Preoperative mechanical bowel preparation using conventional versus hyperosmolar polyethylene glycol-electrolyte lavage solution before laparoscopic resection for colorectal cancer (TLUMP test): a phase III, multicenter randomized controlled non-inferiority trial.

BACKGROUND: A hyperosmolar ascorbic acid-enriched polyethylene glycol-electrolyte (ASC-PEG) lavage solution ensures excellent bowel preparation before colonoscopy; however, no study has demonstrated the efficacy of this lavage solution before surgery. This study aimed to establish the non-inferiority of ASC-PEG to the standard polyethylene glycol-electrolyte solution (PEG-ELS) in patients undergoing laparoscopic resection for colorectal cancer. METHODS: This was a prospective, single-blind, multicenter, randomized, controlled, non-inferiority clinical trial. Overall, 188 patients scheduled for laparoscopic colorectal resection for single colorectal adenocarcinomas were randomly assigned to undergo preparation with different PEG solutions between August 2017 and April 2020 at four hospitals in Japan. Participants received ASC-PEG (Group A) or PEG-ELS (Group B) preoperatively. The primary endpoint was the ratio of successful bowel preparations using the modified Aronchick scale, defined as "excellent" or "good." RESULTS: After exclusion, 86 and 87 patients in Groups A and B, respectively, completed the study, and their data were analyzed. ASC-PEG was not inferior to PEG-ELS in terms of effective bowel preparation prior to laparoscopic colorectal resection (0.93 vs. 0.92; 95% confidence interval, - 0.078 to 0.099, p = 0.007). The total volume of cleansing solution intake was lower in Group A than in Group B (1757.0 vs. 1970.1 mL). Two and three severe postoperative adverse events occurred in Groups A and B, respectively. Patient tolerance of the two solutions was almost equal. CONCLUSIONS: ASC-PEG is effective for preoperative bowel preparation in patients undergoing laparoscopic resection for colorectal cancer and is non-inferior to PEG-ELS.

The incidence of cardiovascular thrombotic complications after laparoscopic resection in colorectal cancer in Japanese hospitals: A large-scale clinical study.

Aim: The aim of this retrospective study was to investigate the incidence of cardiovascular thrombotic complications after laparoscopic resection in colorectal cancer. Methods: This study involved 2017 patients with stages 0-III colorectal cancer who underwent laparoscopic surgery at 17 Japanese hospitals between January 2010 and December 2013. We assessed the incidence of postoperative cardiovascular thrombotic and haemorrhagic complications. Results: Laparoscopic surgeries were performed in 1152 men and 865 women with 1405 colon and 612 rectal cancers, respectively. Overall, 3%, 38%, 17%, 8%, and 9% of patients had comorbidities of heart failure, high blood pressure, diabetes, history of stroke, and vascular disease, respectively. Antithrombotic agents were being consumed by 17% of patients. The types (and perioperative rest periods) of the antithrombotic agents were aspirin in 58% (18.6 days), clopidogrel in 19% (21.1 days), cilostazol in 13% (13.3 days), and warfarin potassium in 21% (14.6 days) of cases with antithrombotic agents. Surgical time and blood loss in the total cohort were 234 minutes and 56 mL. Four cases (0.2%) had cardiovascular thrombotic complications, including one severe cardiac infarction and one stroke with major sequelae (CHADS2 scores were 2 points in both cases). Hemorrhagic complications occurred in 19 cases (0.9%). In particular, the incidence of the major gastroduodenal haemorrhagic ulcer was higher in cases with antithrombotic agents than without them (0.05% vs 0%, P = .02). Conclusion: The incidence of cardiovascular thrombotic complications was rare, although severe cardiac infarction and stroke could occur even after minimally invasive surgery in colorectal cancer.

IL6 Modulates the Immune Status of the Tumor Microenvironment to Facilitate Metastatic Colonization of Colorectal Cancer Cells.

