{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,1]],"date-time":"2026-10-01T15:05:31Z","timestamp":1790867131383,"version":"4.1.0"},"reference-count":35,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2021,10,8]],"date-time":"2021-10-08T00:00:00Z","timestamp":1633651200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100006507","name":"Funda\u00e7\u00e3o Oswaldo Cruz","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100006507","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Med."],"abstract":"<jats:p>\n                    Erythema Nodosum Leprosum (ENL) is a recurrent acute inflammatory complication of leprosy affecting up to 50% of all Borderline Lepromatous and Lepromatous Leprosy (BL\/LL) patients. Although ENL is described as an immune reaction mediated by neutrophils, studies demonstrating the direct role of neutrophils in ENL are still rare. One subpopulation of low-density neutrophils (LDNs), present within the fraction of peripheral blood mononuclear cells (PBMC), has been associated with the pathogenesis and severity of diseases like sepsis, lupus, and tuberculosis. We herein analyzed LDNs and high-density neutrophils (HDNs) in terms of frequency, phenotype, and morphology. Serum levels of MMP-9 (a neutrophilic degranulation marker) were evaluated by ELISA; and LDNs were generated\n                    <jats:italic>in vitro<\/jats:italic>\n                    by stimulating healthy-donor, whole-blood cultures. PBMC layers of ENL patients presented segmented\/hypersegmented cells that were morphologically compatible with neutrophils. Immunofluorescence analyses identified LDNs in ENL. Flow cytometry confirmed the elevated frequency of circulating LDNs (CD14\n                    <jats:sup>\u2212<\/jats:sup>\n                    CD15\n                    <jats:sup>+<\/jats:sup>\n                    ) in ENL patients compared to healthy donors and nonreactional Borderline Tuberculoid (BT) patients. Moreover, flow cytometry analyses revealed that ENL LDNs had a neutrophilic-activated phenotype. ENL patients under thalidomide treatment presented similar frequency of LDNs as observed before treatment but its activation status was lower. In addition,\n                    <jats:italic>Mycobacterium leprae<\/jats:italic>\n                    induced\n                    <jats:italic>in vitro<\/jats:italic>\n                    generation of LDNs in whole blood in a dose-dependent fashion; and TGF-\u03b2, an inhibitor of neutrophilic degranulation, prevented LDNs generation. MMP-9 serum levels of BL\/LL patients with or without ENL correlated with LDNs frequency at the same time that ultrastructural observations of ENL LDNs showed suggestive signs of degranulation. Together, our data provide new insights into the knowledge and understanding of the pathogenesis of ENL while enriching the role of neutrophils in leprosy.\n                  <\/jats:p>","DOI":"10.3389\/fmed.2021.711623","type":"journal-article","created":{"date-parts":[[2021,10,10]],"date-time":"2021-10-10T10:53:03Z","timestamp":1633863183000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":13,"title":["Mycobacterium leprae Induces Neutrophilic Degranulation and Low-Density Neutrophil Generation During Erythema Nodosum Leprosum"],"prefix":"10.3389","volume":"8","author":[{"given":"Isabella Forasteiro","family":"Tavares","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jessica Brand\u00e3o","family":"dos Santos","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fabiana dos Santos","family":"Pacheco","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mariana","family":"Gandini","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rafael M.","family":"Mariante","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Thais Fernanda","family":"Rodrigues","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anna