Evaluating no fixation, endoscopic suture fixation, and an over-the-scope clip for anchoring fully covered self-expanding metal stents in benign upper gastrointestinal conditions: a comparative multicenter international study (with video).

BACKGROUND AND AIMS: Fully covered self-expandable metal stents (FCSEMSs) are widely used in benign upper gastrointestinal (GI) conditions, but stent migration remains a limitation. An over-the-scope clip (OTSC) device (Ovesco Endoscopy) for stent anchoring has been recently developed. The aim of this study was to evaluate the effect of OTSC fixation on SEMS migration rate. METHODS: A retrospective review of consecutive patients who underwent FCSEMS placement for benign upper GI conditions between 1/2011 and 10/2022 at 16 centers. The primary outcome was rate of stent migration. The secondary outcomes were clinical success and adverse events. RESULTS: A total of 311 (no fixation 122, OTSC 94, endoscopic suturing 95) patients underwent 316 stenting procedures. Compared to the no fixation (NF) group (n=49, 39%), the rate of stent migration was significantly lower in the OTSC (SF) (n=16, 17%, p=0.001) and endoscopic suturing (ES) group (n=23, 24%, p=0.01). The rate of stent migration was not different between the SF and ES groups (p=0.2). On multivariate analysis, SF (OR 0.34, CI 0.17-0.70, p<0.01) and ES (OR 0.46, CI 0.23-0.91, p=0.02) were independently associated with decreased risk of stent migration. Compared to the NF group (n=64, 52%), there was a higher rate of clinical success in the SF (n=64, 68%; p=0.03) and ES group (n=66, 69%; p = 0.02). There was no significant difference in the rate of adverse events between the three groups. CONCLUSION: Stent fixation using OTSC is safe and effective at preventing stent migration and may also result in improved clinical response.

De novo design of potential peptide analogs against the main protease of Omicron variant using in silico studies.

SARS-CoV-2 and its variants are crossing the immunity barrier induced through vaccination. Recent Omicron sub-variants are highly transmissible and have a low mortality rate. Despite the low severity of Omicron variants, these new variants are known to cause acute post-infectious syndromes. Nowadays, novel strategies to develop new potential inhibitors for SARS-CoV-2 and other Omicron variants have gained prominence. For viral replication and survival the main protease of SARS-CoV-2 plays a vital role. Peptide-like inhibitors that mimic the substrate peptide have already proved to be effective in inhibiting the Mpro of SARS-CoV-2 variants. Our systematic canonical amino acid point mutation analysis on the native peptide has revealed various ways to improve the native peptide of the main protease. Multi mutation analysis has led us to identify and design potent peptide-analog inhibitors that act against the Mpro of the Omicron sub-variants. Our in-depth analysis of all-atom molecular dynamics studies has paved the way to characterize the atomistic behavior of Mpro in Omicron variants. Our goal is to develop potent peptide-analogs that could be therapeutically effective against Omicron and its sub-variants.

Light-Fueled Primitive Replication and Selection in Biomimetic Chemical Systems.

The concept of chemically evolvable replicators is central to abiogenesis. Chemical evolvability requires three essential components: energy-harvesting mechanisms for nonequilibrium dissipation, kinetically asymmetric replication and decomposition pathways, and structure-dependent selective templating in the autocatalytic cycles. We observed a UVA light-fueled chemical system displaying sequence-dependent replication and replicator decomposition. The system was constructed with primitive peptidic foldamer components. The photocatalytic formation-recombination cycle of thiyl radicals was coupled with the molecular recognition steps in the replication cycles. Thiyl radical-mediated chain reaction was responsible for the replicator death mechanism. The competing and kinetically asymmetric replication and decomposition processes led to light intensity-dependent selection far from equilibrium. Here, we show that this system can dynamically adapt to energy influx and seeding. The results highlight that mimicking chemical evolution is feasible with primitive building blocks and simple chemical reactions.

Advanced endoscopy meets molecular diagnosis of cholangiocarcinoma.

Cholangiocarcinoma remains an aggressive and deadly malignancy that is often diagnosed late. Intrinsic tumour characteristics and the growth pattern of cancer cells contribute to the challenges of diagnosis and chemoresistance. However, establishing an early and accurate diagnosis, and in some instances identifying targetable changes, has the potential to impact survival. Primary sclerosing cholangitis, a chronic cholangiopathy prodromal to the development of a minority of cholangiocarcinomas, poses a particular diagnostic challenge. We present our diagnostic and theranostic approach to the initial evaluation of cholangiocarcinomas, focusing on extrahepatic cholangiocarcinoma. This involves a multipronged strategy incorporating advanced imaging, endoscopic methods, multiple approaches to tissue sampling, and molecular markers. We also provide an algorithm for the sequential use of these tools.

Benefit of Extended Surveillance of Low-Risk Pancreatic Cysts After 5-Year Stability: A Systematic Review and Meta-Analysis.

BACKGROUND & AIMS: Low-risk branch duct intraductal papillary mucinous neoplasms (BD-IPMNs) lacking worrisome features (WF) and high-risk stigmata (HRS) warrant surveillance. However, their optimal duration, especially among cysts with initial 5 years of size stability, warrants further investigation. We systematically reviewed the surveillance of low-risk BD-IPMNs and investigated the incidence of WF/HRS and advanced neoplasia, high-grade dysplasia, and pancreatic cancer during the initial (<5 years) and extended surveillance period (>5-years). METHODS: A systematic search (CRD42020117120) identified studies investigating long-term IPMN surveillance outcomes of low-risk IPMN among the Cochrane Library, Embase, Google Scholar, Ovid Medline, PubMed, Scopus, and Web of Science, from inception until July 9, 2021. The outcomes included the incidence of WF/HRS and advanced neoplasia, disease-specific mortality, and surveillance-related harm (expressed as percentage per patient-years). The meta-analysis relied on time-to-event plots and used a random-effects model. RESULTS: Forty-one eligible studies underwent systematic review, and 18 studies were meta-analyzed. The pooled incidence of WF/HRS among low-risk BD-IPMNs during initial and extended surveillance was 2.2% (95% CI, 1.0%-3.7%) and 2.9% (95% CI, 1.0%-5.7%) patient-years, respectively, whereas the incidence of advanced neoplasia was 0.6% (95% CI, 0.2%-1.00%) and 1.0% (95% CI, 0.6%-1.5%) patient-years, respectively. The pooled incidence of disease-specific mortality during initial and extended surveillance was 0.3% (95% CI, 0.1%-0.6%) and 0.6% (95% CI, 0.0%-1.6%) patient-years, respectively. Among BD-IPMNs with initial size stability, extended surveillance had a WF/HRS and advanced neoplasia incidence of 1.9% (95% CI, 1.2%-2.8%) and 0.2% (95% CI, 0.1%-0.5%) patient-years, respectively. CONCLUSIONS: A lower incidence of advanced neoplasia during extended surveillance among low-risk, stable-sized BD-IPMNs was a key finding of this study. However, the survival benefit of surveillance among this population warrants further exploration through high-quality studies before recommending surveillance cessation with certainty.

The Use of Integrated Molecular Testing in the Assessment and Management of Pancreatic Cysts.

PURPOSE OF REVIEW: As abdominal imaging becomes more sensitive and regularly used, pancreatic cystic lesions (PCLs) are being diagnosed more frequently. A small but clinically significant minority of these lesions have a predisposition to either harbor malignancy or undergo malignant transformation. This review highlights the current state and performance of cystic fluid biomarkers and how they may be incorporated into management. RECENT FINDINGS: Among the major domains of molecular testing for PCLs, DNA based analyses have demonstrated the highest accuracy in identifying cyst type and have the most data to support their clinical use. However, epigenetic and protein biomarker based molecular assessments have emerged with the potential to complement DNA based approaches. In addition, recent studies have increasingly demonstrated the value associated with combinations of mutations and other biomarkers in identifying higher grade mucinous cystic lesions. We present the performance of individual biomarkers in cyst fluid analysis with an emphasis on an algorithmic approach to improve the accurate identification of both cyst type and risk of malignant transformation.

Standardization of EUS imaging and reporting in high-risk individuals of pancreatic adenocarcinoma: consensus statement of the Pancreatic Cancer Early Detection Consortium.

