Endoscopic Improvement of the Adenoma Detection Rate during Colonoscopy - Where Do We Stand in 2015?

BACKGROUND: The presence of colorectal adenomas is considered a major risk factor for colorectal cancer development. The implementation of screening colonoscopy programs in the Western world has led to a substantial reduction of colorectal cancer death. Many efforts have been made to reduce the adenoma miss rates by the application of new endoscopic devices and techniques for better adenoma visualization. SUMMARY: This special review gives the readership an overview of current endoscopic innovations that can aid in the increase of the adenoma detection rate (ADR) during colonoscopy. These innovations include the use of devices like EndoCuff® and EndoRings® as well as new technical equipment like third-eye endoscope® and full-spectrum endoscopy (FUSE®). KEY MESSAGE: Technical improvements and newly developed accessories are able to improve the ADR. However, additional costs and a willingness to invest into potentially expensive equipment might be necessary. Investigator-dependent skills remain the backbone in the ADR detection.

Novel endocuff-assisted colonoscopy significantly increases the polyp detection rate: a randomized controlled trial.

GOALS AND BACKGROUND: Screening colonoscopy for colorectal cancer has proven to reduce mortality rates. Recently the Endocuff (EC), an attachment to the distal tip of the colonoscope, was introduced. The aim of our study was to compare EC-assisted colonoscopies with standard colonoscopies for the detection of colonic polyps. STUDY: This study is a randomized prospective 2-center trial. The study was conducted at 2 tertiary care centers. PARTICIPANTS: A total of 498 patients [249 males; median age 67 y; interquartile range (IQR), 56-75 y] for colon adenoma screening purposes were included. All patients underwent standard colonoscopy with or without the use of EC. Overall polyp detection rate, the number of colonic polyps, and the polyp distribution in the colon were measured. Difference in recognition of polyps with or without the use of EC was assessed. Statistical analysis was applied. RESULTS: In the EC group, the number of polyps detected per patient was 63% higher [2.00 (IQR, 1.00-4.00) vs. 1.00 (IQR, 1.00-2.25), P<0.0001]. The polyp detection rate in patients increased by 14% with the use of EC (56% vs. 42%, P=0.001). For polyp detection, superiority by use of EC could be observed in the sigmoid (P=0.001) and cecum (P=0.002) for polyps <1 cm in diameter. In the EC group, the number of adenomas detected per patient significantly increased by 86% (P=0.002). No major complications occurred in both groups. CONCLUSIONS: The use of the EC is feasible and safe with significantly higher polyp detection rates, especially for those located in the sigmoid region. The cuff system has the potential to improve the accuracy of screening colonoscopies.

CO2 insufflation during single-balloon enteroscopy: a multicenter randomized controlled trial.

BACKGROUND AND STUDY AIMS: Carbon dioxide (CO2) insufflation has previously been shown to have advantages over air insufflation in terms of procedure-related pain and oral insertion depth during double-balloon enteroscopy. The aim of this prospective study was to evaluate the performance of CO2 vs. air insufflation during single-balloon enteroscopy. PATIENTS AND METHODS: This study was a randomized European multicenter trial (ClinicalTrials.gov: NCT01524055). Patients and endoscopists were blinded to the type of insufflation gas used. Patient discomfort during and after the procedure was scored using a visual analog scale. RESULTS: A total of 107 patients were enrolled in the study (52 in the CO2 group and 55 in the air group). Patient characteristics were comparable in both groups. The mean (±SD) oral intubation depth was not significantly deeper in the CO2 group vs. the air group (254±80 vs. 238±55 cm; P=0.726). However, in patients with previous abdominal surgery, oral intubation depth was significantly higher in the CO2 group compared with the air group (258±84 vs. 192±42 cm; P<0.05). In patients undergoing SBE via the anal approach, CO2 showed no significant difference in intubation depth compared with air insufflation (86±67 vs. 110±68 cm; P=0.155). The diagnostic yield was comparable (CO2 67%; air 73%). Procedure times, dosage of sedation, and therapeutic interventions did not differ between the two groups. Patients in the CO2 group reported less pain than those in the air group. CONCLUSIONS: This study demonstrated an advantage of using CO2 insufflation during single-balloon enteroscopy in patients with a history of previous abdominal surgery. Overall, single-balloon enteroscopy was a well-tolerated procedure that may benefit from the use of CO2 insufflation to reduce post-procedural pain.

