Research Spotlight

Asirvatham, J.R. and Jorns, J.M. (2021). “How Do Pathologists in Academic Institutions Across the United States and Canada Evaluate Sentinel Lymph Nodes in Breast Cancer?” Am J Clin Pathol Jun 24;aqab055. [Epub ahead of print].

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OBJECTIVES: There are little data on how changes in the clinical management of axillary lymph nodes in breast cancer have influenced pathologist evaluation of sentinel lymph nodes. METHODS: A 14-question survey was sent to Canadian and US breast pathologists at academic institutions (AIs). RESULTS: Pathologists from 23 AIs responded. Intraoperative evaluation (IOE) is performed for selected cases in 9 AIs, for almost all in 10, and not performed in 4. Thirteen use frozen sections (FSs) alone. During IOE, perinodal fat is completely trimmed in 8, not trimmed in 9, and variable in 2. For FS, in 12 the entire node is submitted at 2-mm intervals. Preferred plane of sectioning is parallel to the long axis in 8 and perpendicular in 12. In 11, a single H&E slide is obtained, whereas 12 opt for multiple levels. In 11, cytokeratin is obtained if necessary, and immunostains are routine in 10. Thirteen consider tumor cells in pericapsular lymphatics as lymphovascular invasion (LVI), and 10 consider it isolated tumor cells (ITCs). CONCLUSIONS: There is dichotomy in practice with near-equal support for routine vs case-by-case multilevel/immunostain evaluation, perpendicular vs parallel sectioning, complete vs incomplete fat removal, and tumor in pericapsular lymphatics as LVI vs ITCs.

Agarwala, A. and Goldberg, A. (2021). “Special Considerations for Lipid-Lowering Therapy in Women Reflecting Recent Randomized Trials.” Curr Atheroscler Rep 23(8): 42.

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PURPOSE OF REVIEW: Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of mortality in women across all racial and ethnic groups within the USA. Despite robust evidence from randomized controlled trials demonstrating that treatment of hypercholesterolemia in women reduces cardiovascular events, women who are eligible for lipid-lowering therapy are less likely than men to be prescribed guideline-recommended therapy or to have therapy prescribed at the appropriate intensity. RECENT FINDINGS: Historically, women have been underrepresented in clinical trials. Recent randomized clinical trials have shown that women derive similar benefits as men when treated with lipid-lowering therapy, and recent studies demonstrate potential uses for lipid-lowering therapies that extend beyond their previously well-established indications. In this review, we will discuss lipid-lowering therapies in the context of recent clinical trials with a focus on special considerations in women.

Xue, F., Zhao, H., Yuan, Q. and Zhang, S.W. (2021). “[Advances in application of tissue clearing technique in hard tissues].” Zhonghua Kou Qiang Yi Xue Za Zhi 56(6): 598-603.

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Tissue clearing is a novel technique developed within recent years, which could make the tissue optical transparency using physical or chemical methods by refractive index matching. Combined with fluorescence imaging and three-dimensional reconstruction technology, it could achieve three-dimensional observing and analyze the tissue structure at the cellular resolution. The tissue clearing technique is mainly applied to soft tissues, as less to hard tissues. In recent years, many researchers have modified tissue clearing methods and made them suitable for hard tissues, such as bone and teeth. The present paper reviews the recent application of tissue clearing techniques in hard tissues.

Pu, Q., Lin, P., Gao, P., Wang, Z., Guo, K., Qin, S., Zhou, C., Wang, B., Wu, E., Khan, N., Xia, Z., Wei, X. and Wu, M. (2021). “Gut Microbiota Regulate Gut-Lung Axis Inflammatory Responses by Mediating ILC2 Compartmental Migration.” J Immunol Jun 16;ji2001304. [Epub ahead of print].

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Gut microbiota is increasingly linked to the development of various pulmonary diseases through a gut-lung axis. However, the mechanisms by which gut commensal microbes impact trafficking and functional transition of immune cells remain largely unknown. Using integrated microbiota dysbiosis approaches, we uncover that the gut microbiota directs the migration of group 2 innate lymphoid cells (ILC2s) from the gut to the lung through a gut-lung axis. We identify Proteobacteria as a critical species in the gut microbiome to facilitate natural ILC2 migration, and increased Proteobacteria induces IL-33 production. Mechanistically, IL-33-CXCL16 signaling promotes the natural ILC2 accumulation in the lung, whereas IL-25-CCL25 signals augment inflammatory ILC2 accumulation in the intestines upon abdominal infection, parabiosis, and cecum ligation and puncture in mice. We reveal that these two types of ILC2s play critical but distinct roles in regulating inflammation, leading to balanced host defense against infection. Overall results delineate that Proteobacteria in gut microbiota modulates ILC2 directional migration to the lung for host defense via regulation of select cytokines (IL-33), suggesting novel therapeutic strategies to control infectious diseases.

Axelrad, I., Safrin, M., Cahan, R., Suh, S.J., Ohman, D.E. and Kessler, E. (2021). “Extracellular proteolytic activation of Pseudomonas aeruginosa aminopeptidase (PaAP) and insight into the role of its non-catalytic N-terminal domain.” PLoS One 16(6): e0252970.

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Pseudomonas aeruginosa secretes several endopeptidases, including elastase, alkaline proteinase (Apr), a lysine-specific endopeptidase (LysC), and an aminopeptidase (PaAP), all of which are important virulence factors. Activation of the endopeptidases requires removal of an inhibitory N-terminal propeptide. Activation of pro-PaAP, in contrast, requires C-terminal processing. The activating proteases of pro-PaAP and their cleavage site(s) have not yet been defined. Studying pro-PaAP processing in a wild type P. aeruginosa strain and strains lacking either elastase or both elastase and Apr, we detected three processing variants, each ~56 kDa in size (AP56). Activity assays and N- and C-terminal sequence analyses of these variants pointed at LysC as the principal activating protease, cleaving a Lys512-Ala513 peptide bond at the C-terminal end of pro-PaAP. Elastase and/or Apr are required for activation of LysC, suggesting both are indirectly involved in activation of PaAP. To shed light on the function(s) of the N-terminal domain of AP56, we purified recombinant AP56 and generated from it the 28 kDa catalytic domain (AP28). The kinetic constants (Km and Kcat) for hydrolysis of Leu-, Lys-, Arg- and Met-p-nitroanilide (pNA) derivatives by AP56 and AP28 were then determined. The catalytic coefficients (Kcat/Km) for hydrolysis of all four substrates by AP28 and AP56 were comparable, indicating that the non-catalytic domain is not involved in hydrolysis of small substrates. It may, however, regulate hydrolysis of natural peptides/proteins. Lys-pNA was hydrolyzed 2 to 3-fold more rapidly than Leu-pNA and ~8-fold faster than Arg- or Met-pNA, indicating that Lys-pNA was the preferred substrate.