It is unknown as to how liver metastases are correlated with host immune status in colorectal cancer. In this study, we found that IL6, a proinflammatory cytokine produced in tumor-bearing states, promoted the metastatic colonization of colon cancer cells in association with dysfunctional antitumor immunity. In IL6-deficient mice, metastatic colonization of CT26 cells in the liver was reduced, and the antitumor effector function of CD8+ T cells, as well as IL12 production by CD11c+ dendritic cells, were augmented in vivo IL6-deficient mice exhibited enhanced IFN-AR1-mediated type I interferon signaling, which upregulated PD-L1 and MHC class I expression on CT26 cells. In vivo injection of anti-PD-L1 effectively suppressed the metastatic colonization of CT26 cells in Il6 -/- but not in Il6 +/+ mice. Finally, we confirmed that colorectal cancer patients with low IL6 expression in their primary tumors showed prolonged disease-free survival. These findings suggest that IL6 may be a promising target for the treatment of metastasis in colorectal cancers by improving host immunity.

Short-term and Long-term Outcomes Following Laparoscopic Gastrectomy for Advanced Gastric Cancer Compared With Open Gastrectomy.

INTRODUCTION: To investigate the oncological feasibility and technical safety of laparoscopic gastrectomy with D2 lymphadenectomy for advanced gastric cancer. METHODS: A total of 186 advanced gastric cancer patients treated by gastrectomy with D2 lymphadenectomy were eligible for inclusion including those with invasion into the muscularis propria, subserosa, and serosa without involvement of other organs, and stages N0-2 and M0. We retrospectively compared the short-term and long-term outcomes between laparoscopic gastrectomy and open gastrectomy. RESULTS: We analyzed short-term outcomes by comparing distal with total gastrectomy results. We found no significant difference for distal gastrectomy for postoperative morbidity [laparoscopic vs. open: n=4 (4.6%) vs. n=1 (3.6%); P=1.00]. We also found no significant difference in postoperative morbidity for total gastrectomy [laparoscopic vs. open: n=2 (4.0%) vs. n=1 (4.0%); P=1.00]. No deaths occurred in any group.The entire cohort analysis revealed no statistically significant differences in overall-free or recurrence-free survival between the laparoscopic and open groups. For overall survival, there were no significant differences between open and laparoscopic groups for clinical stage II or III (P=0.29 and 0.27, respectively), and for pathologic stage II or III (P=0.88 and 0.86, respectively). For recurrence-free survival, there were no significant differences between open and laparoscopic groups for clinical stage II or III (P=0.63 and 0.60, respectively), and for pathologic stage II or III (P=0.98 and 0.72, respectively). CONCLUSION: Laparscopic gastrectomy for advanced gastric cancer compared favorably with open gastrectomy regarding short-term and long-term outcomes.

Preoperative FOLFOX in resectable locally advanced rectal cancer can be a safe and promising strategy: the R-NAC-01 study.

PURPOSE: The aim of this study was to assess the safety of rectal surgery after 5-fluorouracil-leucovorin-oxaliplatin chemotherapy (FOLFOX6). METHODS: This was a prospective, multicenter study in 11 Japanese hospitals. We included patients with rectal cancer who received 4 courses of modified FOLFOX6 (mFOLFOX6) before rectal surgery and examined the postoperative complication rate, the clinicopathological response, and the rate of chemotherapy-related adverse events (UMIN 000012559). RESULTS: The study population included 36 men and 5 women. The average age of the patients was 60.8 years and the average body mass index was 23.1 kg/m2. After 4 courses of chemotherapy, grade 2 peripheral nerve disorder and other grade 3 adverse events were seen in 3 patients each (7.3%). Twenty-eight (73.7%) and 8 (21.1%) patients underwent low anterior resection and abdominoperineal resection, respectively. The pelvic nerves were preserved in 35 patients. Surgical morbidity (grade ≥ 3) occurred in 4 patients (10.5%). Anastomotic leakage occurred after surgery in 2 patients (7.1%). No patients achieved pathologically complete remission. However, downstaging of the clinical stage and N stage was seen in 17 (41.5%) and 22 (53.7%) patients, respectively. CONCLUSIONS: Surgery after four courses of mFOLFOX6 chemotherapy can be a safe and promising strategy for patients with locally advanced rectal cancer.

