IL-1β signaling is required for mechanical allodynia induced by nerve injury and for the ensuing reduction in spinal cord neuronal GRK2
Introduction
Nerve injury caused by trauma, surgery, or inflammation often results in the development of mechanical allodynia and/or hyperalgesia. The increased pain responsiveness during mechanical allodynia is mediated at least in part by increased excitability of neurons in the spinal cord (Hains et al., 2004). The intracellular mechanisms of increased neuronal excitability are thought to include changes in expression and responsiveness of receptors, activation of several kinases, release of neuropeptides and neurotrophins, and local production of inflammatory mediators (Kim et al., 2002, Milligan et al., 2005, Obata et al., 2004, Woolf and Salter, 2000, Yashpal et al., 2001).
Many mediators involved in pain perception and allodynia (e.g. substance P, glutamate, chemokines, prostaglandins) signal via G protein-coupled receptors (GPCRs). GPCR kinase 2 (GRK2) regulates the responsiveness of multiple GPCRs. GRK2 phosphorylates agonist-occupied GPCRs, which facilitates binding of arrestins, uncoupling from the Gα protein, and receptor internalization (Luttrell and Lefkowitz, 2002). More recent studies described an important additional mechanism via which GRK2 can regulate signaling, i.e. via a direct interaction with intracellular signaling molecules (e.g. MEK1/2, Akt, RKIP, p38 MAPK) (Reiter and Lefkowitz, 2006, Ribas et al., 2006). Changes in GRK2 levels modulate the responsiveness of GPCRs including C-C chemokine receptor (CCR)1/5, CCR2, β2-adrenergic receptors, and metabotropic glutamate receptors (Dhami et al., 2004, Jiménez-Sainz et al., 2006, Vroon et al., 2004, Vroon et al., 2007). In general, low cellular GRK2 expression is associated with increased receptor signaling (Fan and Malik, 2003, Vroon et al., 2004, Vroon et al., 2007), whereas GRK2 overexpression is related to decreased receptor signaling (Lombardi et al., 2002).
Based on the role of GRK2 in the regulation of GPCR signaling and the fact that GPCR signaling plays an important role in mechanical allodynia, we have suggested that changes in GRK2 would contribute to inflammation-associated mechanical allodynia. Indeed, we recently demonstrated that λ-carrageenan-induced acute mechanical allodynia was increased in GRK2+/− mice compared to WT mice, indicating that low GRK2 levels are associated with increased sensitivity for inflammatory allodynia (Kleibeuker et al., 2007). Conversely, we showed that neuronal GRK2 expression is diminished in the lumbar spinal cord dorsal horn of rats during chronic constriction injury (CCI)1 of the sciatic nerve, a model of mechanical allodynia (Kleibeuker et al., 2007). During CCI and other models of mechanical allodynia several pro-inflammatory cytokines such as interleukin (IL)-1β and tumor necrosis factor (TNF)-α are produced in the spinal cord that contribute to increased pain sensitivity (Milligan et al., 2005, Raghavendra et al., 2003, Winkelstein et al., 2001). Intrathecal administration of IL-1β can increase nociception, whereas intrathecal administration of IL-1 receptor antagonist (IL-1RA) can prevent the development of and/or reverse established mechanical allodynia (Milligan et al., 2005, Sung et al., 2004). Additional evidence for the role of IL-1β in the development of mechanical allodynia comes from studies using mice with deficiencies in IL-1β signaling. Mechanical allodynia induced by L5–6 spinal nerve ligation or CCI is decreased in IL-1α/β−/− mice (Honore et al., 2006). Moreover, Wolf et al. (2006) showed that mechanical allodynia is abrogated in mice with a targeted deletion of the IL-1 type I receptor (IL-1R−/−) and in mice overexpressing IL-1RA, indicating that IL-1β is crucial for the development of mechanical allodynia after L5 spinal nerve transection (SNT).
GRK2 expression is downregulated during various inflammatory diseases including rheumatoid arthritis, multiple sclerosis, adjuvant arthritis, and experimental allergic encephalomyelitis (Lombardi et al., 1999, Lombardi et al., 2001, Vroon et al., 2003, Vroon et al., 2005), but also after pro-inflammatory cytokine treatment. In vitro, chronic IL-1β treatment of cultured spinal cord slices decreases GRK2 levels (Kleibeuker et al., 2007). In addition, IL-1β and several other pro-inflammatory cytokines (e.g. IFN-γ, IL-6, TNF-α) downregulated GRK2 expression in human peripheral blood lymphocytes or in a smooth muscle cell line (Lombardi et al., 1999, Ramos-Ruiz et al., 2000).
In the present study, we investigated whether L5 SNT-induced mechanical allodynia in mice is associated with a reduced neuronal GRK2 expression in the spinal cord dorsal horn. This may answer the question whether downregulation of neuronal GRK2 is a general mechanism which may contribute to the development of mechanical allodynia. In addition, we hypothesized that IL-1β signaling is required to induce mechanical allodynia as well as a decrease in GRK2 levels. To test this hypothesis, mechanical sensitivity and expression of GRK2 in the spinal cord dorsal horn were determined in the L5 SNT model in mice with a deficiency of IL-1β signaling (IL-1R−/−) and in wild type (WT).
