Acute severe SARS COVID-19 patients produce pro-resolving lipids mediators and eicosanoids.

OBJECTIVE: This study aimed to evaluate the eicosanoid and pro resolutive parameters in SARS COVID-19 patients with the severe acute respiratory syndrome. PATIENTS AND METHODS: Fourteen male patients with an acute respiratory syndrome caused by SARS COVID-19 and four healthy controls were evaluated by measuring the following parameters in plasma: Polyunsaturated fatty acids: EPA, DHA, ARA, and DPA. Specialized Pro-resolving mediators (SPMs) (including monohydroxy-containing precursors 17-HDHA, 18-HEPE, 14-HDHA) resolvins, maresins, protectins, and lipoxins. The eicosanoids group included prostaglandins, thromboxanes, and leukotrienes. RESULTS: Plasma from COVID-19 patients presented higher amounts of pro-inflammatory and pro-thrombotic lipid mediators as compared to healthy subjects (65.7 pg/ml vs. 10.2 pg/ml), including thromboxane (2142.6 pg/ml vs. 10.4 pg/ml), and the ratio between total plasma pro-inflammatory mediators versus total SPM's was 13.2 to 0,4, respectively. CONCLUSIONS: A clear disbalance favoring the pro-inflammatory axis is described, showing the need to perform future clinical interventions in these patients using SPM's or monohydroxylated lipid mediators derivates from fatty acids.

Novel mediators and mechanisms in the resolution of infectious inflammation: evidence for vagus regulation.

Excessive chronic inflammation is linked to many diseases and considered a stress factor in humans (Robbins Pathologic Basis of Disease. Philadelphia: W.B. Saunders Co., 1999, Proc Natl Acad Sci USA, 2008, 105: 17949, Immunity, 44, 2016, 44: 463, N Engl J Med, 2011, 364: 656). Today, the resolution of inflammation is widely recognized as a cellular biochemically active process involving biosynthesis of a novel superfamily of endogenous chemical signals coined specialized pro-resolving mediators (SPMs; Nature, 2014, 510:92). Herein, we review recent evidence, indicating a role for the vagus nerve and vagotomy in the regulation of lipid mediators. Vagotomy reduces pro-resolving mediators, including the lipoxins, resolvins, protectins and maresins, delaying resolution in mouse peritonitis. Vagotomy also delays resolution of Escherichia coli infection in mice. Specifically, right vagus regulates peritoneal Group 3 innate lymphoid cell (ILC-3) number and peritoneal macrophage responses with lipid mediator profile signatures with elevated pro-inflammatory eicosanoids and reduced resolvins, including the novel protective immunoresolvent agonist protectin conjugate in tissue regeneration1 (PCTR1). Acetylcholine upregulates PCTR biosynthesis, and administration of PCTR1 to vagotomized mice restores tissue resolution and host responses to E. coli infections. Results obtained with human vagus ex vivo indicate that vagus can produce both pro-inflammatory eicosanoids, such as prostaglandins and leukotrienes, as well as the SPM. Electrical stimulation of human vagus in vitro reduces both prostaglandins and leukotrienes and enhances resolvins and the other SPM. These results elucidate a host protective mechanism mediated by vagus stimulation of SPM that includes resolvins and PCTR1 to regulate myeloid antimicrobial functions and resolution of infection. Moreover, they define a new pro-resolution of inflammation reflex operative in mice and human tissue that involves a vagus SPM circuit.

Induction of hemeoxygenase-1 expression after inhibition of hemeoxygenase activity promotes inflammation and worsens ischemic brain damage in mice.

Hemeoxygenase (HO) is an enzymatic system that degrades heme. HO-1 is an inducible isoform whereas HO-2 is constitutive. Stroke strongly induces HO-1 expression but the underlying mechanisms are not fully elucidated. Cytokines that are up-regulated after ischemia, like interleukin (IL)-10, can induce HO-1 gene expression, which is positively regulated by the transcriptional activator nuclear factor erythroid 2-related factor 2 (Nrf2) and negatively regulated by the transcriptional repressor breast cancer type 1 susceptibility protein (BRCA1) associated C-terminal helicase 1 (Bach-1). While Nrf2 is activated after ischemia and drugs promoting Nrf2 activation increase HO-1 and are beneficial, the involvement of Bach-1 is unknown. Here we investigated mechanisms involved in HO-1 induction and evaluated the effects of HO activity inhibition in mouse permanent middle cerebral artery occlusion (pMCAO). HO-1 was induced after ischemia in IL-10-deficient mice suggesting that post-ischemic HO-1 induction was IL-10-independent. Attenuation of Bach-1 gene repression after ischemia was associated to enhanced HO-1 induction. Administration of the HO activity inhibitor zinc proto-porphyrin IX (ZnPP) i.p. 24h before pMCAO exacerbated ischemia-induced tumor necrosis factor-α (TNF-α) and IL-1ß, nitro-oxidative stress, and the presence of neutrophils at 8h, and increased infarct volume at day 4. However, ZnPP did not worsen ischemic damage when given 30min before pMCAO. ZnPP induced HO-1 expression in the cerebral vasculature at 24h, when it was still detected by high-performance liquid chromatography (HPLC) in plasma. While ZnPP was not found in brain tissue extracts of controls, it could be detected after ischemia, supporting that a small fraction of the injected drug can reach the tissue following blood-brain barrier breakdown. The deleterious effect of inhibiting HO activity in ischemia became apparent in the presence of ZnPP-induced HO-1, which is known to exert effects independent of its enzymatic activity. In conclusion, HO-1 induction after ischemia was associated to down-regulation of transcriptional repressor Bach-1, and induction of HO-1 when HO enzymatic activity was inhibited was related to worst outcome after brain ischemia.