Interleukins 4 and 13 modulate gene expression and promote proliferation of primary human tenocytes

Abstract

BackgroundTendon disorders (tendinopathies) pose serious biomedical and socioeconomic problems. Despite diverse treatment approaches, the best treatment strategy remains unclear. Surgery remains the last resort because of the associated morbidity and inconsistent outcomes. We hypothesized that, similar to fibroblasts in various organs, tendon fibroblasts (tenocytes) might be responsive to stimulation with interleukins (ILs), particularly IL-4 and IL-13. These two cytokines share sequence homology, receptor chains and functional effects, including stimulation of fibrogenesis. It is unknown whether tenocytes are responsive to stimulation with IL-4 or IL-13. If true, local use of these cytokines might be used to facilitate tendon repair in patients with tendinopathies or used for tendon tissue-engineering approaches to facilitate tenocyte growth on scaffolds in culture.ResultsTendon tissues that would normally be discarded were obtained during reconstructive surgery procedures performed for clinical indications. Primary tenocytes were derived from Achilles, posterior tibial, flexor digitorum longus and flexor hallucis longus tendon tissue samples. Reverse transcriptase quantitative PCR (RT-qPCR) experiments revealed that mRNAs for the receptor (R) chains IL-4Rα, IL-13Rα1 and IL-13Rα2, but not the common γ-chain were present in all tested tendon tissues and in cultured tenocytes. Levels of IL-13R chain mRNAs were significantly higher than those of IL-4R mRNA. The cultures responded, in a dose-dependent fashion, to stimulation with recombinant human IL-4 or IL-13, by increasing proliferation rates 1.5 to 2.0-fold. The mRNA levels of 84 genes related to cell cycle regulation were measured by RT-qPCR after 6 h and 24 h of activation. The expression levels of several genes, notably CDK6 and CDKN2B changed more than twofold. In contrast to their effects on proliferation, stimulation with IL-4 or IL-13 had little if any effect on the levels of collagen mRNA or protein in cultured primary tenocytes. The mRNA levels of 84 other genes related to extracellular matrix and cell adhesion were also measured by RT-qPCR; expression of only five genes was consistently changed.ConclusionsStimulation with IL-4 or IL-13 could be used to facilitate tendon repair in vivo or to aid in tendon tissue engineering, through stimulation of tenocyte proliferation.

Is resection of the tendon edge necessary to enhance the healing process? An evaluation of the expression of collagen type I, IL-1β, IFN-γ, IL-4, and IL-13 in the distal 1 cm of a torn supraspinatus tendon: part II

“…The findings of part I 17 and part II of the study, together with the current knowledge concerning the influence of molecular factors on inflammatory and apoptotic processes, 1,2,12,[24][25][26]36,38,40 confirm the growing need for a proper understanding of their influence on rotator cuff healing. They demonstrate the need for further research on both these factors and the pharmacologic support that can be provided in the near future.…”

“…1 The ability of tenocytes to produce collagen is manifested in an observed rise of type I collagen expression 43 (Tables I and II) in the proximal direction. This is due to a combination of factors: a fall in the expression of pro-apoptotic molecules and the increase of antiapoptotic factors 17 ; the fall of TNF-a stimulating the extracellular apoptotic pathway 10,17,35 and the fall of IFN-g expression slowing the proliferation of tenocytes; and an increase of pro-proliferative IL-4, which also inhibits the anti-proliferative effect of IFN-g 1 and IL-13 12 (Tables I-III). Although the studies by Courneya et al 12 do not confirm increase in the production of type I collagen related to the influence of IL-4 and IL-13, 12 the results of part I 17 and the current findings appear to show that this effect may be expected in the case of a concurrent inhibition of apoptosis and inflammation, which was not included in the Courneya et al 12 tests.…”

“…All RNA samples used in the reverse transcription reaction were treated the same way: diluted to the same concentration and quality with an RNA integrity number value > 7. Polyadenylated RNA was isolated by an Oligotex kit (Qiagen, Chatsworth, CA, USA): 50 ng poly(A) RNA was used for the first-strand complementary DNA (cDNA) synthesis with the SuperScript II RNase Transcriptase System (Invitrogen, Life Technologies, Carlsbad, CA, USA), with oligo(dT) [12][13][14][15][16][17][18] primers according to the manufacturer's instructions.…”

“…Inhibitory interferon-g (IFN-g) and the stimulatory IL-4 and IL-13 are interleukins with the ability to influence tenocyte proliferation. 1,12 The available literature does not, however, discuss the influence of these cytokines and IL-1b on the expression of collagen type I along a 1-cm length of the damaged supraspinatus tendon in a proximal direction from the tear.…”

Outcomes of acute Achilles tendon rupture repair with bone marrow aspirate concentrate augmentation

“…Many mechanisms have been proposed regarding the role of BMAC in tendon healing. Cytokines from platelets produced by BMAC cells modulate the healing response by controlling inflammation, reducing fibrosis and recruiting other cells, including tenocytes and mesenchymal stem cells, as suggested by work demonstrating the ability of interleukins 4 and 13 to promote proliferation of the primary human tenocytes [24]. BMAC has previously been shown to contain hematopoietic and osteogenic growth factors, including vascular endothelial growth factor, platelet-derived growth factor and transforming growth factor beta [25].…”