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HIF-2α-induced chemokines stimulate motility of fibroblast-like synoviocytes and chondrocytes into the cartilage-pannus interface in experimental rheumatoid arthritis mouse models.

Huh YH, Lee G, Lee KB, Koh JT, Chun JS, Ryu JH - Arthritis Res. Ther. (2015)

Bottom Line: Expression patterns of HIF-2α and chemokines were determined via immunostaining, Western blotting and RT-PCR.HIF-2α induced chemokine expression by chondrocytes in both primary culture and cartilage tissue.HIF-2α -induced chemokines by chondrocytes regulated the migration and invasion of FLS.

View Article: PubMed Central - PubMed

Affiliation: BioImaging and Cell Dynamics Research Center, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju, 61005, Republic of Korea. yhuh@gist.ac.k.

ABSTRACT

Introduction: Pannus formation and resulting cartilage destruction during rheumatoid arthritis (RA) depends on the migration of synoviocytes to cartilage tissue. Here, we focused on the role of hypoxia-inducible factor (HIF)-2α-induced chemokines by chondrocytes in the regulation of fibroblast-like synoviocyte (FLS) migration into the cartilage-pannus interface and cartilage erosion.

Methods: Collagen-induced arthritis (CIA), K/BxN serum transfer, and tumor necrosis factor-α transgenic mice were used as experimental RA models. Expression patterns of HIF-2α and chemokines were determined via immunostaining, Western blotting and RT-PCR. FLS motility was evaluated using transwell migration and invasion assays. The specific role of HIF-2α was determined via local deletion of HIF-2α in joint tissues or using conditional knockout (KO) mice. Cartilage destruction, synovitis and pannus formation were assessed via histological analysis.

Results: HIF-2α and various chemokines were markedly upregulated in degenerating cartilage and pannus of RA joints. HIF-2α induced chemokine expression by chondrocytes in both primary culture and cartilage tissue. HIF-2α -induced chemokines by chondrocytes regulated the migration and invasion of FLS. Local deletion of HIF-2α in joint tissues inhibited pannus formation adjacent to cartilage tissue and cartilage destruction caused by K/BxN serum transfer. Furthermore, conditional knockout of HIF-2α in cartilage blocked pannus formation in adjacent cartilage but not bone tissue, along with inhibition of cartilage erosion caused by K/BxN serum transfer.

Conclusion: Our findings suggest that chemokines induced by IL-1β or HIF-2α in chondrocytes regulate pannus expansion by stimulating FLS migration and invasion, leading to cartilage erosion during RA pathogenesis.

No MeSH data available.


Related in: MedlinePlus

HIF-2α upregulates chemokine expression in RA cartilage tissue. a, b Empty virus (Ad-C) or Ad-Epas1 (1 × 109 plaque-forming unit ) was injected into mouse knee joints. Representative hematoxylin/safranin O-stained images in cartilage and pannus regions a. Results of RT-PCR and qRT-PCR analysis of the indicated genes in cartilage tissue b (n = 4). c, d Typical immunofluorescence microscopy images of DAPI, HIF-2α, CXCL1, CXCL2, and CCL5 in cartilage tissue of mice after IA injection with Ad-Epas1c or CIA d. Values presented as mean ± standard error of the mean (*P <0.01). Scale bar: 50 μm. C cartilage, CIA collagen-induced arthritis, DAPI 4′,6-diamidino-2-phenylindole, HIF hypoxia-inducible factor, P pannus
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Fig3: HIF-2α upregulates chemokine expression in RA cartilage tissue. a, b Empty virus (Ad-C) or Ad-Epas1 (1 × 109 plaque-forming unit ) was injected into mouse knee joints. Representative hematoxylin/safranin O-stained images in cartilage and pannus regions a. Results of RT-PCR and qRT-PCR analysis of the indicated genes in cartilage tissue b (n = 4). c, d Typical immunofluorescence microscopy images of DAPI, HIF-2α, CXCL1, CXCL2, and CCL5 in cartilage tissue of mice after IA injection with Ad-Epas1c or CIA d. Values presented as mean ± standard error of the mean (*P <0.01). Scale bar: 50 μm. C cartilage, CIA collagen-induced arthritis, DAPI 4′,6-diamidino-2-phenylindole, HIF hypoxia-inducible factor, P pannus

Mentions: Next, we examined whether HIF-2α regulates the expression of chemokines in mouse cartilage tissue. Consistent with previous findings [7], intra-articular (IA) injection of Ad-Epas1 promoted pannus formation (Fig. 3a). RT-PCR and qRT-PCR analyses of cartilage tissue revealed that HIF-2α induces a significant increase in mRNA levels of the chemokines examined (Fig. 3b). Furthermore, HIF-2α-overexpressing chondrocytes in cartilage tissue of mice IA injected with Ad-Epas1 showed increased levels of CXCL1, CXCL2, and CCL5 proteins, which co-localized with HIF-2α (Fig. 3c). Similarly, CXCL1, CXCL2, and CCL5 proteins were increased in HIF-2α-overexpressing chondrocytes in cartilage tissue of CIA mice and co-localized with HIF-2α (Fig. 3d). Our results collectively indicate that HIF-2α upregulates chemokines in both primary culture chondrocytes and cartilage tissue.Fig. 3


HIF-2α-induced chemokines stimulate motility of fibroblast-like synoviocytes and chondrocytes into the cartilage-pannus interface in experimental rheumatoid arthritis mouse models.

