Kevin R. Bobbitt

Man’s best friend? The effect of pet ownership on house dust microbial communities

Pet-ownership, which has been shown to be protective against allergic disease development, is associated with increased house dust bacterial diversity and fewer fungal species, suggesting a potentially microbial-based mechanism for this protective effect.

Within-woman change in regulatory T cells from pregnancy to the postpartum period.

Regulatory T cells (Treg cells) are an important area of investigation in human health and disease. In this study, the trajectory of percentage of Treg cells (defined as CD4+CD25+Foxp3+CD127--lymphocytes) was measured in the blood of 208 women during pregnancy and up to three additional times in the postpartum period (1, 6 and 12 months postpartum). Whether the trajectory was affected by gravidity, parity, neonatal sex, pet exposure, maternal atopic and asthma status, smoking, maternal race or other pregnancy factors was examined. Multilevel models were fit using full maximum likelihood methods and included both random and fixed effects. Overall, percentages of Treg cells increased from the prenatal to the postpartum period. Among women who were not atopic, nulliparous women had lower percentages of Treg cells over time compared with parous women. Atopic women with pets in the home during pregnancy had lower percentages of Treg cells than atopic women who did not have pets. The trajectory was not affected by the other factors investigated. We conclude that within-woman change in percentages of Treg cells may vary by time in relation to delivery, as well as by maternal atopic status and exposure to pets and number of prior births. The data did not indicate an overall decline in Treg cells in the postpartum period. Future work to better identify the role of Treg cells in successful pregnancy would ideally include a set of well characterized women sampled serially starting prior to pregnancy and throughout the postpartum period.

Treatment with N-acetyl-seryl-aspartyl-lysyl-proline prevents experimental autoimmune myocarditis in rats

Myocarditis is commonly associated with cardiotropic infections and has been linked to development of autoimmunity. N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) is a naturally occurring tetrapeptide that prevents inflammation and fibrosis in hypertension and other cardiovascular diseases; however, its effect on autoimmune-mediated cardiac diseases remains unknown. We studied the effects of Ac-SDKP in experimental autoimmune myocarditis (EAM), a model of T cell-mediated autoimmune disease. This study was conducted to test the hypothesis that Ac-SDKP prevents autoimmune myocardial injury by modulating the immune responses. Lewis rats were immunized with porcine cardiac myosin and treated with Ac-SDKP or vehicle. In EAM, Ac-SDKP prevented both systolic and diastolic cardiac dysfunction, remodeling as shown by hypertrophy and fibrosis, and cell-mediated immune responses without affecting myosin-specific autoantibodies or antigen-specific T cell responses. In addition, Ac-SDKP reduced cardiac infiltration by macrophages, dendritic cells, and T cells, pro-inflammatory cytokines [interleukin (IL)-1α, tumor necrosis factor-α, IL-2, IL-17] and chemokines (cytokine-induced neutrophil chemoattractant-1, interferon-γ-induced protein 10), cell adhesion molecules (intercellular adhesion molecule-1, L-selectin), and matrix metalloproteinases (MMP). Ac-SDKP prevents autoimmune cardiac dysfunction and remodeling without reducing the production of autoantibodies or T cell responses to cardiac myosin. The protective effects of Ac-SDKP in autoimmune myocardial injury are most likely mediated by inhibition of 1) innate and adaptive immune cell infiltration and 2) expression of proinflammatory mediators such as cytokines, chemokines, adhesion molecules, and MMPs.

Regulatory T cells in prenatal blood samples: variability with pet exposure and sensitization☆

Fetal exposures have come under investigation as risk factors of early life allergic disease. In this study we aimed to examine the relationships between dog or cat exposure and naturally occurring regulatory T cells (Treg cells), thought to play an important role in immune tolerance, in pregnant women. A cross-sectional analysis was conducted among 204 pregnant women who were queried regarding dog and cat exposure. Treg cells (CD4+CD25+Foxp3+ lymphocytes) and allergen-specific IgE were measured in venous blood samples. Atopy was defined as allergen-specific IgE > or =0.35kU/l reactive with common allergens including dust mite, dog, cat, Timothy grass, ragweed, Alternaria alternata, egg white or cockroach. Nonparametric Wilcoxon rank sum tests and linear regression models of log transformed Treg cell levels were used in analyses. Among women sensitized to dog, those who had a dog or cat in the home had lower Treg cell levels compared with those who had no dog or cat. However, among women not sensitized to dog, those with a dog or cat in the home had higher Treg cell levels compared with those who did not. Among women sensitized to cat, those who had a dog or cat in the home had lower Treg cell levels compared with those who had no dog or cat. Gestational age at blood draw did not affect the associations. We conclude that Treg cell levels during pregnancy vary in association with both dog and cat exposure and atopic status.

The entirely carbohydrate immunogen Tn-PS A1 induces a cancer cell selective immune response and cytokine IL-17

The tumor-associated carbohydrate antigen/hapten Thomsen-nouveau (Tn; α-D-GalpNAc-ONH2) was conjugated to a zwitterionic capsular polysaccharide, PS A1, from commensal anaerobe Bacteroides fragilis ATCC 25285/NCTC 9343 for the development of an entirely carbohydrate cancer vaccine construct and probed for immunogenicity. This communication discloses that murine anti-Tn IgG3 antibodies both bind to and recognize human tumor cells that display the Tn hapten. Furthermore, the sera from immunization of mice with Tn-PS A1 contain cytokine interleukin 17 (IL-17A), which is known to possess anti-tumor function and represents a striking difference to an IL-2, and IL-6 profile obtained with anti-PS A1 sera.

Early pregnancy vitamin D and patterns of antenatal inflammation in African–American women

Vitamin D is essential for the health of both mother and fetus during pregnancy. In the nonpregnant state, vitamin D demonstrates anti-inflammatory effects, but little is known about this relationship during pregnancy. African-American women are at a higher risk of vitamin D deficiency and for altered inflammatory responses during pregnancy. Therefore, we investigated the association of early pregnancy vitamin D nutrition, as assessed by serum 25-hydroxyvitamin D (25-OHD), with second-trimester inflammatory biomarkers (high-sensitivity C-reactive protein, IL-6, IL-10, IL-1β and TNF-α) in 178 pregnant African-American women. Mean serum 25-OHD was 13.4±8.4 ng/ml, and most women (n=147, 82.6%) had inadequate or deficient levels of 25-OHD (<20 ng/ml). Both serum 25-OHD and some inflammatory cytokines (IL-1β and TNF-α) demonstrated significant seasonal variation. In univariate models, log transformed 25-OHD was significantly and inversely associated with log transformed IL-1β (p=0.002) and log transformed IL-6 (p=0.032). After adjusting for covariates, including seasonality, only the inverse association with IL-1β remained statistically significant (p=0.027). Early pregnancy vitamin D nutrition is associated with some inflammatory biomarkers in mid-pregnancy. Additional studies are needed to determine if low vitamin D nutrition is associated with birth outcomes via an inflammatory-mediated pathway.

Plasma levels of F-actin and F:G-actin ratio as potential new biomarkers in patients with septic shock

Abstract Objective: To compare plasma levels of F-actin, G-actin and thymosin beta 4 (TB4) in humans with septic shock, noninfectious systemic inflammatory response syndrome (SIRS) and healthy controls. Results: F-actin was significantly elevated in septic shock as compared with noninfectious SIRS and healthy controls. G-actin levels were greatest in the noninfectious SIRS group but significantly elevated in septic shock as compared with healthy controls. TB4 was not detectable in the septic shock or noninfectious SIRS group above the assay’s lowest detection range (78 ng/ml). Conclusions: F-actin is significantly elevated in patients with septic shock as compared with noninfectious SIRS. F-actin and the F:G-actin ratio are potential biomarkers for the diagnosis of septic shock.

Regulatory T cells vary over bleeding segments in asthmatic and non-asthmatic women

Sex hormones may play an important role in observed gender differences in asthma incidence and severity. Regulatory T cells (Treg cells) are presumed to be involved in asthma and may vary with hormone levels. To investigate the effects of sex hormones on levels of Treg cells (percentage of CD4+CD25+Foxp3+ lymphocytes that are CD127-), a cohort of 13 women (6 with and 7 without an asthma diagnosis) had blood drawn multiple times over the course of a bleeding segment (bleeding interval plus the following bleeding-free interval) and collected urine samples daily for measurement of estrogen (estrone E1C) and progesterone (pregnanediol-glucuronide PDG) metabolites. The samples from non-asthmatic women indicated no association between bleeding segment day and Treg cells. Asthmatic women showed a 3% increase in Treg cell percentage with each successive day over the bleeding segment. Among non-asthmatic women, Treg cell percentages were not associated with PDG levels on the same day, or 1, 2 or 3 days before Treg cell measurement. E1C was positively correlated with the Treg cell percentage measured only on the same day - a 5% increase in E1C was associated with a 1.4% increase in Treg cell percentage. Among asthmatic women, only E1C was associated with Treg cell percentages after adjusting for PDG on the same day and 1 and 2 days before Treg cell measurement. A 5% increase in E1C was associated with a 2.3% increase in Treg cell percentage. A larger study of contiguous cycles to better determine within-woman cyclicity of the observed patterns is needed.

Cellular Uptake and Radio-sensitization Effect of Small Gold Nanoparticles in MCF-7 Breast Cancer Cells

Gold nanoparticles (AuNPs) are shown to increase cancer cells sensitization to ionizing radiation. Theoretical models predicted that due to the differences in absorption coefficient between gold and soft tissue, maximum sensitization can be achieved at kilovoltage (kV), with minimum to no effect at megavoltage (MV) range, which was indeed demonstrated by previous research on AuNPs radio-sensitization with kV radiation. However, AuNPs effect at MV energies is still not clear. Radio-sensitization depends on AuNPs’ internalization by cancer cells that is in turn affected by AuNPs size. The purpose of this study was to explore, in vitro, radio sensitization potential of AuNPs of 4 and 14 nm size with clinically relevant MV, as well as kV photons in MCF7 breast cancer cell line. We investigated the differences in cellular uptake and intracellular localization between 4 and 14 nm AuNPs by transmission electron microscopy (TEM). We also examined the effect of these AuNPs on MCF7 cells response to irradiation by MTT analysis of cell proliferation, and flow cytometry analysis of H2AX phosphorylation as an indicator of DNA double strand breaks (DSBs). Our results demonstrated significant AuNPs cellular uptake and a selective, size dependent intracellular localization with 4 nm AuNPs mostly residing in cytoplasm and 14 nm in nucleus. Nanoparticles of both sizes sensitized MCF-7 breast cancer cells to radiation at both kV and MV energies, independent of particle size. Radio-sensitization was detected as an increase in radiation induced inhibition of cell proliferation and radiation induced DNA DSBs. This work provides valuable information for further exploring mechanisms of AuNPs radio-sensitization in cancer cell lines that may be important in designing and optimizing AuNPs based radiotherapies.