Contents lists available at ScienceDirect Parasitology International journal homepage: www.elsevier.com/locate/parint Natural nodular worm infection in goats induces eosinophil extracellular DNA trap (EET) formation Anisuzzaman a , Abu Anas a , Md. Golam Yasin a , Sharmin Shahid Labony a , Md. Mokbul Hossain b , Nurjahan Begum b , Takeshi Hatta c , Naotoshi Tsuji c, ⁎ , Md. Abdul Alim a, ⁎ a Department of Parasitology, Faculty of Veterinary Science, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh b Department of Pathology, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh c Department of Parasitology, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami, Sagamihara, Kanagawa 252-0374, Japan ABSTRACT Extracellular DNA Trap (ET) formation by granulocyte is a strong innate immune machinery that plays crucial roles in trapping and killing of pathogens. Here, we show Eosinophil Extracellular DNA Trap (EET) formation in goats naturally infected with nodular worms (Oesophagostomum columbianum, Strongyloidae: Nematoda). By a slaughterhouse based survey, we found that 60% goats were infected with nodular worms. We detected numerous, hard and pale yellow to dark black nodules of variable sizes (0.25–2 cm) in the large intestine and the number of nodules were signifcantly (p < .05) higher in the cecum (21.7 ± 17.9) than in the colon (10.1 ± 9.9). Histologically, pink colored circumscribed caseous mass was surrounded by a dense zone of infltration and fbrous proliferation along with massive infltration of eosinophils in and around the necrotic mass. DAPI staining revealed huge accumulation of extracellular DNA, which formed wide ridge like structure surrounding the necrotic zone. Massive release of eosinophils cationic proteins (ECP), a helmintho-toxic substance, was found into the lesions. Collectively, our results suggest that nodular worm infection induces EETosis and ECP release, and is one of the major parasitic problem afecting Black Bengal goats that causes distortion of normal architecture of the gut wall. 1. Introduction Extracellular DNA Trap (ET) formation by granulocytes is a strong innate immune mechanism that plays vital roles in trapping and killing of pathogens. ET formation by neutrophils (referred as NETosis, neu- trophil extracellular DNA trap) was frst proposed by Brinkmann et al. [1] about a decade ago in bacterial infections and was shown to trap bacteria. ET consists of nuclear DNA as a backbone decorated with histones, anti-microbial peptides and proteins from granules of granu- locytes [2]. Subsequently, formation of ET was shown to play important roles in trapping and killing of protozoan parasites such as Leismania [3] and apicomplexan protozoa [2,4,5]. Now, it is well established that ET is capable of trapping and killing extracellular pathogens, including helminths [2,6]. ET has been shown to trap Haemonchus contortus and Strongyloides stercoralis larvae in vitro [7,8]. ET is released by a novel ‘benefcial suicidal’ cell death and is quite diferent from apoptosis and necrosis. In NETosis, the recruited cells cast their DNA materials like a ‘fsherman’ to entrap the pathogen and the cells themselves die far earlier than their normal lifespan [1,9]. NADPH oxidase (NOX) plays vital role in the formation of ET [10]. Recent studies suggest that parasitic molecules originated from teguments and excretory/secretory products can also induce this efector mechanism [11]. Not only in pathogen induced infammations, NETosis is now implicated to play roles in sterile infammations such as atherosclerosis, thrombosis, dia- betes, ulcerative colitis and SLE [1,12–14]. Furthermore, NETosis has been observed in cancer [15–17]. Goat (Capra hircus) rearing is very common in villages, especially, among poor and pro-poor jobless women, thus; plays an important role in poverty alleviation in Bangladesh. However, parasitism is one of the major obstacles in goat rearing in Bangladesh that bears major eco- nomic impact [18,19]. Oesophagostomum columbianum is a nematode and is commonly known as a “nodular worm” that causes oesopha- gostomiasis or “pimply gut”, a severe chronic granolomatous enteritis in goats [20–22]. Major pathologies are induced by the migratory, immature stages and they produce granuloma, caseous lesions or ab- scesses around the encysted larvae in the small and large intestinal wall, and the disease become life-threatening. The pathology includes hy- perplasia of the goblet cells, infltration of plasma cells, macrophages, lymphocytes, and epitheloidcells; ultimately, leading to protein losing enteropathy, hypoproteinemia, anaemia and death [20,21]. However, innate immune response such as NETosis against nodular worm infec- tion is yet to be demonstrated. Here, we elegantly show Eosinophil Extracellular DNA Trap (EET) formation along with some epidemio- logic aspects of oesophagostomiasis in goats naturally infected with O. https://doi.org/10.1016/j.parint.2020.102178 Received 28 March 2020; Received in revised form 23 June 2020; Accepted 13 July 2020 ⁎ Corresponding authors. E-mail addresses: tsujin@med.kitasato-u.ac.jp (N. Tsuji), aalimpara@bau.edu.bd (Md. A. Alim). Parasitology International 79 (2020) 102178 Available online 20 August 2020 1383-5769/ © 2020 Elsevier B.V. All rights reserved. T