Anatomic Lung Resection Outcomes After Implementation of a Universal Thoracic ERAS Protocol Across a Diverse Health Care System.

OBJECTIVE: We sought to evaluate how implementing a thoracic enhanced recovery after surgery (ERAS) protocol impacted surgical outcomes after elective anatomic lung resection. BACKGROUND: The effect of implementing the ERAS Society/European Society of Thoracic Surgery thoracic ERAS protocol on postoperative outcomes throughout an entire health care system has not yet been reported. METHODS: This was a prospective cohort study within one health care system (January 2019-March, 2023). A thoracic ERAS protocol was implemented on May 1, 2021 for elective anatomic lung resections, and postoperative outcomes were tracked using the electronic health record and Vizient data. The primary outcome was overall morbidity; secondary outcomes included individual complications, length of stay, opioid use, chest tube duration, and total cost. Patients were grouped into pre-ERAS and post-ERAS cohorts. Bivariable comparisons were performed using independent t -test, χ 2 , or Fisher exact tests, and multivariable logistic regression was performed to control for confounders. RESULTS: There were 1007 patients in the cohort; 450 (44.7%) were in the post-ERAS group. Mean age was 66.2 years; most patients were female (65.1%), white (83.8%), had a body mass index between 18.5 and 29.9 (69.7%), and were ASA class 3 (80.6%). Patients in the postimplementation group had lower risk-adjusted rates of any morbidity, respiratory complication, pneumonia, surgical site infection, arrhythmias, infections, opioid usage, ICU use, and shorter postoperative length of stay (all P <0.05). CONCLUSIONS: Postoperative outcomes were improved after the implementation of an evidence-based thoracic ERAS protocol throughout the health care system. This study validates the ERAS Society/European Society of Thoracic Surgery guidelines and demonstrates that simultaneous multihospital implementation can be feasible and effective.

Induction Chemotherapy Plus Neoadjuvant Chemoradiation for Esophageal and Gastroesophageal Junction Adenocarcinoma.

BACKGROUND: Neoadjuvant chemotherapy with concurrent radiotherapy (nCRT) is an accepted treatment regimen for patients with potentially curable esophageal and gastroesophageal junction (GEJ) adenocarcinoma. The purpose of this study is to evaluate whether induction chemotherapy (IC) before nCRT is associated with improved pathologic complete response (pCR) and overall survival (OS) when compared with patients who received nCRT alone for esophageal and GEJ adenocarcinoma. METHODS: Using the National Cancer Database (NCDB), patients who received nCRT and curative-intent esophagectomy for esophageal or GEJ adenocarcinoma from 2006 to 2015 were included. Chemotherapy and radiation therapy start dates were used to define cohorts who received IC before nCRT (IC + nCRT) versus those who only received concurrent nCRT before surgery. Propensity weighting was conducted to balance patient, disease, and facility covariates between groups. RESULTS: 12,460 patients met inclusion criteria, of whom 11,880 (95%) received nCRT and 580 (5%) received IC + nCRT. Following propensity weighting, OS was significantly improved among patients who received IC + nCRT versus nCRT (HR 0.82; 95% CI 0.74-0.92; p < 0.001) with median OS for the IC + nCRT cohort of 3.38 years versus 2.45 years for nCRT. For patients diagnosed from 2013 to 2015, IC + nCRT was also associated with higher odds of pCR compared with nCRT (OR 1.59; 95% CI 1.14-2.21; p = 0.007). CONCLUSION: IC + nCRT was associated with a significant OS benefit as well as higher pCR rate in the more modern patient cohort. These results merit consideration of a sufficiently powered prospective multiinstitutional trial to further evaluate these observed differences.

Conversion to open surgery during minimally invasive esophagectomy portends worse short-term outcomes: an analysis of the National Cancer Database.

OBJECTIVE: The objectives were to determine factors associated with conversion to open surgery in patients with esophageal cancer who underwent minimally invasive esophagectomy (MIE, including laparo-thoracoscopic and robotic) and the impact of conversion to open surgery on patient outcomes. METHODS: We included patients from the National Cancer Database with esophageal and gastroesophageal junction cancer who underwent MIE from 2010 to 2015. Patient-, tumor-, and facility-related characteristics as well as short-term and oncologic outcomes were compared between patients who were converted to open surgery and those who underwent successful MIE without conversion to open surgery. Multivariable logistic regression models were used to analyze risk factors for conversion to open surgery from attempted MIE. RESULTS: 7306 patients underwent attempted MIE. Of these patients, 82 of 1487 (5.2%) robotic-assisted esophagectomies were converted to open, compared to 691 of 5737 (12.0%) laparo-thoracoscopic esophagectomies (p < 0.001). Conversion rates decreased significantly over the study period (ptrend = 0.010). Patient age, tumor size, and nodal involvement were independently associated with conversion. Facility minimally invasive cumulative volume and robotic approach were associated with decreased conversion rates. Patients whose MIEs were converted had increased 90-day mortality [Odds Ratio (OR) 1.49; 95% Confidence Interval (CI) 1.10, 2.02], prolonged hospital stay (OR 1.39; 95% CI 1.17, 1.66), and higher rates of unplanned readmission (OR 1.67; 95% CI 1.27, 2.20). No significant differences were found in surgical margins or number of lymph nodes harvested. CONCLUSION: Patients undergoing attempted MIE requiring conversion to open surgery had significantly worse short-term outcomes including postoperative mortality. Patient factors and hospital experience contribute to conversion rates. These findings should inform surgeons and patients considering esophagectomy for cancer.

The association between patient preoperative disposition and outcomes after diagnostic lung biopsy.

Background: Surgical diagnostic lung biopsy (DLB) is performed to guide the management of pulmonary disease with unclear etiology. However, the utilization of surgical DLB in critically ill patients remains unclear. The purpose of this study was to determine if patient preoperative disposition impacts complication rates after DLB. Methods: This was retrospective cohort study using electronic health record (EHR) data at one academic institution [2013-2021]. Patients who underwent DLB were identified using current procedural terminology (CPT) codes and cohorted based on preoperative disposition. The primary outcome was 30-day mortality; secondary outcomes were overall morbidity, individual complications, and changes to medical therapy. Complication rates were compared using chi-squared tests, Fisher's exact tests, or analysis of variance (ANOVA). Multivariable logistic regression was performed to generate risk-adjusted odds ratios (ORs) for each complication. Results: Of 285 patients, 238 (83.5%) presented from home, 26 (9.1%) from inpatient floor units, and 21 (7.4%) from intensive care units (ICUs). Patients requiring ICU had the highest 30-day rates of mortality, overall morbidity, and all individual complications (all P<0.05). After risk adjustment, non-ICU inpatients had higher odds of postoperative ventilator use, prolonged ventilation, and ICU need than outpatients (all P<0.05). Preoperative ICU disposition was associated with increased OR of 30-day mortality [OR, 70.92; 95% confidence interval (CI): 5.55-906.32] and overall morbidity (OR, 7.27; 95% CI: 1.93-27.42) compared to patients with other preoperative dispositions. There were no differences in changes to medical therapy between the cohorts. Conclusions: Patients requiring ICU before DLB had significantly higher risk-adjusted rates of mortality and postoperative complications than outpatients and other inpatients. A clear benefit from tissue diagnosis should be defined prior to performing DLB on critically ill patients.

Human effector CD8+ T cells derived from naive rather than memory subsets possess superior traits for adoptive immunotherapy.

