Banff 2022 Liver Group Meeting report: Monitoring long-term allograft health.

The Banff Working Group on Liver Allograft Pathology met in September 2022. Participants included hepatologists, surgeons, pathologists, immunologists, and histocompatibility specialists. Presentations and discussions focused on the evaluation of long-term allograft health, including noninvasive and tissue monitoring, immunosuppression optimization, and long-term structural changes. Potential revision of the rejection classification scheme to better accommodate and communicate late T cell-mediated rejection patterns and related structural changes, such as nodular regenerative hyperplasia, were discussed. Improved stratification of long-term maintenance immunosuppression to match the heterogeneity of patient settings will be central to improving long-term patient survival. Such personalized therapeutics are in turn contingent on a better understanding and monitoring of allograft status within a rational decision-making approach, likely to be facilitated in implementation with emerging decision-support tools. Proposed revisions to rejection classification emerging from the meeting include the incorporation of interface hepatitis and fibrosis staging. These will be opened to online testing, modified accordingly, and subject to consensus discussion leading up to the next Banff conference.

Donors risk assessment in transplantation: From the guidelines to their real-world application.

Transplantation of an organ from a donor carries an unavoidable risk of tumor transmission. The need to extend the donor pool increases the use of organs from donors with malignancies and potential disease transmission is a constant tension influencing donor suitability decisions. Current classification systems for the assessment of donor malignancy transmission risk have evolved from reports of potential transmission events in recipients to national donation and transplant surveillance agencies. Although the risk of malignancy transmission is very low in the general transplant setting it must constantly be balanced with the transplant benefits. Guidelines are mainly based on large registries and sparse case reports of transmission, so they cannot cover all the possible situations. For this reason, in 2004 in Italy, the National Transplant Center gave rise to the Second Opinion Service, charged by the Ministry of Health, by structuring expertise in diagnostic oncology and risk transmission and making it available to the Italian Transplant Centers. In this paper the registry of the Italian Oncological Second Opinion was reviewed, from 2016 to 2018, to detail the most frequent and problematic neoplastic topics addressed, those are separately reported and discussed. Furthermore, a review of the most recent strategies and risk stratification is provided, according to the most recent literature evidence and to the European Guidelines.

Innate Immunity Activation in Newly Diagnosed Ileocolonic Crohn's Disease: A Cohort Study.

