Identification of tumour regression in neoadjuvantly treated pancreatic cancer is based on divergent and nonspecific criteria

AIMS

Following the increased use of neoadjuvant therapy for pancreatic cancer, grading of tumour regression (TR) has become part of routine diagnostics. However, it suffers from marked interobserver variation, which is mainly ascribed to the subjectivity of the defining criteria of the categories in TR grading systems. We hypothesized that a further cause for the interobserver variation is the use of divergent and nonspecific morphological criteria to identify tumour regression.

METHODS AND RESULTS

Twenty treatment-naïve pancreatic cancers and 20 pancreatic cancers treated with neoadjuvant chemotherapy were reviewed by three experienced pancreatic pathologists who, blinded for treatment status, categorized each tumour as treatment-naïve or neoadjuvantly treated, and annotated all tissue areas they considered showing tumour regression. Only 50%-65% of the cases were categorized correctly, and the annotated tissue areas were highly discrepant (only 3%-41% overlap). When the prevalence of various morphological features deemed to indicate TR was compared between treatment-naïve and neoadjuvantly treated tumours, only one pattern, characterized by reduced cancer cell density and prominent stroma affecting a large area of the tumour bed, occurred significantly more frequently, but not exclusively, in the neoadjuvantly treated group. Finally, stromal features, both morphological and biological, were investigated as possible markers for tumour regression, but failed to distinguish TR from native tumour stroma.

CONCLUSION

There is considerable divergence in opinion between pathologists when it comes to the identification of tumour regression. Reliable identification of TR is only possible if it is extensive, while lesser degrees of treatment effect cannot be recognized with certainty.

Ex vivo modeling of acquired drug resistance in BRAF - mutated pancreatic cancer organoids uncovers individual therapeutic vulnerabilities

Pancreatic ductal adenocarcinoma (PDAC) has a poor prognosis due to late detection and limited treatment options. Some PDAC patients harbor alterations that qualify for targeted treatment strategies but develop acquired resistance, leading to treatment failure. We here report the ex vivo modeling of acquired drug resistance by creating a PDAC patient-derived tumor organoid (PDTO) model harboring a rare BRAF R506_K507ins VLR mutation resulting in a resistance to trametinib, a MEK inhibitor. Genomic and transcriptomic analyses revealed upregulated WNT signaling in resistant PDTO clones compared to treatment-naïve parental control cells. By combining genomic and transcriptomic analysis with a functional drug testing approach, we uncovered a de novo upregulation and circumventive reliance on WNT signaling in resistant PDTO clones. Ex vivo models such as PDTOs represent valuable tools for resistance modelling and offer the discovery of novel therapeutic approaches for patients in need where clinical diagnostic tools are currently at the limit.

Defatting of Human Livers During Long-Term e x situ Normothermic Perfusion: Novel Strategy to Rescue Discarded Organs for Transplantation

OBJECTIVE

To develop a protocol for the defatting of steatotic liver grafts during long-term ex situ normothermic machine perfusion.

BACKGROUND

Despite the alarming increase in donor organ shortage, the highly prevalent fatty liver grafts are often discarded due to the risk of primary nonfunction. Effective strategies preventing such outcomes are currently lacking. An exciting new avenue is the introduction of ex situ normothermic machine perfusion (NMP), enabling a liver to remain fully functional for up to 2 weeks and providing a unique window of opportunity for defatting before transplantation.

METHODS

Over a 5-year period, 23 discarded liver grafts and 28 partial livers from our resection program were tested during ex situ normothermic machine perfusion. The steatosis degree was determined on serial biopsies by expert pathologists, and triglyceride contents were measured simultaneously.

RESULTS

Of 51 liver grafts, 20 were steatotic, with up to 85% macrovesicular steatosis, and were perfused for up to 12 days. Ten livers displayed marked (5 of which almost complete) loss of fat, while the other 10 did not respond to long-term perfusion. Successful defatting was related to prolonged perfusion, automated glucose control, circadian nutrition, and L-carnitine/fenofibrate supplementation. Pseudopeliotic steatosis and the associated activation of Kupffer/stellate cells were unexpected processes that might contribute to defatting. Synthetic and metabolic functions remained preserved for most grafts until perfusion ended.

CONCLUSION

Ex situ long-term perfusion effectively reduces steatosis while preserving organ viability and may in the future allow transplantation of primarily unusable high-risk grafts, significantly increasing the number of organs available for transplantation.

Determinants of Advanced Liver Fibrosis in Adult Patients After Fontan Palliation: Usefulness of Ultrasound Transient Elastography

BACKGROUND

Fontan-associated liver disease is an increasing concern. Our aim was to assess prevalence and predictors of advanced liver fibrosis with a specific focus on utility of liver stiffness measurement by ultrasound transient elastography.

METHODS

A total of 97 adult Fontan patients (55% male, median age: 23.1 years, interquartile range [IQR]: 18.7-30.6); 92 (95%) were evaluated with transient elastography, and 50 (52%) underwent transjugular liver biopsy. Advanced liver fibrosis was defined as congestive hepatic fibrosis score 3 or 4.

RESULTS

Only 4 patients (4%) had liver stiffness values < 10 kilopascal (kPa). Liver-stiffness measurements correlated weakly with peak oxygen uptake on exercise testing and Fontan pressure but not with Model for End-Stage Liver Disease excluding INR (MELD-XI) score or spleen size. Serial follow-up liver stiffness measurements in 73 clinically stable patients showed large variability among individual patients. Advanced liver fibrosis was present in 35 of 50 (70%) patients on liver biopsy and was associated to MELD-XI-Score ≥ 11 and splenomegaly but not to liver-stiffness measurements. Advanced liver fibrosis was not associated with patient age or time since Fontan operation but with younger age at completion of Fontan (3.7 years, IQR: 2.3-6.3 vs 6.8 years; IQR: 3.5-12.1; P = 0.037).

