Janis MacCallum

Carbon black nanoparticles induce type II epithelial cells to release chemotaxins for alveolar macrophages

BackgroundAlveolar macrophages are a key cell in dealing with particles deposited in the lungs and in determining the subsequent response to that particle exposure. Nanoparticles are considered a potential threat to the lungs and the mechanism of pulmonary response to nanoparticles is currently under intense scrutiny. The type II alveolar epithelial cell has previously been shown to release chemoattractants which can recruit alveolar macrophages to sites of particle deposition. The aim of this study was to assess the responses of a type II epithelial cell line (L-2) to both fine and nanoparticle exposure in terms of secretion of chemotactic substances capable of inducing macrophage migration.ResultsExposure of type II cells to carbon black nanoparticles resulted in significant release of macrophage chemoattractant compared to the negative control and to other dusts tested (fine carbon black and TiO2 and nanoparticle TiO2) as measured by macrophage migration towards type II cell conditioned medium. SDS-PAGE analysis of the conditioned medium from particle treated type II cells revealed that a higher number of protein bands were present in the conditioned medium obtained from type II cells treated with nanoparticle carbon black compared to other dusts tested. Size-fractionation of the chemotaxin-rich supernatant determined that the chemoattractants released from the epithelial cells were between 5 and 30 kDa in size.ConclusionThe highly toxic nature and reactive surface chemistry of the carbon black nanoparticles has very likely induced the type II cell line to release pro-inflammatory mediators that can potentially induce migration of macrophages. This could aid in the rapid recruitment of inflammatory cells to sites of particle deposition and the subsequent removal of the particles by phagocytic cells such as macrophages and neutrophils. Future studies in this area could focus on the exact identity of the substance(s) released by the type II cells in response to particle exposure.

The Pancreas Is Altered by In Utero Androgen Exposure: Implications for Clinical Conditions Such as Polycystic Ovary Syndrome (PCOS)

Using an ovine model of polycystic ovary syndrome (PCOS), (pregnant ewes injected with testosterone propionate (TP) (100 mg twice weekly) from day (d)62 to d102 of d147 gestation (maternal injection – MI-TP)), we previously reported female offspring with normal glucose tolerance but hyperinsulinemia. We therefore examined insulin signalling and pancreatic morphology in these offspring using quantitative (Q) RT-PCR and western blotting. In addition the fetal pancreatic responses to MI-TP, and androgenic and estrogenic contributions to such responses (direct fetal injection (FI) of TP (20 mg) or diethylstilbestrol (DES) (20 mg) at d62 and d82 gestation) were assessed at d90 gestation. Fetal plasma was assayed for insulin, testosterone and estradiol, pancreatic tissue was cultured, and expression of key β-cell developmental genes was assessed by QRT-PCR. In female d62MI-TP offspring insulin signalling was unaltered but there was a pancreatic phenotype with increased numbers of β-cells (P<0.05). The fetal pancreas expressed androgen receptors in islets and genes involved in β-cell development and function (PDX1, IGF1R, INSR and INS) were up-regulated in female fetuses after d62MI-TP treatment (P<0.05–0.01). In addition the d62MI-TP pancreas showed increased insulin secretion under euglycaemic conditions (P<0.05) in vitro. The same effects were not seen in the male fetal pancreas or when MI-TP was started at d30, before the male programming window. As d62MI-TP increased both fetal plasma testosterone (P<0.05) and estradiol concentrations (P<0.05) we assessed the relative contribution of androgens and estrogens. FI-TP (commencing d62) (not FI-DES treatment) caused elevated basal insulin secretion in vitro and the genes altered by d62MI-TP treatment were similarly altered by FI-TP but not FI-DES. In conclusion, androgen over-exposure alters fetal pancreatic development and β-cell numbers in offspring. These data suggest that that there may be a primary pancreatic phenotype in models of PCOS, and that there may be a distinct male and female pancreas.

Effect of Nippostrongylus brasiliensis L3 ES on inflammatory mediator gene transcription in lipopolysaccharide lung inflammation.

The anti‐inflammatory properties of parasitic helminths have been largely linked to their excretory–secretory (ES) products. Some studies have noted a lack of TNF‐α production and limited recruitment of neutrophils into the lungs after Nippostrongylus brasiliensis infection. We previously reported that instillation of ES from L3 larvae of N. brasiliensis to the lungs could inhibit the recruitment of neutrophils on a background of LPS‐induced inflammation. A similar reduction in neutrophil recruitment was observed in this study. This reduction was associated with the significant inhibition in gene transcription of the adhesion molecule, ICAM‐1, and the chemokine, MIP‐2 in bronchoalveolar lavage (BAL) cells. The LPS‐stimulated gene transcription of the pro‐inflammatory cytokines TNF‐α and IL‐1β was also significantly reduced by L3 ES. Inducible nitric oxide synthase (iNOS) is normally elevated in classically activated macrophages, however, in this case gene transcription of iNOS was inhibited by L3 ES and may suggest a phenotype change to anti‐inflammatory. The general inhibition of pro‐inflammatory mediators observed in this study suggests that infective stage L3 larvae excrete and/or secrete inhibitory products capable of modifying the normally potent LPS inflammatory response.

Developmental programming of polycystic ovary syndrome (PCOS): prenatal androgens establish pancreatic islet α/β cell ratio and subsequent insulin secretion

Exogenous androgenic steroids applied to pregnant sheep programmes a PCOS-like phenotype in female offspring. Via ultrasound guidance we applied steroids directly to ovine fetuses at d62 and d82 of gestation, and examined fetal (day 90 gestation) and postnatal (11 months old) pancreatic structure and function. Of three classes of steroid agonists applied (androgen - Testosterone propionate (TP), estrogen - Diethystilbesterol (DES) and glucocorticoid - Dexamethasone (DEX)), only androgens (TP) caused altered pancreatic development. Beta cell numbers were significantly elevated in prenatally androgenised female fetuses (P = 0.03) (to approximately the higher numbers found in male fetuses), whereas alpha cell counts were unaffected, precipitating decreased alpha:beta cell ratios in the developing fetal pancreas (P = 0.001), sustained into adolescence (P = 0.0004). In adolescence basal insulin secretion was significantly higher in female offspring from androgen-excess pregnancies (P = 0.045), and an exaggerated, hyperinsulinaemic response to glucose challenge (P = 0.0007) observed, whereas prenatal DES or DEX treatment had no effects upon insulin secretion. Postnatal insulin secretion correlated with beta cell numbers (P = 0.03). We conclude that the pancreas is a primary locus of androgenic stimulation during development, giving rise to postnatal offspring whose pancreas secreted excess insulin due to excess beta cells in the presence of a normal number of alpha cells.