BACKGROUND: Recent studies showed that early surgery for Crohn's disease leads to a lower recurrence rate. However, the underlying mechanism is unknown. OBJECTIVE: The study aims to analyze the innate immunity microenvironment in ileal mucosa according to the duration of Crohn's disease. DESIGN: A prospective cohort study. SETTINGS: Tertiary referral center for IBD surgery. PATIENTS: A total of 88 consecutive patients with Crohn's disease undergoing ileocolonic resection were prospectively enrolled. Mucosal samples were obtained from both healthy and inflamed ileum. Data from a public data set were analyzed as an external validation cohort. MAIN OUTCOME MEASURES: Neutrophil infiltration was evaluated by histological asessment and macrophage subpopulation was assessed by immunohistochemistry. Expressions of TLR2 , TLR4 , TLR5 , DEFB1 , DEFB4A , DEFB103 , DEFA5 , and DEFA6 were quantified by real-time quantitative polymerase chain reaction. Concentrations of BDNF, CCL-11, ICAM-1, IL-1A, IL-1ß, IL-1RN, IL-12p40, IL-12p70, IL-15, IL-17A, IL-23A, MMP-3, CCL-3, KITLG, and VEGFA were determined with an immunometric assay. RESULTS: Neutrophil infiltration is inversely correlated with disease duration. DEFB4A mRNA expression tended to be higher in late-stage Crohn's disease ( p = 0.07). A higher number of macrophages expressed CD163 at low intensity in late-stage Crohn's disease ( p = 0.04). The concentration of IL-15 ( p = 0.02) and IL-23A ( p = 0.05) was higher in healthy ileal mucosa of early-stage patients. In the external cohort, expressions of DEFB1 ( p = 0.03), DEFB4A ( p = 0.01), IL-2 ( p = 0.04), and IL-3 ( p = 0.03) increased in patients with late-stage Crohn's disease. LIMITATIONS: A relatively small number of patients, especially in the newly diagnosed group. CONCLUSIONS: In newly diagnosed Crohn's disease, high levels of IL-15 and IL-23 in healthy mucosa suggest that innate immunity is the starter of acute inflammation. Moreover, M2 macrophages increase in the healthy mucosa of patients with late-stage Crohn's disease, suggesting that reparative and profibrotic processes are predominant in the long term, and in this phase, anti-inflammatory therapy may be less efficient. See Video Abstract . ACTIVACIN DE LA INMUNIDAD INNATA EN LA RECIENTEMENTE DIAGNOSTICADA ENFERMEDAD DE CROHN ILEOCLICA UN ESTUDIO DE COHORTE: ANTECEDENTES:Estudios recientes demostraron que la cirugía temprana para la enfermedad de Crohn (EC) conduce a una menor tasa de recurrencia. Sin embargo, se desconoce el mecanismo subyacente.OBJETIVO:El estudio tiene como objetivo analizar el microambiente de la inmunidad innata en la mucosa ileal según la duración de la EC.DISEÑO:Un estudio de cohorte prospectivo.AJUSTES:Centro terciario de referencia para cirugía de EII.PACIENTES:Fueron registrados de manera prospectiva y consecutiva 88 pacientes con EC sometidos a resección ileocolónica. Se obtuvieron muestras de mucosa ileal, tanto del íleon sano como del íleon inflamado. Los datos se analizaron como una cohorte de validación externa.PRINCIPALES MEDIDAS DE RESULTADO:Fueron evaluados la infiltración de neutrófilos por histología y la subpoblación de macrófagos por inmunohistoquímica. La expresión de TLR2, TLR4, TLR5, DEFB1, DEFB4A, DEFB103, DEFA5 y DEFA6 fueron cuantificados mediante qPCR en tiempo real. Las concentraciones de BDNF, CCL-11, ICAM-1, IL-1A, IL-1B, IL-1RN, IL-12 p40, IL-12 p70, IL-15, IL-17A, IL-23A, MMP-3, CCL-3, KITLG, VEGFA se determinaron con ensayo inmunométrico.RESULTADOS:La infiltración de neutrófilos se correlaciona inversamente con la duración de la enfermedad. La expresión del ARNm de DEFB4A mostro una tendencia a ser mayor en la EC en etapa tardía ( p = 0,07). Un mayor número de macrófagos expresaron CD163 a baja intensidad en la etapa tardía ( p = 0,04). La concentración de IL15 ( p = 0,02) e IL23A ( p = 0,05) fue mayor en la mucosa ileal sana de pacientes en estadio temprano. En la cohorte externa, la expresión de DEFB1 ( p = 0,03) y DEFB4A ( p = 0,01), IL2 ( p = 0,04) e IL3 ( p = 0,03) aumentó en pacientes en etapa tardía.LIMITACIONES:Un número relativamente pequeño de pacientes, especialmente en el grupo recién diagnosticado.CONCLUSIONES:En la EC recién diagnosticada, los altos niveles de IL-15 e IL-23 en la mucosa sana sugieren que la inmunidad innata es el promotor de la inflamación aguda. Además, los macrófagos M2 aumentan en la mucosa sana de pacientes con EC en etapa tardía, lo que sugiere que los procesos reparadores y profibróticos son predominantes a largo plazo y en esta fase, la terapia antiinflamatoria puede ser menos eficiente. (Traducción-Dr. Osvaldo Gauto ).

Postoperative Hirschsprung's associated enterocolitis (HAEC): transition zone as putative histopathological predictive factor.