CONCLUSIONS

In our cohort, advanced liver fibrosis was present in the majority of adult Fontan patients. Liver stiffness as measured by transient elastography was not associated with the degree of liver fibrosis. Because of its high variability on serial measurements, it seems not to be useful for clinical decision making. The unexpected finding that younger age at completion of Fontan was associated with advanced liver fibrosis merits further evaluation.

Limited Value of Bladder Wash Cytology During Follow-Up of Patients With Non-muscle Invasive Bladder Cancer

Aims We aimed to assess the performance of bladder wash cytology (BWC) in daily clinical practice in a pure follow-up cohort of patients previously diagnosed with non-muscle invasive bladder cancer (NMIBC). Materials and methods We analyzed 2064 BWCs derived from 314 patients followed for NMIBC (2003-2016). Follow-up investigations were performed using cystoscopy (CS) in combination with BWC. Patients with suspicious CS and/or positive BWC underwent bladder biopsy or transurethral resection. BWC was considered positive if malignant or suspicious cells were reported. Sensitivity (Sn) and specificity (Sp) were calculated for the entire cohort and separately for low-grade (LG) and high-grade (HG) tumors, and carcinoma in situ (CIS) subgroups. Results A total of 95 recurrences were detected, of which only three were detected by BWC alone. Overall, Sn and Sp of BWC were 17.9% and 99.5%, respectively. For LG disease, these numbers were 14.0% and 100%, and for HG disease, these were 22.2% and 99.1%, respectively. For patients with CIS at initial diagnosis, Sn and Sp were 11.0% and 71.4%, respectively. For isolated primary CIS, Sn was 50.0%, and Sp was 98.2%. Conclusion Routine use of BWC in the follow-up for NMIBC is of limited value even in HG tumors. In the presence of isolated primary CIS, adjunct BWC might be justified.

The Milan system for reporting salivary gland cytopathology-A single-center study of 2156 cases

BACKGROUND

Fine-needle aspiration cytology (FNAC) represents an important diagnostic tool for the workup of salivary gland (SG) lesions. The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) is a six-tiered system for standardizing diagnoses and improvement of communication between pathologists and clinicians, providing risk of malignancy (ROM) rates for every category. The aims of the present study were (i) to validate the use of MSRSGC in a large series of SG FNAC in a tertiary center in Switzerland, (ii) to determine ROM for each category and compare them with data from MSRSGC and similar studies, and (iii) to investigate whether there were relevant differences of non-diagnostic results between fine-needle aspirations (FNA) performed by cytopathologists compared to non-cytopathologists.

METHODS

The files of the department of Pathology in the University Hospital Zurich (UHZ) were searched for SG FNAC between 2010 and 2019. The MSRSGC guidelines were applied retrospectively. Furthermore, ROM, risk of neoplasia (RON), sensitivity, and specificity were calculated based on the cases with histopathological follow-up.

RESULTS

A total of 2156 SG FNAC including 753 cases with histopathological follow-up were evaluated. Generally, ROM was within the range of values provided by MSRSGC, with some minor deviations. Sensitivity was 94.6%, and specificity was 99.3%.

CONCLUSIONS

Our study confirms the usefulness of MSRSGC. In addition, it provides a detailed insight into the wide spectrum of SG FNAC. Finally, we showed that the rate of non-diagnostic FNA was significantly lower in FNAs performed by cytopathologists compared to non-cytopathologists.

Utility of BAP1, p16 and MTAP immunohistochemistry in cytological and histological samples of pleural mesotheliomas

INTRODUCTION

In most cases the diagnostic workup of pleural mesotheliomas (MPM) starts with cytological examination of pleural effusion, but histology is needed to confirm the diagnosis. The introduction of BAP1 and MTAP immunohistochemistry have become a powerful tool to confirm the malignant nature of mesothelial proliferations also in cytological specimens. The objective of this study is to determine the concordance of BAP1, MTAP and p16 expression between cytological and histological samples of patients with MPM.

METHODS

Immunohistochemistry of BAP1, MTAP and p16 was performed on cytological samples and compared with the corresponding histological specimen of 25 patients with MPM. Inflammatory and stromal cells served as positive internal control for all three markers. In addition, samples of 11 patients with reactive mesothelial proliferations served as an external control group.

RESULTS

Loss of BAP1, MTAP and p16 expression was found in 68%, 72% and 92% of MPM, respectively. Loss of MTAP was associated with loss of p16 expression in all cases. Concordance of BAP1 between cytological and corresponding histological samples was 100% (kappa coefficient 1; p = 0.008). For MTAP and p16 kappa coefficient was 0.9 (p = 0.01) and 0.8 (p = 0.7788), respectively.

CONCLUSIONS

Concordant BAP1, MTAP and p16 expression is found between cytological and corresponding histological samples, indicating that a reliable diagnosis of MPM can be made on cytology only. Of the three markers BAP1 and MTAP are most reliable in distinguishing malignant from reactive mesothelial proliferations.