Maria","family":"Sales","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Milton Oz\u00f3rio","family":"Moraes","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Euzenir Nunes","family":"Sarno","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Veronica","family":"Schmitz","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2021,10,8]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"1209","DOI":"10.1016\/S0140-6736(04)15952-7","article-title":"Leprosy","volume":"363","author":"Britton","year":"2004","journal-title":"Lancet"},{"key":"B2","first-page":"255","article-title":"Classification of leprosy according to immunity. A five-group system","volume":"34","author":"Ridley","year":"1966","journal-title":"Int J Lepr Mycobact Dis."},{"key":"B3","doi-asserted-by":"publisher","first-page":"363","DOI":"10.1590\/S0036-46651998000600005","article-title":"Reactional states in multibacillary Hansen disease patients during multidrug therapy","volume":"40","author":"Nery","year":"1998","journal-title":"Rev Inst Med Trop S\u00e3o Paulo"},{"key":"B4","doi-asserted-by":"publisher","first-page":"e2440","DOI":"10.1371\/journal.pntd.0002440","article-title":"A systematic review on the epidemiological data of erythema nodosum leprosum, a type 2 leprosy reaction","volume":"7","author":"Voorend","year":"2013","journal-title":"PLoS Negl Trop Dis."},{"key":"B5","doi-asserted-by":"publisher","first-page":"233","DOI":"10.3389\/fimmu.2017.00233","article-title":"A systematic review of immunological studies of erythema Nodosum Leprosum","volume":"8","author":"Polycarpou","year":"2017","journal-title":"Front Immunol."},{"key":"B6","doi-asserted-by":"publisher","first-page":"47","DOI":"10.4049\/immunohorizons.1900088","article-title":"Erythema Nodosum Leprosum neutrophil subset expressing IL-10R1 transmigrates into skin lesions and responds to IL-10","volume":"4","author":"Pacheco","year":"2020","journal-title":"Immuno Horizons"},{"key":"B7","doi-asserted-by":"publisher","first-page":"e0007368","DOI":"10.1371\/journal.pntd.0007368","article-title":"Neutrophil extracellular traps contribute to the pathogenesis of leprosy type 2 reactions","volume":"13","author":"Silva","year":"2019","journal-title":"PLoS Negl Trop Dis"},{"key":"B8","doi-asserted-by":"publisher","first-page":"73ra20","DOI":"10.1126\/scitranslmed.3001201","article-title":"Netting neutrophils are major inducers of type I IFN production in pediatric systemic lupus erythematosus","volume":"3","author":"Garcia-Romo","year":"2011","journal-title":"Sci Transl Med"},{"key":"B9","doi-asserted-by":"publisher","first-page":"538","DOI":"10.4049\/jimmunol.1100450","article-title":"Netting neutrophils induce endothelial damage, infiltrate tissues, and expose immunostimulatory molecules in systemic lupus erythematosus","volume":"187","author":"Villanueva","year":"2011","journal-title":"J Immunol."},{"key":"B10","doi-asserted-by":"publisher","first-page":"e1003993","DOI":"10.1371\/journal.ppat.1003993","article-title":"Immune suppression by neutrophils in HIV-1 infection: role of PD-L1\/PD-1 pathway","volume":"10","author":"Bowers","year":"2014","journal-title":"PLoS Pathog"},{"key":"B11","doi-asserted-by":"publisher","first-page":"e0153567","DOI":"10.1371\/journal.pone.0153567","article-title":"Low-density granulocytes are elevated in mycobacterial infection and associated with the severity of tuberculosis","volume":"11","author":"Deng","year":"2016","journal-title":"PLoS One."