過敏性氣喘 (allergic asthma) 為一種呼吸道慢性發炎疾病，當過敏性氣喘病人在吸入空氣中特定物質，如屋塵螨(house dust mites)、花粉、真菌孢等過敏原後，會引起氣管平滑肌收縮，病人會有嗜酸性白血球大量浸潤到呼吸道、呼吸道黏液大量分泌及呼吸道過度反應等TH2類型免疫反應的症狀產生。根據世界衛生組織統計調查，過敏性疾病氣喘人數目有逐年增加的趨勢，是一個日益普遍的重大公共衛生問題，影響全球3億人，其中大部分是兒童。在全民健康保險研究資料庫中，我們發現感染過腸病毒A71型的兒童之後患有嚴重氣喘的風險很高。為了進一步研究腸道病毒A71型感染與氣喘惡化之間的關係，我們建立了腸病毒感染誘發後續嚴重氣喘的動物模式，將腸病毒A71型小鼠適應株(EV-A71/MP4)以腹腔注射的方式感染十四天大的BALB/c 小鼠，感染或未感染的小鼠於其四到五周大時，利用鼻腔滴入方式連續十四天給予HDM，犧牲後評估肺部及全身性免疫反應。實驗結果發現，腸病毒感染並給予塵螨致敏的組別比起其他組，具有較差的肺功能，血清中的total IgE及對於Der p有專一性IgE濃度高於其他組別，病理切片也看到感染並致敏組別的小鼠肺部有明顯免疫細胞浸潤、氣管壁增厚及黏液產生的情形，說明了腸病毒感染確實會增加後續嚴重氣喘的可能性，但是其中的詳細機制尚未明瞭。在其他數據中，我們發現在腸病毒感染並經致敏的小鼠肺沖洗液（BALF）細胞中，有嗜酸性球的浸潤，其中特別的是，嗜中性球更顯著性的增加。然而我們發現，感染並致敏組別的小鼠肺沖洗液中TH2-type cytokines濃度反而下降，並且有更高濃度的IL-17產生。另外我們利用流式細胞儀分析在肺中的T cell，發現腸病毒A71型感染且致敏的小鼠顯示出較高比率的Th2和TH17的CD4 + T細胞。然而，病毒的感染是發生在兒童時期，我們猜測或許病毒的感染會對宿主免疫系統進行一種強而持久的教育過程，進而影響到後續的免疫疾病。由我們結果發現，感染後小鼠的BMDM受到腸病毒抗原刺激後會促進骨髓分化而來的巨噬細胞(BMDM)成熟形成inflammatory phenotype。我們推測這些成熟的巨噬細胞會造成強而持久的作用進而影響到後續TH2-TH17調節的嚴重氣喘發生的可能性。

Allergic asthma is a major public-health problem that affects 300 million people worldwide. It has been increased in prevalence rate in recent decades, particularly among children under 12 years of age. Exposed to inhaled allergens, viral infections, and passive tobacco smoke have been correlated with asthma exacerbation in several clinical studies. In the National Health Insurance Research database, we have found that children who have recovered from Enterovirus A71 (EV-A71) have a high risk of getting severe asthma exacerbation. To further investigate the relationships between EV-A71 infection and asthma exacerbation, we employed a clinically relevant mouse model able to recapitulate EV-A71-induced late onset of asthma exacerbation in children. In our study, we found that mice that recovered from EV-A71 infection and then sensitized with house dust mite (HDM) displayed exacerbated features of asthma when compared to control mice, including severe airway hyper-reactivity, higher serum concentrations of total IgE and HDM specific-IgE, and enhanced airway-inflammatory cell infiltration as well as mucus production. We also found that there were increased numbers of neutrophils in the bronchoalveolar lavage fluid of Enterovirus A71-infected allergic mice. Moreover, these mice exhibited Th17 but not Th2 immunity. To further investigate the interaction mechanisms between EV-A71 infection and severe asthma exacerbations, we analyzed mice’s bone marrow derived macrophage (BMDM) and dendritic cell (BMDC) phenotypes. We found that early life EV-A71 infection caused a trained immunity in BMDM, in which EV-A71 trained BMDM to an inflammatory phenotype. We postulated that this inflammatory macrophage conferred strong and lasting effect to induce late onset of asthma exacerbation and caused it toward TH2-TH17 inflammatory pathways.

1. Zannetos S, Zachariadou T, Zachariades A, Georgiou A, Talias MA. The economic burden of adult asthma in Cyprus; a prevalence-based cost of illness study. BMC public health. 2017;17(1):262. Epub 2017/03/18.