BACKGROUND AND AIMS: Pancreatic ductal adenocarcinoma is an aggressive disease most often diagnosed after local progression or metastatic dissemination, precluding resection and resulting in a high mortality rate. For individuals with elevated personal risk of the development of pancreatic cancer, EUS is a frequently used advanced imaging and diagnostic modality. However, variability in the expertise and definition of EUS findings exists among gastroenterologists, as well as a lack of standardized reporting of relevant findings at the time of examination. Adoption of standardized EUS reporting, using a universally accepted and agreed on terminology, is needed. METHODS: A consensus statement designed to create a standardized reporting template was authored by a multidisciplinary group of experts in pancreatic diseases that includes gastroenterologists, radiologists, surgeons, oncologists, and geneticists. This statement was developed using a modified Delphi process as part of the Pancreatic Cancer Early Detection Consortium, and >75% agreement was required to reach consensus. RESULTS: We identified reporting elements and present standardized reporting templates for EUS indications, procedural data, EUS image capture, and descriptors of findings, tissue sampling, and postprocedural assessment of adequacy. CONCLUSIONS: Adoption of this standardized EUS reporting template should improve consistency in clinical decision-making for individuals with elevated risk of pancreatic cancer by providing complete and accurate reporting of pancreatic abnormalities. Standardization will also help to facilitate research and clinical trial design by using clearly defined and consistent imaging descriptions, thus allowing for comparison of results across different centers.

Tilted State Population of Antimicrobial Peptide PGLa Is Coupled to the Transmembrane Potential.

Cationic antimicrobial peptide PGLa gets into close contact with the anionic bacterial cell membrane, facilitating cross-membrane transport phenomena and membrane disruption depending on the concentration. The mechanisms of action are closely associated with the tilted insertion geometry of PGLa. Therefore, we aimed to understand the interaction between the transmembrane potential (TMP) and the orientation of the membrane-bound PGLa helix. Molecular dynamics simulations were performed with TMP, and we found that the PGLa tilt angle relative to the membrane is coupled with the TMP. Elevated TMP increases the population of the tilted state. We observed positive feedback between the tilt angle and the TMP, which occurs due to the electrostatic interaction between the peptidic helix and the Na+ cations at the membrane-water interface. These TMP coupled phenomena can contribute to understanding the direct antimicrobial and adjuvant effects of PGLa in combination with regular antibiotics.

Interleukin-1ß-induced pancreatitis promotes pancreatic ductal adenocarcinoma via B lymphocyte-mediated immune suppression.

OBJECTIVE: Long-standing chronic pancreatitis is an established risk factor for pancreatic ductal adenocarcinoma (PDAC). Interleukin-1ß (IL-1ß) has been associated in PDAC with shorter survival. We employed murine models to investigate the mechanisms by which IL-1ß and chronic pancreatitis might contribute to PDAC progression. DESIGN: We crossed LSL-Kras+/G12D;Pdx1-Cre (KC) mice with transgenic mice overexpressing IL-1ß to generate KC-IL1ß mice, and followed them longitudinally. We used pancreatic 3D in vitro culture to assess acinar-to-ductal metaplasia formation. Immune cells were analysed by flow cytometry and immunohistochemical staining. B lymphocytes were adoptively transferred or depleted in Kras-mutant mice. B-cell infiltration was analysed in human PDAC samples. RESULTS: KC-IL1ß mice developed PDAC with liver metastases. IL-1ß treatment increased Kras+/G12D pancreatic spheroid formation. CXCL13 expression and B lymphocyte infiltration were increased in KC-IL1ß pancreata. Adoptive transfer of B lymphocytes from KC-IL1ß mice promoted tumour formation, while depletion of B cells prevented tumour progression in KC-IL1ß mice. B cells isolated from KC-IL1ß mice had much higher expression of PD-L1, more regulatory B cells, impaired CD8+ T cell activity and promoted tumorigenesis. IL-35 was increased in the KC-IL1ß pancreata, and depletion of IL-35 decreased the number of PD-L1+ B cells. Finally, in human PDAC samples, patients with PDAC with higher B-cell infiltration within tumours showed significantly shorter survival. CONCLUSION: We show here that IL-1ß promotes tumorigenesis in part by inducing an expansion of immune-suppressive B cells. These findings point to the growing significance of B suppressor cells in pancreatic tumorigenesis.

Missing links - epigenetic regulators of the pancreatic cancer-associated inflammation.

Pancreatic ductal adenocarcinoma (PDAC) features a hostile tumor microenvironment (TME) that renders it remarkably resistant to most therapeutic interventions. Consequently, survival remains among the poorest compared with other gastrointestinal cancers. Concerted efforts are underway to decipher the complex PDAC TME, break down barriers to efficacious therapies and identify novel treatment strategies. In the recent Clinical Science, Li and colleagues identify the long noncoding RNA KLHDC7B-DT as a crucial epigenetic regulator of IL-6 transcription in PDAC and illustrate its potent influences on the pancreatic TME. In this commentary, we introduce epigenetics in pancreatic cancer and put the findings by Li et al. in context with current knowledge.

