PTGER1 and PTGER2 receptors mediate regulation of progesterone synthesis and type 1 11β-hydroxysteroid dehydrogenase activity by prostaglandin E2 in human granulosa–lutein cells

In luteinizing granulosa cells, prostaglandin E2 (PGE2) can exert luteotrophic actions, apparently via the cAMP signalling pathway. In addition to stimulating progesterone synthesis, PGE2 can also stimulate oxidation of the physiological glucocorticoid, cortisol, to its inactive metabolite, cortisone, by the type 1 11β-hydroxysteroid dehydrogenase (11βHSD1) enzyme in human granulosa–lutein cells. Having previously shown these human ovarian cells to express functional G-protein coupled, E-series prostaglandin (PTGER)1, PTGER2 and PTGER4 receptors, the aim of this study was to delineate the roles of PTGER1 and PTGER2 receptors in mediating the effects of PGE2 on steroidogenesis and cortisol metabolism in human granulosa–lutein cells. PGE2-stimulated concentration-dependent increases in both progesterone production and cAMP accumulation (by 1·9±0·1- and 18·7±6·8-fold respectively at 3000 nM PGE2). While a selective PTGER1 antagonist, SC19220, could partially inhibit the steroidogenic response to PGE2 (by 55·9±4·1% at 1000 nM PGE2), co-treatment with AH6809, a mixed PTGER1/PTGER2 receptor antagonist, completely abolished the stimulation of progesterone synthesis at all tested concentrations of PGE2 and suppressed the stimulation of cAMP accumulation. Both PGE2 and butaprost (a preferential PTGER2 receptor agonist) stimulated concentration-dependent increases in cortisol oxidation by 11βHSD1 (by 42·5±3·1 and 40·0±3·0% respectively, at PGE2 and butaprost concentrations of 1000 nM). Co-treatment with SC19220 enhanced the ability of both PGE2 and butaprost to stimulate 11βHSD1 activity (by 30·2±0·2 and 30·5±0·6% respectively), whereas co-treatment with AH6809 completely abolished the 11βHSD1 responses to PGE2 and butaprost. These findings implicate the PTGER2 receptor–cAMP signalling pathway in the stimulation of progesterone production and 11βHSD1 activity by PGE2 in human granulosa–lutein cells

Macrophage Sub-Populations and the Lipoxin A4 Receptor Implicate Active Inflammation during Equine Tendon Repair

Macrophages (Mϕ) orchestrate inflammatory and reparatory processes in injured connective tissues but their role during different phases of tendon healing is not known. We investigated the contribution of different Mϕ subsets in an equine model of naturally occurring tendon injury. Post mortem tissues were harvested from normal (uninjured), sub-acute (3–6 weeks post injury) and chronically injured (>3 months post injury) superficial digital flexor tendons. To determine if inflammation was present in injured tendons, Mϕ sub-populations were quantified based on surface antigen expression of CD172a (pan Mϕ), CD14highCD206low (pro-inflammatory M1Mϕ), and CD206high (anti-inflammatory M2Mϕ) to assess potential polarised phenotypes. In addition, the Lipoxin A4 receptor (FPR2/ALX) was used as marker for resolving inflammation. Normal tendons were negative for both Mϕ and FPR2/ALX. In contrast, M1Mϕ predominated in sub-acute injury, whereas a potential phenotype-switch to M2Mϕ polarity was seen in chronic injury. Furthermore, FPR2/ALX expression by tenocytes was significantly upregulated in sub-acute but not chronic injury. Expression of the FPR2/ALX ligand Annexin A1 was also significantly increased in sub-acute and chronic injuries in contrast to low level expression in normal tendons. The combination of reduced FPR2/ALX expression and persistence of the M2Mϕ phenotype in chronic injury suggests a potential mechanism for incomplete resolution of inflammation after tendon injury. To investigate the effect of pro-inflammatory mediators on lipoxin A4 (LXA4) production and FPR2/ALX expression in vitro, normal tendon explants were stimulated with interleukin-1 beta and prostaglandin E2. Stimulation with either mediator induced LXA4 release and maximal upregulation of FPR2/ALX expression after 72 hours. Taken together, our data suggests that although tenocytes are capable of mounting a protective mechanism to counteract inflammatory stimuli, this appears to be of insufficient duration and magnitude in natural tendon injury, which may potentiate chronic inflammation and fibrotic repair, as indicated by the presence of M2Mϕ

Documenting the Recovery of Vascular Services in European Centres Following the Initial COVID-19 Pandemic Peak: Results from a Multicentre Collaborative Study

Objective: To document the recovery of vascular services in Europe following the first COVID-19 pandemic peak. Methods: An online structured vascular service survey with repeated data entry between 23 March and 9 August 2020 was carried out. Unit level data were collected using repeated questionnaires addressing modifications to vascular services during the first peak (March – May 2020, “period 1”), and then again between May and June (“period 2”) and June and July 2020 (“period 3”). The duration of each period was similar. From 2 June, as reductions in cases began to be reported, centres were first asked if they were in a region still affected by rising cases, or if they had passed the peak of the first wave. These centres were asked additional questions about adaptations made to their standard pathways to permit elective surgery to resume. Results: The impact of the pandemic continued to be felt well after countries’ first peak was thought to have passed in 2020. Aneurysm screening had not returned to normal in 21.7% of centres. Carotid surgery was still offered on a case by case basis in 33.8% of centres, and only 52.9% of centres had returned to their normal aneurysm threshold for surgery. Half of centres (49.4%) believed their management of lower limb ischaemia continued to be negatively affected by the pandemic. Reduced operating theatre capacity continued in 45.5% of centres. Twenty per cent of responding centres documented a backlog of at least 20 aortic repairs. At least one negative swab and 14 days of isolation were the most common strategies used for permitting safe elective surgery to recommence. Conclusion: Centres reported a broad return of services approaching pre-pandemic “normal” by July 2020. Many introduced protocols to manage peri-operative COVID-19 risk. Backlogs in cases were reported for all major vascular surgeries