Arnica montana Stimulates Extracellular Matrix Gene Expression in a Macrophage Cell Line Differentiated to Wound-Healing Phenotype

Abstract

Arnica montana (Arnica m.) is used for its purported anti-inflammatory and tissue healing actions after trauma, bruises, or tissue injuries, but its cellular and molecular mechanisms are largely unknown. This work tested Arnica m. effects on gene expression using an in vitro model of macrophages polarized towards a “wound-healing” phenotype. The monocyte-macrophage human THP-1 cell line was cultured and differentiated with phorbol-myristate acetate and Interleukin-4, then exposed for 24h to Arnica m. centesimal (c) dilutions 2c, 3c, 5c, 9c, 15c or Control. Total RNA was isolated and cDNA libraries were sequenced with a NextSeq500 sequencer. Genes with significantly positive (up-regulated) or negative (down-regulated) fold changes were defined as differentially expressed genes (DEGs). A total of 20 DEGs were identified in Arnica m. 2c treated cells. Of these, 7 genes were up-regulated and 13 were down-regulated. The most significantly up-regulated function concerned 4 genes with a conserved site of epidermal growth factor-like region (p<0.001) and three genes of proteinaceous extracellular matrix, including heparin sulphate proteoglycan 2 (HSPG2), fibrillin 2 (FBN2), and fibronectin (FN1) (p<0.01). Protein assay confirmed a statistically significant increase of fibronectin production (p<0.05). The down-regulated transcripts derived from mitochondrial genes coding for some components of electron transport chain. The same groups of genes were also regulated by increasing dilutions of Arnica m. (3c, 5c, 9c, 15c), although with a lower effect size. We further tested the healing potential of Arnica m. 2c in a scratch model of wound closure based on the motility of bone marrow-derived macrophages and found evidence of an accelerating effect on cell migration in this system. The results of this work, taken together, provide new insights into the action of Arnica m. in tissue healing and repair, and identify extracellular matrix regulation by macrophages as a therapeutic target.

Comparative analysis of PVA hydrogels incorporating two natural antimicrobials: Punica granatum and Arnica montana tinctures

“…Arnica ( A. montana ) is an herbaceous perennial plant from Europe which is cultivated in several places, that is, USA, and it has been used in wound treatment since the 16th century due to its anti‐inflammatory, antimicrobial, and healing properties . The active compounds in Arnica are sesquiterpene lactones, thymol derivatives, flavonoids, acid polysaccharides, and their glycol conjugates and the effective anti‐inflammatory compounds are helenalin and sesquiterpene lactones . Arnica gel has been effective in Wistar rats' wound healing and Arnica‐Stinging nettle extract accelerated human wound healing …”

Fibronectin Gene Up-regulation by Arnica montana in Human Macrophages: Validation by Real-Time Polymerase Chain Reaction Assay

“…Fibrillin 2 and MACF1 genes were slightly stimulated, but the absolute values of MNE were very low and the changes were not statistically significant. CR1 gene was omitted from the RT-qPCR analysis because in RNA-seq results 12 its expression level was extremely low (between 1 and 2.5 reads per kilobase million).…”

“…[1][2][3][4] Investigations of its mechanisms of action have focused on inflammatory pathways, [5][6][7][8][9][10][11] but little is known about its possible action on the stages of tissue formation and renovation. In our laboratory, [11][12][13][14] we used the THP-1 human cell line, commonly employed to explore the function and regulation of monocytes and macrophages, 15 which are involved in inflammation and wound healing. 16 One of these articles 12 was recently retracted by the journal PlosONE due to criticisms raised about the concentration of Arnica m. used in the experiments and about the purported small gene expression changes.…”

“…The previous RNA-seq analysis 12 highlighted some genes whose expression had increased when cells were incubated with Arnica m. 2c: low-density lipoprotein-receptor-related protein 1 (LRP1), fibronectin 1 (FN1), lysine (K)-specific methyltransferase (KMT2D), complement component receptor 1 (CR1), heparan sulphate proteoglycan (perlecan, HSPG2), microtubule-actin crosslinking factor 1 (MACF1) and fibrillin 2 (FBN2). Notably, the most enriched function was the 'extracellular matrix organization', which included four genes, namely FN1, LRP1, FBN2 and HSPG2.…”

Treatment of Postoperative Sore Throat With the Aid of the Homeopathic Remedy Arnica montana: A Report of Two Cases

“…5 Recent research has shown the effectiveness of Arnica montana given in homeopathic potencies in many clinical conditions, 6 and also in the gene expression. 7 …”