Vitamin D ameliorates stress ligand expression elicited by free fatty acids in the hepatic stellate cell line LX-2


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Seydel S., Beilfuss A., Kahraman A., Aksoy K. , Gerken G., AKKIZ H. , et al.

TURKISH JOURNAL OF GASTROENTEROLOGY, cilt.22, ss.400-407, 2011 (SCI İndekslerine Giren Dergi) identifier identifier identifier

  • Cilt numarası: 22 Konu: 4
  • Basım Tarihi: 2011
  • Doi Numarası: 10.4318/tjg.2011.0254
  • Dergi Adı: TURKISH JOURNAL OF GASTROENTEROLOGY
  • Sayfa Sayısı: ss.400-407

Özet

Amaç: Hepatik stellat hücreleri karaci¤er fibrozisinin ilerlemesinde fibriller ve fibril olmayan matriks proteinlerin major kayna¤› olarak önemli rol oynamaktad›r. Naturel killer hücreler hepatik stellat hücrelerin yok edilmesinde anti fibrotik bir etkiye sahiptir. Major histokompatibilite s›n›f I zincir ba¤lant›l› molekül, MICA ve MICB, NKG2D’nin reseptörünün ligand› olarak fonksiyon görmektedir ve hepatik inflamasyon s›ras›nda natürel killer hücrelerinin hepatik stellat hücre duyarl›l›¤›nda önemli bir rol oynamaktad›r. Bu çal›flman›n amac› LX-2 hücrelerinde ve insan primer hepatik stellat hücrelerinde vitamin D2 ve serbest ya¤ asidinin stres ligandlar› ve profibrotik aktivite üzerine olan etkilerini araflt›rmakt›r.Yöntem: LX-2 ve primer insan hepatik stellat hücreleri 24 saat boyunca farkl› konsantrasyonlarda (0,25 mM, 0,5 mM ve 1 mM) serbest ya¤ asidi ve vitamin D ile tedavi edildi ve kantitatif Real Time PCR cihaz› ile stres liganlar› (MICA ve MICB) ve TGF-β, α-SMA, COL1α’nin ekspresyonu de¤erlendirildi. Bulgular: LX-2 hücrelerinde 0.5 mM ve 1 mM serbest ya¤ asidi ile hücrelerin tedavisi sonucunda α-SMA ve TGF-ß’n›n ekspresyonunun indüklendi¤i, ilginç olarak, serbest ya¤ asidinin eklenmesinden sonra COL1α’n›n ekspresyonunun azald›¤›, primer hepatik stlellat hücrelerde MICA/B’nin ekspresyonunun serbest ya¤ asidi tedavisinden etkilenmedi¤i bulunmufltur. LX-2 hücrelerinde vitamin D2 tedavisi serbest ya¤ asidi ile indüklenen TGF-α ve α-SMA’n›n ekspresyonunu downregüle etmifltir. Yani, hepatik stellat hücrelerinde serbest ya¤ asidi tedavisinden ba¤›ms›z olarak vitamin D2 taraf›ndan MICA/B’nin mRNA’s›n›n önemli düzeyde azald›¤› saptanm›flt›r. Sonuç: Bu sonuçlar in vitro ortamda vitamin D2’nin hepatik stellat hücrelerinin inflamatuvar ve profibrogenik aktivitesini azaltabildi¤ini göstermektedir.

Anahtar kelimeler: Hepatik stellat hücreleri, NKG2D ligand›, MICA/B, vitamin D2

Background/aims: Hepatic stellate cells play an important role as the major source of fibrillar and non-fibrillar matrix proteins in the process of liver fibrosis. Natural killer cells have an anti-fibrotic effect through the killing of activated hepatic stellate cells. Major histocompatibility complex class I-related molecules, MICA and MICB, function as ligands for the NKG2D receptor and play an important role in hepatic stellate cells susceptibility to natural killer cells during hepatic inflammation. The aim of this study was therefore to investigate the effect of vitamin D2 and free fatty acids on stress ligands and pro-fibrotic activity in LX-2 cells and human primary hepatic stellate cells. Methods: LX-2 cells and primary human hepatic stellate cells were treated with vitamin D2 (10-6 M) and free fatty acids at different concentrations (0.25 mM, 0.5 mM, and 1 mM) for 24 hours, and expressions of the stress ligands MICA/B as well as of transforming growth factor-β, α-smooth muscle actin and collagen 1α were assessed by quantitative real time-polymerase chain reaction. Results: Treatment of cells with 0.5 mM and 1 mM free fatty acids induced α-smooth muscle actin and transforming growth factor-β expression in LX-2 cells. Moreover, 1 mM free fatty acids resulted in increased expression of MICA. Surprisingly, collagen 1α expression was reduced after addition of free fatty acids. MICA/B expression in primary hepatic stellate cells was not affected by free fatty acids treatment. Vitamin D2 treatment significantly downregulated the free fatty acids-induced expression of transforming growth factor-β and α-smooth muscle actin in LX-2 cells. Further, in hepatic stellate cells, a significant decrease in MICA/B mRNA with vitamin D2, independent of free fatty acids treatment, was detectable. Conclusions: These results indicate that vitamin D2 may reduce inflammatory and pro-fibrogenic activity of stellate cells in vitro.

Key words: Hepatic stellate cells, NKG2D ligand, MICA/B, vitamin D2