Lupus nephritis represents a common and serious complication of the autoimmune disease Systemic Lupus Erythematosus (SLE). Clinical studies suggest that several proteins related to iron metabolism, including transferrin, serve as urinary biomarkers of lupus nephritis. We previously reported that in female NZBWF1 mice, a commonly used mouse model of SLE with a female sex bias, increased urinary transferrin excretion and renal iron accumulation occur around the onset of albuminuria. The current study investigated whether similar findings occur in male mice of a different mouse model of SLE, the MRL/lpr mouse. Two different cohorts were studied: MRL/lpr mice at an early, pre-albuminuric age (8 weeks), and after developing albuminuria (>100 mg/dL, confirmed by ELISA); age-matched MRL/MpJ control strain mice served for comparison. Urinary transferrin excretion was dramatically increased in the older, albuminuric MRL/lpr mice compared to the age-matched MRL/MpJ (P < 0.05), but there was no significant difference between strains at 8 weeks of age. Similarly, there were no significant differences between strains in renal cortical or outer medullary non-heme iron concentrations at 8 weeks. In the older, albuminuric MRL/lpr mice, renal cortical and outer medullary non-heme iron concentrations were significantly increased compared with age-matched MRL/MpJ mice, as was the expression of the iron storage protein ferritin (P < 0.01). Together, these data show that increased urinary transferrin excretion and renal tissue iron accumulation also occurs in albuminuric male MRL/lpr mice, suggesting that renal iron accumulation may be a feature of multiple mouse models of SLE.

In Nebraska, fish are exposed to herbicides in agricultural runoff. The study objectives were to determine 1) if fathead minnows and northern leopard frogs exposed to atrazine experience alterations in gene expression, and 2) whether these changes are elicited by a simulated herbicide mixture. Following a 7-d exposure to atrazine, female minnows were defeminized, whereas male frogs were feminized. The mixture did not elicit statistically significant effects in either species. Environ Toxicol Chem 2018;37:1182-1188. © 2018 SETAC.

Metabolic syndrome (MetS) is common in Systemic Lupus Erythematosus (SLE) patients and is associated with increased cardio-renal risk. Toll-like receptor 7 (TLR7) stimulation promotes the development of SLE through mechanisms including activating type I Interferon (IFN) and autoreactive B cells. The current study tested whether combined TLR7 agonist treatment and exposure to a high fat, high sucrose “Western diet” intervention affects the early-stage development of SLE or MetS features. Female C57BL/6 mice were untreated or treated with the TLR7 agonist imiquimod (IMQ) and fed a high-fat diet (HFD; fat 42% kcal, sucrose 34% kcal) or control diet (fat 12.6% kcal, sucrose 34% kcal) for 6 weeks. Supporting early-stage induction of autoimmunity, spleen weights were significantly increased and anti-nuclear antibody (ANA) positivity was detected in IMQ-treated mice. Increased body weight, gonadal fat pad mass, and plasma leptin levels were observed between HFD and control animals for both IMQ and untreated mice. However, the increase in these parameters with HFD was slightly but significantly diminished in IMQ-treated mice. Both the HFD and IMQ treatments significantly increased fasting blood glucose levels. Notably, IMQ treatment affected fasting insulin concentrations in a diet-dependent manner, with hyperinsulinemia observed in IMQ-HFD treated mice. Together, this indicates that the IMQ model of SLE is associated with metabolic alterations, impaired glycemic control, and hyperinsulinemia under HFD conditions. This model may be helpful in further investigating the relationship between MetS and SLE, and supports a role of TLR7 signaling in promoting or accelerating the development of dysglycemia and hyperinsulinemia.

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Introduction The autoimmune disease systemic lupus erythematosus predominantly affects women and can lead to lupus nephritis (LN) as a common and severe complication in approximately 50% of patients. The F1 hybrid of New Zealand Black (NZB) X New Zealand White (NZW) mice (NZBWF1) is a well‐established mouse model to study LN. Our previous data indicated that the onset of albuminuria in female 34‐week NZBWF1 mice was associated with renal iron accumulation, and iron may contribute to renal injury. This study tests the hypothesis that 34‐week NZBWF1 lupus mice are sensitized to iron's injurious and pro‐inflammatory effects compared to 8‐week normal NZBWF1 mice. As a means to differentiate effects of age as opposed to development of lupus, parallel experiments were performed in 8 and 34‐week‐old NZW mice as healthy controls. Methods and Results Female 8‐week (pre‐autoimmune) and 34‐week NZBWF1 (autoimmune, pre‐albuminuric) mice together with age‐matched healthy control NZW mice underwent 24 h urine collection to confirm non‐albuminuric status. Mice were then were injected i.v. with a single dose of iron‐sucrose (2 mg elemental iron) or vehicle (saline) and sacrificed 24 h later. Plasma blood urea nitrogen (BUN) was measured to determine renal health, SRY‐Box Transcription Factor 9 (SOX‐9)‐ positive cells were quantified in kidney sections as an early tubular injury marker, and plasma monocyte chemoattractant protein‐1 (MCP‐1) was measured by ELISA as an inflammatory marker. Lupus (NZBWF1) and control mice (NZW) were compared within strains by age (8‐week vs. 34‐week) and treatment (Vehicle vs. Treatment). All statistical analyses were done by 2‐way ANOVA (n=7‐12/group), and post‐hoc testing was done using Bonferroni. Iron‐sucrose treatment significantly increased plasma MCP‐1 concentrations in the NZBWF1 and the control NZW mice (PTreatment < 0.01). There was no significant effect of age on this effect for NZW mice (PTreatment*Age = 0.2); however, in NZBWF1 mice, the iron‐sucrose induced increase in MCP‐1 was significantly greater in 34‐week compared to 8‐week mice (PTreatment*Age < 0.05; P<0.05 by posthoc test). BUN was significantly increased with age in both strains (PAge<0.05), but there was no significant effect of iron‐sucrose (PTreatment>0.05). The numbers of SOX‐9+ tubular cells increased in the 34‐week NZBWF1 mice compared to 8‐week mice (Page<0.05), consistent with early stages of renal injury, but iron sucrose treatment did not show any significant effect (PTreatment= 0.9). Conclusion Our data suggest that at the autoimmune but pre‐albuminuric stage, 34‐week NZBWF1 mice show increased pro‐inflammatory responsiveness to iron‐mediated stress. Further studies to determine whether the enhanced pro‐inflammatory effects of iron contribute to pathology in lupus nephritis are ongoing.