Pembrolizumab plus cisplatin and fluorouracil as induction chemotherapy followed by definitive chemoradiotherapy for patients with cT4 and/or supraclavicular lymph node metastasis (M1Lym) of esophageal squamous cell carcinoma.

Definitive chemoradiotherapy (DCRT) is administered as standard treatment for patients with cT4 and/or M1Lym esophageal squamous cell carcinoma (ESCC); however, its long-term result is inadequate. Although several studies have reported that conversion surgery can improve the survival of these patients, none have identified significantly better long-term survival than that achieved by DCRT. Thus, enhancing DCRT seems important to improve the survival of these patients. A strategy of shrinking tumor volume before DCRT and providing consolidation chemotherapy for systemic control is expected to improve the survival of these patients. Pembrolizumab plus cisplatin and fluorouracil has demonstrated good local control and significant improvement in the survival of patients with advanced esophageal cancer. Based on these results, the following strategy is proposed: This protocol should be applied as induction for these patients; then, DCRT should be provided depending on the initial response; and finally, adjuvant chemotherapy with an immune checkpoint inhibitor should be given to all responders.

Accuracy of preoperative staging of gastric stump cancer.

BACKGROUND: In this study, the accuracy of preoperative staging for gastric stump cancer, which has not been thoroughly investigated since the condition is rare, was investigated using computed tomography and gastroscopic imaging. METHODS: Between February 1994 and April 2018, 49 patients with gastric stump cancer, following subtotal or total gastrectomy, were reviewed retrospectively. Preoperative diagnoses of clinical T and clinical N categories were compared with post-operative pathological diagnoses (pT and pN categories). Positive predictive values, accuracy, sensitivity and specificity were also evaluated. RESULTS: The overall accuracy of T staging was 40.8%. The positive predictive value for cT3/T4 was 96.3%, whereas the positive predictive value for cT1/T2 was 72.7%. The overall accuracy for N staging was 61.2%. The positive predictive value of lymph node positive patients was 73.3%. The positive predictive value and sensitivity of over stage II were 96.6% and 84.8%, respectively. CONCLUSIONS: The accuracy of preoperative diagnosis using both computed tomography and gastroscopy imaging may be feasible for T3/T4 advanced gastric stump cancer, whereas diagnosing T1/2 gastric stump cancer must be carefully considered due to high misdiagnosis rates, relating to depth.

Plasma exosome-encapsulated microRNA-21 and microRNA-92a are promising biomarkers for the prediction of peritoneal recurrence in patients with gastric cancer.

In patients with gastric cancer (GC), peritoneal recurrence is a common risk and associated with poor prognosis. A novel biomarker for the prediction of high-risk peritoneal recurrence in patients with GC is desirable. The present study investigated the effectiveness of exosome-encapsulated microRNAs (ex-miRNAs) as minimally invasive biomarkers in patients with GC that received curative surgery. Recurrence-specific ex-miRNAs were selected following comparison of miRNA microarray data from patients with TNM stage II GC with peritoneal recurrence (n=3) and without peritoneal recurrence following curative surgery (n=3), and three healthy volunteers. In this analysis, exosome-encapsulated miRNA-21 (ex-miR-21) and exosomal miR-92a (ex-miR-92a) exhibited the greatest alterations in expression patterns. Using plasma exosome samples collected from another 129 patients with stage II and III GC, the present study investigated the potential value of ex-miR-21 and ex-miR-92a as biomarkers. Ex-miRNA levels were measured using TaqMan miRNA assays. Ex-miR-21 levels were significantly higher and ex-miR-92a levels were significantly lower in samples from patients with GC compared with healthy controls. The overall survival (OS) and peritoneal recurrence-free survival (PRFS) were poorer in stage II and III patients with high ex-miR-21 levels than in patients with low miR-21 levels. OS and PRFS of stage II and III patients with low ex-miR92a levels were significantly worse than those with high ex-miR92a levels. Cox multivariate analyses indicated that ex-miR-21 and ex-miR-92a were independent prognostic factors for OS and PRFS in stage II and III GC. A negative correlation was detected between expression levels of miR-21 and programmed cell death protein 4 mRNA, and miR-92a and prostaglandin E receptor 4 mRNA. Therefore, ex-miR-21 and ex-miR-92a may function as effective and minimally invasive biomarkers for the prediction of peritoneal recurrence and the prognosis of patients with stage II/III GC.