Immunohistochemistry for hepatitis E virus capsid protein cross-reacts with cytomegalovirus-infected cells: a potential diagnostic pitfall

Immunohistochemistry for hepatitis E virus (HEV) ORF2 (capsid) protein is a powerful tool for tissue-based diagnosis of hepatitis E, particularly useful in evaluating abnormal liver values in immunocompromised patients. We report here a previously unobserved reactivity of the HEV ORF2 antibody to human cytomegalovirus (CMV) proteins and contrast the staining patterns encountered in HEV and CMV infection, respectively. As part of a routine diagnostic work-up, the liver biopsy of an immunocompromised patient with elevated liver values was examined histologically for infection with viruses including CMV and HEV. Cytopathic changes were found, suggestive of CMV infection, which was confirmed by immunohistochemistry. Surprisingly, reactivity of a portion of CMV-infected cells with a mouse monoclonal antibody (clone 1E6) against HEV ORF2 protein was also detected. This observation prompted a screening of 22 further specimens (including liver, gastrointestinal, lung, brain and placental biopsies) with confirmed CMV infection/reactivation. Immunoreactivity of CMV-infected cells with HEV ORF2 antibody was observed in 18 of 23 specimens. While the HEV ORF2 antibody showed cytoplasmic, nuclear and canalicular positivity in hepatitis E cases, positivity in CMV-infected cells was limited to the nucleus. In conclusion, the HEV ORF2 antibody (clone 1E6) shows unexpected immunoreactivity against CMV proteins. In contrast to the hepatitis E staining pattern with cytoplasmic, nuclear and occasional canalicular positivity, reactivity in CMV-infected cells is restricted to the nucleus. Awareness of this cross-reactivity and knowledge of the differences in staining patterns will prevent pathologists from misinterpreting positive HEV ORF2 immunohistochemistry in liver specimens.

Hypoxia and Ezrin Expression in Primary Melanoma Have High Prognostic Relevance

Hypoxia affects tumor aggressiveness and activates pathways associated with epithelial mesenchymal transition (EMT) which are crucial for tumor progress. In this study, the correlation of hypoxia and EMT with sentinel lymph node status and tumor-specific survival was investigated in primary melanomas. CD34 for capillary count and Hypoxia inducible factor-1α (HIF-1α) as hypoxia indicators as well as Ezrin and L1-Cell Adhesion Molecule (L1CAM), both critical proteins contributing to EMT, were analyzed using immunohistochemistry in 49 melanoma patients with long follow-up (F/U, mean 110 months; range 12−263 months). We found a significant correlation between Breslow tumor thickness and Ezrin expression (p = 0.018). L1CAM expression in primary melanoma was significantly associated with HIF-1α expression (p < 0.0001) and sentinel lymph node metastasis (p = 0.011). Furthermore, low capillary count, reflecting hypoxic condition, was significantly associated with Ezrin expression (p = 0.047) and decreased tumor-specific survival (p = 0.035). In addition, patients with high Ezrin expression in their primary melanoma had a dramatic loss of life early in their F/U period (mean survival time 29 months; range 15−44 month). Our results highlight the relevance of Ezrin, L1CAM and HIF-1α as prognostic markers in melanoma patients. Additionally, we demonstrate that hypoxia in primary melanoma affects EMT and is at least partly responsible for early metastatic dissemination.

De novo expression of gastrokines in pancreatic precursor lesions impede the development of pancreatic cancer

Molecular events occurring in stepwise progression from pre-malignant lesions (pancreatic intraepithelial neoplasia; PanIN) to the development of pancreatic ductal adenocarcinoma (PDAC) are poorly understood. Thus, characterization of early PanIN lesions may reveal markers that can help in diagnosing PDAC at an early stage and allow understanding the pathology of the disease. We performed the molecular and histological assessment of patient-derived PanINs, tumor tissues and pancreas from mouse models with PDAC (KC mice that harbor K-RAS mutation in pancreatic tissue), where we noted marked upregulation of gastrokine (GKN) proteins. To further understand the role of gastrokine proteins in PDAC development, GKN-deficient KC mice were developed by intercrossing gastrokine-deficient mice with KC mice. Panc-02 (pancreatic cancer cells of mouse origin) were genetically modified to express GKN1 for further in vitro and in vivo analysis. Our results show that gastrokine proteins were absent in healthy pancreas and invasive cancer, while its expression was prominent in low-grade PanINs. We could detect these proteins in pancreatic juice and serum of KC mice. Furthermore, accelerated PanIN and tumor development were noted in gastrokine deficient KC mice. Loss of gastrokine 1 protein delayed apoptosis during carcinogenesis leading to the development of desmoplastic stroma while loss of gastrokine 2 increased the proliferation rate in precursor lesions. In summary, we identified gastrokine proteins in early pancreatic precursor lesions, where gastrokine proteins delay pancreatic carcinogenesis.

Drug screening and genome editing in human pancreatic cancer organoids identifies drug-gene interactions and candidates for off-label treatment

Pancreatic cancer (PDAC) is a highly aggressive malignancy for which the identification of novel therapies is urgently needed. Here, we establish a human PDAC organoid biobank from 31 genetically distinct lines, covering a representative range of tumor subtypes, and demonstrate that these reflect the molecular and phenotypic heterogeneity of primary PDAC tissue. We use CRISPR-Cas9 genome editing and drug screening to characterize drug-gene interactions with ARID1A and BRCA2. We find that missense- but not frameshift mutations in the PDAC driver gene ARID1A are associated with increased sensitivity to the kinase inhibitors dasatinib (p < 0.0001) and VE-821 (p < 0.0001). We conduct an automated drug-repurposing screen with 1,172 FDA-approved compounds, identifying 26 compounds that effectively kill PDAC organoids, including 19 chemotherapy drugs currently approved for other cancer types. We validate the activity of these compounds in vitro and in vivo. The in vivo validated hits include emetine and ouabain, compounds which are approved for non-cancer indications and which perturb the ability of PDAC organoids to respond to hypoxia. Our study provides proof-of-concept for advancing precision oncology and identifying candidates for drug repurposing via genome editing and drug screening in tumor organoid biobanks.

