Blue Light Enhances Bacterial Clearance and Reduces Organ Injury During Sepsis.

OBJECTIVES: The physiology of nearly all mammalian organisms are entrained by light and exhibit circadian rhythm. The data derived from animal studies show that light influences immunity, and these neurophysiologic pathways are maximally entrained by the blue spectrum. Here, we hypothesize that bright blue light reduces acute kidney injury by comparison with either bright red or standard, white fluorescent light in mice subjected to sepsis. To further translational relevance, we performed a pilot clinical trial of blue light therapy in human subjects with appendicitis. DESIGN: Laboratory animal research, pilot human feasibility trial. SETTING: University basic science laboratory and tertiary care hospital. SUBJECTS: Male C57BL/6J mice, adult (> 17 yr) patients with acute appendicitis. INTERVENTIONS: Mice underwent cecal ligation and puncture and were randomly assigned to a 24-hour photoperiod of bright blue, bright red, or ambient white fluorescent light. Subjects with appendicitis were randomized to receive postoperatively standard care or standard care plus high-illuminance blue light. MEASUREMENTS AND MAIN RESULTS: Exposure to bright blue light enhanced bacterial clearance from the peritoneum, reduced bacteremia and systemic inflammation, and attenuated the degree of acute kidney injury. The mechanism involved an elevation in cholinergic tone that augmented tissue expression of the nuclear orphan receptor REV-ERBα and occurred independent of alterations in melatonin or corticosterone concentrations. Clinically, exposure to blue light after appendectomy was feasible and reduced serum interleukin-6 and interleukin-10 concentrations. CONCLUSIONS: Modifying the spectrum of light may offer therapeutic utility in sepsis.

Use of Biotelemetry to Define Physiology-Based Deterioration Thresholds in a Murine Cecal Ligation and Puncture Model of Sepsis.

OBJECTIVES: Murine models of critical illness are commonly used to test new therapeutic interventions. However, these interventions are often administered at fixed time intervals after the insult, perhaps ignoring the inherent variability in magnitude and temporality of the host response. We propose to use wireless biotelemetry monitoring to define and validate criteria for acute deterioration and generate a physiology-based murine cecal ligation and puncture model that is more similar to the conduct of human trials of sepsis. DESIGN: Laboratory and animal research. SETTING: University basic science laboratory. SUBJECTS: Male C57BL/6 mice. INTERVENTIONS: Mice underwent cecal ligation and puncture, and an HD-X11 wireless telemetry monitor (Data Sciences International) was implanted that enabled continuous, real-time measurement of heart rate, core temperature, and mobility. We performed a population-based analysis to determine threshold criteria that met face validity for acute physiologic deterioration. We assessed construct validity by temporally matching mice that met these acute physiologic deterioration thresholds with mice that had not yet met deterioration threshold. We analyzed matched blood samples for blood gas, inflammatory cytokine concentration, cystatin C, and alanine aminotransferase. MEASUREMENTS AND MAIN RESULTS: We observed that a 10% reduction in both heart rate and temperature sustained for greater than or equal to 10 minutes defined acute physiologic deterioration. There was significant variability in the time to reach acute deterioration threshold across mice, ranging from 339 to 529 minutes after cecal ligation and puncture. We found adequate construct validity, as mice that met criteria for acute deterioration had significantly worse shock, systemic inflammation (elevated tumor necrosis factor-α, p = 0.003; interleukin-6, p = 0.01; interleukin-10, p = 0.005), and acute kidney injury when compared with mice that had not yet met acute deterioration criteria. CONCLUSIONS: We defined a murine threshold for acute physiologic deterioration after cecal ligation and puncture that has adequate face and construct validity. This model may enable a more physiology-based model for evaluation of novel therapeutics in critical illness.