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Infection and Chemotherapy

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110https://icjournal.orgThe coronavirus disease 2019 (COVID-19) which started in Wuhan, China, and affected most of the country, is spreading rapidly throughout the world in spite of the concerted efforts from the governments and World Health Organization (WHO) to contain it. The virus spreads 1000 times faster than the other viral strains inside the body and causes various kind of illnesses [1]. Korea is also adversely affected by COVID-19 due to its geographical proximity to China. Considering the high attack rate and aggressive spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), there is a concern that more serious diseases may develop due to a mutated type of the virus. Some treatment experiences in Korea suggest that steroids played an important role in the treatment of COVID-19. According to reports from China, although pneumonia was rare in the pediatric population, the risk of pneumonia increased with age and had a high mortality rate among the elderly in their 70s (8.0%) and 80s (14.8%) [2].Clinical experiences in Korea (unpublished) and the data from Chinese COVID-19 reports indicate that1) Symptoms were mild and pneumonia was rare in the pediatric population. The elderly was more likely to suffer from severe rapidly progressing pneumonia. [2]2) Pneumonia was usually self-limited and resolved within a few weeks in people with normal immune status, but may result in varying degrees of pulmonary fibrosis.3) Usually responded well to steroid treatment (personal communications)Radiology and pathology examinations of patients with COVID-19 revealed inflammatory reactions in the lung that resembled what is observed in hypersensitivity pneumonitis rather than in other viral pneumonia [3, 4].Hypersensitivity pneumonitis (HP) has three variants, namely, 1) acute, 2) subacute, and 3) chronic. The pathophysiology of HP is determined by genetics, environment, age, and immune reactions (both innate and adaptive) [5].The innate immunity is robust in the pediatric population while the complement system and adaptive immunity are not mature yet [6]. In contrast, the innate immunity is not effective while the complement system is increased in the elderly population. Adaptive immunity develops from childhood to adulthood, but declines with older age. Hence, a healthy adult who has been exposed to seasonal coronaviruses many times may suffer pneumonia due to immune enhancement, which resolves with mobilization of regulatory T cells [7, 8]Infect Chemother. 2020 Mar;52(1):110-112https://doi.org/10.3947/ic.2020.52.1.110pISSN 2093-2340·eISSN 2092-6448EditorialReceived: Mar 8, 2020Accepted: Mar 8, 2020Corresponding Author: Hyoung-Shik Shin, MD, PhDDepartment of Internal Medicine, National Medical Center, Eulji-ro 245, Jung-gu,  Seoul 04564, Korea. Tel: +82-2-2260-7557Fax: +82-2-2268-0803E-mail: hyoungsshin@gmail.comCopyright © 2020 by The Korean Society of Infectious Diseases, Korean Society for Antimicrobial Therapy, and The Korean Society for AIDSThis is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (https://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.KeywordsCOVID-19; Coronavirus; SARS-CoV-2; Hypersensitivity pneumonitisORCID iDsYoung Goo Song https://orcid.org/0000-0002-0733-4156Hyoung-Shik Shin https://orcid.org/0000-0001-6504-3413Conflicts of InterestYGS is an editorial board of the journal Infect Chemother. However, he did not involve in the reviewer selection, evaluation, and decision making of this article. Otherwise, no conflicts of interest were reported.Young Goo Song  1 and Hyoung-Shik Shin  21 Division of Infectious Diseases, Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea2Division of Infectious Diseases, Department of Internal Medicine, National Medical Center, Seoul, KoreaCOVID-19, A Clinical Syndrome Manifesting as Hypersensitivity PneumonitisAuthor contributionsConceptualization: HSS. Writing-original draft: YGS. Writing-review & editing: YGS, HSS.Acute HP is more common in the elderly. The defective innate immunity and the accelerated complement activation induced by SARS-CoV-2, similar to that by SARS CoV, leads to a severe rapidly progressing pneumonitis due to the triggering effect of the virus [9, 10]. In contrast, a healthy adult with normal adaptive immunity controls the inflammatory reaction better through immune regulation and manifests as subacute HP. The innate immunity in the pediatric