Cluster of differentiation (CD)8(+) T cells exist as naive, central memory, and effector memory subsets, and any of these populations can be genetically engineered into tumor-reactive effector cells for adoptive immunotherapy. However, the optimal subset from which to derive effector CD8(+) T cells for patient treatments is controversial and understudied. We investigated human CD8(+) T cells and found that naive cells were not only the most abundant subset but also the population most capable of in vitro expansion and T-cell receptor transgene expression. Despite increased expansion, naive-derived cells displayed minimal effector differentiation, a quality associated with greater efficacy after cell infusion. Similarly, the markers of terminal differentiation, killer cell lectin-like receptor G1 and CD57, were expressed at lower levels in cells of naive origin. Finally, naive-derived effector cells expressed higher CD27 and retained longer telomeres, characteristics that suggest greater proliferative potential and that have been linked to greater efficacy in clinical trials. Thus, these data suggest that naive cells resist terminal differentiation, or "exhaustion," maintain high replicative potential, and therefore may be the superior subset for use in adoptive immunotherapy.

Evaluating the implementation of robotic thoracic surgery on a Veterans Administration Hospital.

Robotic thoracic surgery has demonstrated benefits. We aimed to evaluate implementation of a robotic thoracic surgery program on postoperative outcomes at our Veteran's Administration Medical Center (VAMC). We retrospectively reviewed our VAMC database from 2015 to 2021. Patients who underwent surgery with intention to treat lung nodules were included. Primary outcome was patient length of stay (LOS). Patients were grouped by surgical approach and stratified to before and after adoption of robotic surgery. Univariate comparison of postoperative outcomes was performed using Wilcoxon rank sums and chi-squared tests. Multivariate regression was performed to control for ASA class. P values < 0.05 were considered significant. Outcomes of 108 patients were assessed. 63 operations (58%) occurred before and 45 (42%) after robotic surgery implementation. There were no differences in patient preoperative characteristics. More patients underwent minimally invasive surgery (MIS) in the post-implementation era than pre-implementation (85% vs. 42%, p < 0.001). Robotic operations comprised 53% of operations post-implementation. On univariate analysis, patients in the post-implementation era had a shorter LOS vs. pre-implementation, regardless of surgical approach (mean 4.7 vs. 6.0 days, p = 0.04). On multivariate analysis, patients who underwent MIS had a shorter LOS [median 4 days (IQR 2-6 days) vs. 7 days (6-9 days), p < 0.001] and were more likely to be discharged home than to inpatient facilities [OR (95% CI) 13.00 (1.61-104.70), p = 0.02]. Robotic thoracic surgery program implementation at a VAMC decreased patient LOS and increased the likelihood of discharging home. Implementation at other VAMCs may be associated with improvement in some patient outcomes.

Long-Term Patient-Reported Symptom Improvement and Quality of Life after Transthoracic Diaphragm Plication in Adults.

BACKGROUND: Open and robotic-assisted transthoracic approaches for diaphragm plication are accepted surgical interventions for diaphragm paralysis and eventration. However, long-term patient-reported symptom improvement and quality of life (QOL) remains unclear. STUDY DESIGN: A telephone-based survey was developed focusing on postoperative symptom improvement and QOL. Patients who underwent open or robotic-assisted transthoracic diaphragm plication (2008-2020) across three institutions were invited to participate. Patients who responded and provided consent were surveyed. Likert responses on symptom severity were dichotomized and rates before and after surgery were compared using McNemar's test. RESULTS: Forty-one percent of patients participated (43 of 105 responded, mean age 61.0 years, 67.4% male, 37.2% robotic-assisted surgery), with an average time between surgery and survey of 4.1 ± 3.2 years. Patients reported significant improvement in dyspnea while lying flat (67.4% pre- vs 27.9% postoperative, p < 0.001), dyspnea at rest (55.8% pre- vs 11.6% postoperative, p < 0.001), dyspnea with activity (90.7% pre- vs 55.8% postoperative, p < 0.001), dyspnea while bending over (79.1% pre- vs 34.9% postoperative, p < 0.001), and fatigue (67.4% pre- vs 41.9% postoperative, p = 0.008). There was no statistical improvement in chronic cough. 86% of patients reported improved overall QOL, 79% had increased exercise capacity, and 86% would recommend surgery to a friend with a similar problem. Analysis comparing open and robotic-assisted approaches found no statistically significant differences in symptom improvement or QOL responses between the groups. CONCLUSIONS: Patients report significantly improved dyspneic and fatigue symptoms after transthoracic diaphragm plication, regardless of open or robotic-assisted approach. The majority of patients report improved QOL and exercise capacity.

