umu.sePublications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Human tenocytes are stimulated to proliferate by acetylcholine through an EGFR signalling pathway
Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences.
Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
Vancouver Coastal Health and Research Institute.
Show others and affiliations
2013 (English)In: Cell and Tissue Research, ISSN 0302-766X, E-ISSN 1432-0878, Vol. 351, no 3, 465-475 p.Article in journal (Refereed) Published
Abstract [en]

Studies of human patellar and Achilles tendons have shown that primary tendon fibroblasts (tenocytes) not only have the capacity to produce acetylcholine (ACh) but also express muscarinic ACh receptors (mAChRs) through which ACh can exert its effects. In patients with tendinopathy (chronic tendon pain) with tendinosis, the tendon tissue is characterised by hypercellularity and angiogenesis, both of which might be influenced by ACh. In this study, we have tested the hypothesis that ACh increases the proliferation rate of tenocytes through mAChR stimulation and have examined whether this mechanism operates via the extracellular activation of the epidermal growth factor receptor (EGFR), as shown in other fibroblastic cells. By use of primary human tendon cell cultures, we identified cells expressing vimentin, tenomodulin and scleraxis and found that these cells also contained enzymes related to ACh synthesis and release (choline acetyltransferase and vesicular acetylcholine transporter). The cells furthermore expressed mAChRs of several subtypes. Exogenously administered ACh stimulated proliferation and increased the viability of tenocytes in vitro. When the cells were exposed to atropine (an mAChR antagonist) or the EGFR inhibitor AG1478, the proliferative effect of ACh decreased. Western blot revealed increased phosphorylation, after ACh stimulation, for both EGFR and the extracellular-signal-regulated kinases 1 and 2. Given that tenocytes have been shown to produce ACh and express mAChRs, this study provides evidence of a possible autocrine loop that might contribute to the hypercellularity seen in tendinosis tendon tissue.

Place, publisher, year, edition, pages
Springer-Verlag New York, 2013. Vol. 351, no 3, 465-475 p.
Keyword [en]
Muscarinic acetylcholine receptors, Tendinopathy, Tendinosis, Choline acetyltransferase, Vesicular acetylcholine transporter, Atropine, Non-neuronal acetylcholine, Human
National Category
Surgery
Identifiers
URN: urn:nbn:se:umu:diva-67794DOI: 10.1007/s00441-012-1530-5ISI: 000315490400011OAI: oai:DiVA.org:umu-67794DiVA: diva2:614227
Available from: 2013-04-05 Created: 2013-04-03 Last updated: 2017-12-06Bibliographically approved
In thesis
1. Influence of neuromodulators and mechanical loading on pathological cell and tissue characteristics in tendinosis
Open this publication in new window or tab >>Influence of neuromodulators and mechanical loading on pathological cell and tissue characteristics in tendinosis
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Betydelsen av neuromodulatorer och mekanisk belastning för cell- och vävnadsförändringar vid tendinos
Abstract [en]

Background: Tendinosis is a painful chronic, degenerative condition characterized by objective changes in the tissue structure of a tendon. Hallmark features in tendinosis tendons include increased number of cells (hypercellularity), extracellular matrix (ECM) degradation and disorganized collagen. The progression of these pathological changes seen in tendinosis is neither well characterized nor fully understood.

Studies have suggested that there are biochemical and mechanical elements involved in tendinosis. From a biochemical perspective, studies have shown that the tendon cells, tenocytes, produce a number of neuronal signal substances/neuromodulators, such as substance P (SP) and acetylcholine (ACh), traditionally thought to be confined to the nervous system. Furthermore, it has been shown that the expression of these neuromodulators is elevated in tendinosis tendons as compared to normal healthy tendons. Interestingly, studies on other tissue types have revealed that both SP and ACh can induce tissue changes seen in tendinosis, such as hypercellularity and collagen disorganization. From a mechanical angle, it has been suggested that overload of tendons, including extensive strain on the primary tendon cells (tenocytes), causes the degenerative processes associated with tendinosis. In vivo studies have shown that in overloaded tendons, the presence of neuromodulators is elevated, not least SP, which also precedes the development of the tissue changes seen in tendinosis. This further supports the importance of combining biochemical factors and mechanical factors in the pathogenesis of tendinosis.

Hypotheses: In this thesis project, we hypothesize: 1) that neuromodulators, such as SP and ACh when stimulating their preferred receptors, the neurokinin 1 (NK-1 R) and muscarinic receptors (mAChRs), respectively, can cause increased tenocyte proliferation; 2) that the effects of SP and ACh on tenocyte proliferation converge mechanistically via a shared signalling pathway; 3) that mechanical loading of tenocytes results in increased production of SP by the tenocytes; and 4) that SP enhances collagen remodelling by tenocytes via NK-1 R.

Model system: In vitro studies offer insight into the function of healthy tendon matrix and the etiology of tendinopathy. Using a cell culture model of human primary tendon cells, highly controlled experiments were performed in this thesis project to study a subset of biological and mechanical parameters that are implicated in tendinosis. The FlexCell® Tension System was used to study the influence of mechanical loading on tenocytes. As well, a collagen gel contraction assay was used to examine the intrinsic ability of tenocytes to reorganise type I collagen matrices under the influence of the neuromodulator SP.

Results: The studies showed that exogenous administration of SP and ACh results in increased tenocyte proliferation that is mediated via activation of the ERK1/2 mitogenic pathway when the preferred receptors of SP and ACh, the NK-1 R and mAChRs, respectively, are stimulated. Furthermore, the studies resulted in the novel finding that SP and ACh both converge mechanistically via transforming growth factor (TGF)-β1 and that a negative feedback mechanism is present in which TGF-β1 downregulates the expression of mAChRs and NK-1 R. The studies also showed that SP can increase collagen remodelling and upregulate expression of genes related to tendinosis. Finally, it was established that tenocytes are mechanoresponsive by showing that cyclic mechanical loading increases the expression of SP by human tenocytes.

Conclusions: This thesis work concludes that stimulation of NK-1 R and mAChRs results in proliferation of human tenocytes, which both involve the ERK1/2 signalling pathway. It also shows that SP and ACh converge mechanistically via TGF-β1 in their contribution to tenocyte proliferation. The role of hypercellularity in tendinosis tissue is unknown. Possibly, it has different roles at different stages of the disease. The findings also show that SP increases collagen remodelling, suggesting that increased SP not only results in hypercellularity but also contributes to the collagen morphology in tendinosis.

Place, publisher, year, edition, pages
Umeå: Umeå universitet, 2017. 60 p.
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 1882
Keyword
substance P, acetylcholine, transforming growth factor, neuromodulators, mechanical loading, tendinosis
National Category
Cell and Molecular Biology
Research subject
Human Anatomy
Identifiers
urn:nbn:se:umu:diva-131390 (URN)978-91-7601-666-4 (ISBN)
Public defence
2017-03-10, KBC-huset, sal KB.E3.01, Umeå universitet, Umeå, 13:00 (English)
Opponent
Supervisors
Funder
Swedish Research Council, 521-2013-2612Swedish Society of Medicine, SLS-504541Swedish National Centre for Research in Sports, P2013-0055
Available from: 2017-02-17 Created: 2017-02-13 Last updated: 2017-03-16Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Fong, GloriaBackman, LudvigAndersson, GustavDanielson, Patrik
By organisation
AnatomyDepartment of Surgical and Perioperative Sciences
In the same journal
Cell and Tissue Research
Surgery

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 270 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf