CTLA-4 Checkpoint Inhibition Improves Sepsis Survival in Alcohol-Exposed Mice.

Chronic alcohol use increases morbidity and mortality in the setting of sepsis. Both chronic alcohol use and sepsis are characterized by immune dysregulation, including overexpression of T cell coinhibitory molecules. We sought to characterize the role of CTLA-4 during sepsis in the setting of chronic alcohol exposure using a murine model of chronic alcohol ingestion followed by cecal ligation and puncture. Results indicated that CTLA-4 expression is increased on CD4+ T cells isolated from alcohol-drinking septic mice as compared with either alcohol-drinking sham controls or water-drinking septic mice. Moreover, checkpoint inhibition of CTLA-4 improved sepsis survival in alcohol-drinking septic mice, but not water-drinking septic mice. Interrogation of the T cell compartments in these animals following pharmacologic CTLA-4 blockade, as well as following conditional Ctla4 deletion in CD4+ T cells, revealed that CTLA-4 deficiency promoted the activation and proliferation of effector regulatory T cells and the generation of conventional effector memory CD4+ T cells. These data highlight an important role for CTLA-4 in mediating mortality during sepsis in the setting of chronic alcohol exposure and may inform future approaches to develop targeted therapies for this patient population.

Achieving durable compliance with venous thromboembolism prophylaxis in bariatric surgery: 3-year data from a major academic medical center.

BACKGROUND: Metabolic and bariatric surgery (MBS) venous thromboembolism (VTE) prescribing practices vary widely. Our institutional VTE prophylaxis protocol has historically been unstandardized. OBJECTIVES: To create a standardized MBS VTE prophylaxis protocol, track protocol compliance, and identify barriers to protocol compliance and address them with Plan-Do-Study-Act (PDSA) cycles. SETTING: Single Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program-accredited academic hospital. METHODS: We conducted a retrospective study for all patients undergoing MBS (January 2019 to September 2022). A multidisciplinary group of bariatric clinicians reviewed literature and developed the following standardized VTE prophylaxis protocol: 5000 units preoperative subcutaneous (SC) heparin within 60 minutes of anesthesia induction and postoperative 40 mg SC low molecular weight heparin (LMWH) within 24 hours of surgery. This protocol was distributed to relevant clinical stakeholders. We assessed monthly compliance rates through chart review. Goal compliance was ≥90%. We identified sources of noncompliance and addressed them with PDSA methodology. RESULTS: A total of 796 patients were included. Preoperative heparin administration increased from a mean of 47% (107/228) preintervention to 96% (545/568) postintervention (P < .0001), and postoperative LMWH administration increased from 71% (47/66) to 96% (573/597, P = .0002). These compliance rates were sustained for 3 years. Barriers to protocol noncompliance included order set timing errors (n = 45), surgeon error (n = 44), surgeon discretion (n = 40), and nursing error (n = 20). No change in bleeding or VTE rates was observed. CONCLUSIONS: Developing a standardized VTE prophylaxis protocol, monitoring process measures, and engaging relevant stakeholders in PDSA cycles resulted in drastic and durable improvement in VTE prophylaxis compliance rates.

Should Robot-Assisted Surgery Tolerate or Even Accommodate Less Surgical Dexterity?

Since their adoption during the 1990s, minimally invasive surgical techniques have demonstrated postoperative surgical recovery benefits for patients. As robotic surgery platforms continue to be developed and utilized in surgical specialty areas, dexterity and visual field limitations of laparoscopy are coming under close clinical and ethical scrutiny. This article compares robotic and laparoscopic modalities, with special attention to dexterity, surgeon performance, ergonomics, and patient outcomes. This article also examines robotic platforms' advantages for surgeons' technical capacity and career longevity.

Does the use of a suction calibration system (SCS) reduce stapler load firings and operative time? A randomized controlled trial comparing use of endoscopic calibration vs. SCS in laparoscopic sleeve gastrectomy.

