{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,15]],"date-time":"2026-10-15T15:43:42Z","timestamp":1792079022452,"version":"4.4.0"},"reference-count":52,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2021,9,28]],"date-time":"2021-09-28T00:00:00Z","timestamp":1632787200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000027","name":"National Institute on Alcohol Abuse and Alcoholism","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100000027","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Endocrinol."],"abstract":"<jats:p>\n                    Scleroderma, or systemic sclerosis, is a multi-organ connective tissue disease resulting in fibrosis of the skin, heart, and lungs with no effective treatment. Endocannabinoids acting\n                    <jats:italic>via<\/jats:italic>\n                    cannabinoid-1 receptors (CB\n                    <jats:sub>1<\/jats:sub>\n                    R) and increased activity of inducible NO synthase (iNOS) promote tissue fibrosis including skin fibrosis, and joint targeting of these pathways may improve therapeutic efficacy. Recently, we showed that in mouse models of liver, lung and kidney fibrosis, treatment with a peripherally restricted hybrid CB\n                    <jats:sub>1<\/jats:sub>\n                    R\/iNOS inhibitor (MRI-1867) yields greater anti-fibrotic efficacy than inhibiting either target alone. Here, we evaluated the therapeutic efficacy of MRI-1867 in bleomycin-induced skin fibrosis. Skin fibrosis was induced in C57BL\/6J (B6) and Mdr1\n                    <jats:sub>a\/b<\/jats:sub>\n                    -Bcrp triple knock-out (KO) mice by daily subcutaneous injections of bleomycin (2 IU\/100 \u00b5L) for 28 days. Starting on day 15, mice were treated for 2 weeks with daily oral gavage of vehicle or MRI-1867. Skin levels of MRI-1867 and endocannabinoids were measured by mass spectrometry to assess target exposure and engagement by MRI-1867. Fibrosis was characterized histologically by dermal thickening and biochemically by hydroxyproline content. We also evaluated the potential increase of drug-efflux associated ABC transporters by bleomycin in skin fibrosis, which could affect target exposure to test compounds, as reported in bleomycin-induced lung fibrosis. Bleomycin-induced skin fibrosis was comparable in B6 and Mdr1\n                    <jats:sub>a\/b<\/jats:sub>\n                    -Bcrp KO mice. However, the skin level of MRI-1867, an MDR1 substrate, was dramatically lower in B6 mice (0.023 \u00b5M) than in Mdr1\n                    <jats:sub>a\/b<\/jats:sub>\n                    -Bcrp KO mice (8.8 \u00b5M) due to a bleomycin-induced increase in efflux activity of MDR1 in fibrotic skin. Furthermore, the endocannabinoids anandamide and 2-arachidonylglycerol were elevated 2-4-fold in the fibrotic\n                    <jats:italic>vs<\/jats:italic>\n                    . control skin in both mouse strains. MRI-1867 treatment attenuated bleomycin-induced established skin fibrosis and the associated increase in endocannabinoids in Mdr1\n                    <jats:sub>a\/b<\/jats:sub>\n                    -Bcrp KO mice but not in B6 mice. We conclude that combined inhibition of CB\n                    <jats:sub>1<\/jats:sub>\n                    R and iNOS is an effective anti-fibrotic strategy for scleroderma. As bleomycin induces an artifact in testing antifibrotic drug candidates that are substrates of drug-efflux transporters, using Mdr1\n                    <jats:sub>a\/b<\/jats:sub>\n                    -Bcrp KO mice for preclinical testing of such compounds avoids this pitfall.