Recent trends from the results of clinical trials on gastric cancer surgery.

The Japan Clinical Oncology Group has recently conducted large scale clinical trials with findings that have revealed pivotal strategies for the treatment of resectable gastric cancer surgery. These findings include the fact that D3 lymphadenectomy does not improve survival rates when compared to D2 lymphadenectomy, and it is not recommended for resectable gastric cancer. Also, a transhiatal approach is recommended, instead of the left thoraco-abdominal approach, for the treatment of adenocarcinoma of the esophago-gastric junction or gastric cardia which has invaded ≤ 3 cm of the esophagus. Gastrectomy with splenectomy and bursectomy had been recommended as a part of the D2 lymphadenectomy. However, the results of the recent clinical trials revealed that splenectomy should be avoided in total gastrectomy with D2 lymphadenectomy for proximal gastric cancer and that bursectomy should be avoided in gastrectomy with D2 lymphadenectomy for resectable gastric cancer. Both splenectomy and bursectomy were found to be unable to improve survival, but instead increased operative morbidity. These trials revealed that the above-mentioned invasive and aggressive procedures did not provide sufficient survival benefits and that gastric cancer surgery may be trending from an "invasive to less invasive" and "aggressive to more conservative" approach.

Exosome­encapsulated microRNA­23b as a minimally invasive liquid biomarker for the prediction of recurrence and prognosis of gastric cancer patients in each tumor stage.

Recently, exosome­encapsulated microRNAs (miRNAs) have been attracting attention as stable and minimally invasive biomarkers in cancer patients. The aim of the present study was to clarify the value of plasma exosomal microRNA­23b (miR­23b) as a diagnostic and prognostic biomarker in gastric cancer (GC) patients at each tumor stage. We first selected recurrence specific exosomal miRNA by miRNA microarray from 6 GC patients (stage I) with or without recurrence, and 3 healthy volunteers. In this analysis, miR­23b demonstrated the most significant change. Subsequently, we validated the usefulness of miR­23b as a biomarker using the plasma exosome samples collected from 232 GC patients and 20 healthy volunteers. miR­23b levels were evaluated by Taqman microRNA assays. Exosomal miR­23b levels of GC patients were significantly lower than those of the healthy controls. A significant association was revealed between the plasma exosomal miR­23b levels and the expression of miR­23b in primary tumor tissues. Concerning the pathological condition, miR­23b demonstrated a significant association with tumor size, depth of invasion, liver metastasis and TNM stage. The overall survival (OS) rates of low­miR­23b patients were significantly worse than those of high­miR­23b patients at stage I, II, III and IV. The disease­free survival (DFS) rates of low exosomal miR­23b patients were significantly worse than those of high­miR­23b patients at stage I, II and III. Cox multivariate analysis indicated that exosomal miR­23b was an independent prognostic factor for OS and DFS at each tumor stage. Our results revealed that exosomal miR­23b has potential as minimally invasive predictive biomarker for the recurrence and prognosis of GC in patients at all stages.

Two cases of early recurrence after transabdominal preperitoneal inguinal hernia repair.

