Faculty Bibliography

Multiplexed immunohistochemical techniques give insight into contextual cellular relationships by offering the ability to collect cell-specific data with spatial information from formalin-fixed, paraffin-embedded tissue sections. We established an automated sequential elution-stripping multiplex immunohistochemical assay to address two controversial scientific questions in the field of hepatopathology: 1) whether epithelial-to-mesenchymal transition or mesenchymal-to-epithelial transition occurs during liver injury and repair of a chronic liver disease and 2) if there is a stromal:epithelial relationship along the canals of Hering that would support the concept of this biliary structure being a stem/progenitor cell niche. Our 4-plex assay includes both epithelial and mesenchymal clinical immunohistochemical markers and was performed on clinical human liver specimens in patients with primary biliary cholangitis. The assay demonstrated that in each specimen, co-expression of epithelial and mesenchymal markers was observed in extraportal cholangiocytes. In regard to possible mesenchymal components in a stem cell niche, 82.3% ± 5.5% of extraportal cholangiocytes were intimately associated with a vimentin-positive cell. Co-expression of epithelial and mesenchymal markers by extraportal cholangiocytes is evidence for epithelial to mesenchymal transition in primary biliary cholangitis. Vimentin-positive stromal cells are frequently juxtaposed to extraportal cholangiocytes, supporting an epithelial:mesenchymal relationship within the hepatobiliary stem cell niche. Our automated sequential elution-stripping multiplex immunohistochemical assay is a cost-effective multiplexing technique that can be readily applied to a small series of clinical pathology samples in order to answer scientific questions involving cell:cell relationships and cellular antibody expression.

BACKGROUND:Mucinous adenocarcinoma (MAC) is a distinct type of colorectal cancer (CRC) associated with poor response to treatment and poorer prognosis. MAC is diagnosed by WHO definition when the extracellular mucin is more than 50% of the lesion. We aimed at assessing the gene expression profiles of the CRCs with any mucinous features (> 5%) in a retrospective study. METHODS:The data of a 50-gene next generation sequencing (NGS) panel of 166 CRCs was analyzed and the gene mutational profile with morphologic features was correlated. RESULTS:We identified the different genetic mutation profiles between CRCs with and without mucinous component, but noticed a similar genetic profile between MACs and CRCs with mucinous component, irrespective of the percentage (if mucinous component more than 5%). The different genetic mutation profile related to MSI status was also identified between two groups of tumors. The most frequent mutations in CRCs with mucinous component are KRAS (28/49, 57.1%) and BRAF (19/49, 38.7%), PIK3CA (16/49, 32.6%), followed by APC (12/49, 24.5%) and TP53 (11/49, 22.5%). The combined mutation frequency of the two key factors in the EGFR signaling pathway, KRAS and BRAF, in the CRCs with and without mucinous component is 95.9 and 52.1%, respectively. CONCLUSIONS:The dysregulation of EGFR pathway plays a critical role in the development of CRCs with mucinous component, irrespective of the percentage. The result suggested that the current cut off of 50% mucin component to define mucinous adenocarcinoma might be challengeable.

Appendicitis in pregnancy is the most common nonobstetric surgical emergency. Pregnancy causes changes in anatomy, which could lead to uncertainty regarding the diagnosis of appendicitis. This case report describes a case of appendicitis presenting with peritoneovaginal fistula in a pregnant woman in the second trimester, with interesting finding of isolated appendiceal endometriosis on pathology. The importance of complete physical examination, including speculum examination, is emphasized in the pregnant patient presenting with acute-onset abdominal pain. Imaging criteria for diagnosis of appendicitis should be adjusted to account for the gravid uterus, which may cause appendiceal abscess to appear in a variety of locations, such as posterior to the cervix, as in this case.

The human PXR (pregnane X receptor), a master regulator of drug metabolism, has essential roles in intestinal homeostasis and abrogating inflammation. Existing PXR ligands have substantial off-target toxicity. Based on prior work that established microbial (indole) metabolites as PXR ligands, we proposed microbial metabolite mimicry as a novel strategy for drug discovery that allows exploiting previously unexplored parts of chemical space. Here, we report functionalized indole derivatives as first-in-class non-cytotoxic PXR agonists as a proof of concept for microbial metabolite mimicry. The lead compound, FKK6 (Felix Kopp Kortagere 6), binds directly to PXR protein in solution, induces PXR-specific target gene expression in cells, human organoids, and mice. FKK6 significantly represses pro-inflammatory cytokine production cells and abrogates inflammation in mice expressing the human PXR gene. The development of FKK6 demonstrates for the first time that microbial metabolite mimicry is a viable strategy for drug discovery and opens the door to underexploited regions of chemical space.