Monocyte chemoattractant protein 1 is responsible for macrophage recruitment following injury to sciatic nerve

125

131

Although mutations in multiple genes are associated with inherited demyelinating neuropathies, the molecular components and pathways crucial for myelination remain largely unknown. To approach this question, we performed genome-wide expression analysis in several paradigms where the status of peripheral nerve myelination is dynamically changing. Anchor gene correlation analysis, a form of microarray analysis that integrates functional information, using correlation-based clustering, with a statistically rigorous test, the Westfall and Young step-down algorithm, was applied to this data set. Biological pathways active in myelination, genes encoding proteins involved in myelin synthesis, and genes whose mutation results in myelination defects were identified. Many known genes and previously uncharacterized ESTs not heretofore associated with myelination were also identified. One of these ESTs, MASR (myelin-associated SUR4 protein), encodes a member of the SUR4 family of fatty acid desaturases, enzymes involved in elongation of very long chain fatty acids. Its specific localization in myelinating Schwann cells indicates a crucial role for MASR in normal myelin lipid synthesis.

Section: Resultsmentioning

confidence: 66%

Deciphering peripheral nerve myelination by using Schwann cell expression profiling

Nagarajan

Le²,

Mahoney³

et al. 2002

125

131

“…All these cell types may contribute to pain signaling (5,19,20). MCP-1 can act on all of these cell types (12) and has been shown to promote macrophage infiltration into the spinal cord and DRG following nerve injury (21)(22)(23). Therefore, we examined changes in the DRG macrophage population following DMM surgery to assess whether these cells were infiltrating the innervating DRG as a result of the up-regulation of MCP-1.…”

Section: Mcp-1/ccr2 Signaling Is Up-regulated In Innervating Drg Follmentioning

confidence: 99%

CCR2 chemokine receptor signaling mediates pain in experimental osteoarthritis

Miller

Tran

Das

et al. 2012

243

281

Osteoarthritis is one of the leading causes of chronic pain, but almost nothing is known about the mechanisms and molecules that mediate osteoarthritis-associated joint pain. Consequently, treatment options remain inadequate and joint replacement is often inevitable. Here, we use a surgical mouse model that captures the long-term progression of knee osteoarthritis to longitudinally assess pain-related behaviors and concomitant changes in the innervating dorsal root ganglia (DRG). We demonstrate that monocyte chemoattractant protein (MCP)-1 (CCL2) and its high-affinity receptor, chemokine (C-C motif) receptor 2 (CCR2), are central to the development of pain associated with knee osteoarthritis. After destabilization of the medial meniscus, mice developed early-onset secondary mechanical allodynia that was maintained for 16 wk. MCP-1 and CCR2 mRNA, protein, and signaling activity were temporarily up-regulated in the innervating DRG at 8 wk after surgery. This result correlated with the presentation of movement-provoked pain behaviors, which were maintained up to 16 wk. Mice that lack Ccr2 also developed mechanical allodynia, but this started to resolve from 8 wk onwards. Despite severe allodynia and structural knee joint damage equal to wild-type mice, Ccr2-null mice did not develop movement-provoked pain behaviors at 8 wk. In wild-type mice, macrophages infiltrated the DRG by 8 wk and this was maintained through 16 wk after surgery. In contrast, macrophage infiltration was not observed in Ccr2-null mice. These observations suggest a key role for the MCP-1/CCR2 pathway in establishing osteoarthritis pain.O steoarthritis is the most common joint disorder and is one of the leading causes of chronic pain (1, 2). Osteoarthritis commonly affects knees, hips, and hands and is characterized by radiographic changes (primarily joint space narrowing, subchondral bone sclerosis, and osteophytes) accompanied by clinical symptoms, most prominently pain. Treatments that alter the progression of the structural damage in the joint are not yet available. Options for treating the pain include nonsteroidal anti-inflammatory drugs, steroids, and viscosupplementation, but analgesia is often inadequate, and uncontrolled pain is the number one reason why people with osteoarthritis undergo joint-replacement surgery (3). Despite the enormous health and economic burden of osteoarthritis and associated pain (4), very few studies have examined the molecular pathways that mediate osteoarthritis pain. As in all types of chronic pain, osteoarthritis pain is the dynamic result of a complex interaction between local tissue damage and inflammation, peripheral and central sensitization, and the brain (5-7). Joint pain associated with osteoarthritis, however, has unique clinical features that provide insight into the mechanisms that cause it. First, joint pain has a strong mechanical component: it is typically triggered by specific activities (for example, climbing stairs elicits knee pain) and is relieved by rest. As structural joint disease advance...

“…At presymptomatic time points (i.e., weeks 9-12), focal activation occurs for PNS macrophages and spinal cord microglia. Following clinical onset (i.e., weeks [12][13][14][15][16][17][18][19], activation of innate immunity becomes widespread in both tissues as indicated by FACS and histological analysis.…”

Section: Macrophage Activation Occurs Throughout the Peripheral Nervousmentioning

confidence: 99%

Activation of innate and humoral immunity in the peripheral nervous system of ALS transgenic mice

Chiu

Phatnani

Kuligowski

et al. 2009

177

176

During injury to the nervous system, innate immune cells mediate phagocytosis of debris, cytokine production, and axon regeneration. In the neuro-degenerative disease amyotrophic lateral sclerosis (ALS), innate immune cells in the CNS are activated. However, the role of innate immunity in the peripheral nervous system (PNS) has not been well defined. In this study, we characterized robust activation of CD169/CD68/Iba1؉ macrophages throughout the PNS in mutant SOD1 G93A and SOD1 G37R transgenic mouse models of ALS. Macrophage activation occurred pre-symptomatically, and expanded from focal arrays within nerve bundles to a tissue-wide distribution following symptom onset. We found a striking dichotomy for immune cells within the spinal cord and PNS. Flow cytometry and GFP bone marrow chimeras showed that spinal cord microglia were mainly tissue resident derived, dendritic-like cells, whereas in peripheral nerves, the majority of activated macrophages infiltrated from the circulation. Humoral antibodies and complement localized to PNS tissue in tandem with macrophage recruitment, and deficiency in complement C4 led to decreased macrophage activation. Therefore, cross-talk between nervous and immune systems occurs throughout the PNS during ALS disease progression. These data reveal a progressive innate and humoral immune response in peripheral nerves that is separate and distinct from spinal cord immune activation in ALS transgenic mice.innate immunity ͉ macrophage ͉ peripheral nervous system ͉ neuroimmunology ͉ amyotrophic lateral sclerosis