We performed transabdominal preperitoneal inguinal hernia repair in 46 patients (58 diseases), two of whom experienced early recurrence after mesh repair. Case 1 was a 76-year-old man with a bilateral inguinal hernia (recurrence site, left indirect hernia) after appendectomy. The recurrence occurred 1 month after transabdominal preperitoneal inguinal hernia repair. The mesh was dislocated to the lateral side, and we repaired it using the direct Kugel® patch with an anterior technique. Case 2 was a 79-year-old man with a bilateral inguinal hernia (recurrence site, right direct hernia with an orifice >3 cm) after appendectomy. The recurrence occurred 3 months after transabdominal preperitoneal inguinal hernia repair. The mesh was dislocated to the lateral side, and we repaired it using an ULTRAPRO® Plug with an anterior technique under laparoscopic observation. We believe the recurrences resulted from insufficient internal exfoliation and fixation affected by complicated exfoliation of the preperitoneal space with omental adhesion after intraperitoneal surgery.

Clinical Significance of Area of Psoas Major Muscle on Computed Tomography after Gastrectomy in Gastric Cancer Patients.

BACKGROUND: The measurement of a single abdominal image on computed tomography (CT) can provide an estimate of the total body skeletal muscle. We evaluate the change of the area of the psoas major muscle (PMMA) in a CT which was performed routinely after gastrectomy in gastric cancer. METHODS: A total of 119 gastric cancer patients who underwent gastrectomy were enrolled for the study. A CT image at the top of the iliac crest level was obtained at the following times: 3 postoperative months (POM), 6 POM, 1 postoperative year (POY), 2 POY, 3 POY, and 5 POY. We analyzed the change rate of PMMA after gastrectomy and before or after recurrence. RESULTS: PMMA change after gastrectomy was approximately between -8 and -10% over the 5-year observation period. PMMA in the R2 (macroscopic residual tumor)/recurrence group was lower than that in the no recurrence group, and a significant difference was observed at 2 POY (-21.7 ± 3.6% vs. -7.9 ± 2.3%, p < 0.01). PMMA after freshly diagnosed recurrence had decreased significantly by 14.1 ± 1.8% (p < 0.01). CONCLUSIONS: Evaluation of PMMA change by CT after gastrectomy could assist in the diagnosis of the progression of cancer state in gastric cancer patients.

Seven esophageal perforation cases after aortic replacement/stenting for thoracic aortic dissection or aneurysm.

BACKGROUND: Esophageal perforation after aortic replacement/stenting for aortic dissection or aneurysm is a rare but severe complication. However, its cause, standard treatment, and prognosis are unclear. We analyzed the treatment and outcome retrospectively from seven cases experienced at our hospital. CASE PRESENTATION: The median age of the patients was 70 years (range, 41-86), and six of the seven cases were male. As the first treatment, aortic replacement techniques were performed in five, and thoracic endovascular aortic repair (TEVAR) procedure was performed in two. We evaluated the treatment of the perforation, the cause of death, and the median survival time after reparative surgery (esophagectomy). Initial treatment of the perforation was esophagectomy without reconstruction in six and esophagogastric bypass (later, esophagectomy was performed) in one. Three of seven cases could be discharged from hospital or moved to another hospital, but two of these three cases died of major bleeding on postoperative days 320 and 645. The other four esophagectomy cases died in hospital because of sepsis on postoperative days 14, 30, and 41 and major bleeding on postoperative day 54. The one surviving case was a 65-year-old man who underwent reconstruction, and was still alive without signs of infection at 424 days postoperatively. CONCLUSION: The prognosis of esophageal perforation cases after aortic replacement/stenting for thoracic aortic dissection or aneurysm is poor, though there were some cases with relatively long survival. Therefore, the indication for invasive esophagectomy should be decided carefully. Control of infection including regional infection is essential for successful treatment.

Preserving infrapyloric vein reduces postoperative gastric stasis after laparoscopic pylorus-preserving gastrectomy.