A comparison of short-term outcomes following robotic-assisted vs. open transthoracic diaphragm plication.

Diaphragm paralysis and eventration are rare conditions in adults. Symptomatic patients may benefit from surgical plication of the elevated hemidiaphragm. The objective of this study was to compare short-term outcomes and length of stay following robotic-assisted vs. open diaphragm plication. A multicenter retrospective study was conducted that identified patients undergoing unilateral hemidiaphragm plication from 5/2008 to 12/2020. The first RATS plication was performed in 11/2018. Electronic medical records were reviewed, and outcomes were compared between RATS and open approach. One hundred patients underwent diaphragm plication, including thirty-nine (39.0%) RATS and sixty-one (61.0%) open cases. Patients undergoing RATS diaphragm plication were older (64 years vs. 55 years, p = 0.01) and carried a higher burden of comorbidities (Charlson Comorbidity Index: 2.0 vs. 1.0, p = 0.02). The RATS group had longer median operative times (146 min vs. 99 min, p < 0.01), but shorter median hospital length of stays (3.0 days vs. 6.0 days, p < 0.01). There was a non-significant trend toward a decreased rate of 30-day postoperative complications (20.5% RATS vs. 32.8% open, p = 0.18) and 30-day unplanned readmissions (7.7% RATS vs. 9.8% open, p > 0.99). RATS is a technically feasible and safe option for performing diaphragm plications. This approach increases the surgical candidacy of older patients with a higher burden of comorbid disease without increasing complication rates, while reducing length of hospital stay.

Evaluating Riociguat in the Treatment of Pulmonary Arterial Hypertension: A Real-World Perspective.

Pulmonary hypertension (PH) is a broad term describing the mean pulmonary artery pressure, as measured by right heart catheterization, exceeds 20mmHg. Pulmonary arterial hypertension (PAH) exists when PH is accompanied by a normal wedge pressure and elevated pulmonary vascular resistance. PAH is typified by dysmorphic and dysfunctional pulmonary arterial vasculature. Attempting to restore the functionality of the pulmonary artery is a hallmark of care to the PAH patient. Riociguat is a powerful stimulator of soluble guanylate cyclase and increases blood flow through the pulmonary arteries by dilating vascular smooth muscle cells. This review examines the pharmacology of riociguat, the fundamental clinical trials applying it to PAH patients, practical aspects when selecting its use, and future directions for its utilization.

Introduction of robotic surgery does not negatively affect cardiothoracic surgery resident experience.

The objective of this study was to evaluate the educational impact following the implementation of a robotic thoracic surgery program on cardiothoracic (CT) surgery trainees. We hypothesized that the introduction of a robotic thoracic surgery program would adversely affect the CT surgery resident experience, decreasing operative involvement and subsequent competency of surgical procedures. CT surgery residents and thoracic surgery attendings from a single academic institution were administered a recurring, electronic survey from September 2019 to September 2020 following each robotic thoracic surgery case. Surveys evaluated resident involvement and operative performance. This study was exempt from review by our Institutional Review Board. Attendings and residents completed surveys for 86 and 75 cases, respectively. Residents performed > 50% of the operation independently at the surgeon console in 66.2 and 73.3% of cases according to attending and resident responses, respectively. The proportion of trainees able to perform > 75% of the operation increased with each increasing year in training (p = 0.002). Based on the Global Evaluative Assessment of Robotic Skills grading tool, third-year residents averaged higher scores compared to first-year residents (22.9 versus 17.4 out of 30 possible points, p < 0.001), indicating that more extensive prior operative experience could shorten the learning curve of robotic thoracic surgery. CT surgery residents remain actively involved in an operative role during the establishment of a robotic thoracic surgery program. The transition to a robotic thoracic surgery platform appears feasible in a large academic setting without jeopardizing the educational experience of resident trainees.