Structural basis for receptor-regulated SMAD recognition by MAN1.

Receptor-regulated SMAD (R-SMAD: SMAD1, SMAD2, SMAD3, SMAD5 and SMAD8) proteins are key transcription factors of the transforming growth factor-ß (TGF-ß) superfamily of cytokines. MAN1, an integral protein of the inner nuclear membrane, is a SMAD cofactor that terminates TGF-ß superfamily signals. Heterozygous loss-of-function mutations in MAN1 result in osteopoikilosis, Buschke-Ollendorff syndrome and melorheostosis. MAN1 interacts with MAD homology 2 (MH2) domains of R-SMAD proteins using its C-terminal U2AF homology motif (UHM) domain and UHM ligand motif (ULM) and facilitates R-SMAD dephosphorylation. Here, we report the structural basis for R-SMAD recognition by MAN1. The SMAD2-MAN1 and SMAD1-MAN1 complex structures show that an intramolecular UHM-ULM interaction of MAN1 forms a hydrophobic surface that interacts with a hydrophobic surface among the H2 helix, the strands ß8 and ß9, and the L3 loop of the MH2 domains of R-SMAD proteins. The complex structures also show the mechanism by which SMAD cofactors distinguish R-SMAD proteins that possess a highly conserved molecular surface.

Carcinoma in the residual rectum of a long-standing Crohn's disease patient following subtotal colectomy: A case report.

The development of colorectal cancer in long-standing Crohn's disease (CD) patients has become a major complication. Therapeutic guidelines for CD-associated cancer (CDAC) have already been established in Western countries; however, specific guidelines are not currently available in Japan. Surveillance of the residual intestine for cancer screening is important for long-standing CD patients. The present case report describes the occurrence of rectal carcinoma in a patient with a 25-year history of CD. A 37-year-old male with a 17-year history of CD underwent semi-emergent subtotal colectomy and ileostomy for bowel obstruction secondary to the transverse colon stenosis, and multiple severe stenosis and inflammation. Postoperatively, the patient resumed pharmacological treatment and underwent follow-up colonoscopies at ~1-2-year intervals. Despite continued pharmacological treatment, inflammation continued in the residual rectum. A total of 8 years following the primary operation, colonoscopy revealed inflammatory polyposis at the remnant rectum, which was diagnosed as adenocarcinoma. The interval between the last colonoscopy was 16 months. The patient then underwent laparoscopic abdominoperineal resection, and remained without recurrence for 12 months following resection. Thus, in long-standing CD patients, annual colonoscopy of the residual intestine may be considered for cancer screening, and specific surveillance guidelines for CDAC should be established.

Laparoscopic total gastrectomy for advanced gastric cancer in a patient with situs inversus totalis.

Situs inversus totalis (SIT) is a rare congenital anomaly. Generally, laparoscopic surgery is difficult to perform in patients with SIT because of both the potential challenges associated with unexpected vascular anomalies and the lack of standardized strategy for handling such cases. This is the first report of laparoscopic total gastrectomy with lymph node dissection for advanced gastric cancer in a patient with SIT. A 79-year-old man with SIT was diagnosed with advanced gastric cancer. We performed laparoscopic total gastrectomy with modified D2 lymph node dissection (D2 without splenectomy) and esophagojejunal anastomosis using an overlap method involving retrocolic Roux-en-Y reconstruction. The total operating time was 232 min, and blood loss was 110 mL. There were no postoperative complications. In summary, laparoscopic total gastrectomy for gastric cancer can be performed safely, even in a patient with SIT.

Supervision by a technically qualified surgeon affects the proficiency and safety of laparoscopic colectomy performed by novice surgeons.