Clearance of refractory bile duct stones with Extracorporeal Shockwave Lithotripsy: higher failure rate in obese patients.

OBJECTIVE: Bile duct stones that cannot be removed endoscopically are still a challenge in interventional gastroenterology. Extracorporeal shockwave lithotripsy (ESWL) with subsequent endoscopic extraction of residual fragments is an established treatment option if other endoscopic means are not successful. Our study aimed to investigate the efficacy and safety of ESWL for clearance of refractory bile duct stones. MATERIAL AND METHODS: A total of 73 consecutive patients treated for refractory choledocholithiasis with ESWL were retrospectively analyzed. Success and complication rates were calculated. RESULTS: Complete stone clearance was achieved in 66 cases (90%). Patients with complete clearance had a significantly lower body mass index or BMI (25.55 ± 5.01 kg/m² vs. 31.60 ± 6.26 kg/m², p = 0.035) and needed less ESWL treatments (3.61 ± 1.87 vs. 5.00 ± 1.63, p = 0.048). A relevant drop of hemoglobin occurred significantly more often in the group with partial clearance (43% vs. 6%, p = 0.005). CONCLUSIONS: ESWL proves to be an excellent clearing approach to refractory bile duct stones with high success rates. However, obesity is one risk factor for ESWL failure and higher procedural hazard.

Enoxaparin improves the course of dextran sodium sulfate-induced colitis in syndecan-1-deficient mice.

Syndecan-1 (Sdc1) plays a major role in wound healing and modulates inflammatory responses. Sdc1 expression is reduced in lesions of patients with ulcerative colitis. The aim of this study was to investigate the role of Sdc1 in murine dextran sodium sulfate (DSS)-induced colitis. DSS colitis was induced in Sdc1-deficient (knockout (KO)) and wild-type mice by oral administration of 3% DSS. KO mice exhibited a significantly increased lethality as compared with wild-type controls (61 versus 5%, P < 0.05). Impaired mucosal healing and prolonged recruitment of inflammatory cells in KO mice were accompanied by significant up-regulation of tumor necrosis factor-alpha, CC chemokine ligand 3/macrophage inflammatory protein-1alpha, and vascular cell adhesion molecule-1, as determined by histological correlation between 0 and 15 days after colitis induction, TaqMan low-density array analysis, and quantitative real-time PCR. Treatment from days 7 through 14 with enoxaparin, a functional analogue of the Sdc1 heparan sulfate chains, significantly reduced lethality of KO mice due to DSS-induced colitis, which was correlated with improved mucosal healing. In vitro, Sdc1-deficient polymorphonuclear cells displayed increased adhesion to endothelial cells and intercellular adhesion molecule-1, and enoxaparin reverted adhesion to wild-type levels. Small interfering RNA-mediated knockdown of Sdc1 expression resulted in reduced basic fibroblast growth factor-mediated mitogen-activated protein kinase signaling and reduced Caco-2 cell proliferation. We conclude that Sdc1 has a protective effect during experimental colitis. The modification of missing Sdc1 function by heparin analogues may emerge as a promising anti-inflammatory approach.

Out-of-hospital sepsis recognition by paramedics improves the course of disease and mortality: A single center retrospective study.

BACKGROUND: Early recognition of sepsis and a prompt initiation of goal-directed therapy is important for sepsis survival. Little is known about the impact of early recognition of sepsis in the out-of-hospital setting when paramedics are the 1st medical professionals arriving on the scene. OBJECTIVES: To characterize the impact of sepsis recognition by paramedics in the 1st out-of-hospital contact and to establish a predictive model by combining preclinical patient characteristics. MATERIAL AND METHODS: In this retrospective single-center cohort study, we included a total of 263 patients diagnosed with sepsis after admission to the emergency department and correlated them to the emergency medical protocols of the paramedics who have seen the patient out-of-hospital. RESULTS: Only 25 patients were correctly diagnosed by paramedics out-of-hospital. If sepsis was diagnosed, the median time to antibiotic administration was significantly lower (136.50 min compared to 206.98 min, p = 0.0069) and mortality was reduced from 22.8% to 8% (p = 0.0292). We have identified predictors for prognosis and calculated a predictive model with a modified quick Sepsis-related Organ Failure Assessment (qSOFA) score, which fits the needs for out-of-hospital usage and results in a better discrimination of vitally threatened patients (receiver operating characteristic (ROC) area under curve (AUC) of 0.641 compared to 0.719), as compared to the standard qSOFA. CONCLUSIONS: Sepsis recognition by paramedics at the 1st out-of-hospital contact significantly reduces sepsis mortality. The qSOFA and modified qSOFA are suitable tools for sepsis recognition, and have an impact on mortality and disease management when used.