Characteristics and Outcomes of Patients Undergoing Endoscopy During the COVID-19 Pandemic: A Multicenter Study from New York City.

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic has significantly impacted the practice of endoscopy, but characteristics of COVID patients undergoing endoscopy have not been adequately described. AIMS: To compare findings, clinical outcomes, and patient characteristics of endoscopies performed during the pandemic in patients with and without COVID-19. METHODS: This was a retrospective multicenter study of adult endoscopies at six academic hospitals in New York between March 16 and April 30, 2020. Patient and procedure characteristics including age, sex, indication, findings, interventions, and outcomes were compared in patients testing positive, negative, or untested for COVID-19. RESULTS: Six hundred and five endoscopies were performed on 545 patients during the study period. There were 84 (13.9%), 255 (42.2%), and 266 (44.0%) procedures on COVID-positive, negative, and untested patients, respectively. COVID patients were more likely to undergo endoscopy for gastrointestinal bleeding or gastrostomy tube placement, and COVID patients with gastrointestinal bleeding more often required hemostatic interventions on multivariable logistic regression. COVID patients had increased length of stay, intensive care unit admission, and intubation rate. Twenty-seven of 521 patients (5.2%) with no or negative COVID testing prior to endoscopy later tested positive, a median of 13.5 days post-procedure. CONCLUSIONS: Endoscopies in COVID patients were more likely to require interventions, due either to more severe illness or a higher threshold to perform endoscopy. A significant number of patients endoscoped without testing were subsequently found to be COVID-positive. Gastroenterologists in areas affected by the pandemic must adapt to changing patterns of endoscopy practice and ensure pre-endoscopy COVID testing.

Donning a New Approach to the Practice of Gastroenterology: Perspectives From the COVID-19 Pandemic Epicenter.

The COVID-19 pandemic seemingly is peaking now in New York City and has triggered significant changes to the standard management of gastrointestinal diseases. Priorities such as minimizing viral transmission, preserving personal protective equipment, and freeing hospital beds have driven unconventional approaches to managing gastroenterology (GI) patients. Conversion of endoscopy units to COVID units and redeployment of GI fellows and faculty has profoundly changed the profile of most GI services. Meanwhile, consult and procedural volumes have been reduced drastically. In this review, we share our collective experiences regarding how we have changed our practice of medicine in response to the COVID surge. Although we review our management of specific consults and conditions, the overarching theme focuses primarily on noninvasive measures and maximizing medical therapies. Endoscopic procedures have been reserved for those timely interventions that are most likely to be therapeutic. The role of multidisciplinary discussion, although always important, now has become critical. The support of our faculty and trainees remains essential. Local leadership can encourage well-being by frequent team check-ins and by fostering trainee development through remote learning. Advancing a clear vision and a transparent process for how to organize and triage care in the recovery phase will allow for a smooth transition to our new normal.

DPP-4 Cleaves α/ß-Peptide Bonds: Substrate Specificity and Half-Lives.

The incorporation of ß-amino acids into a peptide sequence has gained particular attention as ß- and α/ß-peptides have shown remarkable proteolytic stability, even after a single homologation at the scissile bond. Several peptidases have been shown to cleave such bonds with high specificity but at a much slower rate compared to α-peptide bonds. In this study, a series of analogs of dipeptidyl peptidase-4 (DPP-4) substrate inhibitors were synthesized in order to investigate whether ß-amino acid homologation at the scissile bond could be a valid approach to improving peptide stability towards DPP-4 degradation. DPP-4 cleaved the α/ß-peptide bond after the N-terminal penultimate Pro with a broad specificity and retained full activity regardless of the ß3 -amino acid side chain and peptide length. Significantly improved half-lives were observed for ß3 Ile-containing peptides. Replacing the penultimate Pro with a conformationally constrained Pro mimetic led to proteolytic resistance. DPP-4 cleavage of α/ß-peptide bonds with a broad promiscuity represents a new insight into the stability of peptide analogs containing ß-amino acids as such analogs were thought to be stable towards enzymatic degradation.

New onset diabetes predicts progression of low risk pancreatic mucinous cysts.

