Change search
ReferencesLink to record
Permanent link

Direct link
Akt-mediated anti-apoptotic effects of substance P in Anti-Fas-induced apoptosis of human tenocytes
Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Sports Medicine.
Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
2013 (English)In: Journal of Cellular and Molecular Medicine (Print), ISSN 1582-1838, Vol. 17, no 6, 723-733 p.Article in journal (Refereed) Published
Abstract [en]

Substance P (SP) and its receptor, the neurokinin-1 receptor (NK-1 R), are expressed by human tenocytes, and they are both up-regulated incases of tendinosis, a condition associated with excessive apoptosis. It is known that SP can phosphorylate/activate the protein kinase Akt,which has anti-apoptotic effects. This mechanism has not been studied for tenocytes. The aims of this study were to investigate if Anti-Fastreatment is a good apoptosis model for human tenocytes in vitro, if SP protects from Anti-Fas-induced apoptosis, and by which mechanismsSP mediates an anti-apoptotic response. Anti-Fas treatment resulted in a time- and dose-dependent release of lactate dehydrogenase (LDH), i.e.induction of cell death, and SP dose-dependently reduced the Anti-Fas-induced cell death through a NK-1 R specific pathway. The same trendwas seen for the TUNEL assay, i.e. SP reduced Anti-Fas-induced apoptosis via NK-1 R. In addition, it was shown that SP reduces Anti-Fas-induced decrease in cell viability as shown with crystal violet assay. Protein analysis using Western blot confirmed that Anti-Fas inducescleavage/activation of caspase-3 and cleavage of PARP; both of which were inhibited by SP via NK-1 R. Finally, SP treatment resulted in phosphorylation/activation of Akt as shown with Western blot, and it was confirmed that the anti-apoptotic effect of SP was, at least partly, inducedthrough the Akt-dependent pathway. In conclusion, we show that SP reduces Anti-Fas-induced apoptosis in human tenocytes and that this antiapoptoticeffect of SP is mediated through NK-1 R and Akt-specific pathways.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2013. Vol. 17, no 6, 723-733 p.
Keyword [en]
tendinopathy, tendinosis, Neurokinin-1 Receptor, cell death, tachykinin, caspase-3, PARP, tendon cells
National Category
Cell and Molecular Biology
URN: urn:nbn:se:umu:diva-70190DOI: 10.1111/jcmm.12059ISI: 000320779100004OAI: diva2:619896
Available from: 2013-05-07 Created: 2013-05-07 Last updated: 2013-07-29Bibliographically approved
In thesis
1. Neuropeptide and catecholamine effects on tenocytes in tendinosis development: studies on two model systems with focus on proliferation and apoptosis
Open this publication in new window or tab >>Neuropeptide and catecholamine effects on tenocytes in tendinosis development: studies on two model systems with focus on proliferation and apoptosis
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Background: Achilles tendinopathy is a common clinical syndrome of chronic Achilles tendon pain combined with thickening of the tendon and impaired tendon function. Tendinopathy is often, but not always, induced by mechanical overload, and is frequently accompanied by abnormalities at the tissue level, such as hypercellularity and angiogenesis, in which case the condition is called tendinosis. In tendinosis, there are no signs of intratendinous inflammation, but occasionally increased apoptosis is observed. Tendinosis is often hard to treat and its pathogenesis is still not clear. Recently, a new hypothesis has gained support, suggesting a biochemical model based on the presence of a non-neuronal production of classically neuronal signal substances by the primary tendon cells (tenocytes) in tendinosis. The possible functional importance of these signal substances in tendons is unknown and needs to be studied. In particular, the neuropeptide substance P (SP) and catecholamines are of interest in this regard, since these substances have been found to be up-regulated in tendinosis. As both SP and catecholamines are known to exert effects in other tissues resulting in changes similar to those characteristic of tendinosis, it is possible that they have a role in tendinosis development. It is furthermore unknown what elicits the increased intratendinous neuropeptide production in tendinosis, but given that tendon overload is a prominent riskfactor, it is possible that mechanical stimuli are involved.

