Assessment of the impact of aerosol from heated tobacco compared with cigarette smoke on experimental rheumatoid arthritis Cintia Scucuglia Heluany1; Pablo Scharf1; Ayda Henriques Schneider2; Paula Barbim Donate2; Fernando Queiroz Cunha2; Sandra Helena Poliselli Farsky1* 1Department of Clinical and Toxicological Analysis, Faculty of Pharmaceutical Sciences, University of São Paulo, Brazil; 2Department of Pharmacology, Faculty of Pharmaceutical Sciences, Ribeirão Preto Medical School, University of São Paulo, Brazil c.heluany@surrey.ac.uk Rheumatoid arthritis (RA) is chronic autoimmune disease which is aggravated in smokers. Alternative modified-risk tobacco products are being developed to provide substitute products for smokers who are unable or unwilling to quit. Among then, heat- not-burn tobacco (HNBT) products generate reduced yields of toxicants compared with cigarettes and hold great potential for reducing the harms associated with tobacco. We aimed to investigate and compare the effects of CS exposure and the aerosol from HNBT on an experimental RA model. Male adults C57BL/6 mice were exposed to air, HNBT or commercial cigarettes in smoking chambers, following the Canada regimen, for 1 hour, twice a day, during the developmental phase of antigen-induced arthritis (AIA), between days 14 to 20. Mice were injected s.c. on day 0 with 500 μg of mBSA in an emulsion of saline and CFA, and boosted on days 7 and 14 with the same preparation in IFA. Intra-articular challenge was carried out on day 21 and after 24 h clinical symptoms were evaluated. Data obtained showed CS-exposed mice presented higher levels of blood carboxihemoglobin, higher articular hyperalgesia and edema, higher amount of NETs and MCP-1 in the synovia and higher number of granulocytes in the bone marrow than their counterparts. HNBT-exposed mice presented similar picture of the disease than air-exposed mice, except by reduced influx of cells in the synovial fluid. Nevertheless, such CS or HNBT exposures reduced the amount of IL-10 in the synovia and number of splenocytes and cells in the DLNs. Moreover, CS delivered higher amounts of toxic metals into exposure chambers, and lungs of CS-exposed mice showed higher histopathological score than other groups. Our data highlight HNBT exposure does not worse the local and systemic AIA symptomatology as CS exposure does, providing novel evidence surrounding the HNBT as a possible alternative to reduce the smoking-related health risks, mainly in chronic diseases. CONCLUSION METHODS Financial support Financial support: *Ethics Local Committee (Protocol CEUA/FCF -USP #563) Male C57BL/6 mice were exposed, 1 hour, 2 times/day, using a smoking chamber, to synthetic air (control) or heated tobacco (48 Heatsticks/day) or commercial cigarettes (24 cigarettes/day) during the developmental phase of antigen-induced arthritis (AIA), as shown in the scheme below. On day 21, mice were challenged by i.a injection of mBSA (30 µg) into the knee joint and after 24h, animals were euthanized and clinical parameters were assessed. Day 0 Day 7 Day 14 Day 21 Booster mBSA + IFA s.c. Booster mBSA + IFA s.c Immunization mBSA + CFA Intra-articular challenge + 24h: Euthanasia Day 20 Air Heated tobacco Cigarette smoke 1 hour (2x/day) (between days 14-20) AIM Investigate and compare the effects of cigarette smoke exposure and the aerosol from heated tobacco on an experimental rheumatoid arthritis (RA) model. Cigarette smoke (CS): major environmental risk factor involved with the induction and aggravation of rheumatoid arthritis (RA) Alternative modified-risk tobacco products are being developed to provide substitute products for smokers who are unable or unwilling to quit. Among then: heat-not-burn tobacco products generate reduced yields of toxicants compared with cigarettes and hold great potential for reducing the harms associated with cigarette use. RESULTS INTRODUCTION 2) CS increased the neutrophil influx into the joints and the product