Background & Aims
Endometriosis (EM) impacts ~4 million women in the US (Agarwal et al., 2019). EM lesions are infiltrated with mast cells (MCs) (Fonseca et al., 2023; Matsuzaki et al., 1998) and have elevated expression of vascular endothelial growth factor (VEGF) (Rein et al., 2010) and its cognate receptor VEGFR2 (Steinthorsdottir et al., 2016). MCs in human lung tissue express VEGF (Marcella et al., 2021). However, it is unclear whether MCs and/or VEGF contribute to EM-associated chronic pelvic pain (EM-CPP). We adopted an improved non-invasive mouse model of EM-CPP recently developed by Fattori et al. to test the hypothesis that MC-mediated release of VEGF drives pelvic tactile allodynia and treatments that either stabilize MCs or inhibit VEGFR2 reverse pelvic tactile allodynia.
Methods
Female C57BL/6J donor mice (6-weeks old) received an injection of estradiol benzoate (10µg), and 4 days later, each uterine horn was excised and placed in Hank’s Balanced Salt Solution (HBSS) and minced. Recipient mice received an intraperitoneal (i.p.) injection of HBSS (500µl; “Shams”) or HBSS+donor mice minced uterine horn (500µl; “EM mice”). To assess the development of pelvic tactile allodynia, von Frey (vF) filaments were applied to the suprapubic region before (baseline) and 28 days after tissue injection. We i.p. administered ?-nicotinamide mononucleotide (NMN;150mg/kg) or saline on day 28, and assessed vF thresholds. In a separate cohort, we i.p. injected SKLB1002 (SB;100mg/kg) or saline on day 56. In a dose-response study, we intrauterinely (i.u.) infused saline or VEGF (0.001-1pg) on days 1, 4, and 7 and vF tested for 56 days. In a separate experiment, we i.u. infused saline or VEGF (1pg) and then i.u. infused ketotifen fumarate (Keto;10mg/kg) or saline on day 56.
Results
We first assessed the effect of NMN on mechanical hypersensitivity. In Shams, saline nor NMN changed mechanical thresholds. In EM mice, NMN but not saline reversed pelvic tactile allodynia (F(15,60)=3.551;p=0.0002) from 9 to 36 hrs. Then, we determined the effect of SB on mechanical hypersensitivity. In Shams, saline nor SB altered mechanical hypersensitivity. In EM mice, SB but not saline blunted pelvic tactile allodynia (F(15,30)=3.628;p=0.0003) from 60 to 90 min. Next, in mice without EM, we demonstrated that i.u. saline or 0.001-0.01pg VEGF does not induce mechanical hypersensitivity. VEGF at 0.1pg revealed mechanical hypersensitivity for 14 days (p<0.05). VEGF at 1pg induced mechanical hypersensitivity for up to 56 days (p<0.05). Thus, we investigated the effect of Keto on VEGF-induced hypersensitivity. Mechanical thresholds remain unchanged in controls. However, Keto but not saline reversed VEGF-induced pelvic tactile allodynia (F(15,70)=1.942;p=0.033) from 9 to 18 hrs.
Conclusions
Altogether, 1) stabilizing MCs or inhibiting VEGFR2 alleviates pelvic tactile allodynia in mice with EM, and 2) intrauterine VEGF dose-dependently elicits pelvic tactile allodynia that is reversible with blunting of MC activity.
References
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Presenting Author
Sarvesh Acharya
Poster Authors
Topics
- Models: Visceral