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Expression of adiponectin receptors in human and rat intervertebral disc cells and changes in receptor expression during disc degeneration using a rat tail temporary static compression model

View Article: PubMed Central - PubMed

ABSTRACT

Background: Adipose tissue is a large endocrine organ known to secret adiponectin, which has anti-diabetic, anti-atherogenic, and anti-inflammatory properties. Adiponectin is widely involved in systemic disease, diabetes mellitus, and cardiac infraction. This study aimed to investigate the involvement of adiponectin in intervertebral disc (IVD) degeneration.

Methods: Adipose and IVD tissues were obtained from human patients undergoing surgery (n = 4) and from skeletally mature Sprague–Dawley rats (n = 21). Tissues were stained immunohistochemically for adiponectin and adiponectin receptors AdipoR1 and AdipoR2. Changes in adiponectin receptor expression with IVD degeneration severity were then investigated using a rat tail temporary compression model. Rat IVD tissues were stained immunohistochemically with AdipoR1 or AdipoR2, and immunopositive cell percentages were calculated. Rat nucleus pulposus (NP) and annulus fibrosus (AF) tissues were isolated separately and treated with recombinant adiponectin (Ad 0.1 or 1.0 μg/ml) and/or interleukin-1 beta (IL-1β) (0.2 μg/ml) for 24 h. The four groups were as follows: control group (no treatment), IL-1β group (IL-1β-only treatment), IL-1β+Ad (0.1) group (IL-1β and adiponectin [0.1 μg/ml] treatment), and IL-1β+Ad (1.0) group (IL-1β and adiponectin [1.0 μg/ml]). Real-time reverse transcription-polymerase chain reaction was performed to evaluate messenger-RNA (mRNA) expression of tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6).

Results: Adiponectin was widely expressed in human subcutaneous and epidural adipose tissue. In rat IVD tissue, adiponectin was not observed in NP and AF. However, both AdipoR1 and AdipoR2 were widely expressed in both human and rat IVD tissues, with no significant differences in expression levels between receptors. Furthermore, expression levels of AdipoR1 and AdipoR2 were gradually decreased with increased IVD degeneration severity. Interestingly, mRNA expression levels of TNF-α and IL-6 were significantly upregulated by IL-1β stimulation. TNF-α expression in the IL-1β+Ad 1.0 group was significantly lower than that in the IL-1β group in both NP and AF cells (P < 0.05). Finally, IL-6 expression was not affected by adiponectin treatment in IVD cells.

Conclusions: This study investigated for the first time the expression of adiponectin receptors in human and rat IVD cells. The findings indicate that adiponectin produced by the systemic or epidural adipose tissue may be involved in the pathomechanism of IVD degeneration.

No MeSH data available.


Immunohistochemical staining of AdipoR1 and AdipoR2 in human and rat IVDs. (Top) Photomicrographs demonstrating immunohistochemical localization of AdipoR1 and AdipoR2 in both NP and AF: bars = 100 μm. (Bottom) Percentage (%) of positive immunostained cells. Data were obtained from human IVD (N = 4) and rat IVD (N = 4), and expression is shown as mean + SD. R1 AdipoR1, R2 AdipoR2
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Fig2: Immunohistochemical staining of AdipoR1 and AdipoR2 in human and rat IVDs. (Top) Photomicrographs demonstrating immunohistochemical localization of AdipoR1 and AdipoR2 in both NP and AF: bars = 100 μm. (Bottom) Percentage (%) of positive immunostained cells. Data were obtained from human IVD (N = 4) and rat IVD (N = 4), and expression is shown as mean + SD. R1 AdipoR1, R2 AdipoR2

Mentions: AdipoR1 and AdipoR2 expression was observed in both NP and AF cells from human IVDs. The mean percentage of AdipoR1 and AdipoR2 was 39.4 ± 17.4% and 37.8 ± 14.5% in NP cells and 51.6 ± 14.3% and 55.4 ± 21.6% in AF cells, respectively. When expression levels of AdipoR1 and AdipoR2 were compared, no significant differences were observed for either NP or AF cells. Expression of AdipoR1 and AdipoR2 was observed in rat IVD cells: with a mean percentage of AdipoR1 and AdipoR2 at 79.6 ± 9.8% and 69.2 ± 15.8% in NP cells and 63.2 ± 17.5% and 66.2 ± 14.1% in AF cells, respectively. Expression of AdipoR1 and AdipoR2 was diffuse throughout the whole NP and AF. Localization of these receptors was not observed in human or rat IVD (Fig. 2).Fig. 2