Introduction of robotic surgery leads to increased rate of segmentectomy in patients with lung cancer.

BACKGROUND: Pulmonary segmentectomy provides an anatomic lung resection while avoiding removal of excess normal lung tissue. This may be beneficial in patients with minimal pulmonary reserve who present with early-stage non-small cell lung cancer (NSCLC). However, the operative performance of a segmentectomy using a video-assisted thoracoscopic approach can be technically challenging. We hypothesized that introduction of the robotic surgical system would facilitate the performance of a segmentectomy as measured by an increase in the proportion of segmentectomies being pursued. METHODS: We completed a retrospective analysis of thoracoscopic and robotic anatomic lung resections, including lobectomies and segmentectomies, performed in patients with primary lung cancer from the time of initiation of the robotic thoracic surgery program in November 2017 to November 2019. We compared the proportion of thoracoscopic and robotic segmentectomies performed during the first year compared to the second year of the data collection period. RESULTS: A total of 138 thoracoscopic and robotic anatomic lung resections were performed for primary lung cancer. Types of lung cancer resected (adenocarcinoma, squamous cell carcinoma, or other), tumor size based on clinical T staging (T1-T4), and tumor location were not significantly different between years (P=0.44, P=0.98, and P=0.26, respectively). The proportion of segmentectomies increased from 8.6% during the first year to 25.0% during the second year (P=0.01). One out of 6 (16.7%) segmentectomies were performed using the robot during the first year versus 15 out of 17 (88.2%) during the second year (P=0.003). CONCLUSIONS: Use of the robot led to a significant increase in the number of segmentectomies performed in patients undergoing anatomic lung resection. With increasing lung cancer awareness and widely available screening, a greater number of small, early-stage tumors suitable for segmentectomy will likely be detected. We conclude that robotic-assisted surgery may facilitate the challenges of performing a minimally invasive segmentectomy.

Outcomes After Converted Minimally Invasive to Open Esophagectomy in Patients With Esophageal Cancer.

BACKGROUND: The objective of this study was to evaluate the impact of unplanned conversion to open esophagectomy during minimally invasive esophagectomy (MIE) on postoperative morbidity and mortality for patients with esophageal cancer, as well as to evaluate the variables that influence the need for conversion. METHODS: This study was a retrospective analysis of patients with esophageal cancer who underwent open esophagectomy or MIE by either a laparothoracoscopic approach or a robotic approach from 2016 to 2018 by using the esophagectomy-specific American College of Surgeons (ACS) National Surgical Quality Improvement Program (NSQIP) database. Poisson regression models were used to analyze 30-day outcomes and risk factors for conversion to open esophagectomy during attempted MIE. RESULTS: A total of 2616 patients were identified. The overall conversion rate for MIE was 6.3%. Compared with completed MIE, patients requiring conversion to open esophagectomy had a significantly increased risk of 30-day mortality (risk ratio, 2.63; 95% confidence interval, 1.03 to 6.69) and experienced a variety of other postoperative complications. Patients requiring conversion to open esophagectomy during MIE also experienced worse perioperative outcomes when compared to patients who underwent planned open esophagectomy. Estimated surgical risk on the basis of the ACS NSQIP Surgical Risk Calculator was the only variable found to be independently associated with conversion from minimally invasive to open esophagectomy (risk ratio, 1.03; 95% confidence interval, 1.01 to 1.04, for each 10% increase in risk score). CONCLUSIONS: Unplanned conversion to open esophagectomy during MIE is associated with significantly greater morbidity and a 2.6-fold increased risk of death when compared with both completed MIE and planned open esophagectomy. The ACS NSQIP Surgical Risk Calculator may help identify patients preoperatively who are at higher risk for conversion to open esophagectomy during MIE.

