Blocking CTGF/CCN2 reverses neural fibrosis and sensorimotor declines in a rat model of overuse‐induced median mononeuropathy

Abstract

Encapsulation of median nerves is a hallmark of overuse-induced median mononeuropathy and contributes to functional declines. We tested if an antibody against CTGF/CCN2 (termed FG-3019 or Pamrevlumab) reduces established neural fibrosis and sensorimotor declines in a clinically relevant rodent model of overuse in which median mononeuropathy develops. Young adult female rats performed a high repetition high force (HRHF) lever-pulling task for 18 weeks. Rats were then euthanised at 18 weeks (HRHF untreated), or rested and systemically treated for 6 weeks with either an anti-CCN2 monoclonal antibody (HRHF-Rest/FG-3019) or IgG (HRHF-Rest/IgG), with results compared with nontask control rats. Neuropathology was evident in HRHF-untreated and HRHF-Rest/IgG rats as increased perineural collagen deposition and degraded myelin basic protein (dMBP) in median nerves, and increased substance P in lower cervical dorsal root ganglia (DRG), compared with controls. Both groups showed functional declines, specifically, decreased sensory conduction velocity in median nerves, noxious cold temperature hypersensitivity, and grip strength declines, compared with controls. There were also increases of ATF3-immunopositive nuclei in ventral horn neurons in HRHFuntreated rats, compared with controls (which showed none). FG-3019-treated rats showed no increase above control levels of perineural collagen or dMBP in median nerves, Substance P in lower cervical DRGs, or ATF3-immunopositive nuclei in ventral horns, and similar median nerve conduction velocities and thermal sensitivity, compared with controls. We hypothesize that neural fibrotic processes underpin the sensorimotor declines by compressing or impeding median nerves during movement, and that inhibiting fibrosis using an anti-CCN2 treatment reverses these effects.

Key indicators of repetitive overuse-induced neuromuscular inflammation and fibrosis are prevented by manual therapy in a rat model

“…We have previously reported increased sensorimotor declines in long-term untreated TASK rats (such as, enhanced cold sensitivity, declines in reflexive grip strength, and spontaneous indices of discomfort during task performance) in parallel with both increased inflammatory and fibrogenic tissue changes [ 10 , 11 , 13 ]. Therefore, we next assessed these behaviors.…”

“…Twenty rats were operatively shaped to perform a high repetition high force task (TASK) and then randomly separated into two groups of 10 rats each. One group received treatment to both upper extremities (UE; TASK-Tx, n = 10) since rats use both limbs to perform this task [ 11 , 12 , 35 ]. The other group received a similar treatment to the lower extremities (LE), thus serving as an active control treatment (Task-Ac, n = 10).…”

“…From one limb per rat of the TASK groups ( n = 10 per group) and C groups ( n = 5 per group), mid-to proximal regions of the flexor digitorum muscles were separated from bones and then tendons with a scalpel, rinsed in sterile saline, dissected into smaller samples of about 50–100 mg each, and flash frozen in liquid nitrogen before storage at -80 °C, as previously described [ 7 , 40 ]. A randomization scheme was used so that a mix of right and left limbs was collected for each assay choice (biochemical versus histology, a strategy used previously [ 11 , 35 ], since TASK rats use both limbs for reaching).…”

CCN2 (Cellular Communication Network factor 2) in the bone marrow microenvironment, normal and malignant hematopoiesis

“…Targeting CCN2 may be a therapeutic option for diseases associated with increased CCN2 expression, malignant as well as non-malignant. CCN2 can be inhibited by: The use of an anti-CCN2 antibody (Aikawa et al 2006 ; Alapati et al 2011 ; Barbe et al 2020a , b ; Bickelhaupt et al 2017 ; Dornhofer et al 2006 ; Finger et al 2014 ; Makino et al 2017 ; Moran-Jones et al 2015 ; Neesse et al 2013 ; Ohara et al 2018 ; Raghu et al 2016 ; Richeldi et al 2020 ; Sakai et al 2017 ), Gene expression silencing by antisense oligonucleotides (ASOs) or small interfering RNAs (siRNAs) (Chen et al 2014 ; Gale et al 2018 ; Gibson et al 2017 ; Jensen et al 2018 ; Kang et al 2020 ; Li et al 2006 ; Okada et al 2005 ; Sisco et al 2008 ; Sung et al 2013 ; Yokoi et al 2004 ; Yoon et al 2016 ), Drugs that indirectly (and less specifically) inhibit CCN2 expression, for example by targeting Sirtuin 1 (Sirt1) (Ren et al 2017 ), peroxisome proliferator-activated receptor gamma (PPARγ) (Sun et al 2006 ; Zhao et al 2006 ), the CCN2 transcriptional regulators YAP and TAZ (Ji et al 2018 ), or proteins involved in signaling pathways affecting CCN2 transcription such FAK (Peidl et al 2019 ), The use of CCN3, as it can antagonize the effects of CCN2 (Peidl et al 2019 ; Riser et al 2009 , 2010 , 2014 ). Of the above, only the use of an anti-CCN2 antibody and the use of ASOs and siRNAs have made it to clinical trials for their direct effect on CCN2 (Gale et al 2018 ; Jensen et al 2018 ; https://www.prnewswire.com/news-releases/rxi-pharmaceuticals-announces-positive-results-from-phase-12-trial-with-rxi-109-for-retinal-scarring-300690078.html ; http://www.sc...…”

“…The use of an anti-CCN2 antibody (Aikawa et al 2006 ; Alapati et al 2011 ; Barbe et al 2020a , b ; Bickelhaupt et al 2017 ; Dornhofer et al 2006 ; Finger et al 2014 ; Makino et al 2017 ; Moran-Jones et al 2015 ; Neesse et al 2013 ; Ohara et al 2018 ; Raghu et al 2016 ; Richeldi et al 2020 ; Sakai et al 2017 ),…”