BACKGROUND: It is critical to ensure appropriate and consistent sleeve size and orientation during laparoscopic sleeve gastrectomy (LSG). Various devices are used to achieve this, including weighted rubber bougies, esophagogastroduodenoscopy (EGD), and suction calibration systems (SCS). Prior reports suggest that SCSs may decrease operative time and stapler load firings but are limited by single-surgeon experience and retrospective design. We performed the first randomized controlled trial comparing SCS against EGD in patients undergoing LSG to investigate whether the SCS decreases the number of stapler load firings. METHODS: This was a randomized, non-blinded study from a single MBSAQIP-accredited academic center. Appropriate LSG candidates ≥ 18 years of age were randomized to EGD or SCS calibration. Exclusion criteria included prior gastric or bariatric surgery, detection of hiatal hernia before surgery, and intraoperative hiatal hernia repair. A randomized block design was employed controlling for body mass index, gender, and race. Seven surgeons employed a standardized LSG operative technique. The primary endpoint was the number of stapler load firings. Secondary endpoints were operative duration, reflux symptoms, and change in total body weight (TBW). Endpoints were analyzed via t-test. RESULTS: A total of 125 LSG patients (84% female) underwent study enrollment, with an average age of 44 ± 12 years and average BMI of 49 ± 8 kg/m2. Overall, 117 patients were randomized to receive EGD (n = 59) or SCS (n = 58) calibration. No significant differences in baseline characteristics were identified. The mean number of stapler load firings for EGD and SCS groups were 5.43 ± 0.89 and 5.31 ± 0.81, respectively (p = 0.463). The mean operative times for EGD and SCS groups were 94.4 ± 36.5 and 93.1 ± 27.9 min, respectively (p = 0.83). There were no significant differences in post-operative reflux, TBW loss, or complications. CONCLUSION: Use of EGD and SCS resulted in a similar number of LSG stapler load firings and operative duration. Additional research is needed to compare LSG calibration devices in different patients and settings to optimize surgical technique.

The financial impact of the COVID-19 pandemic on sleeve gastrectomy at a major academic institution.

INTRODUCTION: The COVID-19- pandemic significantly impacted metabolic and bariatric surgery (MBS) practices due to large-scale surgery cancellations along with staff and supply shortages. We analyzed sleeve gastrectomy (SG) hospital-level financial metrics before and after the COVID-19 pandemic. METHODS: Hospital cost-accounting software (MicroStrategy, Tysons, VA) was reviewed for revenues, costs, and profits per SG at an academic hospital (2017-2022). Actual figures were obtained, not insurance charge estimates or hospital projections. Fixed costs were obtained through surgery-specific allocation of inpatient hospital and operating-room costs. Direct variable costs were analyzed with sub-components including: (1) labor and benefits, (2) implants, (3) drug costs, and 4) medical/surgical supplies. The pre-COVID-19 period (10/2017-2/2020) and post-COVID-19 period (5/2020-9/2022) financial metrics were compared with student's t-test. Data from 3/2020 to 4/2020 were excluded due to COVID-19-related changes. RESULTS: A total of 739 SG patients were included. Average length of stay (LOS), Center for Medicaid and Medicare Case Mix Index (CMI), and percentage of patients with commercial insurance were similar pre vs. post-COVID-19 (p > 0.05). There were more SG performed per quarter pre-COVID-19 than post-COVID-19 (36 vs. 22; p = 0.0056). Pre-COVID-19 and post-COVID-19 financial metrics per SG differed significantly for, respectively, revenues ($19,134 vs. $20,983) total variable cost ($9457 vs. $11,235), total fixed cost ($2036 vs. $4018), total profit ($7571 vs. $5442), and labor and benefits cost ($2535 vs. $3734; p < 0.05). CONCLUSIONS: The post-COVID-19 period was characterized by significantly increased SG fixed cost (i.e., building maintenance, equipment, overhead) and labor costs (increased contract labor), resulting in precipitous profit decline that crosses the break-even in calendar year quarter (CQ) 3, 2022. Potential solutions include minimizing contract labor cost and decreasing LOS.

Junctional adhesion molecule-A deletion increases phagocytosis and improves survival in a murine model of sepsis.

Expression of the tight junction-associated protein junctional adhesion molecule-A (JAM-A) is increased in sepsis, although the significance of this is unknown. Here, we show that septic JAM-A -/- mice have increased gut permeability, yet paradoxically have decreased bacteremia and systemic TNF and IL-1ß expression. Survival is improved in JAM-A-/- mice. However, intestine-specific JAM-A-/- deletion does not alter mortality, suggesting that the mortality benefit conferred in mice lacking JAM-A is independent of the intestine. Septic JAM-A-/- mice have increased numbers of splenic CD44hiCD4+ T cells, decreased frequency of TNF+CD4+ cells, and elevated frequency of IL-2+CD4+ cells. Septic JAM-A-/- mice have increased numbers of B cells in mesenteric lymph nodes with elevated serum IgA and intraepithelial lymphocyte IgA production. JAM-A-/- × RAG-/- mice have improved survival compared with RAG-/- mice and identical mortality as WT mice. Gut neutrophil infiltration and neutrophil phagocytosis are increased in JAM-A-/- mice, while septic JAM-A-/- mice depleted of neutrophils lose their survival advantage. Therefore, increased bacterial clearance via neutrophils and an altered systemic inflammatory response with increased opsonizing IgA produced through the adaptive immune system results in improved survival in septic JAM-A-/- mice. JAM-A may be a therapeutic target in sepsis via immune mechanisms not related to its role in permeability.

How We Do It: Remediation Pathways in a Surgical Simulation Curriculum for Competency Improvement.

OBJECTIVE: Validated assessment of procedural knowledge and skills with formative remediation is a foundational part of achieving surgical competency. High-fidelity simulation programs provide a unique area to assess resident proficiency and independence, as well as to assist in identifying residents in need of further practice. While several studies have validated the use of simulation to attain proficiency of specific technical skills, few have validated remediation pathways for their trainees objectively. In this descriptive analysis, we review 2 remediation pathways within our simulation training curricula and how these are used in assessments of resident proficiency. MATERIALS AND METHODS: Two methods of remediation were formulated for use in high-fidelity simulation labs. One remediation pathway was a summative process, where ultimate judgment of resident competency was assessed through intra-operative assessments of a holistic skill set. The second remediation pathway was a formative "coaching" process, where feedback is given at several intervals along the pathway towards a specific technical skills competence. All general surgery residents are enrolled in the longitudinal, simulation curricula. RESULTS: Approximately one-third of surgical residents entered into a remediation pathway for either of the high-fidelity simulation curricula. Both residents and faculty expressed support for the summative and formative remediation pathways as constructed. Residents who entered remediation pathways believed it was a beneficial exercise, and the most common feedback was that remediation principles should be expanded to all residents. Interestingly, faculty demonstrated stronger support for the formative coaching feedback model than the summative assessment model. CONCLUSIONS: Through the complementary use of both formative and summative remediation pathways, resident competence can be enriched in a constructive, nonpunitive method for self-directed performance improvement. Both trainees and faculty express high satisfaction with programs explicitly organized to ensure that skills are rated through a standardized process.

Development of a laparoscopic surgical skills simulation curriculum: Enhancing resident training through directed coaching and closed-loop feedback.

BACKGROUND: Performance feedback through peer coaching and rigorous self-assessment is a critical part of technical skills improvement. However, formal collaborative programs using operative video-based skills assessments to generate peer coaching feedback have only been validated among attending surgeons. In this study, we developed a unique longitudinal, simulation video-based laparoscopic skills resident curriculum using video-based peer coaching and evaluated its association with skills acquisition among surgical trainees. METHODS: The laparoscopic simulation curriculum consists of a pre-practice laparoscopic skill video recording, followed by receipt of directed coaching and feedback on performance from a faculty coach, a peer coach, and self-coaching. Residents then completed 6 weeks of feedback-directed practice and submitted a second post-practice laparoscopic skill video recording of the same skill, which was evaluated by a minimally invasive surgery expert grader. All general surgery residents in a single institution were enrolled, with 107 residents completing the curriculum in its initial 2 years. RESULTS: Overall, more than two-thirds of residents achieved skills proficiency on their expert assessments, with similar rates of residents achieving skills proficiency at all postgraduate year levels. Significant improvements between the pre-practice assessments and post-practice assessments were most frequently seen in the instrument handling, precision, and motion & flow categories (P < .05 each). Faculty provided the highest number and proportion of closed-loop comments; residents' self-coaching feedback had the lowest number of closed-loop comments, with 83% of self-assessments containing none. CONCLUSION: In this study, we describe the successful implementation of a longitudinal laparoscopic skills video-based coaching curriculum designed to improve residents' laparoscopic technical abilities through iterative directed practice supplemented by formative closed-loop feedback. This feasible, reproducible, and low-cost simulation curriculum can be adapted to other training programs and skills acquisition endeavors. This program also prepares trainees for ongoing performance feedback after completion of residency through rigorous self-assessment and peer-to-peer coaching.

Pneumococcal Disease Outbreak at a State Prison, Alabama, USA, September 1-October 10, 20181.

A pneumococcal disease outbreak caused by Streptococcus pneumoniae serotype 12F occurred in a state prison in Alabama, USA. Among 1,276 inmates, 40 cases were identified (3 confirmed, 2 probable, 35 suspected). Close living quarters, substance use, and underlying conditions likely contributed to disease risk. Prophylaxis for close contacts included azithromycin and 23-valent pneumococcal polysaccharide vaccine.

Patterns of Antibiotic Nonsusceptibility Among Invasive Group A Streptococcus Infections-United States, 2006-2017.

BACKGROUND: Treatment of severe group A Streptococcus (GAS) infections requires timely and appropriate antibiotic therapy. We describe the epidemiology of antimicrobial-resistant invasive GAS (iGAS) infections in the United States (US). METHODS: We analyzed population-based iGAS surveillance data at 10 US sites from 2006 through 2017. Cases were defined as infection with GAS isolated from normally sterile sites or wounds in patients with necrotizing fasciitis or streptococcal toxic shock syndrome. GAS isolates were emm typed. Antimicrobial susceptibility was determined using broth microdilution or whole genome sequencing. We compared characteristics among patients infected with erythromycin-nonsusceptible (EryNS) and clindamycin-nonsusceptible (CliNS) strains to those with susceptible infections. We analyzed proportions of EryNS and CliNS among isolates by site, year, risk factors, and emm type. RESULTS: Overall, 17 179 iGAS cases were reported; 14.5% were EryNS. Among isolates tested for both inducible and constitutive CliNS (2011-2017), 14.6% were CliNS. Most (99.8%) CliNS isolates were EryNS. Resistance was highest in 2017 (EryNS: 22.8%; CliNS: 22.0%). All isolates were susceptible to ß-lactams. EryNS and CliNS infections were most frequent among persons aged 18-34 years and in persons residing in long-term care facilities, experiencing homelessness, incarcerated, or who injected drugs. Patterns varied by site. Patients with nonsusceptible infections were significantly less likely to die. The emm types with >30% EryNS or CliNS included types 77, 58, 11, 83, and 92. CONCLUSIONS: Increasing prevalence of EryNS and CliNS iGAS infections in the US is predominantly due to expansion of several emm types. Clinicians should consider local resistance patterns when treating iGAS infections.

Optimal Management of the Hyperkinetic Gallbladder: A Comparison of Outcomes Between Operative and Nonoperative Approaches.

BACKGROUND: A hyperkinetic gallbladder is defined as a hepatobiliary iminodiacetic acid (HIDA) scan ejection fraction (EF) of >80%. This condition is poorly described, and there is no current consensus on optimal management. The intent of this study was to determine if cholecystectomy improves symptoms in patients with a hyperkinetic gallbladder when compared to those managed nonoperatively and if there were variables predictive of symptom improvement with or without cholecystectomy. MATERIALS AND METHODS: This retrospective study included patients from 3 academic hospitals in the Atlanta metro area between the years 2006 and 2018. All patients with an EF >80% were included. Following voluntary exclusion patients were contacted by phone. Each patient was administered a questionnaire regarding their surgical history, medical management, and current symptom profile via Otago score. Institutional Institutional Review Board approval was obtained. RESULTS: 4785 HIDA scans were performed, and 194 reported an EF >80% (incidence 15.7%). 96% of these scans were reported as normal by the radiologist. 68 patients were able to be contacted by phone and completed the questionnaire. 18 patients underwent cholecystectomy, and 89% reported that their symptoms attributed to gallbladder disease were no longer present. 50 patients did not undergo cholecystectomy, and alternate diagnoses, medication prescriptions, diet modification, emergency department visits, and Otago score were higher in this cohort. DISCUSSION: Patients who undergo cholecystectomy for a diagnosis of hyperkinetic gallbladder, on average, report improvement in symptoms when compared to patients managed nonoperatively. This study supports the practice of reporting and managing hyperkinetic gallbladders as a pathologic entity.

