mesenchymal-stem-cell-regulation-macrophage-phagocytosis-quantitation

Mesenchymal Stem Cell Regulation of Macrophage Phagocytosis; Quantitation and Imaging

Mesenchymal stem cells (MSC) have traditionally been studied for their regenerative properties, but more recently, their immunoregulatory characteristics ...

Molloy College

Adrenocorticotropic hormone (ACTH) is among several melanocortin peptide hormones that are derived from proopiomelanocortin (POMC). ACTH has been found to enhance osteogenesis and chondrogenesis. We show that, in the presence of dexamethasone, ACTH dose-dependently increases chondrogenic nodule formation in bone marrow stromal cells (BMSC) from the Wistar Kyoto (WKY) rat. The nodules consist in condensed cells highly expressing alkaline phosphatase, Sox9 and type II collagen transcripts and a proteoglycan-rich matrix. Immunoblot analysis of crude membrane fractions has shown that these cells express three melanocortin receptors (MC-R), namely MC2-R, MC3-R and MC5-R and the melanocortin 2-receptor accessory protein (MRAP). To determine which of these receptors mediate ACTH-induced effects, we have used MC-R-specific peptides and the known agonist profiles of the receptors. Neither α-MSH, a strong agonist of MC5-R, nor γ2-MSH, a strong agonist of MC3-R, duplicates ACTH effects in rat BMSC. In addition, calcium flux has been examined as a mechanism for ACTH action at the MC2-R. Consistent with MC2-R and MRAP expression patterns in the BMSC cultures, ACTH-induced transient increases in intracellular calcium are increased with dexamethasone treatment. Neither α-MSH nor γ2-MSH affects calcium flux. Dexamethasone increases MC2-R and MRAP expression and POMC peptide expression and cleavage increasing the production of the lipolytic β-lipotropic hormone product. Therefore, the effects of ACTH in rat BMSC enriched for mesenchymal progenitors are consistent with an MC2-R signaling mechanism, with dexamethasone being capable of regulating components of the melanocortin system in these cells.

ACTH promotes chondrogenic nodule formation and induces transient elevations in intracellular calcium in rat bone marrow cell cultures via MC2-R signaling.

Mesenchymal progenitor cells interact with immune cells and modulate inflammatory responses. The cellular characteristics required for this modulation are under fervent investigation. Upon interaction with macrophage cells, they can contribute to or suppress an inflammatory response. Current studies have focused on mesenchymal progenitors derived from bone marrow, adipose, and placenta. However, the arterial wall contains many mesenchymal progenitor cells, which during vascular disease progression have the potential to interact with macrophage cells. To examine the consequence of vascular-tissue progenitor cell-macrophage cell interactions in an inflammatory environment, we used a recently established mesenchymal progenitor cell line derived from the mouse aorta.

Mouse aorta-derived mesenchymal progenitor cells contribute to and enhance the immune response of macrophage cells under inflammatory conditions.

Mesenchymal progenitor cell characteristics that can identify progenitor populations with specific functions in immunity are actively being investigated. Progenitors from bone marrow and adipose tissue regulate the macrophage (MΦ) inflammatory response by promoting the switch from an inflammatory to an anti-inflammatory phenotype. Conversely, mesenchymal progenitors from the mouse aorta (mAo) support and contribute to the MΦ response under inflammatory conditions. We used cell lines with purported opposing immune-regulatory function, a bone marrow derived mesenchymal progenitor cell line (D1) and a mouse aorta derived mesenchymal progenitor cell line (mAo). Their interaction and regulation of the MΦ cell response to the inflammatory mediator, lipopolysaccharide (LPS), was examined by coculture. As expected, D1 cells suppressed NO, TNF-, and IL-12p70 production but MΦ phagocytic activity remained unchanged. The mAo cells enhanced NO and TNF- production in coculture and enhanced MΦ phagocytic activity. Using flow cytometry and PCR array, we then sought to identify sets of MSC-associated genes and markers that are expressed by these progenitor populations. We have determined that immune-supportive mesenchymal progenitors highly express chondrogenic and tenogenic transcription factors while immunosuppressive mesenchymal progenitors highly express adipogenic and osteogenic transcription factors. These data will be useful for the isolation, purification, and modification of mesenchymal progenitors to be used in the treatment of inflammatory diseases.

Mouse Mesenchymal Progenitor Cells Expressing Adipogenic and Osteogenic Transcription Factors Suppress the Macrophage Inflammatory Response.

[This corrects the article DOI: 10.1155/2017/5846257.].

Corrigendum to "Mouse Mesenchymal Progenitor Cells Expressing Adipogenic and Osteogenic Transcription Factors Suppress the Macrophage Inflammatory Response".

Jodi F. Evans

Molloy College

Mesenchymal Stem Cell Regulation of Macrophage Phagocytosis; Quantitation and Imaging