PURPOSE: Laparoscopic pylorus-preserving gastrectomy (LPPG) is performed to preserve function in treating early gastric cancer. However, gastric stasis is a potential complication of LPPG that could decrease postoperative quality of life, possibly due to gastric edema of the pyloric cuff caused by venous stasis. We introduced an infrapyloric vein (IPV)-preserving LPPG (iLPPG) procedure to prevent pyloric cuff edema and thus minimize the incidence of gastric stasis and investigated the early clinical outcomes of iLPPG. METHODS: We reviewed 150 patients with gastric cancer who underwent LPPG between August 2011 and June 2013 at the Cancer Institute Hospital and analyzed postoperative complications, incidence of gastric stasis (requiring starvation longer than 72 h or an invasive treatment), and transient delayed gastric emptying (TDGE). RESULTS: Of the 150 patients, 56 underwent iLPPG and 94 underwent conventional LPPG without preservation of the IPV (cLPPG). Morbidity rates were 5.4% in the iLPPG group and 23.4% in the cLPPG group (P = 0.003). The incidence of both gastric stasis and TDGE was significantly lower in the iLPPG group than in the cLPPG group (0 vs. 8.5%, P = 0.03 and 0 vs. 7.4%, P = 0.046, respectively). Median postoperative stay was significantly shorter in the iLPPG group compared to the cLPPG group (9 vs. 11 days, P < 0.001, respectively). CONCLUSIONS: Preservation of the IPV might prevent the incidence of postoperative gastric stasis after LPPG, resulting in a shorter postoperative stay.

Radical esophagectomy for a 92-year-old woman with granulocyte colony-stimulating factor-producing esophageal squamous cell carcinoma: a case report.

BACKGROUND: Granulocyte colony-stimulating factor (G-CSF)-producing esophageal squamous cell carcinoma (ESCC) has been considered to have a poor prognosis. We successfully treated a case of G-CSF-producing ESCC in a 92-year-old woman. CASE PRESENTATION: A 92-year-old woman was admitted to our hospital with the complaints of choking while swallowing and dysphagia. Esophagogastroduodenoscopy and contrast-enhanced computed tomography revealed a type 2 esophageal cancer located 26-35 cm from the dental arch, with no distant metastasis. The patient was diagnosed with G-CSF-producing ESCC based on remarkable leukocytosis and high G-CSF levels. The patient underwent radical subtotal esophagectomy. Subsequently, the level of neutrophils (from 23,500/µL to 5000/µL) and the level of G-CSF (from 131 to <19.5 pg/mL) decreased significantly. Immunohistochemistry analysis of the resected tissue specimen showed positive staining for G-CSF in the cytoplasm of the tumor cells. Although the patient developed aspiration pneumonitis, after antibiotic treatment, she promptly recovered and was discharged. CONCLUSIONS: Herein, we describe a case of successfully treated G-CSF-producing ESCC in a 92-year-old woman. Precise detection and safely performed immediate radical operation are considered essential to achieve a good clinical course.

Feasibility of Gastrectomy with Standard Lymphadenectomy for Patients Over 85 Years Old with Gastric Cancer.

BACKGROUND: The feasibility of gastrectomy with standard lymphadenectomy for patients over 85 years of age is not known. This study investigated short- and long-term outcomes and the tolerability of gastrectomy with standard lymphadenectomy for patients over 85 years with gastric cancer. METHODS: Altogether, 77 patients aged over 85 years underwent gastrectomy with lymphadenectomy for gastric cancer at the Cancer Institute Hospital, Japan from May 2000 to February 2012. Postoperative short-term outcomes and survivals were analyzed retrospectively. Standard lymphadenectomy was defined according to the Japanese Gastric Cancer Association guidelines. Lymphadenectomy without splenectomy during total gastrectomy was called "reduced" lymphadenectomy. RESULTS: Distal gastrectomy was performed in 51 patients, total gastrectomy in 20, remnant total gastrectomy in 5, and proximal gastrectomy in 1 patient. Gastrectomy with standard lymphadenectomy was initially planned for 50 (64.9 %) patients and completed in 42 (54.5 %) patients. The other 8 patients underwent reduced lymphadenectomy because they required R1 or R2 resection. There were no deaths. The morbidity rate was 55.8 % overall and 54.8 % with standard lymphadenectomy. The most frequent complication was intestinal hypoperistalsis (29.9 %). The mean postoperative hospital stay was 19 days (range 10-70 days). The median overall survival time was 46.8 months. CONCLUSION: Coupled with comprehensive postoperative medical care due to the relative high morbidity risk, gastrectomy with standard lymphadenectomy for gastric cancer may be acceptable for relatively healthy patients over 85 years of age. Decisions to reduce the extent of lymphadenectomy during gastrectomy should not be based on advanced age alone.

