Studies of ApoD-/- and ApoD-/-ApoE-/- mice uncover the APOD significance for retinal metabolism, function, and status of chorioretinal blood vessels.

Apolipoprotein D (APOD) is an atypical apolipoprotein with unknown significance for retinal structure and function. Conversely, apolipoprotein E (APOE) is a typical apolipoprotein with established roles in retinal cholesterol transport. Herein, we immunolocalized APOD to the photoreceptor inner segments and conducted ophthalmic characterizations of ApoD-/- and ApoD-/-ApoE-/- mice. ApoD-/- mice had normal levels of retinal sterols but changes in the chorioretinal blood vessels and impaired retinal function. The whole-body glucose disposal was impaired in this genotype but the retinal glucose metabolism was unchanged. ApoD-/-ApoE-/- mice had altered sterol profile in the retina but apparently normal chorioretinal vasculature and function. The whole-body glucose disposal and retinal glucose utilization were enhanced in this genotype. OB-Rb, both leptin and APOD receptor, was found to be expressed in the photoreceptor inner segments and was at increased abundance in the ApoD-/- and ApoD-/-ApoE-/- retinas. Retinal levels of Glut4 and Cd36, the glucose transporter and scavenger receptor, respectively, were increased as well, thus linking APOD to retinal glucose and fatty acid metabolism and suggesting the APOD-OB-Rb-GLUT4/CD36 axis. In vivo isotopic labeling, transmission electron microscopy, and retinal proteomics provided additional insights into the mechanism underlying the retinal phenotypes of ApoD-/- and ApoD-/-ApoE-/- mice. Collectively, our data suggest that the APOD roles in the retina are context specific and could determine retinal glucose fluxes into different pathways. APOD and APOE do not play redundant, complementary or opposing roles in the retina, rather their interplay is more complex and reflects retinal responses elicited by lack of these apolipoproteins.

Pathological manifestation of autoimmune myocarditis is detected prior to glomerulonephritis in a murine model of lupus nephritis.

OBJECTIVE: Since enhanced cardiac magnetic resonance imaging (cMRI) signals have been associated with lupus disease activity in humans prior to renal failure and novel, cardiac-focused therapeutic strategies could be investigated with an associated animal model, autoimmune myocarditis was characterized in murine lupus nephritis (NZM2410). METHODS: Weekly blood urea nitrogen (BUN) levels and weights were recorded. Cardiac function was assessed by echocardiogram. Myocardial edema was measured with quantitative T2 cMRI mapping. Endpoint serum and cardiac tissue were collected for histopathological analysis and cytokine measurements. RESULTS: Despite showing no signs of significant renal disease, mice displayed evidence of myocarditis and fibrosis histologically at 30-35 weeks. Moreover, T2 cMRI mapping displayed robust signals and analysis of sagittal heart sections showed significant myocardium thickening. Cytokine expression levels of IL-2, IL-10, TNF-α, CXCL1, and IL-6 were significantly enhanced in serum. Echocardiograms demonstrated significantly increased ventricular diameters and reduced ejection fractions, while immunohistochemical staining identified CD4+ and CD8+ T cells, and IL-17 in cardiac infiltrates. Human lupus cardiac tissue showed similar histopathology with enhanced infiltrates by H&E, fibrosis, and CD4+ detection. CONCLUSIONS: Histopathology, functional abnormalities, and enhanced cMRI signals indicative of myocarditis are detected in NZM2410 mice without glomerulonephritis, which supports the primary pathological role of autoimmune-mediated, cardiac-targeted inflammation in lupus.

Physical activity prevents acute inflammation in a gout model by downregulation of TLR2 on circulating neutrophils as well as inhibition of serum CXCL1 and is associated with decreased pain and inflammation in gout patients.

OBJECTIVES: Gout is the most prevalent inflammatory arthritis. To study the effects of regular physical activity and exercise intensity on inflammation and clinical outcome, we examined inflammatory pathogenesis in an acute model of murine gout and analyzed human gout patient clinical data as a function of physical activity. METHODS: NF-κB-luciferase reporter mice were organized into four groups and exercised at 0 m/min (non-exercise), 8 m/min (low-intensity), 11 m/min (moderate-intensity), and 15 m/min (high-intensity) for two weeks. Mice subsequently received intra-articular monosodium urate (MSU) crystal injections (0.5mg) and the inflammatory response was analyzed 15 hours later. Ankle swelling, NF-κB activity, histopathology, and tissue infiltration by macrophages and neutrophils were measured. Toll-like receptor (TLR)2 was quantified on peripheral monocytes/neutrophils by flow cytometry and both cytokines and chemokines were measured in serum or synovial aspirates. Clinical data and questionnaires accessing overall physical activity levels were collected from gout patients. RESULTS: Injection of MSU crystals produced a robust inflammatory response with increased ankle swelling, NF-κB activity, and synovial infiltration by macrophages and neutrophils. These effects were partially mitigated by low and moderate-intensity exercise. Furthermore, IL-1ß was decreased at the site of MSU crystal injection, TLR2 expression on peripheral neutrophils was downregulated, and expression of CXCL1 in serum was suppressed with low and moderate-intensity exercise. Conversely, the high-intensity exercise group closely resembled the non-exercised control group by nearly all metrics of inflammation measured in this study. Physically active gout patients had significantly less flares/yr, decreased C-reactive protein (CRP) levels, and lower pain scores relative to physically inactive patients. CONCLUSIONS: Regular, moderate physical activity can produce a quantifiable anti-inflammatory effect capable of partially mitigating the pathologic response induced by intra-articular MSU crystals by downregulating TLR2 expression on circulating neutrophils and suppressing systemic CXCL1. Low and moderate-intensity exercise produces this anti-inflammatory effect to varying degrees, while high-intensity exercise provides no significant difference in inflammation compared to non-exercising controls. Consistent with the animal model, gout patients with higher levels of physical activity have more favorable prognostic data. Collectively, these data suggest the need for further research and may be the foundation to a future paradigm-shift in conventional exercise recommendations provided by Rheumatologists to gout patients.