Surgery for limited stage small cell lung cancer.

Small cell lung cancer (SCLC) is an aggressive tumor type characterized by rapid growth and overall poor prognosis. For the past several decades, chemotherapy and radiotherapy have served as the cornerstone of treatment. Recently, however, the role of surgery for early stage disease has gained considerable interest. Multiple retrospective and observational studies have shown excellent survival for early stage SCLC treated with surgical resection. We herein review the past and present evidence regarding surgical options for limited stage SCLC.

Analysis of Discharge Destination After Open Versus Minimally Invasive Surgery for Lung Cancer.

BACKGROUND: Patients express strong opinion regarding discharge destination, preferring discharge home vs elsewhere. As focus on patient satisfaction increases, we sought to understand differences in postoperative discharge destination after minimally invasive vs open anatomic lung resection for lung cancer to guide patient education and management and better understand the postoperative patient experience. METHODS: Procedures were identified by Current Procedural Terminology and International Classification of Diseases codes using the 2012-2017 American College of Surgeons National Surgical Quality Improvement Program dataset. Propensity score analysis was used to assess the relationship between the surgical approach and nonhome discharge destination (primary outcome) and postoperative complications; related, unplanned readmission; and mortality (secondary outcomes). RESULTS: A total of 17,303 patients underwent anatomic lung resection for lung cancer, including 10,121 (58.5%) minimally invasive and 7182 (41.5%) open resections. Patients undergoing open resection had 60% greater odds of nonhome discharge (P < .001), 58% greater odds of postoperative mortality (P = .003), 36% greater odds of postoperative complication (P < .001), and 17% greater odds of readmission (P = .04) compared with patients undergoing minimally invasive resection. CONCLUSIONS: The minimally invasive approach to lung resection for lung cancer offers patients a more desirable patient-centered postoperative experience, as well as more favorable clinical outcomes, and should be favored when feasible.

Improved Mortality Associated With the Use of Extracorporeal Membrane Oxygenation.

BACKGROUND: Our objective was to evaluate the association of bridge to transplant (BTT) extracorporeal membrane oxygenation (ECMO) on survival after lung transplantation (LTx) and determine the degree to which transplant center volume affects this relationship. METHODS: Using the United Network for Organ Sharing database, we performed a retrospective cohort study evaluating the survival of patients undergoing LTx between 2005 and 2017. On the basis of previous literature, LTx centers were classified into 3 groups using their average annual LTx volume over the preceding 5 years: less than 25, 25 to 49, and more than 50. Survival of BTT ECMO and non-ECMO patients was analyzed using a log-rank test. Propensity scores for BTT ECMO were calculated, and a weighted proportional hazards model was used to compare BTT ECMO and non-ECMO patients by center volume. RESULTS: There were 20,976 patients who met inclusion criteria, with 611 (2.9%) undergoing BTT ECMO. Overall, BTT ECMO was associated with increased posttransplantation hazard of mortality (hazard ratio, 1.37; 95% confidence interval, 1.14 to 1.64). Kaplan-Meier plots by center volume suggest that BTT ECMO-associated mortality may be mitigated at high-volume LTx centers. In the propensity score-weighted proportional hazards model, we determined that when centers perform more than 35 LTxs per year, the increased hazard of BTT ECMO on mortality is no longer observed. CONCLUSIONS: BTT ECMO can be performed as a bridge to LTx without significantly increasing patient mortality in high-volume centers. Patients undergoing BTT ECMO at LTx centers that perform more than 35 LTxs annually have equivalent mortality to those who do not require ECMO before transplantation.

A cruel twist: post-operative cecal volvulus.