Secondary sclerosing cholangitis as cause of persistent jaundice in patients with severe COVID-19

BACKGROUND & AIMS

Little is known about cholestasis, including its most severe variant secondary sclerosing cholangitis (SSC), in critically ill patients with coronavirus disease 19 (COVID-19). In this study, we analysed the occurrence of cholestatic liver injury and SSC, including clinical, serological, radiological and histopathological findings.

METHODS

We conducted a retrospective single-centre analysis of all consecutive patients admitted to the intensive care unit (ICU) as a result of severe COVID-19 at the University Hospital Zurich to describe cholestatic injury in these patients. The findings were compared to a retrospective cohort of patients with severe influenza A.

RESULTS

A total of 34 patients with severe COVID-19 admitted to the ICU were included. Of these, 14 patients (41%) had no cholestasis (group 0), 11 patients (32%, group 1) developed mild and 9 patients (27%, group 2) severe cholestasis. Patients in group 2 had a more complicated disease course indicated by significantly longer ICU stay (median 51 days, IQR 25-86.5) than the other groups (group 0: median 9.5 days, IQR 3.8-18.3, P = .001; and group 1: median 16 days, IQR 8-30, P < .05 respectively). Four patients in group 2 developed SSC compared to none in the influenza A cohort. The available histopathological findings suggest an ischaemic damage to the perihilar bile ducts.

CONCLUSIONS

The development of SSC represents an important complication of critically ill COVID-19 patients and needs to be considered in the diagnostic work up in prolonged cholestasis. The occurrence of SSC is of interest in the ongoing pandemic since it is associated with considerable morbidity and mortality.

β6-Integrin Serves as a Potential Serum Marker for Diagnosis and Prognosis of Pancreatic Adenocarcinoma

INTRODUCTION

Despite enormous efforts during the past decades, pancreatic adenocarcinoma (PAC) remains one of the most deleterious cancer entities. A useful biomarker for early detection or prognosis of PAC does not yet exist. The goal of our study was the characterization of β6-integrin (ITGB6) as a novel serum tumor marker for refined diagnosis and prognosis of PAC. Serum ITGB6 levels were analyzed in 3 independent PAC cohorts consisting of retrospectively and prospectively collected serum and/or (metastatic) PAC tissue specimens.

METHODS

Using 2 independent cohorts, we measured serum ITGB6 concentrations in 10 chronic pancreatitis patients, 10 controls, as well as in 27 (cohort 1) and 24 (cohort 2) patients with PAC, respectively. In these patients, we investigated whether ITGB6 serum levels correlate with known clinical and prognostic markers for PAC and whether they might differ between patients with PAC or benign inflammatory diseases of the pancreas.

RESULTS

We found that elevated serum ITGB6 levels (≥0.100 ng/mL) in patients suffering from metastasizing PAC presented an unfavorable prognostic outcome. By correlating the ITGB6 tissue expression in primary and metastatic PAC with clinical parameters, we found that positive ITGB6 expression in the tumor tissue is linked to increased serum ITGB6 levels in nonmetastatic PAC and correlates with carbohydrate antigen 19-9 and clinical outcome.

DISCUSSION

Our findings suggest that ITGB6 might serve as a novel serum biomarker for early diagnosis and prognosis of PAC. Given the limited specificity and sensitivity of currently used carbohydrate antigen 19-9-based assays, ITGB6 may have the potential to improve the diagnostic accuracy for PAC.

In vivo adenine base editing of PCSK9 in macaques reduces LDL cholesterol levels

Most known pathogenic point mutations in humans are C•G to T•A substitutions, which can be directly repaired by adenine base editors (ABEs). In this study, we investigated the efficacy and safety of ABEs in the livers of mice and cynomolgus macaques for the reduction of blood low-density lipoprotein (LDL) levels. Lipid nanoparticle-based delivery of mRNA encoding an ABE and a single-guide RNA targeting PCSK9, a negative regulator of LDL, induced up to 67% editing (on average, 61%) in mice and up to 34% editing (on average, 26%) in macaques. Plasma PCSK9 and LDL levels were stably reduced by 95% and 58% in mice and by 32% and 14% in macaques, respectively. ABE mRNA was cleared rapidly, and no off-target mutations in genomic DNA were found. Re-dosing in macaques did not increase editing, possibly owing to the detected humoral immune response to ABE upon treatment. These findings support further investigation of ABEs to treat patients with monogenic liver diseases.

Autochthonous hepatitis E as a cause of acute-on-chronic liver failure and death: histopathology can be misleading but transaminases may provide a clue

BACKGROUND AND AIM

Acute decompensation and death have been observed in patients with acute hepatitis E virus (HEV) infection and preexisting liver cirrhosis. However, the clinical, laboratory and histological features need to be fully characterised.

METHODS

Some of us recently described the histological presentation of hepatitis E in a large panel of liver tissue specimens. Here, we conducted a case-control study to investigate the clinical and laboratory features of the subset of patients with HEV-related acute-on-chronic liver failure (ACLF) and death. Each patient was matched to three control patients with histologically confirmed severe alcoholic hepatitis based on sex, age, total bilirubin, INR, serum creatinine and MELD score on admission.