BACKGROUND: Patients with low-risk lesions require ongoing surveillance since the rate of progression to pancreatic cancer (PC), while small, is much greater than in the general population. Our objective was to study the relationship between new onset diabetes (NODM) and progression in patients with low risk mucinous cysts. METHODS: We evaluated a prospectively maintained cohort of 442 patients with a suspected mucinous cyst without worrisome features (WF) or high-risk stigmata (HRS). Multivariable Cox models were developed for progression to WF and HRS, with diabetes status formulated as both time independent and dependent covariates. The adjusted cumulative risk of progression was calculated using the corrected group prognosis method. RESULTS: The 5-year cumulative progression rates to WFs and HRS were 12.8 and 3.6%, respectively. After controlling for other risk factors, the development of NODM was strongly associated with progression to HRS (HR = 11.6; 95%CI, 3.5-57.7%), but not WF. Among patients with the smallest cysts (<10 mm) at baseline, those who developed NODM had a 5-year adjusted cumulative risk of progression to HRS of 8.6% (95%CI, 0.0%-20.2%), compared to only 0.8% (95%CI, 0.0%-2.3%) for patients without NODM. Among patients with the largest cysts (20-29 mm), those who developed NODM during surveillance had a 5-year adjusted cumulative risk of progression of 53.5% (95%CI, 19.6%-89.9%) compared to only 7.5% (95%CI, 1.6%-15.2%) for patients without NODM. CONCLUSION: New onset diabetes may predict progression in patients with low risk mucinous cysts. Pending validation with large-scale studies, these findings support regular diabetes screening among patients surveilled for suspected IPMNs or MCNs.

Pancreatic cyst surveillance imposes low psychological burden.

BACKGROUND/OBJECTIVES: For the currently recommended pancreatic cyst surveillance to be feasible, participant adherence is a prerequisite. Our objective was to evaluate the psychological burden of pancreatic cyst surveillance from a participant's perspective. METHODS: The present participant survey is part of an international cohort study (PACYFIC study, www.pacyfic.net), which prospectively records the outcome of surveillance of asymptomatic pancreatic cysts. Participants are invited to complete questionnaires before and during cyst surveillance. RESULTS: 109 participants, 31 enrolled before and 78 during surveillance (median time since cyst diagnosis 16.5 (IQR 36) months), returned a total of 179 questionnaires. The majority indicated that surveillance reduces concerns of developing pancreatic cancer (82%), gives a sense of certainty (81%) and is a good method to detect cancer (91%). Participants already undergoing surveillance reported more negative aspects than those still to commence, like sleeping worse (30% vs 13%, P = 0.035), postponing plans (32% vs 13%, P = 0.031), and finding the follow-up burdensome (33% vs 13%, P = 0.044). Overall, the vast majority (94%) deemed advantages to outweigh disadvantages. Anxiety and depression scores were low (median Hospital Anxiety and Depression Scale 4 for anxiety (IQR 6), 2 for depression (IQR 5)). CONCLUSION: The psychological burden of pancreatic cyst surveillance is low. Therefore, participant adherence is expected to be high and annual surveillance seems feasible.

Incremental value of DNA analysis in pancreatic cysts stratified by clinical risk factors.

BACKGROUND AND AIMS: We determined the incremental predictive value of pancreatic cyst fluid molecular analysis to assessing malignancy risk over long-term follow-up of a well-characterized cohort, given the underlying predictive value of imaging parameters routinely used to triage such patients. METHODS: Patients who lacked initial cytologic malignancy in cyst fluid and had final pathology or a follow-up period of more than 2 years were included. Patient outcomes determined the malignancy-free survival of patients with high-risk stigmata (HRS), worrisome features (WFs), and DNA abnormalities. DNA analysis included 3 abnormalities: loss of heterozygosity mutations among a panel of tumor suppressor genes, Kras mutation, and elevated DNA quantity. RESULTS: Included were 478 patients; 209 had surgical pathology-derived outcomes and 269 had clinical follow-up of >2 years. Eleven percent had malignant outcome. Forty-two patients had HRS, 272 lacked both HRS and WFs, and 164 lacked HRS but had WFs. DNA abnormalities did not statistically change long-term malignancy risk in patients with HRS or in patients lacking both HRS and WFs. Among patients with WFs, the presence of ≥2 DNA abnormalities significantly increased malignancy risk (relative risk, 5.2; P = .002) and the absence of all DNA abnormalities significantly decreased risk (relative risk, .4; P = .040). Sensitivity analysis confirmed results of survival analysis over differing baseline malignancy probabilities. CONCLUSIONS: Our study defines the clinical characteristic of patients in which DNA abnormality testing has the greatest impact on patient outcomes. Use of DNA abnormality testing is supported in a carefully selected patient population limited to cysts with WFs.