Huh YH, Lee G, Lee KB, Koh JT, Chun JS, Ryu JH - Arthritis Res. Ther. (2015)

HIF-2α upregulates chemokine expression in RA cartilage tissue. a, b Empty virus (Ad-C) or Ad-Epas1 (1 × 109 plaque-forming unit ) was injected into mouse knee joints. Representative hematoxylin/safranin O-stained images in cartilage and pannus regions a. Results of RT-PCR and qRT-PCR analysis of the indicated genes in cartilage tissue b (n = 4). c, d Typical immunofluorescence microscopy images of DAPI, HIF-2α, CXCL1, CXCL2, and CCL5 in cartilage tissue of mice after IA injection with Ad-Epas1c or CIA d. Values presented as mean ± standard error of the mean (*P <0.01). Scale bar: 50 μm. C cartilage, CIA collagen-induced arthritis, DAPI 4′,6-diamidino-2-phenylindole, HIF hypoxia-inducible factor, P pannus
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4625947&req=5

Fig3: HIF-2α upregulates chemokine expression in RA cartilage tissue. a, b Empty virus (Ad-C) or Ad-Epas1 (1 × 109 plaque-forming unit ) was injected into mouse knee joints. Representative hematoxylin/safranin O-stained images in cartilage and pannus regions a. Results of RT-PCR and qRT-PCR analysis of the indicated genes in cartilage tissue b (n = 4). c, d Typical immunofluorescence microscopy images of DAPI, HIF-2α, CXCL1, CXCL2, and CCL5 in cartilage tissue of mice after IA injection with Ad-Epas1c or CIA d. Values presented as mean ± standard error of the mean (*P <0.01). Scale bar: 50 μm. C cartilage, CIA collagen-induced arthritis, DAPI 4′,6-diamidino-2-phenylindole, HIF hypoxia-inducible factor, P pannus
Mentions: Next, we examined whether HIF-2α regulates the expression of chemokines in mouse cartilage tissue. Consistent with previous findings [7], intra-articular (IA) injection of Ad-Epas1 promoted pannus formation (Fig. 3a). RT-PCR and qRT-PCR analyses of cartilage tissue revealed that HIF-2α induces a significant increase in mRNA levels of the chemokines examined (Fig. 3b). Furthermore, HIF-2α-overexpressing chondrocytes in cartilage tissue of mice IA injected with Ad-Epas1 showed increased levels of CXCL1, CXCL2, and CCL5 proteins, which co-localized with HIF-2α (Fig. 3c). Similarly, CXCL1, CXCL2, and CCL5 proteins were increased in HIF-2α-overexpressing chondrocytes in cartilage tissue of CIA mice and co-localized with HIF-2α (Fig. 3d). Our results collectively indicate that HIF-2α upregulates chemokines in both primary culture chondrocytes and cartilage tissue.Fig. 3

Bottom Line: Expression patterns of HIF-2α and chemokines were determined via immunostaining, Western blotting and RT-PCR.HIF-2α induced chemokine expression by chondrocytes in both primary culture and cartilage tissue.HIF-2α -induced chemokines by chondrocytes regulated the migration and invasion of FLS.

View Article: PubMed Central - PubMed

Affiliation: BioImaging and Cell Dynamics Research Center, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju, 61005, Republic of Korea. yhuh@gist.ac.k.

ABSTRACT

Introduction: Pannus formation and resulting cartilage destruction during rheumatoid arthritis (RA) depends on the migration of synoviocytes to cartilage tissue. Here, we focused on the role of hypoxia-inducible factor (HIF)-2α-induced chemokines by chondrocytes in the regulation of fibroblast-like synoviocyte (FLS) migration into the cartilage-pannus interface and cartilage erosion.

Methods: Collagen-induced arthritis (CIA), K/BxN serum transfer, and tumor necrosis factor-α transgenic mice were used as experimental RA models. Expression patterns of HIF-2α and chemokines were determined via immunostaining, Western blotting and RT-PCR. FLS motility was evaluated using transwell migration and invasion assays. The specific role of HIF-2α was determined via local deletion of HIF-2α in joint tissues or using conditional knockout (KO) mice. Cartilage destruction, synovitis and pannus formation were assessed via histological analysis.

Results: HIF-2α and various chemokines were markedly upregulated in degenerating cartilage and pannus of RA joints. HIF-2α induced chemokine expression by chondrocytes in both primary culture and cartilage tissue. HIF-2α -induced chemokines by chondrocytes regulated the migration and invasion of FLS. Local deletion of HIF-2α in joint tissues inhibited pannus formation adjacent to cartilage tissue and cartilage destruction caused by K/BxN serum transfer. Furthermore, conditional knockout of HIF-2α in cartilage blocked pannus formation in adjacent cartilage but not bone tissue, along with inhibition of cartilage erosion caused by K/BxN serum transfer.

Conclusion: Our findings suggest that chemokines induced by IL-1β or HIF-2α in chondrocytes regulate pannus expansion by stimulating FLS migration and invasion, leading to cartilage erosion during RA pathogenesis.

No MeSH data available.


Related in: MedlinePlus