RESULTS

Of 5 patients who died in a context of HEV-related ACLF, 3 (60%) were male and the median age was 66 years (range 51&ndash;76). Median alanine aminotransferase (ALT) at presentation was 2610 U/l (range 705&ndash;3134) and aspartate aminotransferase (AST) 2818 U/l (range 1176&ndash;8611). Liver function was heavily altered in all patients. Histological analyses revealed steatohepatitis on a background of cirrhosis, suggestive of an alcoholic or nonalcoholic origin. Based on histopathology, alcoholic hepatitis was initially suspected in two patients and corticosteroid treatment was initiated. Ribavirin was started in four patients. Median time from hospitalisation to death was 17 days (range 6&ndash;25 days). AST levels in patients with HEV-related ACLF were significantly higher as compared to the matched patients with severe alcoholic hepatitis.

CONCLUSION

Typical histopathological features of viral hepatitis may be absent in ACLF caused by HEV infection. HEV infection should be sought in acute decompensation of cirrhosis and ACLF even in the absence of histological changes suggesting viral infection.

NASH limits anti-tumour surveillance in immunotherapy-treated HCC

Hepatocellular carcinoma (HCC) can have viral or non-viral causes^1-5. Non-alcoholic steatohepatitis (NASH) is an important driver of HCC. Immunotherapy has been approved for treating HCC, but biomarker-based stratification of patients for optimal response to therapy is an unmet need^6,7. Here we report the progressive accumulation of exhausted, unconventionally activated CD8⁺PD1⁺ T cells in NASH-affected livers. In preclinical models of NASH-induced HCC, therapeutic immunotherapy targeted at programmed death-1 (PD1) expanded activated CD8⁺PD1⁺ T cells within tumours but did not lead to tumour regression, which indicates that tumour immune surveillance was impaired. When given prophylactically, anti-PD1 treatment led to an increase in the incidence of NASH-HCC and in the number and size of tumour nodules, which correlated with increased hepatic CD8⁺PD1⁺CXCR6⁺, TOX⁺, and TNF⁺ T cells. The increase in HCC triggered by anti-PD1 treatment was prevented by depletion of CD8⁺ T cells or TNF neutralization, suggesting that CD8⁺ T cells help to induce NASH-HCC, rather than invigorating or executing immune surveillance. We found similar phenotypic and functional profiles in hepatic CD8⁺PD1⁺ T cells from humans with NAFLD or NASH. A meta-analysis of three randomized phase III clinical trials that tested inhibitors of PDL1 (programmed death-ligand 1) or PD1 in more than 1,600 patients with advanced HCC revealed that immune therapy did not improve survival in patients with non-viral HCC. In two additional cohorts, patients with NASH-driven HCC who received anti-PD1 or anti-PDL1 treatment showed reduced overall survival compared to patients with other aetiologies. Collectively, these data show that non-viral HCC, and particularly NASH-HCC, might be less responsive to immunotherapy, probably owing to NASH-related aberrant T cell activation causing tissue damage that leads to impaired immune surveillance. Our data provide a rationale for stratification of patients with HCC according to underlying aetiology in studies of immunotherapy as a primary or adjuvant treatment.

Pancreatic fistulas following distal pancreatectomy are unrelated to the texture quality of the pancreas

PURPOSE

The relevance of pancreatic texture for pancreatic fistula (POPF) formation after distal pancreatectomy (DP) remains ill defined. Recent POPF definition adjustments and common subjective pancreatic texture assessment are further drawbacks in the investigation of pancreatic texture as a factor for POPF development after DP.

METHODS

The predictive value of pancreatic texture by histologic assessment was investigated for POPF formation after DP, respecting the updated 2016 fistula definition. Histologic evaluation at the resection margin included amount of steatosis, degree of fibrosis, and pancreatic duct size.

RESULTS

A total of 102 patients who underwent DP were included. Thirty-six patients developed POPF. There was no difference in histologic variables in patients with and without POPF. In the univariate analysis, none of the three histologic features showed significant correlation with POPF formation. The ROC (receiver operating characteristic) curve demonstrated poor utility for the grade of steatosis 0.481 ± 0.058 (p = 0.75) and grade of fibrosis 0.466 ± 0.058 (p = 0.57) as predictive factors for POPF formation.

CONCLUSION

Results indicate that pancreatic texture does not predict POPF formation following DP. This is particularly relevant in the context of the increasing use of robotic and laparoscopic approaches for DPs with limited clinical pancreatic texture assessment by palpation.

Amelioration of Murine Autoimmune Pancreatitis by Targeted LTβR Inhibition and Anti-CD20 Treatment

Autoimmune pancreatitis (AIP) is a rare form of chronic pancreatitis, for which treatment options, especially the long-term management, are limited. The only therapy that has been established and accepted so far is corticosteroids, but the relapse rate is significant. In the current study, we discern the effector mechanisms of targeted LTβR pathway inhibition using LTβR-Ig. Furthermore, the efficacy of LTβR-Ig therapy is compared with the depletion of immune cell subsets (CD4⁺ and CD20⁺), which are suggested to play a pathological role in AIP development. Three well-established mouse models of AIP were used to examine treatment efficacies and mechanisms. Tg(Ela1-Lta,b) mice represent a genetic model, in which AIP develops spontaneously. In MRL/Mp and IL-10^-/- mice, AIP is induced by repeated polyinosinic:polycytidylic acid injection. Mice with AIP were treated with anti-CD20, anti-CD4 mAbs, or targeted LTβR-Ig. LTβR-Ig and anti-CD20 treatment led to significant improvement of AIP, including a decrease in autoantibody production and pancreatic inflammation in Tg(Ela1-Lta,b) and IL-10^-/- mice. The molecular mechanism of this beneficial effect possibly involves the downregulation of Stat3 and noncanonical NF-κb activation. Anti-CD4 treatment reduced Th1 and Th2 signature but did not alleviate AIP. Additionally, in contrast to anti-CD20 or anti-CD4 treatments, blocking LTβR signaling disrupted tertiary lymphoid organs in all three models. We demonstrate that treatment with LTβR-Ig or anti-CD20 Ab alleviated murine AIP. LTβR-Ig treatment for AIP was effective in both lymphotoxin-dependent and lymphotoxin-independent AIP models, possibly because of its dual anti-inflammatory and antiautoimmune mechanisms.