AIMS: Hirschsprung's-associated enterocolitis (HAEC) is the most severe complication of Hirschsprung disease (HD), and its pathogenesis is still unknown. Length of transition zone (TZ) interposed between aganglionic and normal bowel has been poorly explored as predictor for postoperative HAEC (post-HAEC). This study aimed to identify potential predictive factors for post-HAEC, with a particular focus on histopathological findings. METHODS: Data from Hirschsprung patients treated in a single Italian centre between 2010 and 2022 with a follow-up >6 months were collected. Thorough histopathological examination of the resected bowel was conducted, focusing on length of TZ and aganglionic bowel.The degree of inflammatory changes in ganglionic resected bowel was further obtained. Ultra-long HD, total colonic aganglionosis and ultra-short HD were excluded. Bivariate and multivariate regression analysis were performed. RESULTS: Thirty-one patients were included; 5 experienced preoperative HAEC (pre-HAEC) and later post-HAEC (16.1%), further 10 patients developed post-HAEC (total post-HAEC 48.38%). Pre-HAEC-history and a TZ<2.25 cm correlated with an early development of post-HAEC. Multivariate analysis identified a TZ<2.25 cm as an independent post-HAEC predictive factor (p=0.0096). Inflammation within the ganglionic zone and a TZ<2.25 cm correlated with higher risk of post-HAEC (p=0.0074, 0.001, respectively). Severe post-HAEC more frequently occurred in patients with pre-HAEC (p=0.011), histological inflammation (p=0.0009) and short TZ (p=0.0015). CONCLUSIONS: This study suggests that TZ<2.25 cm predicts the risk of post-HAEC. Preoperative clinical and histopathology inflammation may predispose to worst post-HAEC. Readily available histopathological findings might help identifying patients at higher risk for HAEC and implementing prevention strategies.

Pre-Implantation Kidney Biopsies in Extended Criteria Donors: From On Call to Expert Pathologist, from Conventional Microscope to Digital Pathology.

The number of patients awaiting a kidney transplant is constantly rising but lack of organs leads kidneys from extended criteria donors (ECD) to be used to increase the donor pool. Pre-transplant biopsies are routinely evaluated through the Karpinski-Remuzzi score but consensus on its correlation with graft survival is controversial. This study aims to test a new diagnostic model relying on digital pathology to evaluate pre-transplant biopsies and to correlate it with graft outcomes. Pre-transplant biopsies from 78 ECD utilized as single kidney transplantation were scanned, converted to whole-slide images (WSIs), and reassessed by two expert nephropathologists using the Remuzzi-Karpinski score. The correlation between graft survival at 36 months median follow-up and parameters assigned by either WSI or glass slide score (GSL) by on-call pathologists was evaluated, as well as the agreement between the GSL and the WSIs score. No relation was found between the GSL assessed by on-call pathologists and graft survival (P = 0.413). Conversely, the WSI score assigned by the two nephropathologists strongly correlated with graft loss probability, as confirmed by the ROC curves analysis (DeLong test P = 0.046). Digital pathology allows to share expertise in the transplant urgent setting, ensuring higher accuracy and favoring standardization of the process. Its employment may significantly increase the predictive capability of the pre-transplant biopsy evaluation for ECD, improving the quality of allocation and patient safety.

Leaving behind a diseased small bowel during surgery for Crohn's disease: Long-term outcomes.

PURPOSES: Stricture is a common complication of Crohn's disease (CD) and may be treated with bowel-sparing procedures. Our study analyzed what happens in terms of intestinal and systemic inflammation when the diseased bowel is left behind following surgery. METHODS: In this retrospective study, we enrolled 42 consecutive patients who underwent strictureplasty (alone or with resection) for stricturing CD. Control patients who underwent complete diseased bowel resection were identified and propensity score-matched for the sex, age, and history of abdominal surgery. Biohumoral values were collected at follow-up examinations at 1, 6, and 12 months after surgery. Magnetic resonance imaging (MRI) was performed before and after strictureplasty in 19 patients. RESULTS: In the strictureplasty group, fecal calprotectin levels were decreased at 12 months (p = 0.03), whereas in the resectiongroup, they were decreased at 6 months (p = 0.02). On MRI, the ADC [apparent diffusion coefficient] (p < 0.001), wall thickness (p = 0.046) and Magnetic Resonance Index of Activity (MaRIA) (p < 0.001) and Clermont (p < 0.001) scores were improved after strictureplasty. Surgical recurrence was more frequent in the strictureplasty group than in the resection group (p = 0.003). CONCLUSIONS: Our retrospective study showed that even if the diseased bowel was left behind after surgery, the intestinal inflammatory activity still decreased. However, the permanence of the diseased bowel still increased the risk of reoperation, probably because of the fibrotic nature of the stenosis and the multifocality of CD.

Second Opinion in the Italian Organ Procurement Transplantation: The Pathologist Is In.

Second opinion consultation is a well-established practice in different clinical settings of diagnostic medicine. However, little is known about second opinion consultation activity in transplantation, and even less is known about it concerning donor assessment. The consultations provided by the second opinion service led to the safer and homogeneous management of donors with a history of malignancy or ongoing neoplasm by transplant centers. Indeed, two of the most important aspects are the reduction of semantic differences in cancer reporting and the standardization of procedures, which are mainly due to the different settings and logistics of different pathology services. This article aims to discuss the role and the future of the second opinion in Italy during organ procurement, highlighting the critical issues and areas for improvement.