Section snippets
Animals
IL-1R−/− mice (Labow et al., 1997) and their C57BL/6 X 129/Sv WT control male mice, 10–14 weeks old, were employed in this study (Jackson Laboratory, Bar Harbor, ME, USA). All mice were housed in groups of 4–5 in 26.5 × 20 × 13.5 cm cages or groups of 7–10 in 37 × 30 × 15 cm cages. Food and water were available ad libitum. All measurements were performed during the dark phase of a reversed 12 h light-dark cycle (lights off at 08:00). The experiments were performed according to international guidelines and
GRK2 expression in the mouse spinal cord
We have previously shown that the GRK2 antibody used in this study can be used to detect differences in GRK2 expression in the rat spinal cord using immunohistochemistry. Moreover, the antibody recognizes a single band on Western blots of mouse spinal cord, and GRK2 expression, as determined by Western blotting, is significantly reduced in the spinal cord of GRK2+/− mice (Kleibeuker et al., 2007). As shown in Fig. 1A and B, the difference in GRK2 expression between WT and GRK2+/− mice can also
Discussion
This study demonstrates that neuronal GRK2 levels in the lumbar spinal cord dorsal horn were downregulated in a murine model of mechanical allodynia (L5 SNT). Interestingly, in IL-1R−/− mice, which do not develop mechanical allodynia after L5 SNT, no such reduction was observed. These results indicate that IL-1β signaling is required for the decrease in neuronal GRK2 levels, as well as for the development of L5 SNT-induced mechanical allodynia.
We previously demonstrated that CCI of the sciatic
References (39)
- et al.
Intrathecal anti-IL-6 antibody and IgG attenuates peripheral nerve injury-induced mechanical allodynia in the rat: possible immune modulation in neuropathic pain
Brain Res.
(2000) - et al.
G Protein-coupled receptor kinase 2 regulator of G protein signaling homology domain binds to both metabotropic glutamate receptor 1a and Galphaq to attenuate signaling
J. Biol. Chem.
(2004) - et al.
Role of the sensory neuron cytoskeleton in second messenger signaling for inflammatory pain
Neuron
(2003) - et al.
Interleukin-1alphabeta gene-deficient mice show reduced nociceptive sensitivity in models of inflammatory and neuropathic pain but not post-operative pain
Behav. Brain Res.
(2006) - et al.
p38 map kinase regulates TNF-alpha production in human astrocytes and microglia by multiple mechanisms
Cytokine
(2000) - et al.
Functional role of exogenous administration of substance P in chronic constriction injury model of neuropathic pain in gerbils
Pharmacol. Biochem. Behav.
(2003) - et al.
Contribution of degeneration of motor and sensory fibers to pain behavior and the changes in neurotrophic factors in rat dorsal root ganglion
Exp. Neurol.
(2004) - et al.
GRKs and beta-arrestins: roles in receptor silencing, trafficking and signaling
Trends Endocrinol. Metab.
(2006) - et al.
Intrathecal interleukin-1beta administration induces thermal hyperalgesia by activating inducible nitric oxide synthase expression in the rat spinal cord
Brain Res.
(2004) - et al.
Intrathecal interleukin-1 receptor antagonist in combination with soluble tumor necrosis factor receptor exhibits an anti-allodynic action in a rat model of neuropathic pain
Neuroscience
(2001)
Taxol normalizes the impaired agonist-induced beta(2)-adrenoceptor internalization in splenocytes from GRK2+/− mice
Eur. J. Pharmacol.
Changes in the G-protein-coupled receptor desensitization machinery during relapsing-progressive experimental allergic encephalomyelitis
J. Neuroimmunol.
Genetic impairment of interleukin-1 signaling attenuates neuropathic pain, autotomy, and spontaneous ectopic neuronal activity, following nerve injury in mice
Pain
Differential effects of NMDA and group I mGluR antagonists on both nociception and spinal cord protein kinase C translocation in the formalin test and a model of neuropathic pain in rats
Pain
ERK is sequentially activated in neurons, microglia, and astrocytes by spinal nerve ligation and contributes to mechanical allodynia in this neuropathic pain model
Pain
Toll-like receptor-4 (TLR4) signaling augments chemokine-induced neutrophil migration by modulating cell surface expression of chemokine receptors
Nat. Med.
Altered sodium channel expression in second-order spinal sensory neurons contributes to pain after peripheral nerve injury
J. Neurosci.
Essential role of beta-adrenergic receptor kinase 1 in cardiac development and function
Proc. Natl. Acad. Sci. USA
G protein-coupled receptor kinase 2 negatively regulates chemokine signaling at a level downstream from g protein subunits
Mol. Biol. Cell
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