},{"key":"B12","doi-asserted-by":"publisher","first-page":"1239","DOI":"10.1189\/jlb.4HI0616-255R","article-title":"Frontline science: defects in immune function in patients with sepsis are associated with PD-1 or PD-L1 expression and can be restored by antibodies targeting PD-1 or PD-L1","volume":"100","author":"Patera","year":"2016","journal-title":"J Leukoc Biol"},{"key":"B13","doi-asserted-by":"publisher","first-page":"90969","DOI":"10.18632\/oncotarget.18771","article-title":"Phenotypic and clinical characterization of low density neutrophils in patients with advanced lung adenocarcinoma","volume":"8","author":"Liu","year":"2017","journal-title":"Oncotarget"},{"key":"B14","doi-asserted-by":"publisher","first-page":"632","DOI":"10.1038\/s41598-017-19091-2","article-title":"Low density neutrophils (LDN) in postoperative abdominal cavity assist the peritoneal recurrence through the production of neutrophil extracellular traps (NETs)","volume":"8","author":"Kanamaru","year":"2018","journal-title":"Sci Rep"},{"key":"B15","doi-asserted-by":"publisher","first-page":"3284","DOI":"10.4049\/jimmunol.0902199","article-title":"A distinct subset of proinflammatory neutrophils isolated from patients with systemic lupus erythematosus induces vascular damage and synthesizes type I IFNs","volume":"184","author":"Denny","year":"2010","journal-title":"J Immunol"},{"key":"B16","doi-asserted-by":"publisher","first-page":"562","DOI":"10.1016\/j.celrep.2014.12.039","article-title":"Phenotypic diversity and plasticity in circulating neutrophil subpopulations in cancer","volume":"10","author":"Sagiv","year":"2015","journal-title":"Cell Rep"},{"key":"B17","doi-asserted-by":"publisher","first-page":"e0004065","DOI":"10.1371\/journal.pntd.0004065","article-title":"ENLIST 1: an international multi-centre cross-sectional study of the clinical features of Erythema Nodosum Leprosum","volume":"9","author":"Walker","year":"2015","journal-title":"PLoS Negl Trop Dis"},{"key":"B18","doi-asserted-by":"publisher","first-page":"793","DOI":"10.1084\/jem.20061301","article-title":"The humoral pattern recognition receptor PTX3 is stored in neutrophil granules and localizes in extracellular traps","volume":"204","author":"Jaillon","year":"2007","journal-title":"J Exp Med"},{"key":"B19","doi-asserted-by":"publisher","first-page":"2829","DOI":"10.1016\/j.celrep.2015.11.055","article-title":"Type I interferon transcriptional signature in neutrophils and low-density granulocytes are associated with tissue damage in malaria","volume":"13","author":"Rocha","year":"2015","journal-title":"Cell Rep"},{"key":"B20","doi-asserted-by":"publisher","first-page":"155","DOI":"10.1111\/j.1365-2249.2007.03376.x","article-title":"Inhibition of human neutrophil degranulation by transforming growth factor-beta1","volume":"149","author":"Shen","year":"2007","journal-title":"Clin Exp Immunol"},{"key":"B21","doi-asserted-by":"publisher","first-page":"495","DOI":"10.3389\/fimmu.2019.00495","article-title":"Neutrophils in leprosy","volume":"10","author":"Schmitz","year":"2019","journal-title":"Front Immunol"},{"key":"B22","doi-asserted-by":"publisher","first-page":"80","DOI":"10.1002\/jlb.56.1.80","article-title":"Changes in subcellular localization and surface expression of L-selectin, alkaline phosphatase, and Mac-1 in human neutrophils during stimulation with inflammatory mediators","volume":"56","author":"Borregaard","year":"1994","journal-title":"J Leukoc Biol"},{"key":"B23","doi-asserted-by":"publisher","first-page":"455","DOI":"10.1007\/s00281-013-0375-7","article-title":"Low-density granulocytes: a distinct class of neutrophils in systemic autoimmunity","volume":"35","author":"Carmona-Rivera","year":"2013","journal-title":"Semin Immunopathol"},{"key":"B24","doi-asserted-by":"publisher","first-page":"e48939","DOI":"10.1371\/journal.pone.0048939","article-title":"Characterization of a novel population of low-density granulocytes associated with disease severity in HIV-1 infection","volume":"7","author":"Cloke","year":"2012","journal-title":"PLoS One."