BACKGROUND: The use of laparoscopic colectomy is becoming widespread and acquisition of its technique is challenging. In this study, we investigated whether supervision by a technically qualified surgeon affects the proficiency and safety of laparoscopic colectomy performed by novice surgeons. METHODS: The outcomes of 23 right colectomies and 19 high anterior resections for colon cancers performed by five novice surgeons (experience level of <10 cases) between 2014 and 2016 were assessed. A laparoscopic surgeon qualified by the Endoscopic Surgical Skill Qualification System (Japan Society for Endoscopic Surgery) participated in surgeries as the teaching assistant. RESULTS: In the right colectomy group, one patient (4.3%) required conversion to open surgery and postoperative morbidities occurred in two cases (8.6%). The operative time moving average gradually decreased from 216 to 150 min, and the blood loss decreased from 128 to 28 mL. In the CUSUM charts, the values for operative time decreased continuously after the 18th case, as compared to the Japanese standard. The values for blood loss also plateaued after the 18th case. In the high anterior resection group, one patient (5.2%) required conversion to open surgery and no postoperative complication occurred in any patient. The operative time moving average gradually decreased from 258 to 228 min, and the blood loss decreased from 33 to 18 mL. The CUSUM charts showed that the values of operative time plateaued after the 18th case, as compared to the Japanese standard. In the CUSUM chart for blood loss, no distinguishing peak or trend was noted. CONCLUSIONS: Supervision by a technically qualified surgeon affects the proficiency and safety of laparoscopic colectomy performed by novice surgeons. The trainee's learning curve in this study represents successful mentoring by the laparoscopic surgeon qualified by the Endoscopic Surgical Skill Qualification System.

Mentor Tutoring: An Efficient Method for Teaching Laparoscopic Colorectal Surgical Skills in a General Hospital.

OBJECTIVE: We retrospectively assessed the efficacy of our mentor tutoring system for teaching laparoscopic colorectal surgical skills in a general hospital. MATERIALS AND METHODS: A series of 55 laparoscopic colectomies performed by 1 trainee were evaluated. Next, the learning curves for high anterior resection performed by the trainee (n=20) were compared with those of a self-trained surgeon (n=19). RESULTS: Cumulative sum analysis and multivariate regression analyses showed that 38 completed cases were needed to reduce the operative time. In high anterior resection, the mean operative times were significantly shorter after the seventh average for the tutored surgeon compared with that for the self-trained surgeon. In cumulative sum charting, the curve reached a plateau by the seventh case for the tutored surgeon, but continued to increase for the self-trained surgeon. CONCLUSIONS: Mentor tutoring effectively teaches laparoscopic colorectal surgical skills in a general hospital setting.

The Balance Between Surgical Resident Education and Patient Safety in Laparoscopic Colorectal Surgery: Surgical Resident's Performance has No Negative Impact.

OBJECTIVE: This study aimed to evaluate the feasibility and effectiveness of a comprehensive theoretical and hands-on training program in performing laparoscopic colonic resections under supervision of an expert surgeon. MATERIALS AND METHODS: Laparoscopic right colectomy was performed in 78 patients (10 with benign disease, 68 with carcinoma). Demographic, intraoperative, pathologic examination, and short-term outcome data were retrospectively compared between 25 patients operated by surgical residents (R group) and 53 patients operated by senior surgeons (S group). The residents who performed surgeries in the R group had between 1 and 6 years after graduation; no experience with open or laparoscopic colorectal surgery was necessary. The residents completed a training program under supervision of a single expert laparoscopic colorectal surgeon, which included 6 steps, from basic skills to certification. RESULTS: There were no differences in patient age, sex, and body mass index between the R and S groups. Significantly more patients in the R group had early cancer and benign lesions (P<0.05). Thirteen of the 16 residents (81.2 %) had not had prior experience with colonic resection. The time of suturing and knot tying in the dry box did not differ between residents and senior surgeons (68 and 69 s, respectively). All the residents performed laparoscopic right colectomy without intraoperative complications. There were no significant differences in operating time (R group: 173±34 min, S group: 172±52 min), mean estimated blood loss (50±111 vs. 49±100 mL), number of lymph nodes dissected (20.8±12.8 vs. 17.1±9.0), and mean postoperative hospital stay (9.1±3.3 vs. 10.7±4.1 d). On the basis of the year of their residency period, all 3 residents at 6 years after graduation had far greater experience than the other residents and therefore performed the surgery with minor verbal support from the expert. However, residents with 1 or 2 years after graduation had to receive guidance provision by the expert during surgery. CONCLUSIONS: When supervised and led by an expert laparoscopic surgeon, surgical residents are capable of performing laparoscopic surgery without negative effects on outcomes.