The role of macrophages type 2 and T-regs in immune checkpoint inhibitor related adverse events

Immune checkpoint inhibitory (ICI) therapy represents a novel approach in a variety of cancers, with impressive survival benefit. With ICIs, however, a new spectrum of immune related adverse events (irAE) including life threatening hypohysitis has emerged. This autopsy study aimed to investigate inflammatory cells, PD-1 and PD-L1 expression in cases of patients who developed hypophysitis and involvement of other organs. We analysed 6 patients, who were treated with ICIs and developed hypophysitis. Two received an additional MAP-kinase inhibitor, MEK-inhibitor and cytotoxic chemotherapy. Besides the pituitary gland, all investigated adrenal glands (5/5) were affected; three cases had other organs involved (liver (2/6), thyroid (2/6), lung (1/6), myocardium (1/6), colon (1/6). The inflammatory cells of involved organs were further specified and PD1 and PDL-1 expression was analyzed using immunohistochemistry. We observed that patients treated with ICIs alone showed T-cell predominant lymphocytic infiltrates, whereas patients receiving additional therapies demonstrated an increase in B- and T-lymphocytes. Surprisingly, the dominant inflammatory population was not T-cell, but type 2 macrophages. CD25 positive T-regs were sparse or absent. Our study suggests that T cell activation is only partially responsible for irAE. ICI therapy interaction with CTLA-4, PD-1 and PDL-1 in type 2 macrophages appears to result in disturbance of their control. Furthermore, depletion of T-regs seems to contribute significantly. Our findings with simultaneous pituitary and adrenal gland involvement underlines the systemic involvement as well as the importance of monitoring cortisol levels to avoid potentially life threatening hypocortisolism.

A dual role for hepatocyte-intrinsic canonical NF-κB signaling in virus control

BACKGROUND & AIMS

Hepatic innate immune control of viral infections has largely been attributed to Kupffer cells, the liver-resident macrophages. However, hepatocytes, the parenchymal cells of the liver, also possess potent immunological functions in addition to their known metabolic functions. Owing to their abundance in the liver and known immunological functions, we aimed to investigate the direct antiviral mechanisms employed by hepatocytes.

METHODS

Using lymphocytic choriomeningitis virus (LCMV) as a model of liver infection, we first assessed the role of myeloid cells by depletion prior to infection. We investigated the role of hepatocyte-intrinsic innate immune signaling by infecting mice lacking canonical NF-κB signaling (Ikkβ^ΔHep) specifically in hepatocytes. In addition, mice lacking hepatocyte-specific interferon-α/β signaling-(Ifnar^ΔHep), or interferon-α/β signaling in myeloid cells-(Ifnar^ΔMyel) were infected.

RESULTS

Here, we demonstrate that LCMV activates NF-κB signaling in hepatocytes. LCMV-triggered NF-κB activation in hepatocytes did not depend on Kupffer cells or TNFR1 signaling but rather on Toll-like receptor signaling. LCMV-infected Ikkβ^ΔHep livers displayed strongly elevated viral titers due to LCMV accumulation within hepatocytes, reduced interferon-stimulated gene (ISG) expression, delayed intrahepatic immune cell influx and delayed intrahepatic LCMV-specific CD8⁺ T cell responses. Notably, viral clearance and ISG expression were also reduced in LCMV-infected primary hepatocytes lacking IKKβ, demonstrating a hepatocyte-intrinsic effect. Similar to livers of Ikkβ^ΔHep mice, enhanced hepatocytic LCMV accumulation was observed in livers of Ifnar^ΔHep mice, whereas Ifnar^ΔMyel mice were able to control LCMV infection. Hepatocytic NF-κB signaling was also required for efficient ISG induction in HDV-infected dHepaRG cells and interferon-α/β-mediated inhibition of HBV replication in vitro.

CONCLUSIONS

Together, these data show that hepatocyte-intrinsic NF-κB is a vital amplifier of interferon-α/β signaling, which is pivotal for strong early ISG responses, immune cell infiltration and hepatic viral clearance.

LAY SUMMARY

Innate immune cells have been ascribed a primary role in controlling viral clearance upon hepatic infections. We identified a novel dual role for NF-κB signaling in infected hepatocytes which was crucial for maximizing interferon responses and initiating adaptive immunity, thereby efficiently controlling hepatic virus replication.