Soluble syndecan-1 as marker of intestinal inflammation: A preliminary study and evaluation of a new panel of biomarkers for non-invasive prediction of active ulcerative colitis.

BACKGROUND: Syndecan-1 (Sdc1) is a heparin sulfate proteoglycan expressed in intestinal epithelium, which plays a crucial role in inflammation and epithelial repair. Sdc1-knockout mice have a deteriorated course of dextran sulfate sodium-induced colitis as compared to controls. Syndecan-1 is also shed into the serum during inflammation of the epithelium. We hypothesized that an increased serum level of soluble Sdc1 is a biomarker of intestinal inflammation in ulcerative colitis (UC). OBJECTIVES: To evaluate serum soluble Sdc1 as a biomarker of intestinal inflammation in UC. MATERIAL AND METHODS: This is a proof-of-concept study. Patients were recruited by the University Hospital Münster and HELIOS Albert Schweitzer Klinik Northeim (Germany). Blood samples were collected from UC patients actively suffering from this condition and those in remission. The levels of Sdc1 were measured with Diaclone CD 138 ELISA kit (Diaclone Research, Besançon, France) and routine clinical data were collected (C-reactive protein (CRP) levels, calprotectin in stool samples). Data were analyzed using SPSS software. RESULTS: Soluble Sdc1 levels were significantly elevated in the active UC group as compared to the inactive UC group (94.5 ±68.1 ng/mL compared to 28.3 ±12.6 ng/mL, p = 0.0020). The levels of Sdc1 also significantly correlated with the severity of UC as measured with the Mayo score (p = 0.0248). Receiver operating characteristic (ROC) analysis showed a good correlation of Sdc1 with an endoscopic Mayo score ≥2, with a value of 0.7747 (95% confidence interval (95% CI) = 0.5775-0.9718). A cutoff value of 37.1 ng/mL of Sdc1 showed a sensitivity of 78% and a specificity of 77%. A panel of biomarkers including CRP, hemoglobin, hematocrit, and Sdc1 was able to precisely predict active UC with an area under the curve (AUC) = 0.9395 (95% CI = 0.8509-1.0000). CONCLUSIONS: Serum soluble Sdc1 correlates significantly with mucosa inflammation and Mayo score in UC. Clinical trials No. NCT02333526.

Indications of Persistent Glycocalyx Damage in Convalescent COVID-19 Patients: A Prospective Multicenter Study and Hypothesis.

The COVID-19 pandemic is caused by the SARS CoV-2 virus and can lead to severe lung damage and hyperinflammation. In the context of COVID-19 infection, inflammation-induced degradation of the glycocalyx layer in endothelial cells has been demonstrated. Syndecan-1 (SDC-1) is an established parameter for measuring glycocalyx injury. This prospective, multicenter, observational, cross-sectional study analyzed SDC-1 levels in 24 convalescent patients that had been infected with SARS-CoV-2 with mild disease course without need of hospitalization. We included 13 age-matched healthy individuals and 10 age-matched hospitalized COVID-19 patients with acute mild disease course as controls. In convalescent COVID-19 patients, significantly elevated SDC-1 levels were detected after a median of 88 days after symptom onset compared to healthy controls, whereas no difference was found when compared to SDC-1 levels of hospitalized patients undergoing acute disease. This study is the first to demonstrate signs of endothelial damage in non-pre-diseased, convalescent COVID-19 patients after mild disease progression without hospitalization. The data are consistent with studies showing evidence of persistent endothelial damage after severe or critical disease progression. Further work to investigate endothelial damage in convalescent COVID-19 patients should follow.

Standard versus Endocuff versus cap-assisted colonoscopy for adenoma detection: A randomised controlled clinical trial.