Interleukin-6/STAT3 signaling as a promising target to improve the efficacy of cancer immunotherapy.

Overcoming the immunosuppressive state in tumor microenvironments is a critical issue for improving the efficacy of cancer immunotherapy. Interleukin (IL)-6, a pleiotropic cytokine, is highly produced in the tumor-bearing host. Previous studies have indicated that IL-6 suppresses the antigen presentation ability of dendritic cells (DC) through activation of signal transducer and activator of transcription 3 (STAT3). Thus, we focused on the precise effect of the IL-6/STAT3 signaling cascade on human DC and the subsequent induction of antitumor T cell immune responses. Tumor-infiltrating CD11b+ CD11c+ cells isolated from colorectal cancer tissues showed strong induction of the IL-6 gene, downregulated surface expression of human leukocyte antigen (HLA)-DR, and an attenuated T cell-stimulating ability compared with those from peripheral blood mononuclear cells, suggesting that the tumor microenvironment suppresses antitumor effector cells. In vitro experiments revealed that IL-6-mediated STAT3 activation reduced surface expression of HLA-DR on CD14+ monocyte-derived DC. Moreover, we confirmed that cyclooxygenase 2, lysosome protease and arginase activities were involved in the IL-6-mediated downregulation of the surface expression levels of HLA class II on human DC. These findings suggest that IL-6-mediated STAT3 activation in the tumor microenvironment inhibits functional maturation of DC to activate effector T cells, blocking introduction of antitumor immunity in cancers. Therefore, we propose in this review that blockade of the IL-6/STAT3 signaling pathway and target molecules in DC may be a promising strategy to improve the efficacy of immunotherapies for cancer patients.

Lack of interleukin-6 in the tumor microenvironment augments type-1 immunity and increases the efficacy of cancer immunotherapy.

Conquering immunosuppression in tumor microenvironments is crucial for effective cancer immunotherapy. It is well known that interleukin (IL)-6, a pleiotropic cytokine, is produced in the tumor-bearing state. In the present study, we investigated the precise effects of IL-6 on antitumor immunity and the subsequent tumorigenesis in tumor-bearing hosts. CT26 cells, a murine colon cancer cell line, were intradermally injected into wild-type and IL-6-deficient mice. As a result, we found that tumor growth was decreased significantly in IL-6-deficient mice compared with wild-type mice and the reduction was abrogated by depletion of CD8+ T cells. We further evaluated the immune status of tumor microenvironments and confirmed that mature dendritic cells, helper T cells and cytotoxic T cells were highly accumulated in tumor sites under the IL-6-deficient condition. In addition, higher numbers of interferon (IFN)-γ-producing T cells were present in the tumor tissues of IL-6-deficient mice compared with wild-type mice. Surface expression levels of programmed death-ligand 1 (PD-L1) and MHC class I on CT26 cells were enhanced under the IL-6-deficient condition in vivo and by IFN-γ stimulation in vitro. Finally, we confirmed that in vivo injection of an anti-PD-L1 antibody or a Toll-like receptor 3 ligand, polyinosinic-polycytidylic acid, effectively inhibited tumorigenesis under the IL-6-deficient condition. Based on these findings, we speculate that a lack of IL-6 produced in tumor-bearing host augments induction of antitumor effector T cells and inhibits tumorigenesis in vivo, suggesting that IL-6 signaling may be a promising target for the development of effective cancer immunotherapies.

Usefulness of PET/CT for early detection of internal malignancies in patients with Muir-Torre syndrome: report of two cases.

