymphocytes from stage IB patients were cultured in the presence of interleukin-16 alone and in combination with interleukin-15, and their ability to survive and proliferate was determined by cell counts and [3H]TdR incorporation.

RESULTS

The data indicate that loss of both nuclear and intracellular pro-interleukin-16 highly correspond to disease stage, with a concomitant increase in secreted mature interleukin-16 in both culture supernatants and patients' plasma that peaks at stage IB. Loss of intracellular interleukin-16 strongly corresponded to loss of surface CD26, which has been shown to occur with more advanced stage of CTCL. Nuclear translocation of pro-interleukin-16 was not observed in late stages of Sézary syndrome, indicating this loss is not reversible.

CONCLUSIONS

We propose that it is feasible to use plasma levels of IL-16 as a potential diagnostic marker of Sézary syndrome and to use loss of intracellular IL-16 as a prognostic indicator of disease severity and stage.

RNAIII-inhibiting-peptide-loaded polymethylmethacrylate prevents in vivo Staphylococcus aureus biofilm formation

Staphylococci, common orthopedic pathogens, form antibiotic-resistant biofilms. Polymethylmethacrylate (PMMA) beads loaded with the quorum-sensing inhibitor RNAIII-inhibiting peptide (RIP) were implanted in rats and shown to prevent methicillin-resistant Staphylococcus aureus infection. RIP release was bimodal, typical of previously-tested antibiotics. These results suggest that RIP-PMMA warrants further evaluation for management of orthopedic infections caused by staphylococci.

Cross-reactivity of human lupus anti-DNA antibodies with alpha-actinin and nephritogenic potential

OBJECTIVE

Cross-reactivity with kidney antigens is believed to be a critical determinant in the renal pathogenicity of anti-double-stranded DNA (anti-dsDNA) antibodies. Murine nephritogenic anti-dsDNA antibodies have been shown to cross-react with alpha-actinin, and anti-alpha-actinin antibodies have been found to be deposited in the kidneys of lupus mice with active nephritis. Furthermore, in humans with systemic lupus erythematosus (SLE), it has been found that a greater proportion of polyclonal IgG anti-dsDNA antibodies from patients with renal involvement bind to alpha-actinin than do those from patients without renal disease. We undertook this study to substantiate a direct link between cross-reactive anti-dsDNA/anti-alpha-actinin antibodies and the pathogenesis of lupus nephritis in humans.

METHODS

A panel of 10 anti-dsDNA and/or anti-alpha-actinin antibodies was generated by Epstein-Barr virus transformation of lymphocytes from patients with SLE and was extensively characterized. Antibody binding was studied by enzyme-linked immunosorbent assay and Western blotting. Antibody potential for pathogenicity was assessed by measuring binding to isolated glomeruli and mesangial cells and by evaluation of histologic features of the kidney following injection in vivo.

RESULTS

All anti-dsDNA antibodies isolated also bound alpha-actinin. Cross-reactive antibodies bound to mesangial cells and to isolated glomeruli ex vivo. Binding to glomeruli was not inhibited by DNase treatment, but could be abrogated by alpha-actinin. Furthermore, histopathologic abnormalities seen in mice injected intraperitoneally with a cross-reactive cell line included fusion of podocyte foot processes and subepithelial and subendothelial deposition.

CONCLUSION

These studies provide strong support for the hypothesis that alpha-actinin is a major cross-reactive target for anti-dsDNA antibodies in SLE patients. Cross-reactive anti-dsDNA/anti-alpha-actinin antibodies from SLE patients are pathogenic and may contribute to the kidney lesions in lupus nephritis.

Strong T cell type-1 immune responses to HIV-1 Tat (1–72) protein-coated nanoparticles

A significant emphasis has been placed on the development of adjuvants and/or delivery systems to improve both antibody production and cell-mediated immune responses. We previously reported on a novel anionic nanoparticle, which led to enhanced humoral and T helper type-1 (Th1) biased immune responses in mice when coated with cationized model antigen. Tat (1-72) is a conserved regulatory HIV-1 protein. It was hypothesized that HIV vaccine strategies employing Tat (1-72) may be a promising approach. Although previous reports have suggested that Tat (1-86) may be immunosuppressive, it was demonstrated in this present study that Tat (1-72) was not immunosuppressive when co-administered to mice with ovalbumin (OVA). Tat (1-72) was coated on novel anionic nanoparticles. BALB/c mice were immunized with Tat (5 microg)-coated nanoparticles (15 microg) by subcutaneous injection on days 0 and 14. Antibody and cytokine release were determined on day 28 and compared to Tat (5 microg) adjuvanted with Alum (15 microg) as a Th2 control, Tat (5 microg) adjuvanted with Lipid A (50 microg) as a Th1 control. Immunization of BALB/c mice with Tat-coated nanoparticles resulted in antibody levels (IgG and IgM) comparable to those elicited from Tat and Alum. However, Tat-coated nanoparticles led to a Th1 biased immune response. The IFN-gamma release from splenocytes with Tat-coated nanoparticles was comparable to that from mice immunized with Tat and Lipid A, and 3.3-fold greater than that from mice immunized with Tat and Alum. These studies warrant further investigation of these nanoparticles to enhance both antibody and cellular-based immune responses.