population appears to block the viral invasion at the mucosal level, and results in minimal to no symptoms.We believe that there is an urgent need to establish a better sophisticated treatment strategy for COVID-19, because there may be a serious risk owing to the subtle mutations of the virus, which can lead to a more aggressive spread and more severe immunologic reaction in the host.HP has been reported in the literature for the past several decades, but its pathophysiology remains poorly understood. The possibility of obtaining the exact pathogenesis is less with the current knowledge and technology. Considering our current understanding of the pathophysiology and clinical features of HP, the treatment strategy for COVID-19 needs to be tailored according to the patient's age and immune status. Traditional HP treatment methods such as decreasing the antigen (virus) and controlling the abnormal immune response must be part of the strategy. SARS-CoV-2 is more likely to spread in the elderly and lead to severe pneumonia. Hence, COVID-19 patients would benefit from the administration of antiviral medications (nucleotide inhibitors, Human Immunodeficiency Virus (HIV) nucleoside reverse transcriptase inhibitor (NRTI), HIV non-nucleoside reverse transcriptase inhibitor (NNRTI), HIV protease inhibitor (PI), dextran sulfate, and combination therapy, etc.) that will limit the spread of less virulent virus both within the body and in the population. Prophylactic and therapeutic low dose steroid oral tablets/inhalers at the earlier stage of COVID-19 and high dose steroid treatment according to the severity of the disease can play important roles in decreasing the fatality and pulmonary fibrosis. Additionally, safer treatment options that control the complement cascade could be considered in cases of acute HP.God Bless You and me… See the Sky with humble eyes and simple minds.REFERENCES 1. Sigrist CJ, Bridge A, Le Mercier P. A potential role for integrins in host cell entry by SARS-CoV-2. Antiviral Res 2020;177:104759.PUBMED | CROSSREF 2. Wu Z, McGoogan JM. Characteristics of and important lessons from the Coronavirus disease 2019 (COVID-19) outbreak in China: Summary of a report of 72,314 cases from the Chinese center for disease control and prevention. JAMA 2020. [Epub ahead of print].PUBMED | CROSSREF 3. Bernheim A, Mei X, Huang M, Yang Y, Fayad ZA, Zhang N, Diao K, Lin B, Zhu X, Li K, Li S, Shan H, Jacobi A, Chung M. Chest CT findings in coronavirus disease-19 (COVID-19): Relationship to duration of infection. Radiology 2020:200463. [Epub ahead of print].PUBMED | CROSSREF 4. Tian S, Hu W, Niu L, Liu H, Xu H, Xiao SY. Pulmonary pathology of early-phase 2019 novel coronavirus (COVID-19) pneumonia in two patients with lung cancer. J Thorac Oncol 2020:pii: S1556-0864(20)30132-5. [Epub ahead of print].PUBMED | CROSSREF 5. King TE Jr. Hypersensitivity pneumonitis (extrinsic allergic alveolitis): Epidemiology, causes, and pathogenesis. Available at: https://www.uptodate.com/contents/hypersensitivity-pneumonitis-extrinsic-allergic-alveolitis-epidemiology-causes-and-pathogenesis. Assecced 7 March 2020.111https://icjournal.org https://doi.org/10.3947/ic.2020.52.1.110COVID-19 manifesting as HP 6. Johnston RB Jr. An overview of the innate immune system. Available at: https://www.uptodate.com/contents/an-overview-of-the-innate-immune-system. Accessed 7 March 2020. 7. Wang SF, Tseng SP, Yen CH, Yang JY, Tsao CH, Shen CW, Chen KH, Liu FT, Liu WT, Chen YM, Huang JC. Antibody-dependent SARS coronavirus infection is mediated by antibodies against spike proteins. Biochem Biophys Res Commun 2014;451:208-14. PUBMED | CROSSREF 8. Chen J, Subbarao K. The immunobiology of SARS. Annu Rev Immunol 2007;25:443-72. PUBMED | CROSSREF 9. Wang R, Xiao H, Guo R, Li Y, Shen B. The role of C5a in acute lung injury induced by highly pathogenic viral infections. Emerg Microbes Infect 2015;4:e28. PUBMED | CROSSREF 10. Gralinski LE, Sheahan TP, Morrison TE, Menachery VD, Jensen K, Leist SR, Whitmore A, Heise MT, Baric RS. Complement activation contributes to severe acute respiratory syndrome coronavirus pathogenesis. mBio 2018;9:pii: e01753-18. PUBMED | CROSSREF112https://icjournal.org https://doi.org/10.3947/ic.2020.52.1.110COVID-19 manifesting as HP

COVID-19, A Clinical Syndrome Manifesting as Hypersensitivity Pneumonitis

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COVID-19, A Clinical Syndrome Manifesting as Hypersensitivity Pneumonitis

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