BACKGROUND: Muir-Torre syndrome (MTS) is a rare autosomal dominant genodermatosis caused by mutations in mismatch repair genes. It is characterized by the presence of at least one sebaceous skin tumor associated with internal malignancies. Whether positron emission tomography/computed tomography (PET/CT) is useful for the detection of malignancies in patients with MTS has not been determined. We herein report two cases in which PET/CT was useful for the diagnosis and follow-up of internal malignancies in patients with MTS. CASE PRESENTATION: In case 1, a 57-year-old woman underwent excision of a sebaceous carcinoma on the left upper eyelid. She underwent follow-up PET/CT once yearly thereafter. Forty-two months after the eyelid surgery, PET/CT showed intense tracer uptake in the right lower abdomen. An ascending colon tumor was identified, and examination of a biopsy specimen showed adenocarcinoma. In case 2, a 77-year-old man presented for evaluation of three continuous papules with telangiectasia on his right cheek. Examination of a skin biopsy specimen of the cheek papule revealed a sebaceous carcinoma. He underwent PET/CT to detect other malignancies. PET/CT showed intense tracer uptake in the sigmoid colon. A sigmoid colon tumor was identified, and examination of a biopsy specimen showed adenocarcinoma. Both patients underwent resection of their tumors, and both were still free of recurrence of the sebaceous and colon carcinomas at the time of this writing. CONCLUSION: PET/CT is a reliable imaging modality for the detection of internal malignancies and is useful for the diagnosis and follow-up of MTS.

Anastomotic complications after laparoscopic total gastrectomy with esophagojejunostomy constructed by circular stapler (OrVil™) versus linear stapler (overlap method).

BACKGROUND: Esophagojejunostomy after laparoscopic total gastrectomy (LTG) is the most technically difficult type of anastomosis; thus, anastomotic complications such as leakage and stenosis sometimes occur. Identification of the safest anastomotic procedure is important for successful LTG. We have performed LTG since 2004 either with a circular stapler using an OrVil™ anvil or via the overlap Orringer method with a linear stapler. This retrospective study aimed to determine which method results in a lower incidence of anastomotic complications in patients undergoing LTG. METHODS: Data on 188 consecutive patients who underwent LTG between April 2004 and August 2016 were retrospectively reviewed. Patients were divided into those who underwent esophagojejunostomy performed via a circular stapler using an OrVil™ anvil (group C, n = 49) or via the overlap method (group L, n = 139). RESULTS: Anastomotic complications occurred in five of 188 esophagojejunostomies (2.7%). They comprised three cases of leakage (1.6%), and two of stenosis (1.1%). There was no significant difference in patient characteristics or hematological variables between groups C and L. There was no significant difference between groups in operation time, blood loss, lymph node dissection, and intraoperative anastomotic problems. The rate of anastomotic complications was significantly lower in group L (0.7%, 1/139) than in group C (8.2%, 4/49; p = 0.005). In particular, anastomotic leakage in group L tended to be lower (0.7% 1/139) than in group C (4.1% 2/49), although this difference was not significant. The rate of anastomotic stenosis in group L was significantly lower (0%, 0/139) than in group C (4.1%, 2/49; p = 0.017). Furthermore multivariate analysis showed anastomotic procedure was an independent factor for anastomotic complication. CONCLUSIONS: There were fewer anastomotic complications after overlap esophagojejunostomy than after esophagojejunostomy via the OrVil™ procedure, especially regarding anastomotic stenosis. We therefore recommend the overlap technique when performing esophagojejunostomy.

Two cases of melanomas paradoxically metastasizing to the intestinal tract during nivolumab therapy.