Cecal volvulus is an uncommon cause of intestinal obstruction, accounting for less than 1% of cases in Western countries. In the literature, it has been described as a complication following numerous common surgeries as well as a number of minimally invasive procedures. Presumably, it is more likely to occur following any surgical procedure which might require some degree of medial visceral rotation or disruption of the fusion plane between the cecum or ascending colon with the lateral peritoneum, providing sufficient mobility to allow for cecal volvulization to occur. In addition, cadaver and autopsy studies have also suggested that 10-20% of the population may have sufficient mobility of the colon to allow for volvulization. We present a review of the literature pertaining to the diagnosis and management of cecal volvulus as well as the case of J.R., a 78-year-old male with cecal volvulus six days following a right radical nephrectomy for renal cell carcinoma.

The Biology of Pulmonary Metastasis.

The process of metastasis relies on a series of stochastic and sequential steps, with selective pressure exerted on a large number of genetically volatile cancer cells to produce a very small fraction of tumor cells with the ability to navigate the transition from primary tumor cell to end-organ metastasis. This process is intricately determined by cell-microenvironment interactions, the mechanistic understanding of which is steadily increasing. The continued elucidation of pathways that govern these interactions offers potential therapeutic options to patients with advanced disease.

Memory T cell-driven differentiation of naive cells impairs adoptive immunotherapy.

Adoptive cell transfer (ACT) of purified naive, stem cell memory, and central memory T cell subsets results in superior persistence and antitumor immunity compared with ACT of populations containing more-differentiated effector memory and effector T cells. Despite a clear advantage of the less-differentiated populations, the majority of ACT trials utilize unfractionated T cell subsets. Here, we have challenged the notion that the mere presence of less-differentiated T cells in starting populations used to generate therapeutic T cells is sufficient to convey their desirable attributes. Using both mouse and human cells, we identified a T cell-T cell interaction whereby antigen-experienced subsets directly promote the phenotypic, functional, and metabolic differentiation of naive T cells. This process led to the loss of less-differentiated T cell subsets and resulted in impaired cellular persistence and tumor regression in mouse models following ACT. The T memory-induced conversion of naive T cells was mediated by a nonapoptotic Fas signal, resulting in Akt-driven cellular differentiation. Thus, induction of Fas signaling enhanced T cell differentiation and impaired antitumor immunity, while Fas signaling blockade preserved the antitumor efficacy of naive cells within mixed populations. These findings reveal that T cell subsets can synchronize their differentiation state in a process similar to quorum sensing in unicellular organisms and suggest that disruption of this quorum-like behavior among T cells has potential to enhance T cell-based immunotherapies.

Retinoic acid controls the homeostasis of pre-cDC-derived splenic and intestinal dendritic cells.

Dendritic cells (DCs) comprise distinct populations with specialized immune-regulatory functions. However, the environmental factors that determine the differentiation of these subsets remain poorly defined. Here, we report that retinoic acid (RA), a vitamin A derivative, controls the homeostasis of pre-DC (precursor of DC)-derived splenic CD11b(+)CD8α(-)Esam(high) DCs and the developmentally related CD11b(+)CD103(+) subset within the gut. Whereas mice deprived of RA signaling significantly lost both of these populations, neither pre-DC-derived CD11b(-)CD8α(+) and CD11b(-)CD103(+) nor monocyte-derived CD11b(+)CD8α(-)Esam(low) or CD11b(+)CD103(-) DC populations were deficient. In fate-tracking experiments, transfer of pre-DCs into RA-supplemented hosts resulted in near complete conversion of these cells into the CD11b(+)CD8α(-) subset, whereas transfer into vitamin A-deficient (VAD) hosts caused diversion to the CD11b(-)CD8α(+) lineage. As vitamin A is an essential nutrient, we evaluated retinoid levels in mice and humans after radiation-induced mucosal injury and found this conditioning led to an acute VAD state. Consequently, radiation led to a selective loss of both RA-dependent DC subsets and impaired class II-restricted auto and antitumor immunity that could be rescued by supplemental RA. These findings establish a critical role for RA in regulating the homeostasis of pre-DC-derived DC subsets and have implications for the management of patients with immune deficiencies resulting from malnutrition and irradiation.