SUMMARYThe genetic backgrounds of lupus-prone murine models are a valuable resource for studying the influence of environmental exposure on autoimmune diseases in sensitive populations. Epidemiological studies have shown associations between silica exposure and several autoimmune diseases, including scleroderma and systemic lupus erythematosus. To determine whether silica exposure can exacerbate systemic autoimmunity in genetically predisposed animals, New Zealand mixed mice were intranasally instilled twice with saline or saline suspensions of 1 mg silica or 500 m g TiO 2 , a dose equivalent in surface area, and were evaluated with respect to health and immune status. Survival in silica exposed NZM mice was decreased compared to saline and TiO 2 exposed mice. Proteinuria levels were elevated in silica exposed mice. Levels of circulating immune complexes, autoantibodies to nuclear antigen (ANA), histone, and double stranded DNA were measured every two weeks by ELISA. Circulating immune complexes showed a trend towards an increased acceleration in levels in the silica exposed mice compared to saline and TiO 2 exposed mice. ANA levels were significantly higher in silica exposed animals compared to saline and TiO 2 exposed animals (0·237 ± 0·03 versus 0·140 ± 0·029 and 0·125 ± 0·03, P < 0·05) 16 weeks postexposure. Autoantibodies to histone were also significantly elevated after 16 weeks in silica exposed animals compared to saline and TiO 2 exposed animals (0·227 ± 0·03 versus 0·073 ± 0·015 and 0·05 ± 0·03, P < 0·05). In contrast, serum IgG levels were decreased in silica exposed NZM mice compared to the saline controls, however, IgM levels were unaffected. Lungs of the silica-exposed mice had increased inflammatory infiltrates as well as fibrotic lesions characterized by excess collagen deposition. Therefore, although NZM mice are susceptible to SLE, silica exposure significantly exacerbated the course of disease.

Metastatic prostate cancer cells display EphB receptor-mediated attraction when they contact stromal fibroblasts but EphA-driven repulsion when they contact one another. The impact of these ‘social’ interactions between cells during cancer cell invasion and the signalling mechanisms downstream of Eph receptors are unclear. Here we show that EphA receptors regulate prostate cancer cell dissemination in a 2D dispersal assay and in a 3D cancer cell spheroid assay. We show that EphA receptors signal via the exchange factor Vav2 to activate RhoA and that both Vav2 and RhoA are required for prostate cancer cell–cell repulsion. Furthermore, we find that in EphA2/EphA4, Vav2 or RhoA siRNA-treated cells, contact repulsion can be restored by partial microtubule destabilisation. We propose that EphA–Vav2–RhoA-mediated repulsion between contacting cancer cells at the tumour edge could enhance their local invasion away from the primary tumour.

. Environmental oxygen tension affects phenotype in cultured bone marrow-derived macrophages. Am J Physiol Lung Cell Mol Physiol 286: L354-L362, 2004. First published October 3, 2003 10.1152/ajplung.00380.2002This study tested the hypothesis that the unique phenotype of alveolar macrophages (AM) is maintained through adaptation to the relatively high oxygen partial pressure (PO 2) of the lung, through modification of redox-sensitive transcription factors. BALB/c mouse bone marrowderived macrophages (BMC) were differentiated under different PO 2 and compared functionally to AM and peritoneal macrophages (PM). BMC differentiated in normoxia (PO 2 140 Torr, BMChigh) were similar to AM in having low phagocytic and antigen presenting cell (APC) activities. However, BMC grown in low oxygen tension as found in other tissues (Ͻ40 Torr, BMC low) were better phagocytes and APCs, similar to PM. BMC high were more oxidative intracellularly than BMC low, based on oxidation of dichlorofluorescein and higher glutathione disulfide/glutathione (GSH) ratios, despite having more GSH. Finally, lipopolysaccharide-induced nuclear factor-B translocation, measured by laser scanning cytometry, was reduced in BMC high and AM, compared with BMClow and PM, respectively. These data suggest that regulation of the AM phenotype may occur, at least in part, via inhibition of NF-B by the unique redox environment.redox; alveolar macrophage; glutathione; nuclear factor-B

No abstract

Enhanced airway responsiveness (AR) is a well-established characteristic of asthma that epidemiological evidence has linked with inhalation of ambient particulate matter (PM). To determine whether acute exposure to urban particulate matter PM1648 can exacerbate airway responsiveness and alter the early inflammatory state, a unique murine model was created using DO11.10 mice, transgenic for a T cell receptor recognizing ovalbumin323-339. Because these mice are sensitive to ovalbumin, immunization procedures involving adjuvant or long aerosolization procedures are not necessary and, therefore, allow for the study of an acute AR response to particulate and antigen in young animals. AR was assessed by barometric whole body plethysmography and measured by enhanced pause (Penh). PM1648 and ovalbumin were administered intranasally 72 and 4 h before to AR assessment, respectively. A dose-response relationship between PM1648 and Penh was determined, and doses at or above 500 μg had Penh values significantly higher than saline controls. Penh values of control particle titanium dioxide (TiO2) were similar to saline controls demonstrating no nonspecific particulate effect on AR. Lung lavage at time of AR assessment showed no significant inflammation due to particulate exposure or ovalbumin alone; however, PM1648/ovalbumin and TiO2/ovalbumin combinations resulted in significant neutrophilia. In addition, treatment with polymyxin B to remove surface-bound endotoxin did not significantly affect Penh levels. These results indicate that PM1648 specifically increases AR in a dose-dependent manner and that this exacerbation is not a direct response to increased neutrophil concentration, particle-bound endotoxin or nonspecific particle effects.

Objective: Atherosclerosis contributes to 30% of deaths in systemic lupus erythematosus (SLE) and cardiovascular mortality is 50% higher in rheumatoid arthritis (RA) than in the general population. Little is known about mechanisms leading to progression of atherosclerosis at the cellular level. Here we analyze expression of key cholesterol transport proteins that impact atheroma development in BMDM from KRNAg7 (RA) and apoE‐/‐Fas‐/‐ (SLE) mice as disease evolves. Methods: Male homozygous C57BL/6J, apoE‐/‐ , apoE‐/‐Fas‐/‐ , KRN and KRNAg7 mice (n=5 per group) were studied. Femurs were dissected and cell suspensions obtained by flushing bones. BMDM were generated by culturing cells for 7 days with MCSF. Expression of efflux proteins ATP binding cassette transporters (ABC)A1 and ABCG1, and scavenger receptors CD36 and LOX1 were evaluated by QRT‐PCR. Results: 6 wk mice had no significant changes in cholesterol efflux proteins. 30 wk apoE‐/‐, apoE‐/‐Fas‐/‐ mice display 2‐fold reduction in ABCA1 and ABCG1 mRNA (n=3, P<0.01). 6 wk KRNAg7 mice show increased CD36 (225.5±54% vs. wt mice at 100%) (n=3, P<0.01). LOX‐1 did not differ significantly from C57BL/6J and KRN mice. ApoE‐/‐Fas‐/‐ mice had increase in CD36 mRNA (150±23% at 6 wk; 161.3±12.3% at 30 wk, n=3, P<0.05) LOX1 expression was unchanged. In contrast, apoE‐/‐ mice display a 2‐fold increase in both CD36 and LOX1 at 6 wk and up to a 5‐fold increase at 30 wk. Conclusions: This study provides insight into molecular alterations that contribute to atherogenesis in SLE and RA. We demonstrate that imbalance between cholesterol efflux and influx contributes to atherosclerosis progression. Further metabolic screening may identify optimal time‐points for intervention.