BACKGROUND AND AIMS: Adenoma detection rate (ADR) in colon cancer screening is most important for cancer prophylaxis. This work is the first three-armed randomised controlled clinical trial aimed at comparing a head-to-head setting standard colonoscopy (SC) with Endocuff-assisted colonoscopy (EC) and cap-assisted colonoscopy (CAC) for improvement of ADR. METHODS: Patients from Poland and Germany with independent indication for colonoscopy were randomised into three arms of this trial: EC, CAC and SC. Exclusion criteria were age <18 years, active Crohn's disease or ulcerative colitis, known stenosis and post-colonic resection status. RESULTS: A total of 585 patients (195 SC, 189 EC and 186 CAC) were enrolled in this study. Indications were not different between the groups (colorectal cancer screening 51%, diagnostic colonoscopy in 31% and post-polypectomy follow-up in 18%; p = 0.94). Withdrawal time was a mean of 7 min in all groups (p = 0.658), and bowel preparation did not differ between the groups. The time to reach the caecum was significantly reduced when using the cap (a mean of 6 min for CAC vs. 7 min for SC; p = 0.0001). There was no significant difference in the primary outcome of the ADR between the groups (EC 32%, CAC 30%, SC 30%; p = 0.815). EC proved to be superior (EC vs. SC) in the sigmoid colon and transverse colon for polyp detection. CONCLUSION: The use of EC increased the total number of polyps seen during colonoscopy. In contrast to recent studies, no significant improvement of the ADR was detected.

Modulatory effect of curcumin on survival of irradiated human intestinal microvascular endothelial cells: role of Akt/mTOR and NF-{kappa}B.

Radiation therapy is an essential modality in the treatment of colorectal cancers. Radiation exerts an antiangiogenic effect on tumors, inhibiting endothelial proliferation and survival in the tumor microvasculature. However, damage from low levels of irradiation can induce a paradoxical effect, stimulating survival in endothelial cells. We used human intestinal microvascular endothelial cells (HIMEC) to define effects of radiation on these gut-specific endothelial cells. Low-level irradiation (1-5 Gy) activates NF-kappaB and the phosphatidylinositol 3-kinase (PI3K)/Akt pathway, which is involved in cell cycle reentry and cell survival in HIMEC. A downstream target of PI3K/Akt is mammalian target of rapamycin (mTOR), which contributes to endothelial proliferation and angiogenesis. The aim of this study was to investigate the signaling molecules involved in the radiosensitizing effects of curcumin on HIMEC subjected to low levels of irradiation. We have demonstrated that exposure of HIMEC to low levels of irradiation induced Akt and mTOR phosphorylation, which was attenuated by curcumin, rapamycin, LY294002, and mTOR small interference RNA (siRNA). Activation of NF-kappaB by low levels of irradiation was inhibited by curcumin, SN-50, and mTOR siRNA. Curcumin also induced apoptosis by induction of caspase-3 cleavage in irradiated HIMEC. In conclusion, curcumin significantly inhibited NF-kappaB and attenuated the effect of irradiation-induced prosurvival signaling through the PI3K/Akt/mTOR and NF-kappaB pathways in these gut-specific endothelial cells. Curcumin may be a potential radiosensitizing agent for enhanced antiangiogenic effect in colorectal cancer radiation therapy.

Preoperative prediction of curative surgery of perihilar cholangiocarcinoma by combination of endoscopic ultrasound and computed tomography.

BACKGROUND: Perihilar cholangiocarcinomas are often considered incurable. Late diagnosis is common. Advanced disease therefore frequently causes questioning of curative surgical outcome. AIM: This study aimed to develop a prediction model of curative surgery in patients suffering from perihilar cholangiocarcinomas based on preoperative endosonography and computer tomography. METHODS: A cohort of 81 patients (median age 67 (54-75) years, 62% male) with perihilar cholangiocarcinoma was retrospectively analyzed. Multivariate logistic regression analysis of staging variables taken from the European Staging System was performed and applied to ROC analysis. RESULTS: The correlation of predicted rates of eligibility for surgery with actual rates reached AUC values between 0.652 and 0.758 for endosonography and computer tomography (p < 0.05 each). Best prediction for curative surgical option was achieved by combining endosonography and computer tomography (AUC: 0.787; 95% CI 0.680-0.893, p < 0.0001). A predictive model (pSurg) was developed using multivariate analysis. CONCLUSIONS: Our predictive web-based model pSurg with inclusion of T, N, M, B, PV, HA and V stage of the recently published European Staging System for perihilar cholangiocarcinoma results in highly significant predictability for curative surgery when combining preoperative endosonography and computer tomography, thus allowing for better patient selection in terms of possibility of curative surgery.