Totally laparoscopic pylorus-preserving gastrectomy for early gastric cancer in the middle stomach: technical report and surgical outcomes.

INTRODUCTION: The feasibility, safety, and improved quality of postoperative life following laparoscopy-assisted pylorus-preserving gastrectomy (LAPPG) with a hand-sewn anastomosis via a mini-laparotomy for early gastric cancer (EGC) have been previously established. Here we describe the surgical procedure of totally laparoscopic pylorus-preserving gastrectomy (TLPPG) using an intracorporeal delta-shaped anastomosis technique, and the short-term surgical outcomes of 60 patients with EGC in the middle stomach are reported. METHODS: After lymphadenectomy and mobilization of the stomach, intraoperative gastroscopy was performed in order to verify the location of the tumor, and then the distal and proximal transecting lines were established, 5 cm from the pyloric ring and just proximal to Demel's line, respectively. Following transection of the stomach, a delta-shaped intracorporeal gastrogastrostomy was made with linear staplers. RESULTS: There were no intraoperative complications or conversions to open surgery. Mean operation time and blood loss were 259 min and 28 mL, respectively. Twelve patients (20.0%) experienced postoperative complications classified as grade II using the Clavien-Dindo classification, with the most frequent complication being gastric stasis (6 cases, 10.0 %). The incidence of severe complications classified as grade III or above was 1.7%; only one patient required reoperation and intensive care due to postoperative intraabdominal bleeding and subsequent multiple organ failure. CONCLUSION: TLPPG with an intracorporeal delta-shaped anastomosis was found to be a safe procedure, although it tended to require a longer operating time than the well-established LAPPG with a hand-sewn gastrogastrostomy.

Long-term and surgical outcomes of laparoscopic surgery for gastric gastrointestinal stromal tumors.

BACKGROUND: Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract. Surgical resection with a free margin is the gold standard treatment for these lesions. OBJECTIVE: The aim of this study was to evaluate the feasibility of performing laparoscopic resection for gastric GIST from the viewpoint of operative and long-term oncological outcomes. METHODS: Between 2005 and 2011, a total of 78 consecutive patients undergoing laparoscopic resection of gastric GISTs were enrolled in a retrospective single-center study. Patient and tumor characteristics, surgical procedures, risk classification, postoperative complications, mortality, recurrence, and survival time were collected from a database, and the descriptive statistics were estimated. RESULTS: Patients (N = 78; 32 males and 46 females) with a median age of 63 years (range 31-82) were evaluated. The tumors were located at the cardia (10.3%), upper stomach (59.0%), middle stomach (23.1), and lower stomach (7.7%). The mean size of the tumors was 34.7 ± 12.1 mm. The laparoscopic procedures included wedge resection (92.3%), such as laparoscopy and endoscopy cooperative surgery (51.3%), and gastrectomy (7.7%). All cases exhibited a pathologically negative margin. The mean operative time was 147.5 ± 63.8 min, and the mean estimated amount of blood loss was 17.8 ± 47.9 ml. The mean length of hospitalization was 9.4 ± 12.8 days. The incidence of perioperative complications higher than grade III was 2.6%, including two cases of anastomotic leakage. Regarding risk classification, low, intermediate and high were observed in 61, 6, and 11 cases, respectively. During a mean follow-up period of 45.3 ± 18.5 months, one patient experienced local recurrence in the omentum. Meanwhile, four patients died due to other diseases; all other patients survived. CONCLUSIONS: Adequate oncologic resection was achieved in all cases. Laparoscopic surgery is a feasible option for gastric GISTs <5 cm.