The hypothesis of this thesis work was that intratendinous production of SP is up-regulated in response to load of Achilles tendons/tenocytes, and thatstimulation of the preferred SP receptor, the neurokinin-1 receptor (NK-1 R), aswell as stimulation of the catecholamine α2 adrenoreceptors, contribute to the hypercellularity seen in tendinosis, via increased proliferation and/or decreased apoptosis, and that SP stimulates tendon angiogenesis. The purpose of the studies was to test this hypothesis. To achieve this, two model systems were used: One in vivo (rabbit Achilles tendon overload model of tendinosis) and one in vitro (human primary Achilles tendon cell culture model).

Results: In the rabbit Achilles tendon tissue, SP and NK-1 R expression was extensive in the blood vessel walls, but also to some extent seen in the tenocytes. Quantification of endogenously produced SP in vivo confirmed intratendinous production of the peptide. The production of SP by human tendon cells in vitro was furthermore demonstrated. The catecholamine synthesizing enzyme tyrosine hydroxylase (TH), as well as the α2A adrenoreceptor (α2A AR), were detected in the tenocytes, both in vivo in the rabbit tissue and in vitro in the human tendon cells. As a response to mechanical loading in the in vivo model, the intratendinous levels of SP increased, and this elevation was found to precede distinct tendinosis changes. The in vitro model demonstrated the same response to load, i.e. an increased SP expression, but in this case also a decrease in the NK-1 R expression. In the in vivo model, exogenously administered SP, as well as clonidine (an α2 AR agonist), accelerated tenocyte hypercellularity, an effect that was not seen when administrating a specific α2A AR antagonist. Exogenous administration of SP also resulted in intratendinous angiogenesis and paratendinous inflammation. In the in vitro model, both SP and clonidine had proliferative effects on the human tenocytes, specifically mediated via NK-1R and α2A AR, respectively; both of which in turn involved activation/phosphorylation of the extracellular signal-regulated kinases 1 and 2 (ERK1/2). Exogenously administered SP, in Anti-Fas induced apoptosis of the tenocytes in vitro, confirmed SP to have an anti-apoptotic effect on these cells. This effect was specifically mediated via NK-1 R and the known anti-apoptotic Akt pathway.

Conclusions: In summary, this thesis concludes that stimulation of NK-1 R and α2A AR on tenocytes, both in vitro and in vivo, mediates significant cell signalling effects leading to processes known to occur in tendinosis, including hypercellularity. The pathological role of the hypercellularity in tendinosis is still unclear, but it is likely to affect collagen metabolism/turnover and arrangement, and thereby indirectly tendon biomechanical function. Additional evidence is here provided showing that SP not only causes tenocyte proliferation, but also contributes to anti-apoptotic events. Furthermore, it was concluded that SP may be involved in the development of tendinosis, since its production is increased in response to load, preceding tendinosis, and since SP accelerates tendinosis changes, through some mechanistic pathways here delineated. These findings suggest that inhibition of SP, and possibly also catecholamines, could be beneficial in the reconstitution/normalization of tendon structure in tendinosis.

Place, publisher, year, edition, pages
Umeå: Umeå Universitet, 2013. 80 p.
Umeå University medical dissertations, ISSN 0346-6612 ; 1572
substance P, neurotransmitter, tendinopathy, overuse injury, rabbit, tendon cell, Achilles tendon
National Category
Cell and Molecular Biology
urn:nbn:se:umu:diva-70193 (URN)978-91-7459-633-5 (Print) (ISBN)978-91-7459-634-2 (PDF) (ISBN)
Public defence
2013-06-05, sal BiA201, Biologihuset, Umeå universitet, Umeå, 09:00 (English)
Available from: 2013-05-15 Created: 2013-05-07 Last updated: 2013-05-15Bibliographically approved

Open Access in DiVA

fulltext(477 kB)193 downloads
File information
File name FULLTEXT02.pdfFile size 477 kBChecksum SHA-512
Type fulltextMimetype application/pdf

Other links

Publisher's full text

Search in DiVA

By author/editor
Backman, Ludvig JDanielson, Patrik
By organisation
AnatomySports Medicine
In the same journal
Journal of Cellular and Molecular Medicine (Print)
Cell and Molecular Biology

Search outside of DiVA

GoogleGoogle Scholar
Total: 193 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 89 hits
ReferencesLink to record
Permanent link

Direct link