Higher adenoma detection rates with endocuff-assisted colonoscopy - a randomized controlled multicenter trial.

OBJECTIVES: The Endocuff is a device mounted on the tip of the colonoscope to help flatten the colonic folds during withdrawal. This study aimed to compare the adenoma detection rates between Endocuff-assisted (EC) colonoscopy and standard colonoscopy (SC). METHODS: This randomized prospective multicenter trial was conducted at four academic endoscopy units in Germany. PARTICIPANTS: 500 patients (235 males, median age 64[IQR 54-73]) for colon adenoma detection purposes were included in the study. All patients were either allocated to EC or SC. The primary outcome measure was the determination of the adenoma detection rates (ADR). RESULTS: The ADR significantly increased with the use of the Endocuff compared to standard colonoscopy (35.4%[95% confidence interval{CI} 29-41%] vs. 20.7%[95%CI 15-26%], p<0.0001). Significantly more sessile polyps were detected by EC. Overall procedure time and withdrawal time did not differ. Caecal and ileum intubation rates were similar. No major adverse events occurred in both groups. In multivariate analysis, age (odds ratio [OR] 1.03; 95%[CI] 1.01-1.05), male sex (OR 1.74; 95%CI 1.10-2.73), withdrawal time (OR 1.16; 95%CI 1.05-1.30), procedure time (OR 1.07; 95%CI 1.04-1.10), colon cleanliness (OR 0.60; 95%CI 0.39-0.94) and use of Endocuff (OR 2.09; 95%CI 1.34-3.27) were independent predictors of adenoma detection rates. CONCLUSIONS: EC increases the adenoma detection rate by 14.7%(95%CI 6.9-22.5%). EC is safe, effective, easy to handle and might reduce colorectal interval carcinomas. TRIAL REGISTRATION: ClinicalTrials.gov NCT02034929.

Effect of curcumin on acidic pH-induced expression of IL-6 and IL-8 in human esophageal epithelial cells (HET-1A): role of PKC, MAPKs, and NF-kappaB.

Human esophageal epithelial cells play a key role in esophageal inflammation in response to acidic pH during gastroesophageal reflux disease (GERD), increasing secretion of IL-6 and IL-8. The mechanisms underlying IL-6 and IL-8 expression and secretion in esophageal epithelial cells after acid stimulation are not well characterized. We investigated the role of PKC, MAPK, and NF-kappaB signaling pathways and transcriptional regulation of IL-6 and IL-8 expression in HET-1A cells exposed to acid. Exposure of HET-1A cells to pH 4.5 induced NF-kappaB activity and enhanced IL-6 and IL-8 secretion and mRNA and protein expression. Acid stimulation of HET-1A cells also resulted in activation of MAPKs and PKC (alpha and epsilon). Curcumin, as well as inhibitors of NF-kappaB (SN-50), PKC (chelerythrine), and p44/42 MAPK (PD-098059) abolished the acid-induced expression of IL-6 and IL-8. The JNK inhibitor SP-600125 blocked expression/secretion of IL-6 but only partially attenuated IL-8 expression. The p38 MAPK inhibitor SB-203580 did not inhibit IL-6 expression but exerted a stronger inhibitory effect on IL-8 expression. Together, these data demonstrate that 1) acid is a potent inducer of IL-6 and IL-8 production in HET-1A cells; 2) MAPK and PKC signaling play a key regulatory role in acid-mediated IL-6 and IL-8 expression via NF-kappaB activation; and 3) the anti-inflammatory plant compound curcumin inhibits esophageal activation in response to acid. Thus IL-6 and IL-8 expression by acid may contribute to the pathobiology of mucosal injury in GERD, and inhibition of the NF-kappaB/proinflammatory cytokine pathways may emerge as important therapeutic targets for treatment of esophageal inflammation.

Role of MutS homolog 2 (MSH2) in intestinal myofibroblast proliferation during Crohn's disease stricture formation.