A longitudinal cadaver-based simulation curriculum creates sustainable increases in resident confidence and exposure to fundamental techniques: Results of a 5-year program evaluation.

INTRODUCTION: For the past five years, our surgical residency program has led a cadaver-based simulation course focused on fundamental surgical maneuvers. This study aimed to quantify the impact of this course on resident exposure to surgical skills and longitudinal impact on resident education. METHODS: General surgery residents participated in an annual cadaver-based simulation curriculum. Participants completed surveys regarding improvements in knowledge and confidence; these results were stratified between course iterations (P1: 2 years, 2014-15; P2: 3 years, 2016-2018). RESULTS: Residents reported a sustained increase in knowledge of anatomy and technical dissection, confidence in performing operative skills independently, and exposure to operative skills that were otherwise not encountered in clinical rotations. Junior residents demonstrated an increase in gaining skills they would otherwise not achieve (87% vs. 98%, p = 0.028) and confidence to safely perform these procedures in the clinical setting (94% vs. 100%, p = 0.077). CONCLUSION: This annual, longitudinal cadaver-based skills course focused on fundamental maneuvers demonstrates a sustained impact in resident and faculty surgical confidence in resident's operative skills as a component of a longitudinal simulation curriculum to enhance competency-based promotion.

A Novel Approach to Managing a Strangulated De Garengeot's Hernia.

De Garengeot's hernia, the presence of an incarcerated vermiform appendix within a femoral hernia, is a rare general surgery emergency that predominantly affects elderly female patients. Due to its rarity, there is significant variation in surgical technique; however, most case reports favor an open approach. Here we present a case of a De Garengeot's hernia with a unique hybrid open and laparoscopic repair, utilizing the hernia defect as a port site. We will also review the relevant literature.

Assessment of Health Care Exposures and Outcomes in Adult Patients With Sepsis and Septic Shock.

Importance: Current information on the characteristics of patients who develop sepsis may help in identifying opportunities to improve outcomes. Most recent studies of sepsis epidemiology have focused on changes in incidence or have used administrative data sets that provided limited patient-level data. Objective: To describe sepsis epidemiology in adults. Design, Setting, and Participants: This retrospective cohort study reviewed the medical records, death certificates, and hospital discharge data of adult patients with sepsis or septic shock who were discharged from the hospital between October 1, 2014, and September 30, 2015. The convenience sample was obtained from hospitals in the Centers for Disease Control and Prevention Emerging Infections Program in 10 states (California, Colorado, Connecticut, Georgia, Maryland, Minnesota, New Mexico, New York, Oregon, and Tennessee). Patients 18 years and older with discharge diagnosis codes for severe sepsis or septic shock were randomly selected. Data were analyzed between May 1, 2018, and January 31, 2019. Main Outcomes and Measures: The population's demographic characteristics, health care exposures, and sepsis-associated infections and pathogens were described, and risk factors for death within 30 days after sepsis diagnosis were assessed. Results: Among 1078 adult patients with sepsis (569 men [52.8%]; median age, 64 years [interquartile range, 53-75 years]), 973 patients (90.3%) were classified as having community-onset sepsis (ie, sepsis diagnosed within 3 days of hospital admission). In total, 654 patients (60.7%) had health care exposures before their hospital admission for sepsis; 260 patients (24.1%) had outpatient encounters in the 7 days before admission, and 447 patients (41.5%) received medical treatment, including antimicrobial drugs, chemotherapy, wound care, dialysis, or surgery, in the 30 days before admission. A pathogen associated with sepsis was found in 613 patients (56.9%); the most common pathogens identified were Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, and Clostridioides difficile. After controlling for other factors, an association was found between underlying comorbidities, such as cirrhosis (odds ratio, 3.59; 95% CI, 2.03-6.32), immunosuppression (odds ratio, 2.52; 95% CI, 1.81-3.52), vascular disease (odds ratio, 1.54; 95% CI, 1.10-2.15), and 30-day mortality. Conclusions and Relevance: Most adults experienced sepsis onset outside of the hospital and had recent encounters with the health care system. A sepsis-associated pathogen was identified in more than half of patients. Future efforts to improve sepsis outcomes may benefit from examination of health maintenance practices and recent health care exposures as potential opportunities among high-risk patients.

The gut microbiome alters immunophenotype and survival from sepsis.

The microbiome is increasingly implicated in immune regulation and mortality from sepsis. Mice with identical genetic backgrounds but distinct microbiomes were obtained from different vendors and analyzed following cecal ligation and puncture (CLP). ß diversity of the microbiome measured from feces demonstrated significant differences between The Jackson Laboratory (Jax; Bar Harbor, ME, USA) and Charles River Laboratories (CR; Wilmington, MA, USA) C57/B6 mice. Jax mice had 7-d mortality of 90% following CLP, whereas CR mice had a mortality of 53%. Differences in vendor were associated with altered immunophenotype with increased splenic IFN-γ+CD4+ T cells, effector memory CD4+ T cells, and central memory CD4+ T cells and increased Peyer's patch effector memory CD4+ T cells in septic CR mice. To determine whether differences in the microbiome were responsible for these differences, Jax and CR mice were cohoused for 3 wk, after which they assumed a similar microbiota composition. Cohoused mice had improved survival following CLP compared to Jax mice and had similar survival regardless of their vendor of origin. All differences in immunophenotype between septic Jax and CR mice disappeared following cohousing. These findings suggest that the microbiome plays a crucial role in survival and the host immune response from sepsis and represents a potential target for therapeutic intervention.-Fay, K. T., Klingensmith, N. J., Chen, C.-W., Zhang, W., Sun, Y., Morrow, K. N., Liang, Z., Burd, E. M., Ford, M. L., Coopersmith, C. M. The gut microbiome alters immunophenotype and survival from sepsis.

Antenatal and intrapartum nucleic acid amplification test use for group B Streptococcus screening-United States, 2016.

Perinatal group B Streptococcus (GBS) disease prevention guidelines in 2010 allowed for processing of screening specimens by nucleic acid amplification tests (NAATs); however, the extent of NAAT use is unknown. A 2016 laboratory survey sent to 10 surveillance sites found that 18.7% of responding laboratories offered NAAT for GBS screening (antenatal only: 7.3%; intrapartum only: 4.1%; both: 3.4%).

Regulators of Intestinal Epithelial Migration in Sepsis.

The gut is a continuously renewing organ, with cell proliferation, migration, and death occurring rapidly under basal conditions. As the impact of critical illness on cell movement from crypt base to villus tip is poorly understood, the purpose of this study was to determine how sepsis alters enterocyte migration. Wild-type, transgenic, and knockout mice were injected with 5-bromo-2'deoxyuridine (BrdU) to label cells in S-phase before and after the onset of cecal ligation and puncture and were sacrificed at predetermined endpoints to determine distance proliferating cells migrated up the crypt-villus unit. Enterocyte migration rate was decreased from 24 to 96 h after sepsis. BrdU was not detectable on villi 6 days after sham laparotomy, meaning all cells had migrated the length of the gut and been exfoliated into its lumen. However, BrdU positive cells were detectable on villi 10 days after sepsis. Multiple components of gut integrity altered enterocyte migration. Sepsis decreased crypt proliferation, which further slowed enterocyte transit as mice injected with BrdU after the onset of sepsis (decreased proliferation) had slower migration than mice injected with BrdU before the onset of sepsis (normal proliferation). Decreasing intestinal apoptosis via gut-specific overexpression of Bcl-2 prevented sepsis-induced slowing of enterocyte migration. In contrast, worsened intestinal hyperpermeability by genetic deletion of JAM-A increased enterocyte migration. Sepsis therefore significantly slows enterocyte migration, and intestinal proliferation, apoptosis and permeability all affect migration time, which can potentially be targeted both genetically and pharmacologically.

Chronic Alcohol Ingestion Worsens Survival and Alters Gut Epithelial Apoptosis and CD8+ T Cell Function After Pseudomonas Aeruginosa Pneumonia-Induced Sepsis.

