Introduction The inflammatory potential of SARS-CoV-2 Spike S1 (Spike) has never been tested in human primary macrophages (MΦ). Different recombinant Spikes might display different effects in vitro, according to protein length and glycosylation, and endotoxin (lipopolysaccharide, LPS) contamination. Objectives To assess (1) the effects of different Spikes on human primary MΦ inflammation; (2) whether LPS contamination of recombinant Spike is (con)cause in vitro of increased MΦ inflammation. Methods Human primary MΦ were incubated in the presence/absence of several different Spikes (10 nM) or graded concentrations of LPS. Pro-inflammatory marker expression (qPCR and ELISA) and supernatant endotoxin contamination (LAL test) were the main readouts. Results LPS-free, glycosylated Spike (the form expressed in infected humans) caused no inflammation in human primary MΦ. Two (out of five) Spikes were contaminated with endotoxins ≥ 3 EU/ml and triggered inflammation. A non-contaminated non-glycosylated Spike produced in E. coli induced MΦ inflammation. Conclusions Glycosylated Spike per se is not pro-inflammatory for human MΦ, a feature which may be crucial to evade the host innate immunity. In vitro studies with commercially available Spike should be conducted with excruciating attention to potential LPS contamination. Graphical abstract

Ketogenesis takes place in hepatocyte mitochondria where acetyl-CoA derived from fatty acid catabolism is converted to ketone bodies (KB), namely β-hydroxybutyrate (β-OHB), acetoacetate and acetone. KB represent important alternative energy sources under metabolic stress conditions. Ketogenic diets (KDs) are low-carbohydrate, fat-rich eating strategies which have been widely proposed as valid nutritional interventions in several metabolic disorders due to its substantial efficacy in weight loss achievement. Carbohydrate restriction during KD forces the use of FFA, which are subsequently transformed into KB in hepatocytes to provide energy, leading to a significant increase in ketone levels known as “nutritional ketosis”. The recent discovery of KB as ligands of G protein-coupled receptors (GPCR) - cellular transducers implicated in a wide range of body functions - has aroused a great interest in understanding whether some of the clinical effects associated to KD consumption might be mediated by the ketone/GPCR axis. Specifically, anti-inflammatory effects associated to KD regimen are presumably due to GPR109A-mediated inhibition of NLRP3 inflammasome by β-OHB, whilst lipid profile amelioration by KDs could be ascribed to the actions of acetoacetate via GPR43 and of β-OHB via GPR109A on lipolysis. Thus, this review will focus on the effects of KD-induced nutritional ketosis potentially mediated by specific GPCRs in metabolic and endocrinological disorders. To discriminate the effects of ketone bodies per se, independently of weight loss, only studies comparing ketogenic vs isocaloric non-ketogenic diets will be considered as well as short-term tolerability and safety of KDs.

Objective: To investigate the role of CTLA-4, PD-1 (programmed death-1), and PD-L1 (programmed death-ligand 1) single nucleotide polymorphisms (SNPs) in predicting clinical outcome of patients with advanced non-small cell lung cancer (NSCLC) treated with immune checkpoint inhibitors (ICIs). Methods: A total of 166 consecutive patients were included. We correlated SNPs with clinical benefit, progression-free survival, time to treatment failure, and overall survival and evaluated the incidence of SNPs in nonresponder and long clinical benefit groups. Results: Considering the entire cohort, no correlation was found between SNPs and clinical outcome; however, PD-L1 rs4143815 SNP and the long clinical benefit group showed a statistically significant association ( p = 0.02). The nonresponder cohort displayed distinctive PD-L1 haplotype ( p = 0.05). Conclusion: PD-L1 SNPs seem to be marginally involved in predicting clinical outcome of NSCLC treated with ICI, but further investigations are required.