\n                  <\/jats:p>","DOI":"10.3389\/fendo.2021.744857","type":"journal-article","created":{"date-parts":[[2021,9,28]],"date-time":"2021-09-28T01:39:49Z","timestamp":1632793189000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":24,"title":["Peripheral Hybrid CB1R and iNOS Antagonist MRI-1867 Displays Anti-Fibrotic Efficacy in Bleomycin-Induced Skin Fibrosis"],"prefix":"10.3389","volume":"12","author":[{"given":"Charles N.","family":"Zawatsky","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Joshua K.","family":"Park","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jasmina","family":"Abdalla","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"George","family":"Kunos","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Malliga R.","family":"Iyer","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Resat","family":"Cinar","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2021,9,28]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","DOI":"10.1146\/annurev-pathol-011110-130312","article-title":"The Pathogenesis of Systemic Sclerosis","volume":"6","author":"Katsumoto","year":"2011","journal-title":"Annu Rev Pathol"},{"key":"B2","doi-asserted-by":"publisher","DOI":"10.1016\/S0889-857X(03)00022-X","article-title":"Scleroderma Epidemiology","volume":"29","author":"Mayes","year":"2003","journal-title":"Rheum Dis Clin North Am"},{"key":"B3","doi-asserted-by":"publisher","DOI":"10.1136\/annrheumdis-2013-204487","article-title":"All Participating, Disease Progression in Systemic Sclerosis-Overlap Syndrome Is Significantly Different From Limited and Diffuse Cutaneous Systemic Sclerosis","volume":"74","author":"Moinzadeh","year":"2015","journal-title":"Ann Rheum Dis"},{"key":"B4","doi-asserted-by":"publisher","DOI":"10.1136\/ard.2006.066068","article-title":"Changes in Causes of Death in Systemic Sclerosis, 1972-2002","volume":"66","author":"Steen","year":"2007","journal-title":"Ann Rheum Dis"},{"key":"B5","doi-asserted-by":"publisher","DOI":"10.1097\/DAD.0b013e3182712d1a","article-title":"Dermal Dendritic Cell Population and Blood Vessels Are Diminished in the Skin of Systemic Sclerosis Patients: Relationship With Fibrosis Degree and Disease Duration","volume":"35","author":"de-Sa-Earp","year":"2013","journal-title":"Am J Dermatopathol"},{"key":"B6","doi-asserted-by":"publisher","first-page":"411","DOI":"10.1007\/s11926-014-0411-1","article-title":"Recent Advances in Understanding the Pathogenesis of Scleroderma-Interstitial Lung Disease","volume":"16","author":"Akter","year":"2014","journal-title":"Curr Rheumatol Rep"},{"key":"B7","article-title":"Systemic Sclerosis: From Pathogenesis to Targeted Therapy","volume":"33","author":"Denton","year":"2015","journal-title":"Clin Exp Rheumatol"},{"key":"B8","doi-asserted-by":"publisher","DOI":"10.1016\/j.lfs.2003.10.042","article-title":"iNOS-Mediated Nitric Oxide Production and Its Regulation","volume":"75","author":"Aktan","year":"2004","journal-title":"Life Sci"},{"key":"B9","doi-asserted-by":"publisher","first-page":"521958","DOI":"10.1155\/2012\/521958","article-title":"Modulation of Fibrosis in Systemic Sclerosis by Nitric Oxide and Antioxidants","volume":"2012","author":"Dooley","year":"2012","journal-title":"Cardiol Res Pract"},{"key":"B10","doi-asserted-by":"publisher","DOI":"10.1006\/niox.2000.0309","article-title":"Increased Nitric Oxide Production in Patients With Systemic Sclerosis","volume":"4","author":"Sud","year":"2000","journal-title":"Nitric Oxide"},{"key":"B11","doi-asserted-by":"publisher","DOI":"10.1016\/S1089-8603(02)00120-9","article-title":"Effect of N-Acetyl-L-Cysteine on Peroxynitrite and Superoxide Anion Production of Lung Alveolar Macrophages in Systemic Sclerosis","volume":"7","author":"Failli","year":"2002","journal-title":"Nitric Oxide"},{"key":"B12","article-title":"Nitric Oxide Production and Inducible Nitric Oxide Synthase Expression in Systemic Sclerosis","volume":"25","author":"Yamamoto","year":"1998","journal-title":"J Rheumatol"},{"key":"B13","doi-asserted-by":"publisher","DOI":"10.1093\/rheumatology\/41.8.843","article-title":"Beauty and the Beast. 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