Mesenchymal cell proliferation and excessive extracellular matrix deposition are the key features of Keloid lesions.

Microarray analyses demonstrating the mechanism of keloid development are available, but there are fewer data about the molecular pathology that contributes to keloid development.

A study by Asai M. et al explores the underlying essential molecules of keloids using microarrays. They performed microarray analyses of keloid and non-lesional skin tissues both in vivo and in vitro and compared Gene expression levels between tissues and cells.  the expression levels of molecules of interest in keloid tissues were determined utilizing Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and immunopathological staining.

They found-

• Upregulation of numerous common molecules in both keloid tissues and keloid-lesional fibroblasts.
• Upregulation of PTPRD and NTM were found both in vivo and in vitro.
• MDFI and ITGA4 occupied the central portion of the gene co-expression network analysis using keloid tissues.
• significant expression levels of PTPRD and MDFI in keloid tissues were demonstrated by qRT-PCR.
• MDFI-positive cells, which have fibroblast characteristics, occupying a place in the keloid-associated lymphoid tissue (KALT) portion of the keloid tissue were demonstrated in Immunopathological staining.

Thus they concluded by mentioning that gene expression profiles of keloids distinguished the difference between lesional tissue and cultured lesional fibroblasts. MDFI was found to be commonly expressed in both tissues and cells. 

Finally, they advocated the importance of MDFI-positive cells, located in the KALT, in in-vitro keloid studies and keloid pathogenesis.

Source: Asai M, Koike Y, Kuwatsuka Y, Yagi Y, Kashiyama K, Tanaka K, Mishima H, Yoshiura K, Utani A, Murota H. Multifaceted array-based keloidal gene expression profiling reveals specific MDFI upregulation in keloid lesions. Clin Exp Dermatol. 2021 Apr 26. doi: 10.1111/ced.14698. Epub ahead of print. PMID: 33899950.