Impact of human CA8 on thermal antinociception in relation to morphine equivalence in mice

Abstract

Recently, we showed murine DRG Car8 expression is a cis-regulated eQTL that determines analgesic responses. In this report, we show transduction via SN injection of DRG with human wildtype CA8 using AAV viral particles (AAV8-V5-CA8WT) produces analgesia in naïve male C57BL/6J mice and anti-hyperalgesia after carrageenan treatment. A peak mean increase of about 4 seconds in thermal hindpaw withdrawal latency equaled increases in thermal withdrawal latency produced by 10 mg/kg IP morphine in these mice. Allometric conversion of this IP morphine dose in mice equals an oral morphine dose of about 146 mg in a 60 kg adult. Our work quantifies for the first time analgesia and anti-hyperalgesia in an inflammatory pain model after DRG transduction by CA8 gene therapy.

Human carbonic anhydrase-8 AAV8 gene therapy inhibits nerve growth factor signaling producing prolonged analgesia and anti-hyperalgesia in mice

“…In the present study, we demonstrate that the human carbonic anhydrase-8 (CA8) overexpression inhibited NGF-induced pITPR1 and [Ca2+]i increases in NBL and HEK cells. We also show, once again that sciatic nerve injection of AAV8-V5-CA8 WT produced profound analgesia in mice 3 and effectively prevented and treated mechanical and thermal hyperalgesia after SNL in mice. Collectively, our data demonstrate that CA8 functions in mouse-derived cell lines and the mouse somatosensory nervous system, to inhibit murine ITPR1-mediated calcium release and pain processing.…”

“…Systemic analgesics, including opioids, can be limited by side effects and are inadequate in relieving pain. 3 Regional anesthesia can be considered a potential therapy for these patients. Unfortunately, a major limitation in treating acute, subacute, and certain forms of chronic pain with regional techniques is the lack of available local anesthetics exceeding 12 hours in duration.…”

Profound analgesia is associated with a truncated peptide resulting from tissue specific alternative splicing of DRG CA8-204 regulated by an exon-level cis-eQTL

“…Mice receiving CA8-201 or CA8-204 G , but not those injected with CA8-201 MT , demonstrated elevations in their thermal latencies starting at Day 13 reaching a maximum by Day 15 (two-way repeated measures ANOVA test, post-hoc test, overall P-value <0.001; CA8-201 vs. CA8-201 MT , P-value<0.001; CA8-201 MT vs. CA8-204 G, P-value<0.001) of approximately 3.0 seconds above baseline. This increase in thermal withdrawal latencies in C57BL/6J mice exceeds a dose of 80 mg of oral morphine in a 60 kg adult, after allometric conversion [7]. Following carrageenan injection thermal paw withdrawal latencies reached a minimum on Day 16.…”

“…As previously shown, analgesic and anti-hyperalgesic activity is abolished in the (S100P) null mutant AAV8-V5-CA8-201 MT (CA8-201 MT ) [6], that was used as a negative control; and AAV8-FLAG-CA8-204 G (CA8-204 G ) was used as the test group. SN (sciatic nerve) injections of viral particles was followed using a previously prescribed procedure [7]. We have used V5 and FLAG tags due to their small size as tags, and data that have shown these tags lack effects in neurobehavioral studies [5, 6, 38–40].…”

“…Additionally, we reported Car8/CA8 gene therapy was analgesic and anti-hyperalgesic in animal models of pain [5, 6]. In order to quantify analgesic responses observed in animal models after Car8/CA8 gene therapy, we used allometric conversions indicating profound analgesia that exceeded an oral dose of 250 mg of morphine in an average sized adult [7]. Using integrative genomics to understand the impact of Car8 genetic regulation on nociceptive responses we identified a murine gene-level cis- expression quantitative trait (eQTL) in DRG associated with variable Car8 gene expression.…”