[S-1 monotherapy achieved twenty-month survival for peritoneal lavage cytology-positive gastric cancer patient undergoing noncurative resection].

We report a gastric cancer patient with positive peritoneal lavage cytology (CY1) who achieved 20-month progression free survival by S-1 monotherapy. An 82-year-old male patient who underwent distal gastrectomy with residual disease for type 4 scirrhous gastric cancer manifesting pyloric stenosis, direct invasion to the pancreas, and CY1. He received S-1 monotherapy postoperatively. His ECOG performance status (PS) was 0. The initial treatment schedule was 100mg/day, twice daily for 4 weeks with a 2-week rest, repeated every 6 weeks. Grade 2 thrombocytopenia at the end of the 5th course of treatment required discontinuation of one course of treatment, and subsequent treatment was continued with a dose reduction to 80mg/day. Afterwards, although treatment was temporarily postponed for 2 weeks, the dose modification enabled him to receive S-1 for 20 months, leading to a relative dose intensity of 81%. There was no evidence of disease progression. The most severe adverse events were transient grade 3 neutropenia as well as leukocytopenia, anemia, and thrombocytopenia, grade 2 each, without gastrointestinal toxicities. His PS was not deteriorated. Although survivalrates of CY1 gastric cancer patients are still poor, our case suggests that S-1 monotherapy is effective against CY1, even for patients aged over 80, if the relative dose intensity is maintained by comprehensive patient management and appropriate dose modification.

Pathological complete response of synchronous multiple liver metastases associated with advanced gastric cancer to gastrectomy and prompt S-1 treatment in combination with fractional cisplatin: report of a case.

Systemic chemotherapy is the treatment recommended for prolonged survival in cases of metastatic gastric cancer. There have been a number of clinical reports of surgical resection of liver metastasis in selected patients with gastric cancer. Here, we report on a case of treatment of far advanced gastric cancer with synchronous multiple liver metastases with prompt S-1 in combination with fractional cisplatin sandwiched between twostage surgery. Metastases including peritoneal dissemination and extensive lymph node involvement were absent so it was feasible to completely remove all of the macroscopic liver metastases. Each step of the chemotherapy progressed satisfactorily and histological examination after the hepatectomy yielded a pathologically complete response of liver metastases from the gastric cancer. This strategy provides a promising treatment for far advanced gastric cancer with a limited number of synchronous liver metastases. The referral to surgical oncology is a crucial step for the documentation of pathological complete response.

[Current state of treatment for advanced gastric cancer].

The radical treatment of gastric cancer is complete resection of the tumor by surgery. For advanced gastric cancer, a multidisciplinary approach has been attempted to improve patient prognosis. Potentially resectable and curable advanced gastric cancer is treated with routine surgery, followed by postoperative adjuvant chemotherapy. For highly advanced gastric cancer, extended radical surgery or preoperative adjuvant chemotherapy have been attempted. Laparoscopic gastrectomy for advanced gastric cancer has not been widely used because of the difficult surgical technique involved, but enhanced magnification in the surgical field is expected to improve the accuracy of the lymph node dissection procedure. In future, the significance of currently available treatments should be investigated. The key treatment for advanced gastric cancer at present is surgery.

Triangulating stapling technique for anastomosis in laparoscopy-assisted pylorus-preserving gastrectomy.

