Old Mice Demonstrate Organ Dysfunction as well as Prolonged Inflammation, Immunosuppression, and Weight Loss in a Modified Surgical Sepsis Model*

Abstract

Objectives: Our goal was to “reverse translate” the human response to surgical sepsis into the mouse by modifying a widely adopted murine intra-abdominal sepsis model to engender a phenotype that conforms to current sepsis definitions and follows the most recent expert recommendations for animal preclinical sepsis research. Furthermore, we aimed to create a model that allows the study of aging on the long-term host response to sepsis. Design: Experimental study. Setting: Research laboratory. Subjects: Young (3–5 mo) and old (18–22 mo) C57BL/6j mice. Interventions: Mice received no intervention or were subjected to polymicrobial sepsis with cecal ligation and puncture followed by fluid resuscitation, analgesia, and antibiotics. Subsets of mice received daily chronic stress after cecal ligation and puncture for 14 days. Additionally, modifications were made to ensure that “Minimum Quality Threshold in Pre-Clinical Sepsis Studies” recommendations were followed. Measurements and Main Results: Old mice exhibited increased mortality following both cecal ligation and puncture and cecal ligation and puncture + daily chronic stress when compared with young mice. Old mice developed marked hepatic and/or renal dysfunction, supported by elevations in plasma aspartate aminotransferase, blood urea nitrogen, and creatinine, 8 and 24 hours following cecal ligation and puncture. Similar to human sepsis, old mice demonstrated low-grade systemic inflammation 14 days after cecal ligation and puncture + daily chronic stress and evidence of immunosuppression, as determined by increased serum concentrations of multiple pro- and anti-inflammatory cytokines and chemokines when compared with young septic mice. In addition, old mice demonstrated expansion of myeloid-derived suppressor cell populations and sustained weight loss following cecal ligation and puncture + daily chronic stress, again similar to the human condition. Conclusions: The results indicate that this murine cecal ligation and puncture + daily chronic stress model of surgical sepsis in old mice adhered to current Minimum Quality Threshold in Pre-Clinical Sepsis Studies guidelines and met Sepsis-3 criteria. In addition, it effectively created a state of persistent inflammation, immunosuppression, and weight loss, thought to be a key aspect of chronic sepsis pathobiology and increasingly more prevalent after human sepsis.

Older Sepsis Survivors Suffer Persistent Disability Burden and Poor Long‐Term Survival

“…Older sarcopenic patients have anabolic resistance that makes them nonresponsive to nutritional interventions . Moreover, the dysregulated systemic immune response is clearly affected by aging . At baseline, older patients have alterations in adaptive immunity (decreased lymphocyte number and function) that makes them more susceptible to infectious challenges .…”

Single‐cell deconstruction of post‐sepsis skeletal muscle and adipose tissue microenvironments

“…The cecal ligation and puncture (CLP) model was performed as previously described 20,21 with minor modifications. Briefly, C57Bl/6 mice were anaesthetized using an IP injection of ketamine (Ketaset; Ketamine HCL Injection, USP 100 mg/mL)/ xylazine (AnaSed; Xylazine 20 mg/mL) dissolved in sterile saline.…”

Transcriptomic responses from improved murine sepsis models can better mimic human surgical sepsis

“…[6][7][8] Although the importance and accuracy of the Seok et al paper is not in question, some have questioned the subsequent reaction to its results. 9 "Strive for progress, not perfection" has been stated by some regarding animal research for inflammation and infection. 9 Our laboratory has been particularly active in trying to decipher if murine sepsis and trauma research can be clinically relevant, thus providing insights in underlying mechanisms and allowing the testing therapeutic interventions.…”

“…9 "Strive for progress, not perfection" has been stated by some regarding animal research for inflammation and infection. 9 Our laboratory has been particularly active in trying to decipher if murine sepsis and trauma research can be clinically relevant, thus providing insights in underlying mechanisms and allowing the testing therapeutic interventions. [9][10][11][12] Recently, the scientific community has published the "Minimum Quality Threshold in Pre-Clinical Sepsis Studies (MQTiPSS): "an international expert consensus initiative for improvement of animal modeling in sepsis".…”

“…9 Our laboratory has been particularly active in trying to decipher if murine sepsis and trauma research can be clinically relevant, thus providing insights in underlying mechanisms and allowing the testing therapeutic interventions. [9][10][11][12] Recently, the scientific community has published the "Minimum Quality Threshold in Pre-Clinical Sepsis Studies (MQTiPSS): "an international expert consensus initiative for improvement of animal modeling in sepsis". 13 Using "reverse translation" and following the recommendations of MQTiPPS, we created a murine model of surgical sepsis that was a significant improvement over pre-existing rodent sepsis models, especially in how it replicated the human disease.…”