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Seasonal Travel Stressors Modulates Hypertension in Adult Female Lupus Mice

Systemic lupus erythematosus (SLE) is linked to renal inflammation and hypertension. We use a murine
model of SLE (NZBWF1) that travels to our university pre-puberty (3–6 weeks), develop autoantibodies
(20 weeks), and become consistently hypertensive (35 weeks). We observed that autoantibodies were
higher in mice that traveled in summer vs. in winter, especially in mice that traveled to our university as
adults (18–19 weeks), suggesting that seasonal factors, travel stressors, and age alter disease severity. It
is unknown whether these alter inflammation and blood pressure. Thus, we hypothesized that travelinduced seasonal stressors exacerbate hypertension and renal inflammation in adult SLE mice. Female SLE
mice traveled to our university in summer or winter, pre-puberty or adulthood, and were implanted with
carotid catheters at 35 weeks to assess mean arterial pressure (MAP). Tissues were collected to monitor
plasma/renal proinflammatory interleukin (IL)-6. No seasonal differences were found in MAP of mice that
traveled pre-puberty in summer (n = 17) and winter (n = 39) (143.6 ± 3.5 vs. 140.2 ± 2.2 mmHg; p = 0.4096)
nor in plasma IL-6 (26.06 ± 7.25 vs. 15.54 ± 8.622 pg/mL; p = 0.2370) or renal IL-6 (0.01156 ± 0.00603 vs.
0.01099 ± 0.00523 pg/µg; p = 0.9445). Adult mice that traveled in summer had higher MAP than those
that traveled in winter (136.12 ± 2.63 vs. 128.81 ± 1.55 mmHg; p = 0.0339; n = 5–7), alongside higher
plasma IL-6 (723.28 ± 220.72 vs. 280.73 ± 67.99 pg/mL; p = 0.0339) and renal IL-6 (0.078956 ± 0.017192
vs. 0.023413 ± 0.003801 pg/µg; p < 0.0001). Our findings indicate that hypertension and renal
inflammation in mice subjected to travel stress as adults is seasonally dependent. Since there were no
seasonal differences in hypertension in mice that traveled pre-puberty, there may be a factor related to
age, seasonal environmental factors, and/or timing of the stressors that is causing the detrimental effect.