BACKGROUND/AIMS: The anastomosis performed during laparoscopy-assisted pylorus-preserving gastrectomy (PPG) is usually handsewn; however, the technique is sometimes difficult because it is done through a small incision and the level of skill of each operator may vary. The present study describes a triangulating stapling technique used during an anastomosis in laparoscopy-assisted pylorus-preserving gastrectomy. METHOD: The 80-mm stapler was used 3 times for the triangulating stapling technique. The posterior walls, including the stay sutures, were joined by firing the stapler, and the anterior stomach ends were stapled in an everting fashion using two firings of the stapler. Both the anterior staple lines should overlap in the middle. Patient demographics and the operative data were examined. RESULTS: The triangulating stapling technique was performed during laparoscopy-assisted PPG in 9 patients. The median time for the anastomosis during laparoscopy-assisted PPG using the triangulating stapling technique was 19.0 min (16.0-31.0). Postoperative complications, including gastric stasis and anastomotic failure, were not found in any of the present patients. CONCLUSION: The triangulating stapling technique using a linear stapler is a safe and reliable technique to perform and can be easily conducted in a short time. We therefore consider it a useful anastomosis method for laparoscopy-assisted pylorus-preserving gastrectomy, even by unskilled surgeons.

A single base mutation in the PRAT4A gene reveals differential interaction of PRAT4A with Toll-like receptors.

Toll-like receptors (TLRs) play an essential role in defense responses. Immune cells express multiple TLRs which are simultaneously activated by microbial pathogens. PRotein Associated with Tlr4 A (PRAT4A) is a chaperone-like endoplasmic reticulum (ER)-resident protein required for the proper subcellular distribution of multiple TLRs. PRAT4A(-/-) mice show impaired expression of TLR2/4 on the cell surface and the lack of ligand-induced TLR9 relocation from the ER to endolysosome. Consequently, TLR responses to whole bacteria as well as to TLR2, 4 and 9 ligands are impaired. We here compare the interaction of these TLRs with PRAT4A. Association of endogenous PRAT4A was easily detected only with TLR4. The TLR4 region responsible for strong interaction with PRAT4A is very close to the site necessary for interaction with MD-2. By using transient expression, we were able to detect PRAT4A interaction with TLR2 and TLR9. The PRAT4A single-nucleotide mutant replacing methionine 145 with lysine (M145K) associates with TLR9 but does not rescue ligand-dependent TLR9 trafficking. By contrast, the M145K mutant weakly, if at all, associates with TLR2 and TLR4. The M145K mutant appreciably rescues cell-surface TLR2 expression and its responses in PRAT4A(-/-) bone marrow-derived dendritic cells, whereas little if any rescue of cell-surface TLR4/MD-2 expression and its responses occurs. These results demonstrate that PRAT4A differentially interacts with each TLR and suggest that a single-nucleotide change in the PRAT4A gene influences not only the strength of TLR responses but can also alter the relative activity of each TLR.

A protein associated with Toll-like receptor (TLR) 4 (PRAT4A) is required for TLR-dependent immune responses.

Immune cells express multiple Toll-like receptors (TLRs) that are concomitantly activated by a variety of pathogen products. Although there is presumably a need to coordinate the expression and function of TLRs in individual cells, little is known about the mechanisms governing this process. We show that a protein associated with TLR4 (PRAT4A) is required for multiple TLR responses. PRAT4A resides in the endoplasmic reticulum, and PRAT4A knockdown inhibited trafficking of TLR1 and TLR4 to the cell surface and ligand-induced trafficking of TLR9 to lysosomes. Other cell-surface molecules were expressed normally on immunocytes from PRAT4A-/- mice. There was impaired cytokine production to TLR ligands, except to the TLR3 ligand poly(I:C), and to whole bacteria. Activation of antigen-specific T helper type 1 responses were also defective. Moreover, PRAT4A-/- bone marrow chimeric mice were resistant to lipopolysaccharide-induced sepsis. These results suggest that PRAT4A regulates the subcellular distribution and response of multiple TLRs and is required for both innate and adaptive immune responses.