},{"key":"B25","doi-asserted-by":"publisher","first-page":"1334","DOI":"10.1002\/art.1780291105","article-title":"Low density neutrophils in patients with systemic lupus erythematosus, rheumatoid arthritis, and acute rheumatic fever","volume":"29","author":"Hacbarth","year":"1986","journal-title":"Arthritis Rheum"},{"key":"B26","doi-asserted-by":"publisher","first-page":"1635","DOI":"10.1093\/infdis\/jix267","article-title":"Elevated pentraxin-3 concentrations in patients with leprosy: potential biomarker of Erythema Nodosum Leprosum","volume":"216","author":"Mendes","year":"2017","journal-title":"J Infect Dis"},{"key":"B27","doi-asserted-by":"publisher","first-page":"1355","DOI":"10.1007\/s00438-020-01705-6","article-title":"Reanalysis and integration of public microarray datasets reveals novel host genes modulated in leprosy","volume":"295","author":"Leal-Calvo","year":"2020","journal-title":"Mol Genet Genomics"},{"key":"B28","doi-asserted-by":"publisher","first-page":"1012","DOI":"10.1128\/IAI.00896-09","article-title":"High matrix metalloproteinase production correlates with immune activation and leukocyte migration in leprosy reactional lesions","volume":"78","author":"Teles","year":"2010","journal-title":"Infect Immun"},{"key":"B29","doi-asserted-by":"publisher","first-page":"214","DOI":"10.1189\/jlb.0605353","article-title":"Regulation of matrix metalloproteinase-9 (MMP-9) in TNF-stimulated neutrophils: novel pathways for tertiary granule release","volume":"79","author":"Chakrabarti","year":"2006","journal-title":"J Leukoc Biol"},{"key":"B30","doi-asserted-by":"publisher","first-page":"448","DOI":"10.3389\/fimmu.2014.00448","article-title":"Granule protein processing and regulated secretion in neutrophils","volume":"5","author":"Sheshachalam","year":"2014","journal-title":"Front Immunol."},{"key":"B31","doi-asserted-by":"publisher","first-page":"6","DOI":"10.1097\/01.qai.0000188336.94090.14","article-title":"CC chemokines induce neutrophils to chemotaxis, degranulation, and alpha-defensin release","volume":"41","author":"Jan","year":"2006","journal-title":"J Acquir Immune Defic Syndr."},{"key":"B32","doi-asserted-by":"publisher","first-page":"3294","DOI":"10.4049\/jimmunol.1800753","article-title":"Increased mitochondrial biogenesis and reactive oxygen species production accompany prolonged CD4+ T cell activation","volume":"201","author":"Akkaya","year":"2018","journal-title":"J Immunol."},{"key":"B33","doi-asserted-by":"publisher","first-page":"254","DOI":"10.1016\/j.ejcb.2017.03.003","article-title":"Mitochondrial reactive oxygen species are involved in chemoattractant-induced oxidative burst and degranulation of human neutrophils in vitro","volume":"96","author":"Vorobjeva","year":"2017","journal-title":"Eur J Cell Biol"},{"key":"B34","doi-asserted-by":"publisher","first-page":"A4","DOI":"10.1186\/1753-6561-9-S1-A4","article-title":"The impact of endoplasmic reticulum stress on neutrophil function in alpha 1 antitrypsin deficiency","volume":"9","author":"Shaharom","year":"2015","journal-title":"BMC Proc"},{"key":"B35","doi-asserted-by":"publisher","first-page":"695","DOI":"10.3390\/cells9030695","article-title":"ER stress responses: an emerging modulator for innate immunity","volume":"9","author":"Di Conza","year":"2020","journal-title":"Cells"}],"container-title":["Frontiers in Medicine"],"original-title":[],"link":[{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fmed.2021.711623\/full","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2021,10,10]],"date-time":"2021-10-10T10:53:06Z","timestamp":1633863186000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fmed.2021.711623\/full"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,10,8]]},"references-count":35,"alternative-id":["10.3389\/fmed.2021.711623"],"URL":"https:\/\/doi.org\/10.3389\/fmed.2021.711623","relation":{},"ISSN":["2296-858X"],"issn-type":[{"value":"2296-858X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,10,8]]},"article-number":"711623"}}