Impact of DNA mismatch repair proteins deficiency on number and ratio of lymph nodal metastases in colorectal adenocarcinoma.

BACKGROUND: Approximately 15 % of colorectal adenocarcinomas (CRCs) are characterized by an altered expression of DNA mismatch repair (MMR) proteins (i.e. MMR deficiency [MMRd]). Lymph node ratio (LNR) represents one of the most important prognostic markers in non-advanced CRCs. No significant data are available regarding LNR distribution depending on MMR status. PURPOSE OF THE STUDY: The aim of the present work was to compare pathological and clinical characteristics of MMRd tumors versus MMR proficient (MMRp) cases. Particular attention was paid to how these molecular sub-groups relate to the LNR. MATERIALS AND METHODS: A mono-Institutional series of 1037 consecutive surgically treated stage I-IV CRCs were retrospectively selected and data were obtained from pathological reports. Cases were characterized for MMR/MSI status by means of immunohistochemistry or for microsatellite instability (MSI) analysis. RESULTS: MMRd/MSI tumors (n = 194; 18.7 %) showed significant differences in comparison to MMRp lesions for sex (female prevalence 50.5 % vs 40.7 %; p = 0.013), age (74.2 vs 69.2; p < 0.001), location (right side; p < 0.001), diameter (larger than MMRp; p < 0.001), growth pattern (expansive pattern of growth; p < 0.001), peri- (p = 0.0002) and intra-neoplastic (p = 0.0018) inflammatory infiltrate, presence of perineural invasion (p < 0.001), stage (lower stage at presentation; p < 0.001), grade (higher prevalence of high-grade tumors; p < 0.001), and LNR (lower; p < 0.001). CONCLUSIONS: MMRd/MSI tumors are a distinct molecular CRC subtype characterized by a significantly lower LNR in comparison to MMRp lesions. These data further support the prognostic impact of MMRd/MSI status in early-stage CRCs.

Dasatinib-induced Crohn's-like colitis.

Dasatinib is a second-generation multityrosine kinase inhibitor used in the first-line and second-line treatment of Philadelphia chromosome-positive leukaemia. The most frequent type of Dasatinib-induced intestinal injury is haemorrhagic colitis; other morphologic patterns include apoptotic colopathy, CD8+ T-cell-mediated colitis and non-specific colitis. Aim of this study is to describe a novel Crohn's-like histopathologic pattern of Dasatinib-induced colitis. Four patients developed diarrhoea during Dasatinib treatment; colonoscopy was performed and biopsy sets were taken for histological analysis. All patients showed patchy, chronic active inflammation with cryptitis and microgranulomas (two patients). Ileal and rectal biopsies showed either no or mild, focal inflammation. An increase in lamina propria eosinophils was seen (two patients) and apoptoses were seen (three patients). Complete remission was observed after interruption of treatment. Dasatinib-induced colitis and Crohn's disease may share histologic features including microgranulomas, which can potentially lead to misdiagnosis if no information on treatment is provided.

Validation of the Padova Prognostic Score for Colitis in Predicting Long-Term Outcome After Restorative Proctocolectomy.