Expression of adiponectin receptors in human and rat intervertebral disc cells and changes in receptor expression during disc degeneration using a rat tail temporary static compression model
Immunohistochemical staining of AdipoR1 and AdipoR2 in human and rat IVDs. (Top) Photomicrographs demonstrating immunohistochemical localization of AdipoR1 and AdipoR2 in both NP and AF: bars = 100 μm. (Bottom) Percentage (%) of positive immunostained cells. Data were obtained from human IVD (N = 4) and rat IVD (N = 4), and expression is shown as mean + SD. R1 AdipoR1, R2 AdipoR2
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Related In: Results  -  Collection

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Fig2: Immunohistochemical staining of AdipoR1 and AdipoR2 in human and rat IVDs. (Top) Photomicrographs demonstrating immunohistochemical localization of AdipoR1 and AdipoR2 in both NP and AF: bars = 100 μm. (Bottom) Percentage (%) of positive immunostained cells. Data were obtained from human IVD (N = 4) and rat IVD (N = 4), and expression is shown as mean + SD. R1 AdipoR1, R2 AdipoR2
Mentions: AdipoR1 and AdipoR2 expression was observed in both NP and AF cells from human IVDs. The mean percentage of AdipoR1 and AdipoR2 was 39.4 ± 17.4% and 37.8 ± 14.5% in NP cells and 51.6 ± 14.3% and 55.4 ± 21.6% in AF cells, respectively. When expression levels of AdipoR1 and AdipoR2 were compared, no significant differences were observed for either NP or AF cells. Expression of AdipoR1 and AdipoR2 was observed in rat IVD cells: with a mean percentage of AdipoR1 and AdipoR2 at 79.6 ± 9.8% and 69.2 ± 15.8% in NP cells and 63.2 ± 17.5% and 66.2 ± 14.1% in AF cells, respectively. Expression of AdipoR1 and AdipoR2 was diffuse throughout the whole NP and AF. Localization of these receptors was not observed in human or rat IVD (Fig. 2).Fig. 2

View Article: PubMed Central - PubMed

ABSTRACT

Background: Adipose tissue is a large endocrine organ known to secret adiponectin, which has anti-diabetic, anti-atherogenic, and anti-inflammatory properties. Adiponectin is widely involved in systemic disease, diabetes mellitus, and cardiac infraction. This study aimed to investigate the involvement of adiponectin in intervertebral disc (IVD) degeneration.

Methods: Adipose and IVD tissues were obtained from human patients undergoing surgery (n = 4) and from skeletally mature Sprague–Dawley rats (n = 21). Tissues were stained immunohistochemically for adiponectin and adiponectin receptors AdipoR1 and AdipoR2. Changes in adiponectin receptor expression with IVD degeneration severity were then investigated using a rat tail temporary compression model. Rat IVD tissues were stained immunohistochemically with AdipoR1 or AdipoR2, and immunopositive cell percentages were calculated. Rat nucleus pulposus (NP) and annulus fibrosus (AF) tissues were isolated separately and treated with recombinant adiponectin (Ad 0.1 or 1.0 μg/ml) and/or interleukin-1 beta (IL-1β) (0.2 μg/ml) for 24 h. The four groups were as follows: control group (no treatment), IL-1β group (IL-1β-only treatment), IL-1β+Ad (0.1) group (IL-1β and adiponectin [0.1 μg/ml] treatment), and IL-1β+Ad (1.0) group (IL-1β and adiponectin [1.0 μg/ml]). Real-time reverse transcription-polymerase chain reaction was performed to evaluate messenger-RNA (mRNA) expression of tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6).

Results: Adiponectin was widely expressed in human subcutaneous and epidural adipose tissue. In rat IVD tissue, adiponectin was not observed in NP and AF. However, both AdipoR1 and AdipoR2 were widely expressed in both human and rat IVD tissues, with no significant differences in expression levels between receptors. Furthermore, expression levels of AdipoR1 and AdipoR2 were gradually decreased with increased IVD degeneration severity. Interestingly, mRNA expression levels of TNF-α and IL-6 were significantly upregulated by IL-1β stimulation. TNF-α expression in the IL-1β+Ad 1.0 group was significantly lower than that in the IL-1β group in both NP and AF cells (P < 0.05). Finally, IL-6 expression was not affected by adiponectin treatment in IVD cells.

Conclusions: This study investigated for the first time the expression of adiponectin receptors in human and rat IVD cells. The findings indicate that adiponectin produced by the systemic or epidural adipose tissue may be involved in the pathomechanism of IVD degeneration.

No MeSH data available.