Editorial: Multiplex Immunohistochemistry/Immunofluorescence Technique: The Potential and Promise for Clinical Application

Abstract

Conventional immunohistochemistry (IHC) has long been regarded as the "gold standard" for the diagnosis of tissue pathology. However, the diagnostic-prognostic value of this technique is limited by factors such as high inter-observer variability, restricted labeling potential and insufficient availability of samples for testing (Tan et al., 2020). However, the emergence of multiplex immunohistochemistry/immunofluorescence (mIHC/IF) techniques has provided an opportunity to overcome many of these challenges. These techniques facilitate investigation of multiple biomarkers on a single slide as well as exploration of tissue-level biology, classification of cell-cell interactions, and identification of rare cellular phenotypes. mIHC/IF is also a powerful supplement to technologies such as next generation sequencing. As such, mIHC/IF holds the potential to revolutionize cancer therapies and diagnostic pathology (Tan et al., 2020; Hernandez et al.; Lazcano et al.; Parra). In this special edition of Frontiers in Molecular Biosciences we review the importance and clinical translational potential of mIHC/IF.The COVID-19 pandemic has resulted in an urgent need to understand the implications of myocardial involvement in disease mortality, necessitating detection of viral components within tissue samples. Chong et al., used a combination of mIHC/IF and molecular techniques to examine cardiac autopsy specimens from 12 intensive care unit (ICU) naïve, SARS-CoV-2 PCR-positive patients. These novel findings revealed histopathologic changes in coronary vessels, as well as inflammation of the myocardium in these patients. This study provided crucial insights into the characteristics of COVID-19 patients at risk of sudden death, and suggested the possibility of longterm complications in patients with persistent virus (Chong et al.).As well as detecting viral particles within tissue samples, mIHC/IF can be used to explore the tumour immune microenvironment (TIME). Through the development of a multiplex panel for the identification of proliferating B cells, follicular helper T cells, and follicular regulatory T cells, Boisson et al., demonstrated the power of mIHC/IF for studying marker co-localization in

The promise and challenge of spatial omics in dissecting tumour microenvironment and the role of AI

“…Secondly, consistent and quality data is a prerequisite for clinical translation. Several taskforces, such as the Society for Immunotherapy of Cancer ( 132 ) and the Joint Effort to Develop Multiplex Immunofluorescence Standards ( 133 ), gather international efforts to standardize the workflow of OPAL-based assays, with similar efforts needed for other spatial omics techniques. Thirdly, existing computational tools often require extensive user inputs, such as number of clusters or neighbors, and distance threshold, which hinders adoption.…”

Preclinical Models and Emerging Technologies to Study the Effects of the Tumor Microenvironment on Cancer Heterogeneity and Drug Resistance

“…Chemo-and biosensors can be integrated in this type of models to optimize the control of oxygen and metabolites levels (131). 3D bioprinting techniques can also be used to develop preclinical models fully recapitulating the architecture of parental tumors, including a functional vascular system and enabling a uniform distribution of different cellular components (132,133). This approach consists in the controlled deposition of layers of patient-derived cancer and stromal cells, signalling molecules and other biomaterials to generate spheroids or organoids with a functional TME.…”

“…However, it is important to remember that current in vitro 3D models do not have the ability to fully replace rodent models, as their complexity is highly limited by the amount of different cell types able to co-exist in the same matrix, as well as by their simplified architecture that can only partially mimic a real tissue unit. Moreover, off target cytotoxicity cannot be easily tested with 3D models as it would require the development of bodies-on-a-chip [the reader can refer to these reviews for more information about these systems (132,133)] that are extremely challenging to develop and run. At the same time, even though this and other reviews describe in length the advantages of testing drug compounds in 3D systems, it is worth noting that these models are still thought to be complicated and costly, making them less attractive than 2D monocultures in a high-throughput context (134).…”

“…Single-cell profiling of tumor heterogeneity and the microenvironment has been done in many cancer types and metastasis (133) including advanced non-small cell lung cancer, triple-negative breast cancer (TNBC) primary tumor, and paired lymph nodes (134).…”

“…To this concern, mammospheres derived from freshly isolated BC samples exhibit CSC-like properties and multiple drug resistances (132). L. Hamm and coworkers established a high throughput tumor spheroid microprinting technology to produce homogeneouslysized spheroids to model the interaction of CAFs and TNBC cells and examine drug resistance (133). In another work, the 3D bioprint technology was leveraged to manufacture a 3D structure containing BC cells in the core and adipose-derived mesenchymal stem/stromal cells (ADMSCs) in the edges.…”