First Clinicopathologic Evidence of a Non-PSMA-Related Uptake Mechanism for 68Ga-PSMA-11 in Salivary Glands

The intense accumulation of prostate-specific membrane antigen (PSMA) radioligands in salivary glands is still not well understood. It is of concern for therapeutic applications of PSMA radioligands, because therapeutic radiation will damage these glands. A better understanding of the uptake mechanism is, therefore, crucial to find solutions to reduce toxicity. The aim of this study was to investigate whether the accumulation of PSMA-targeting radioligands in submandibular glands (SMGs) can be explained with PSMA expression levels using autoradiography (ARG) and immunohistochemistry (IHC). Methods: All patients gave written informed consent for further utility of the biologic material. The SMG of 9 patients, pancreatic tissue of 4 patients, and prostate cancer (PCA) lesions of 9 patients were analyzed. Tissue specimens were analyzed by means of PSMA-IHC (using an anti-PSMA-antibody and an immunoreactivity score system [IRS]) and ARG using ¹⁷⁷Lu-PSMA-617 (with quantification of the relative signal intensity compared with a PSMA-positive standard). The SUV_max in salivary glands, pancreas, and PCA tissues were quantified in 60 clinical ⁶⁸Ga-PSMA-11 PET scans for recurrent disease as well as the 9 primary tumors selected for ARG and IHC. Results: PCA tissue samples revealed a wide range of PSMA staining intensity on IHC (IRS = 70-300) as well as in ARG (1.3%-22% of standard). This variability on PCA tissue could also be observed in ⁶⁸Ga-PSMA-11 PET (SUV_max, 4.4-16) with a significant correlation between ARG and SUV_max (P < 0.001, R ² = 0.897). On IHC, ARG, and ⁶⁸Ga-PSMA-11 PET, the pancreatic tissue was negative (IRS = 0, ARG = 0.1% ± 0.05%, SUV_max of 3.1 ± 1.1). The SMG tissue displayed only focal expression of PSMA limited to the intercalated ducts on IHC (IRS = 10-15) and a minimal signal on ARG (1.3% ± 0.9%). In contrast, all SMG showed a high ⁶⁸Ga-PSMA-11 accumulation on PET scans (SUV_max 23.5 ± 5.2). Conclusion: Our results indicate that the high accumulation of PSMA radioligands in salivary glands does not correspond to high PSMA expression levels determined using ARG and IHC. These findings provide evidence, that the significant accumulation of PSMA radioligands in SMG is not primarily a result of PSMA-mediated uptake.

Commonly Used Pancreatic Stellate Cell Cultures Differ Phenotypically and in Their Interactions with Pancreatic Cancer Cells

Activated pancreatic stellate cells (PSCs) play a central role in the tumor stroma of pancreatic ductal adenocarcinoma (PDAC). Given the limited availability of patient-derived PSCs from PDAC, immortalized PSC cell lines of murine and human origin have been established; however, it is not elucidated whether differences in species, organ disease status, donor age, and immortalization alter the PSC phenotype and behavior compared to that of patient-derived primary PSC cultures. Therefore, a panel of commonly used PSC cultures was examined for important phenotypical and functional features: three primary cultures from human PDAC, one primary from normal human pancreas, and three immortalized (one from human, two from murine pancreas). Growth rate was considerably lower in primary PSCs from human PDAC. Basal collagen synthesis varied between the PSC cultures, and TGF-β stimulation increased collagen synthesis only in non-immortalized cultures. Differences in secretome composition were observed along with a divergence in the DNA synthesis, migration, and response to gemcitabine of PDAC cell lines that were grown in conditioned medium from the various PSC cultures. The findings reveal considerable differences in features and functions that are key to PSCs and in the interactions with PDAC. These observations may be relevant to researchers when selecting the most appropriate PSC culture for their experiments.

Pathology assessment of pancreatic cancer following neoadjuvant treatment: Time to move on

Neoadjuvant treatment has increasingly become an integral part of the multimodal management of patients with pancreatic cancer. In patients who are able to undergo surgery following preoperative therapy, tumour regression grading remains the diagnostic gold standard for the histomorphological assessment of the effect of neoadjuvant treatment. In recent years, however, there has been growing concern about inherent flaws of tumour regression grading systems as well as their imprecise and impractical criteria that result in divergence of practice and lack of interobserver agreement. Furthermore, existing tumour regression systems differ in their defining criteria and thresholds, leading to incomparability of data. In this review, the principles and limitations of the main existing tumour regression systems are discussed, and potential alternative assessment approaches and novel markers are presented.

Drug-induced bile duct injury

Drug-induced liver injury includes a spectrum of pathologies, some related to the mode of injury, some to the cell type primarily damaged. Among these, drug-induced bile duct injury is characterized by the destruction of the biliary epithelium following exposure to a drug. Most of the drugs associated with bile duct injury cause immune-mediated lesions to the epithelium of interlobular ducts. These share common histopathological features with primary biliary cholangitis, such as inflammation and necrosis at the expense of cholangiocytes and, if the insult persists, bile duct loss and biliary cirrhosis. Some drugs selectively target larger ducts. Such injury is often dose-dependent and thought to be the result of intrinsic drug toxicity. The histological changes resemble those seen in primary sclerosing cholangitis. This overview focuses on the clinical and pathological features of bile duct injury associated with drug treatment and on the immunological and biochemical effects that drugs exert on the biliary epithelium. This article is part of a Special Issue entitled: Cholangiocytes in Health and Disease edited by Jesus Banales, Marco Marzioni, Nicholas LaRusso and Peter Jansen.

Visualization of hepatitis E virus RNA and proteins in the human liver

BACKGROUND & AIMS

Although hepatitis E constitutes a substantial disease burden worldwide, surprisingly little is known about the localization of hepatitis E virus (HEV) in the human liver. We therefore aimed to visualize HEV RNA and proteins in situ.

METHODS

A panel of 12 different antibodies against HEV open reading frame (ORF) 1-3 proteins was evaluated for immunohistochemistry (IHC) and two probes for in situ hybridization (ISH) in formalin-fixed, paraffin-embedded (FFPE) HuH7 cells transfected with HEV ORF1-3 expression vectors. IHC (and partly ISH) were then applied to Hep293TT cells replicating infectious HEV and liver specimens from patients with hepatitis E (n=20) and controls (n=134).

RESULTS

Whereas ORF1-3 proteins were all detectable in transfected, HEV protein-expressing cells, only ORF2 and 3 proteins were traceable in cells replicating infectious HEV. Only the ORF2-encoded capsid protein was also unequivocally detectable in liver specimens from patients with hepatitis E. IHC for ORF2 protein revealed a patchy expression in individual or grouped hepatocytes, generally stronger in chronic compared to acute hepatitis. Besides cytoplasmic and canalicular, ORF2 protein also displayed a hitherto unknown nuclear localization. Positivity for ORF2 protein in defined areas correlated with HEV RNA detection by ISH. IHC was specific and comparably sensitive as PCR for HEV RNA.

CONCLUSIONS

ORF2 protein can be reliably visualized in the liver of patients with hepatitis E, allowing for sensitive and specific detection of HEV in FFPE samples. Its variable subcellular distribution in individual hepatocytes of the same liver suggests a redistribution of ORF2 protein during infection and interaction with nuclear components.

LAY SUMMARY

The open reading frame (ORF) 2 protein can be used to visualize the hepatitis E virus (HEV) in the human liver. This enabled us to discover a hitherto unknown localization of the HEV ORF2 protein in the nucleus of hepatocytes and to develop a test for rapid histopathologic diagnosis of hepatitis E, the most common cause of acute hepatitis worldwide.

Hepatitis E Virus and the Liver: Clinical Settings and Liver Pathology

Infection with hepatitis E virus (HEV) is a leading cause of acute hepatitis worldwide, now increasingly recognized also in nonendemic regions. Clinical manifestation of hepatitis E includes mostly asymptomatic/subclinical presentations or acute, self-limiting hepatitis, but also potentially fatal liver failure or chronic hepatitis in immunocompromised individuals. Accordingly, hepatitis E histolpathologic patterns range from an unremarkable histology over acute (cholestatic) hepatitis with variable degree of necrosis to chronic hepatitis with fibrosis. Awareness of hepatitis E and its differential diagnoses, knowledge of its clinico-pathologic manifestations and familiarity with its diagnostic tools will enable clinicians and pathologists to competently make this diagnosis.

Disseminated VZV infection and asymptomatic VZV vasculopathy after steroid abuse

A 60-year-old man who abused corticosteroids developed thoracic-distribution zoster. Varicella zoster virus (VZV) DNA was found in non-healing skin 3 months later. He died suddenly 2 months later. Skin was ulcerated and necrotic. VZV was widespread in organs and arteries, particularly coronary arteries and aorta, with VZV vasculopathy in the posterior cerebral artery.

An Aggressive Hypoxia Related Subpopulation of Melanoma Cells is TRP-2 Negative

Despite existing vaccination strategies targeting TRP-2, its function is not yet fully understood. TRP-2 is an enzyme involved in melanin biosynthesis and therefore discussed as a differentiation antigen. However, in mice Trp-2 was shown to be expressed in melanocyte stem cells of the hair follicle and therefore also considered as an indicator of stemness. A proper understanding of the TRP-2 function is crucial, considering a vaccination targeting cells with stemness properties would be highly effective in contrast to a therapy targeting differentiated melanoma cells. Analysing over 200 melanomas including primaries, partly matched metastases and patients' cell cultures we show that TRP-2 is correlated with Melan A expression and decreases with tumor progression. In mice it is expressed in differentiated melanocytes as well as in stem cells. Furthermore, we identify a TRP-2 negative, proliferative, hypoxia related cell subpopulation which is significantly associated with tumor thickness and diseases progression. Patients with a higher percentage of those cells have a less favourable tumor specific survival. Our findings underline that TRP-2 is a differentiation antigen, highlighting the importance to combine TRP-2 vaccination with other strategies targeting the aggressive undifferentiated hypoxia related subpopulation.

HBME-1 expression in hyalinizing trabecular tumours of the thyroid gland

AIMS

Hyalinizing trabecular tumour (HTT) is a rare thyroid neoplasm with a trabecular growth pattern, marked intratrabecular hyalinization and nuclear features of papillary thyroid carcinoma (PTC). Immunohistochemical HBME-1 expression was reported recently in PTC, but not in HTT. To clarify further the value of HBME-1 expression as a tool in differential diagnosis, we investigated the immunophenotype of HTT.

METHODS AND RESULTS

Eight HTT diagnosed from 1997 to 2012 were reviewed on H&E-stained tissue sections and analysed for HBME-1, galectin-3, CK19 and Ki67 expression by immunohistochemistry. Three of eight HTTs (37.5%) were HBME-1 positive, with staining of tumour cells as well as of intratrabecular hyaline matrix material. All cases were CK19 negative. Galectin-3 was expressed weakly in four of eight cases (50%). Five of eight cases (62.5%) showed weak-to-moderate cytoplasmic Ki67 positivity.

CONCLUSIONS

Immunohistochemical HBME-1 expression is present in HTT and may not serve as a reliable marker in differentiating HTT from PTC. The HBME-1 positivity of the hyaline matrix suggests that this material is partly of cytoplasmic origin.