Background: In 10%-20% of cases it is impossible to make a differential diagnosis between ulcerative colitis and Crohn's colitis. A 50% failure rate of J pouch ilea-anal anastomosis is observed in Crohn's colitis. In 2009, we created the Padua Prognostic Score for Colitis (PPSC) to predict the long-term clinical and functional outcome and quality of life of patients undergoing restorative proctocolectomy with J pouch. The aim of the present study is to establish and validate the accuracy of a prognostic score for chronic inflammatory bowel diseases (IBD). Patient population and methods: The PPSC was created in 2009 by integrating clinical and histological information of patients undergoing RPC. It included preoperative perianal abscess or fistula, rectal sparing, terminal ileum involvement, skip lesions and histological diagnosis of indeterminate colitis or Crohn's colitis on the operative specimen. The validity of this score was tested in predicting postoperative abscess or fistula, anal canal disease, pouchitis, pouch failure and new diagnosis of Crohn's disease. Correlation analysis, ROC curve analysis and survival analysis were used to validate the PPSC in a different cohort from the previous one. Results: We retrospectively enrolled in this study 138 consecutive patients undergoing CPR for ulcerative colitis (n = 127) or indeterminate colitis (n = 11) in our institution since 2005 to 2020. In this period, we observed 11 patients with postoperative abscess or fistula, 3 with anal canal disease, 40 with pouchitis, 6 with pouch failure and 6 with new diagnosis of Crohn's disease. In the new validation cohort, the PPSC confirmed to have a good accuracy in predicting the onset of postoperative CD (AUC = 74.5%, p = 0.018). Kaplan Meier curves demonstrate how a PPSC over 1 can reliably predicts the long-term onset of, pouchitis (p = 0.002) and anal abscess or fistulae (p = 0.04). Conclusions: In this validation study we confirmed the accuracy of the PPSC in predicting postoperative fistulas or abscesses and pouchitis. Therefore, we believe that in clinical practice patients with a PPSC score greater than 1 should be warned of this risk of possible Crohn's disease diagnosis and pouch failure.

Validation of portable tablets for transplant pathology diagnosis according to the College of American Pathologists Guidelines.

Despite increased use of digital pathology, its application in the transplantation setting remains limited. One of the restraints is related to concerns that this technology is inadequate for supporting diagnostic work. In this study, we sought to establish non inferiority of whole slide imaging (WSI) to light microscopy (LM) for intraoperative transplantation diagnosis using inexpensive portable devices. A validation study was conducted according to updated guidelines from the College of American Pathologists (CAP) utilizing 80 intraoperative transplantation cases. Two pathologists reviewed glass slides with LM and digital slides on two different tablets after a washout period of 4 weeks. Diagnostic concordance and intra-observer agreement were recorded. A total of 45 (56%) cases were suitable for rendering transplant diagnoses and 35 (44%) for assessing cancer risk. Intra-observer agreement was 95.1% for organ suitability and 100% for cancer risk. There were no major discordances that could affect patient transplant management. Digital evaluation of intraoperative transplant specimens using tablets to view whole slide images was non-inferior to LM for primary diagnosis. This suggests that after validating WSI these digital tools can be safely used for remote intraoperative transplantation diagnostic work.

Impact of Positive Radial Margin on Recurrence and Survival in Perihilar Cholangiocarcinoma.

In resected perihilar cholangiocarcinoma (PHC), positive ductal margin (DM) is associated with poor survival. There is currently little knowledge about the impact of positive radial margin (RM) when DM is negative. The aim of this study was to evaluate the incidence and the role of positive RM. Patients who underwent surgery between 2005 and 2017 where retrospectively reviewed and stratified according to margin positivity: an isolated RM-positive group and DM ± RM group. Of the 75 patients identified; 34 (45.3%) had R1 resection and 17 had positive RM alone. Survival was poorer in patients with R1 resection compared to R0 (p = 0.019). After stratification according to margin positivity; R0 patients showed better survival than DM ± RM-positive patients (p = 0.004; MST 43.9 vs. 23.6 months), but comparable to RM-positive patients (p = 0.361; MST 43.9 vs. 39.5 months). Recurrence was higher in DM ± RM group compared to R0 (p = 0.0017; median disease-free survival (DFS) 15 vs. 30 months); but comparable between RM and R0 group (p = 0.39; DFS 20 vs. 30 months). In univariate and multivariate analysis, DM positivity resulted as a negative prognostic factor both for survival and recurrence. In conclusion, positive RM resections appear to have different recurrence patterns and survival rates than positive DM resections.

Prognostic impact of FGFR2/3 alterations in patients with biliary tract cancers receiving systemic chemotherapy: the BITCOIN study.