Magnetite nanoparticles program the assembly, response, and reconfiguration of structured emulsions.

Endoskeletal droplets-non-spherical emulsion droplets that respond to external stimuli with shape change-are modified with ferromagnetic iron oxide nanoparticles to make them susceptible to magnetic fields. The resulting droplets can be manipulated using static or oscillating magnetic fields, each producing a different response. Static fields control the orientation and position of the droplets, important in driving assembly into organized structures. Oscillating fields are shown to cause magnetic hyperthermia in ferrofluid nanoparticles, leading to droplet heating and forcing droplet reconfiguration. We demonstrate the use of static and dynamic fields to affect the organization and stability of endoskeletal droplets and their assemblies, producing highly-tunable programmable colloids that adapt to changing environmental conditions.

Comparison of Endoscopic Ultrasound-Fine-Needle Aspiration and Endoscopic Ultrasound-Fine-Needle Biopsy for Solid Lesions in a Multicenter, Randomized Trial.

BACKGROUND & AIMS: Endoscopic ultrasound with fine-needle aspiration (FNA) is the standard of care for tissue sampling of solid lesions adjacent to the gastrointestinal tract. Fine-needle biopsy (FNB) may provide higher diagnostic yield with fewer needle passes. The aim of this study was to assess the difference in diagnostic yield between FNA and FNB. METHODS: This is a multicenter, prospective randomized clinical trial from 6 large tertiary care centers. Patients referred for tissue sampling of solid lesions were randomized to either FNA or FNB of the target lesion. Demographics, size, location, number of needle passes, and final diagnosis were recorded. RESULTS: After enrollment, 135 patients were randomized to FNA (49.3%), and 139 patients were randomized to FNB (50.7%).The following lesions were sampled: mass (n = 210, 76.6%), lymph nodes (n = 46, 16.8%), and submucosal tumors (n = 18, 6.6%). Final diagnosis was malignancy (n = 192, 70.1%), reactive lymphadenopathy (n = 30, 11.0%), and spindle cell tumors (n = 24, 8.8%). FNA had a diagnostic yield of 91.1% compared with 88.5% for FNB (P = .48). There was no difference between FNA and FNB when stratified by the presence of on-site cytopathology or by type of lesion sampled. A median of 1 needle pass was needed to obtain a diagnostic sample for both needles. CONCLUSIONS: FNA and FNB obtained a similar diagnostic yield with a comparable number of needle passes. On the basis of these results, there is no significant difference in the performance of FNA compared with FNB in the cytologic diagnosis of solid lesions adjacent to the gastrointestinal tract. ClinicalTrials.gov identifier: NCT01698190.

Disturbed spermatogenic signaling in pituitary adenylate cyclase activating polypeptide-deficient mice.

PACAP is a neuropeptide with diverse functions in various organs, including reproductive system. It is present in the testis in high concentrations, and in addition to the stage-specific expression within the seminiferous tubules, PACAP affects spermatogenesis and the functions of Leydig and Sertoli cells. Mice lacking endogenous PACAP show reduced fertility, but the possibility of abnormalities in spermatogenic signaling has not yet been investigated. Therefore, we performed a detailed morphological analysis of spermatozoa, sperm motility and investigated signaling pathways that play a role during spermatogenesis in knockout mice. No significant alterations were found in testicular morphology or motility of sperm in homozygous and heterozygous PACAP-deficient mice in spite of the moderately increased number of severely damaged sperms. However, we found robust changes in mRNA and/or protein expression of several factors that play an important role in spermatogenesis. Protein kinase A expression was markedly reduced, while downstream phospho-ERK and p38 were elevated in knockout animals. Expression of major transcription factors, such as Sox9 and phospho-Sox9, was decreased, while that of Sox10, as a redundant factor, was increased in PACAP-deficient mice. The reduced phospho-Sox9 expression was partly due to increased expression and activity of phosphatase PP2A in knockout mice. Targets of Sox transcription factors, such as collagen type IV, were reduced in knockout mice. In summary, our results show that lack of PACAP leads to disturbed signaling in spermatogenesis, which could be a factor responsible for reduced fertility in PACAP knockout mice, and further support the role of PACAP in reproduction.