Background Empagliflozin can curb inflammation and oxidative stress, through sodium-proton exchanger (NHE) inhibition, in a model of lipotoxicity in human myeloid angiogenic cells (MAC), which mediate endothelial repairing processes. Aim of this study is to assess in human MAC whether: (1) Stearic acid (SA) induced inflammation and increase in oxidant stress is accompanied by bioenergetic alterations; (2) empagliflozin anti-lipotoxic action is concomitant with coherent changes in bioenergetic metabolism, possibly via NHE blockade. Methods MAC were isolated from peripheral blood of healthy volunteers and incubated in the presence/absence of SA (100 μM for 3 h) with/without empagliflozin (EMPA 100 μM) or amiloride (Ami 100 μM) for 1 h. Cell respiration (oxygen consumption rate OCR) and anaerobic glycolysis (measured as proton production rate) were recorded in real-time by Seahorse technology, and ATP production (anaerobic glycolysis- and oxphos-derived) rates were calculated. Results SA, at the concentration causing inflammation and increased oxidant stress, altered cell bioenergetics of human MAC, with overall reductions in basal OCR and oxphos-derived ATP production (all p < 0.05), pointing to mitochondrial alterations. EMPA, at the concentration counteracting SA-induced lipotoxicity, both alone and in the presence of SA, caused NHE-independent extensive bioenergetic alterations (from p < 0.05 to p < 0.01), greater than those induced by SA alone. Conclusions In human MAC: (1) SA altered cell bioenergetics, concomitantly with inflammation and oxidant stress; (2) EMPA possibly inhibited mitochondrial respiration, (3) the protective effect of EMPA against SA-induced lipotoxicity was unlikely to be mediated through bioenergetic metabolism.

SGLT-2 inhibitors (SGLT2i) reduce cardiovascular (CV) risk in people with type 2 diabetes and atherosclerotic CV diseases. The inflammatory function of macrophages (Mφ) - which play a pivotal role in atherosclerosis - is strictly dependent on their metabolism. Aim: To determine whether empagliflozin (EMPA) reduces inflammation and modifies bioenergetic metabolism in proinflammatory human Mφ (M1). Methods: M1 were differentiated from healthy donors’ monocytes and incubated with/without EMPA 100 µM for 16h. Biomarkers of inflammation and oxidative stress were quantified by qPCR. Steady-state energetic metabolism (fluxes: pmol/min for 5x104 cells) was measured by indirect microcalorimetry [oxidations of lipids (LipOX,) glucose and amino acids; anaerobic glycolysis (AnaerGlyc); tricarboxylic acid cycle (TCA); energy expenditure (EPR); maximum estimate of ATP production (ATPflux)] which is based on the integration of measured O2 and H+ (Agilent Seahorse), lactate and NH4 (enzymatic method) fluxes with the stoichiometric equations of metabolic pathways. Results: In M1, EMPA reduces (≈50%) inflammation (IL1β, IL8, TNFα and MCP1; p&lt;0.05-0.001) and oxidative stress (GPX and HO-1; p &lt;0.05). EMPA lowers OCR (133±9.7 vs. 153±10.3, p&lt;0.001), LipOX (1.15±0.1 vs. 1.33±0.1; p&lt;0.005), TCA (45±3 vs. 52±4; p&lt;0.001), AnaerGlyc (210±23 vs. 268±24; p&lt;0.01), ATPflux (1097±94 vs. 1313±94; p&lt;0.005) and EPR (83±7 vs. 98±7 µJ/min; p&lt;0.001). After dissipating mitochondrial membrane potential and forcing maximal OCR with FCCP, TCA (77±11 vs. 97±12, p=0.001), LipOX (1.7±0.3 vs. 2.2±0.4, p&lt;0.005) and EPR (125±17 vs. 153±17; p&lt;0.005), but not AnaerGlyc, remain inhibited by EMPA. Conclusions: EMPA alters M1 inflammation along with cytosolic (AnaerGlyc) and - to a greater extent - mitochondrial (TCA) bioenergetics. EMPA-induced metabolic dysfunction of M1 in vivo might result into reduced metaflammation and contribute to SGLT2i-dependent CV protection. Disclosure V. Spigoni: None. G. Cinquegrani: None. F. Fantuzzi: None. S. Lorusso: None. A. Dei cas: Other Relationship; Self; Novo Nordisk. R. C. Bonadonna: Advisory Panel; Self; Sanofi, Speaker’s Bureau; Self; AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Eli Lilly and Company. Funding Italian Diabete Ricerca Foundation; Eli Lilly Italy