AIM: FGFR2 rearrangements have been identified as a novel therapeutic target of biliary tract cancer (BTC). However, reliable prevalence estimates of this molecular alteration and its prognostic role have not been fully elucidated. METHODS: A retrospective mono-institutional series of 286 patients affected by locally advanced or metastatic BTC (183 intrahepatic cholangiocarcinomas, 67 extrahepatic cholangiocarcinomas, 36 gallbladder carcinomas) was profiled by means of targeted DNA/RNA next-generation sequencing, immunohistochemistry and fluorescence in situ hybridisation for FGFR2/3, ERBB2, NTRK alterations, IDH1/2 and BRAF mutations and DNA mismatch repair complex proteins alterations/microsatellite instability. RESULTS: FGFR2 rearrangements, amplifications and point mutations were detected in 15 (5.2%), 1 and 3 cases, respectively. FGFR3 alterations were observed in 5 (1.7%) cases. IDH1/2 were mutated in 35/223 cases (15.7%). A total of 9/258 (3.5%) and 6/260 (2.3%) BTCs had ERBB2 and BRAF gene alterations, respectively. Two cases (2/242; 0.8%) had NTRK1 amplifications but no rearrangement was found. A deficit of mismatch repair protein expression was identified in 9/237 cases (3.8%). At multivariate analysis, age, ECOG performance status, number of metastatic sites, tumour stage, FGFR2/3 alterations and IDH1/2 mutations were prognostic factors of overall survival. CONCLUSIONS: These data provide a strong proof - challenged with a robust and detailed multivariate model - that FGFR2/3 aberrations (including FGFR2 rearrangements) and IDH1/2 mutations can be prognostic for better survival in patients with BTC . The recognition and the measurement of their prognostic impact could be of primary importance for the correct interpretation of currently available data and in the design of new therapeutic trials.

Not only a small liver - The pathologist's perspective in the pediatric liver transplant setting.

Pediatric liver transplantation represents a safe and long-lasting treatment option for various disease types, requiring the pathologist's input. Indeed, an accurate and timely diagnosis is crucial in reporting and grading native liver diseases, evaluating donor liver eligibility and identifying signs of organ injury in the post-transplant follow-up. However, as the procedure is more frequently and widely performed, deceptive and unexplored histopathologic features have emerged with relevant consequences on patient management, particularly when dealing with long-term treatment and weaning of immunosuppression.In this complex and challenging scenario, this review aims to depict the most relevant histopathologic conditions which could be encountered in pediatric liver transplantation. We will tackle the conditions representing the main indications for transplantation in childhood as well as the complications burdening the post-transplant phases, either immunologically (i.e., rejection) or non-immunologically mediated. Lastly, we hope to provide concise, yet significant, suggestions related to innovative pathology techniques in pediatric liver transplantation.

Advantages of Using a Web-based Digital Platform for Kidney Preimplantation Biopsies.

BACKGROUND: In the setting of kidney transplantation, histopathology of kidney biopsies is a key element in the organ assessment and allocation. Despite the broad diffusion of the Remuzzi-Karpinski score on preimplantation kidney biopsies, scientific evidence of its correlation to the transplantation outcome is controversial. The main issues affecting the prognostic value of histopathology are the referral to general on-call pathologists and the semiquantitative feature of the score, which can raise issues of interpretation. Digital pathology has shown very reliable and effective in the oncological diagnosis and treatment; however, the spread of such technologies is lagging behind in the field of transplantation. The aim of our study was to create a digital online platform where whole-slide images (WSI) of preimplantation kidney biopsies could be uploaded and stored. METHODS: We included 210 kidney biopsies collected between January 2015 and December 2019 from the joint collaboration of the transplantation centers of Padua and Verona. The selected slides, stained with hematoxylin and eosin, were digitized and uploaded on a shared web platform. For each case, the on-call pathologists' Remuzzi grades were obtained from the original report, together with the clinical data and the posttransplantation follow-up. RESULTS: The storage of WSI of preimplantation kidney biopsies would have several clinical, scientific, and educational advantages. The clinical utility relies on the possibility to consult online expert pathologists and real-time quality checks of diagnosis. From the perspective of follow-up, the archived digitized biopsies can offer a useful comparison to posttransplantation biopsies. In addition, the digital online platform is a precious tool for multidisciplinary meetings aimed both at the clinical discussion and at the design of research projects. Furthermore, this archive of readily available WSI is an important educational resource for the training of professionals. CONCLUSIONS: Finally, the web platform lays the foundation for the introduction of artificial intelligence in the field of transplantation that would help create new diagnostic algorithms and tools with the final aim of increasing the precision of organ assessment and its predictive value for transplant outcome.

Case Report: Intestinal Nodular Lymphoid Hyperplasia as First Manifestation of Activated PI3Kδ Syndrome Due to a Novel PIK3CD Variant.

