Cnr1-/- has minimal impact on chlorpyrifos-mediated effects in the mouse endocannabinoid system, but it does alter lipopolysaccharide-induced cytokine levels in splenocytes

Chlorpyrifos (CPF) is an organophosphate pesticide that can inhibit endocannabinoid (eCB) metabolizing enzymes in animal models at levels that do not significantly alter acetylcholinesterase (AChE) in the central nervous system (CNS). Previous studies indicated that repeated low-level CPF exposure in developing rats increased the levels of eCBs in the brain. Because eCBs play a role in immune homeostasis through their engagement with cannabinoid receptors, we investigated the role of cannabinoid receptor 1 (CB1, encoded by the Cnr1 gene) on the CPF-mediated effects in the spleen and lung of neonatal and adult female mice. We treated neonatal and adult female Cnr1^-/- mice with 2.5 mg/kg oral CPF or vehicle for 7 days. Tissues were harvested 4 h after the last CPF dose to evaluate eCB metabolic enzyme activity, levels of eCBs, and tissue immunophenotype. There were a small number of genotype-dependent alterations noted in the endpoints following CPF treatment that were specific to age and tissue type, and differences in eCB metabolism caused by CPF treatment did not correlate to changes in eCB levels. To explore the role of CB1 in CPF-mediated effects on immune endpoints, in vitro experiments were performed with WT murine splenocytes exposed to chlorpyrifos oxon (CPO; oxon metabolite of CPF) and challenged with lipopolysaccharide (LPS). While CPO did not alter LPS-induced pro-inflammatory cytokine levels, inactivation of CB1 by the antagonist SR141716A augmented LPS-induced IFN-γ levels. Additional experiments with WT and Cnr1^-/- murine splenocytes confirmed a role for CB1 in altering the production of LPS-induced pro-inflammatory cytokine levels. We conclude that CPF-mediated effects on the eCB system are not strongly dependent on CB1, although abrogation of CB1 does alter LPS-induced cytokine levels in splenocytes.

Potential for TCDD to induce regulatory functions in B cells as part of the mechanism for T cell suppression in EAE

Part of the mechanism by which 2,3,7.8-tetrachlorodibenzo-p-dioxin (TCDD) suppresses immune function involves induction of regulatory T cells and suppression of effector T cells. The goal of this project was to examine whether TCDD's suppression of effector T cells was due in part to inducing B regulatory cells (Bregs). TCDD's potential to increase the percentage and/or function of CD24+CD38+ B cells was assessed in response to lipopolysaccharide (LPS) + interleukin (IL)-4 in vitro and in a mild model of experimental autoimmune encephalomyelitis (EAE) in vivo. In vitro, TCDD did not consistently increase the percentage of CD19+CD24+CD38+ cells using splenocytes, purified B cells or bone marrow (BM) cells. However, TCDD increased IL-10 in all three culture preparations, and TCDD increased the percentage of CD5+CD24+CD38+ cells producing IL-10. In EAE, TCDD did not affect the percentage of the CD24+CD38+ cell population in CD19, B220 or CD5 B cells in splenocytes (SPLC), lymph nodes (LN) nor BM cells at end-stage disease. On the other hand, TCDD increased the CD19+CD24+CD38+ percentage in the spinal cord (SC) in EAE. Moreover, TCDD-treated B cells isolated from spleens or TCDD-treated BM cells in EAE mice modestly reduced the ability of naïve effector T cells to express interferon (IFN)-γ and tumor necrosis factor (TNF)-α. Together these data show that TCDD can induce regulatory functions in B cells, although it was not obvious simply by examining the expression of regulatory markers but by assessing function by cytokine production or mixed lymphocyte responses.

[The contribution of teleconsultation and isolation of symptomatic cases in control of the COVID-19 outbreak a military base]

Position du problème

La première vague de la COVID-19 a déferlé sur la France au cours du premier trimestre 2020 entraînant une saturation du réseau de soins. Nous avons voulu étudier, au sein d’une antenne médicale militaire française soutenant un des plus grands effectifs des armées, l’impact de la téléconsultation ainsi que de l’isolement systématique de tous les cas possibles, probables et confirmés de COVID-19.

Méthodes

Il s’agit d’une étude rétrospective réalisée du 9 mars au 31 mai 2020 à partir de notre registre d’activité. Les variables recueillies étaient notamment le type d’épisode, le statut professionnel, la classification du cas et la date de début des symptômes. Nous avons mis en parallèle notre activité à celle de SOS Médecins et des services d’urgence d’Île-de-France.

Résultats et discussion

Au cours de cette période, 1719 épisodes de soins (téléconsultations ou consultations physiques) ont été enregistrés dont 91 % (n = 1561) en lien avec la COVID-19. Nous avons identifié 598 cas “suspects” (possibles et probables) et confirmés. Les téléconsultations “isolées” (non suivies d’une consultation médicale en présentiel, d’un prélèvement ou ayant nécessité l’envoi de prompt-secours) ont représenté 86 % des épisodes de soins (n = 1482). La comparaison de notre activité et du nombre de nouveaux cas aux bases de données de SOS Médecins et des services d’urgences d’Île-de-France laisse supposer que notre stratégie d’isolement a été rapidement efficace.

Conclusion

L’apport de la téléconsultation a été majeur et sécurisant. La téléconsultation permet d’absorber un volume de patients important, est facile à mettre en œuvre et se caractérise par l’absence de risque nosocomial. L’isolement des patients contaminés doit constituer une priorité en période épidémique. Cette attitude doit s’étendre, lorsque l’on veut maitriser rapidement une épidémie, à l’ensemble des patients symptomatiques.