We report two cases of melanomas in patients who developed intestinal metastasis despite other metastatic sites responding to nivolumab and despite the patients having favorable findings such as vitiligo and normal lactate dehydrogenase. The first case is an 85-year-old man who had been administrated nivolumab for lung/cutaneous metastases. After 22 courses of nivolumab therapy, fever and anorexia had appeared and his bodyweight had decreased. An intussusception on the ileocecal valve was revealed by computed tomography, and emergency surgery revealed metastatic lesions on the colon. The second case is an 87-year-old woman treated with nivolumab for lymph node metastases. After 10 courses, laboratory tests had revealed anemia and positive fecal occult blood. Her bodyweight had decreased. Capsule endoscopy showed scattered tumors and clots, indicating metastases of melanoma. The frequency of symptomatic intestinal metastasis of melanoma is very low. Further, intestinal metastasis of melanoma is difficult to detect through routine examinations. Our cases suggest that fecal occult blood test and decreased bodyweight are indications of intestinal metastases.

IL-6 down-regulates HLA class II expression and IL-12 production of human dendritic cells to impair activation of antigen-specific CD4(+) T cells.

Immunosuppression in tumor microenvironments critically affects the success of cancer immunotherapy. Here, we focused on the role of interleukin (IL)-6/signal transducer and activator of transcription (STAT3) signaling cascade in immune regulation by human dendritic cells (DCs). IL-6-conditioned monocyte-derived DCs (MoDCs) impaired the presenting ability of cancer-related antigens. Interferon (IFN)-γ production attenuated by CD4(+) T cells co-cultured with IL-6-conditioned MoDCs corresponded with decreased DC IL-12p70 production. Human leukocyte antigen (HLA)-DR and CD86 expression was significantly reduced in CD11b(+)CD11c(+) cells obtained from peripheral blood mononuclear cells (PBMCs) of healthy donors by IL-6 treatment and was STAT3 dependent. Arginase-1 (ARG1), lysosomal protease, cathepsin L (CTSL), and cyclooxygenase-2 (COX2) were involved in the reduction of surface HLA-DR expression. Gene expressions of ARG1, CTSL, COX2, and IL6 were higher in tumor-infiltrating CD11b(+)CD11c(+) cells compared with PBMCs isolated from colorectal cancer patients. Expression of surface HLA-DR and CD86 on CD11b(+)CD11c(+) cells was down-regulated, and T cell-stimulating ability was attenuated compared with PBMCs, suggesting that an immunosuppressive phenotype might be induced by IL-6, ARG1, CTSL, and COX2 in tumor sites of colorectal cancer patients. There was a relationship between HLA-DR expression levels in tumor tissues and the size of CD4(+) T and CD8(+) T cell compartments. Our findings indicate that IL-6 causes a dysfunction in human DCs that activates cancer antigen-specific Th cells, suggesting that blocking the IL-6/STAT3 signaling pathway might be a promising strategy to improve cancer immunotherapy.

IL-11 induces differentiation of myeloid-derived suppressor cells through activation of STAT3 signalling pathway.

Myeloid-derived suppressor cells (MDSCs) are immune negative regulators in the tumour microenvironment. Interleukin (IL)-11, a member of IL-6 family cytokines, functions through the unique receptor IL-11 receptor α coupled with the common signal transducer gp130. IL-11-gp130 signalling causes activation of the JAK/STAT3 pathway. IL-11 is highly upregulated in many types of cancers and one of the most important cytokines during tumourigenesis and metastasis. However, the precise effect of IL-11 on differentiation into MDSCs is still unknown. Here, we found that CD11b+CD14+ monocytic MDSCs were generated from peripheral blood mononuclear cells (PBMCs) of healthy donors in the presence of IL-11. IL-11-conditioned PBMCs induced higher expression of immunosuppressive molecules such as arginase-1. A reduction of T-cell proliferation was observed when MDSCs generated in the presence of IL-11 were co-cultured with CD3/CD28-stimulated, autologous T cells of healthy donors. Culture of normal PBMCs with IL-11 led to STAT3 phosphorylation and differentiation into MDSCs via STAT3 activation. We confirmed expressions of both IL-11 and phosphorylated STAT3 in tumour tissues of colorectal cancer patients. These findings suggest that monocytic MDSCs may be induced by IL-11 in the tumour microenvironment. Thus, IL-11-mediated regulation in functional differentiation of MDSCs may serve as a possible target for cancer immunotherapy.