Tissue remodeling and mesenchymal cell accumulation accompanies chronic inflammatory disorders involving joints, lung, vasculature, and bowel. Chronic inflammation may alter DNA-mismatch repair (MMR) systems in mesenchymal cells, but is not defined in Crohn's disease (CD) and its associated intestinal remodeling and stricture formation. We determined whether DNA-MMR alteration plays a role in the pathogenesis of CD tissue remodeling. Control and CD bowel tissues were used to generate primary cultures of muscularis mucosa myofibroblasts, which were assessed directly or following stimulation with TNF-alpha/LPS or H2O2. MutS homolog (MSH)2, MSH3, and MSH6 expression in tissues and myofibroblasts was determined. Immunohistochemical staining revealed an increased expression of MSH2 in CD muscularis mucosa and submucosal tissues compared with controls or uninvolved CD tissue, and MSH2 expression was increased in CD myofibroblasts compared with control cells. TNF-alpha/LPS and H2O2 further enhanced MSH2 expression in both control and CD cells, which were decreased by simvastatin. There were no significant changes in MSH3 and MSH6 expression. Proliferating cell nuclear antigen and Ki67 staining of CD tissue revealed increased proliferation in the muscularis mucosa and submucosa of chronically inflamed tissues, and enhanced proliferation was seen in CD myofibroblasts compared with controls. Simvastatin reversed the effects of inflammatory stress on the DNA-MMR and inhibited proliferation of control and CD myofibroblasts. Gene silencing with MSH2 siRNA selectively decreased CD myofibroblast proliferation. These data demonstrate a potential role for MSH2 in the pathogenesis of nonneoplastic mesenchymal cell accumulation and intestinal remodeling in CD chronic inflammation.

"Pancreatic lesion" outside the pancreas: value of endoscopic ultrasound.

Tumors of the small intestine are rare as compared to malignant tumors of the pancreas. Here we report on the case of a 61-year-old man suffering from chronic pancreatitis presenting with a lesion projecting into the pancreatic head shown by both computed tomography and transabdominal ultrasound. Pancreatic cancer was suspected, but endoscopic ultrasound revealed this lesion to be situated in the submucosal layer of the duodenal wall. Surgery was performed since biopsy of this lesion was not diagnostic and a malignant leiomyosarcoma could therefore not be excluded. Limited surgery comprised resection of the duodenal lesion, whereas based on computed tomography alone, exploration of the pancreas would have been performed. Thus, in the present case endoscopic ultrasound leads to a more appropriate, less invasive therapeutic measure.

Ischaemic colitis mimicking inflammatory bowel disease in a young adult receiving oral anticoagulation.

Ischaemic colitis (IC) is the most frequent form of gastrointestinal ischaemia. Discrepancy between non-specific symptoms and objective findings is a hallmark of IC. Thus delay of diagnosis is common due to its often subtle and unpredictable presentation. In particular, the clinical symptoms and signs of IC can overlap with those of inflammatory bowel disease. We present a case of a young man with known factor-V-Leiden mutation in whom IC developed during effective therapy with oral anticoagulants, presenting with symptoms and endoscopic findings suggestive of inflammatory bowel disease.

Absence of CCR6 inhibits CD4+ regulatory T-cell development and M-cell formation inside Peyer's patches.

The chemokine Mip3alpha is specifically expressed by the follicle-associated epithelia (FAE) covering intestinal Peyer's patches (PPs) and is the only known chemokine ligand for the chemokine receptor CCR6. Although CCR6-deficient mice are known to have a perturbed intestinal immune system, little is known about the specific impact of this interaction for Peyer's patch formation. To elucidate the effect of Mip3alpha on PP lymphocyte development, we used a CCR6/enhanced green fluorescent protein (EGFP) knock-in mouse model and analyzed lymphocyte development by immunohistochemistry and flow cytometry. PPs of CCR6-/- mice were significantly size-reduced with a proportional loss of B cells and T cells, whereas T-cell subsets were disturbed with a decreased CD4/CD8 ratio paralleled with a loss of regulatory CD4+ CD45Rb(low) T cells. The analysis of cytokine production by CCR6-expressing cells could demonstrate that CCR6 is involved in the regulation of cytokine secretion such as interleukin-12 by dendritic cells. Quantification of UEA-1+ cells inside the FAE showed reduced M-cell numbers in CCR6-deficient mice. These results suggest that the interaction of CCR6 with its ligand Mip3alpha is important for immune responses generated inside the PPs, particularly for the generation of regulatory CD4+ T cells residing inside PPs and for the formation of M cells.