Nodular lymphoid hyperplasia (NLH) is a lymphoproliferative disease caused by non-clonal expansion of lymphoid cells in the gut mucosa. Little is known about the pathogenesis of NLH, which is often disregarded as an insignificant or para-physiologic phenomenon. We present the case of a girl with isolated diffuse NLH (extending from the stomach to the rectum) caused by activated PI3Kδ syndrome (APDS) due to the novel p.Glu525Gly variant in PIK3CD. The gain-of-function effect of the variant was confirmed by demonstration of over activation of the Akt/mTOR pathway in the patient's cells. APDS diagnosis led to treatment with sirolimus, which resulted in the complete remission of NLH and in the prevention of extra intestinal complications. In conclusion, we identify APDS as a novel cause of isolated NLH and suggest that patients with severe pan-enteric NLH should be screened for this disorder that may not be apparent on first-line immunological testing.

GM-CSF Nitration Is a New Driver of Myeloid Suppressor Cell Activity in Tumors.

Reactive oxygen species, including RNS, contribute to the control of multiple immune cell functions within the tumor microenvironment (TME). Tumor-infiltrating myeloid cells (TIMs) represent the archetype of tolerogenic cells that actively contribute to dismantle effective immunity against cancer. TIMs inhibit T cell functions and promote tumor progression by several mechanisms including the amplification of the oxidative/nitrosative stress within the TME. In tumors, TIM expansion and differentiation is regulated by the granulocyte-macrophage colony-stimulating factor (GM-CSF), which is produced by cancer and immune cells. Nevertheless, the role of GM-CSF in tumors has not yet been fully elucidated. In this study, we show that GM-CSF activity is significantly affected by RNS-triggered post-translational modifications. The nitration of a single tryptophan residue in the sequence of GM-CSF nourishes the expansion of highly immunosuppressive myeloid subsets in tumor-bearing hosts. Importantly, tumors from colorectal cancer patients express higher levels of nitrated tryptophan compared to non-neoplastic tissues. Collectively, our data identify a novel and selective target that can be exploited to remodel the TME and foster protective immunity against cancer.

The histomorphological and molecular landscape of colorectal adenomas and serrated lesions.

The 2019 WHO classification of digestive system tumors significantly reformed the classificatory definition of serrated lesions of the colorectal mucosa and added new essential diagnostic criteria for both conventional adenomas and hereditary gastrointestinal polyposis syndromes. Histopathological examination of colorectal adenocarcinoma precursors lesions represents an important segment of daily clinical practice in a pathology department and is essential for the implementation of current colorectal adenocarcinoma secondary prevention strategies. This overview will focus on a schematic histopathological and molecular classification of precursor lesions arising within colorectal mucosa.

IFIH1 loss-of-function variants contribute to very early-onset inflammatory bowel disease.

Genetic defects of innate immunity impairing intestinal bacterial sensing are linked to the development of Inflammatory Bowel Disease (IBD). Although much evidence supports a role of the intestinal virome in gut homeostasis, most studies focus on intestinal viral composition rather than on host intestinal viral sensitivity. To demonstrate the association between the development of Very Early Onset IBD (VEOIBD) and variants in the IFIH1 gene which encodes MDA5, a key cytosolic sensor for viral nucleic acids. Whole exome sequencing (WES) was performed in two independent cohorts of children with VEOIBD enrolled in Italy (n = 18) and USA (n = 24). Luciferase reporter assays were employed to assess MDA5 activity. An enrichment analysis was performed on IFIH1 comparing 42 VEOIBD probands with 1527 unrelated individuals without gastrointestinal or immunological issues. We identified rare, likely loss-of-function (LoF), IFIH1 variants in eight patients with VEOIBD from a combined cohort of 42 children. One subject, carrying a homozygous truncating variant resulting in complete LoF, experienced neonatal-onset, pan-gastrointestinal, IBD-like enteropathy plus multiple infectious episodes. The remaining seven subjects, affected by VEOIBD without immunodeficiency, were carriers of one LoF variant in IFIH1. Among these, two patients also carried a second hypomorphic variant, with partial function apparent when MDA5 was weakly stimulated. Furthermore, IFIH1 variants were significantly enriched in children with VEOIBD as compared to controls (p = 0.007). Complete and partial MDA5 deficiency is associated with VEOIBD with variable penetrance and expressivity, suggesting a role for impaired intestinal viral sensing in IBD pathogenesis.