Mortality is higher in septic patients with a history of alcohol use disorder than in septic patients without a history of chronic alcohol usage. We have previously described a model of chronic alcohol ingestion followed by sepsis from cecal ligation and puncture in which alcohol-fed septic mice have higher mortality than water-fed septic mice, associated with altered gut integrity and increased production of TNF and IFNγ by splenic CD4 T cells without alterations in CD8 T cell function. The purpose of this study was to determine whether this represents a common host response to the combination of alcohol and sepsis by creating a new model in which mice with chronic alcohol ingestion were subjected to a different model of sepsis. C57Bl/6 mice were randomized to receive either alcohol or water for 12 weeks and then subjected to Pseudomonas aeruginosa pneumonia. Mice were sacrificed either 24 hours after the onset of sepsis or followed for survival. Alcohol-fed septic mice had significantly higher 7-day mortality than water-fed septic mice (96% vs 58%). This was associated with a 5-fold increase in intestinal apoptosis in alcohol-fed septic animals, accompanied by an increase in the pro-apoptotic protein Bax. Serum IL-6 levels were higher and IL-2 levels were lower in alcohol-fed septic mice. In contrast, CD8 T cell frequency was lower in alcohol-fed mice than water-fed septic mice, associated with increased production of IFNγ and TNF in stimulated splenocytes. No significant differences were noted in CD4 T cells, lung injury or bacteremia. Mice with chronic alcohol ingestion thus have increased mortality regardless of their septic insult, associated with changes in both the gut and the immune system.

Increased mortality in CD43-deficient mice during sepsis.

CD43 is a large transmembrane protein involved in T cell activation. Previous studies of CD43-/- mice in viral models have demonstrated a role for CD43 in Th1/Th2 skewing, activation of Foxp3+ Treg, and T cell apoptosis. However, the role of CD43 during sepsis has never been tested. Thus, we interrogated the role of CD43 during sepsis using a murine cecal ligation and puncture (CLP) model, and found that CD43-/- mice demonstrated significantly worsened mortality compared to B6 mice following CLP. Phenotypic analysis of splenocytes isolated 24 h after septic insult revealed significantly increased apoptosis of central memory cells in both CD4+ and CD8+ T cell compartments in CD43-/- septic mice compared to WT septic mice. Furthermore, CD43-/-septic mice exhibited a prominent Th2 skewing following sepsis relative to WT septic mice, as evidenced by a significant decrease in the frequency of IL-2+ CXCR3+ TH1 cells as a significant increase in the frequency of IL-4+ CCR4+ TH2 cells. Finally, septic CD43-/- animals contained significantly fewer CD25+ Foxp3+ TReg cells as compared to WT septic animals. Importantly, depleting CD25+ Treg eliminated the increased mortality observed in CD43-/- mice. Taken together, these data demonstrate an important role of CD43 in modulating immune dysregulation and mortality following sepsis.

CXCR4 blockade decreases CD4+ T cell exhaustion and improves survival in a murine model of polymicrobial sepsis.

Sepsis is a dysregulated systemic response to infection involving many inflammatory pathways and the induction of counter-regulatory anti-inflammatory processes that results in a state of immune incompetence and can lead to multi-organ failure. CXCR4 is a chemokine receptor that, following ligation by CXCL12, directs cells to bone marrow niches and also plays an important role in T cell cosignaling and formation of the immunological synapse. Here, we investigated the expression and function of CXCR4 in a murine model of polymicrobial sepsis. Results indicate that CXCR4 is selectively upregulated on naïve CD4+ and CD8+ T cells and CD4+ central memory T cells following the induction of sepsis, and that CXCR4 antagonism resulted in a significant decrease in sepsis-induced mortality. We probed the mechanistic basis for these findings and found that CXCR4 antagonism significantly increased the number of peripheral CD4+ and CD8+ T cells following sepsis. Moreover, mice treated with the CXCR4 antagonist contained fewer PD-1+ LAG-3+ 2B4+ cells, suggesting that blockade of CXCR4 mitigates CD4+ T cell exhaustion during sepsis. Taken together, these results characterize CXCR4 as an important pathway that modulates immune dysfunction and mortality following sepsis, which may hold promise as a target for future therapeutic intervention in septic patients.