2. Proceedings of the ATS workshop on refractory asthma: current understanding, recommendations, and unanswered questions. American Thoracic Society. American journal of respiratory and critical care medicine. 2000;162(6):2341-51. Epub 2000/12/09.
3. Choy DF, Hart KM, Borthwick LA, Shikotra A, Nagarkar DR, Siddiqui S, et al. TH2 and TH17 inflammatory pathways are reciprocally regulated in asthma. Science translational medicine. 2015;7(301):301ra129. Epub 2015/08/21.
4. Wenzel SE. Severe asthma in adults. Experimental lung research. 2005;31 Suppl 1:22. Epub 2006/01/07.
5. Lloyd CM. IL-33 family members and asthma - bridging innate and adaptive immune responses. Current opinion in immunology. 2010;22(6):800-6. Epub 2010/11/13.
6. Lloyd CM, Hessel EM. Functions of T cells in asthma: more than just T(H)2 cells. Nature reviews Immunology. 2010;10(12):838-48. Epub 2010/11/10.
7. Bousquet J, Jeffery PK, Busse WW, Johnson M, Vignola AM. Asthma. From bronchoconstriction to airways inflammation and remodeling. American journal of respiratory and critical care medicine. 2000;161(5):1720-45. Epub 2000/05/12.
8. Bartlett NW, Walton RP, Edwards MR, Aniscenko J, Caramori G, Zhu J, et al. Mouse models of rhinovirus-induced disease and exacerbation of allergic airway inflammation. Nature medicine. 2008;14(2):199-204. Epub 2008/02/05.
9. Beale J, Jayaraman A, Jackson DJ, Macintyre JDR, Edwards MR, Walton RP, et al. Rhinovirus-induced IL-25 in asthma exacerbation drives type 2 immunity and allergic pulmonary inflammation. Science translational medicine. 2014;6(256):256ra134. Epub 2014/10/03.
10. Collison A, Hatchwell L, Verrills N, Wark PA, de Siqueira AP, Tooze M, et al. The E3 ubiquitin ligase midline 1 promotes allergen and rhinovirus-induced asthma by inhibiting protein phosphatase 2A activity. Nature medicine. 2013;19(2):232-7. Epub 2013/01/22.
11. Jackson DJ, Makrinioti H, Rana BM, Shamji BW, Trujillo-Torralbo MB, Footitt J, et al. IL-33-dependent type 2 inflammation during rhinovirus-induced asthma exacerbations in vivo. American journal of respiratory and critical care medicine. 2014;190(12):1373-82. Epub 2014/10/29.
12. Gern JE, Vrtis R, Grindle KA, Swenson C, Busse WW. Relationship of upper and lower airway cytokines to outcome of experimental rhinovirus infection. American journal of respiratory and critical care medicine. 2000;162(6):2226-31. Epub 2000/12/09.
13. Braciale TJ, Sun J, Kim TS. Regulating the adaptive immune response to respiratory virus infection. Nature reviews Immunology. 2012;12(4):295-305. Epub 2012/03/10.
14. Hussell T, Bell TJ. Alveolar macrophages: plasticity in a tissue-specific context. Nature reviews Immunology. 2014;14(2):81-93. Epub 2014/01/22.
15. Bedoret D, Wallemacq H, Marichal T, Desmet C, Quesada Calvo F, Henry E, et al. Lung interstitial macrophages alter dendritic cell functions to prevent airway allergy in mice. The Journal of clinical investigation. 2009;119(12):3723-38. Epub 2009/11/13.
16. Holt PG, Oliver J, Bilyk N, McMenamin C, McMenamin PG, Kraal G, et al. Downregulation of the antigen presenting cell function(s) of pulmonary dendritic cells in vivo by resident alveolar macrophages. The Journal of experimental medicine. 1993;177(2):397-407. Epub 1993/02/01.
17. Lauzon-Joset JF, Marsolais D, Langlois A, Bissonnette EY. Dysregulation of alveolar macrophages unleashes dendritic cell-mediated mechanisms of allergic airway inflammation. Mucosal immunology. 2014;7(1):155-64. Epub 2013/05/30.
18. Lambrecht BN, Hammad H. The immunology of asthma. Nature immunology. 2015;16(1):45-56. Epub 2014/12/19.
19. Webley WC, Aldridge KL. Infectious asthma triggers: time to revise the hygiene hypothesis? Trends in microbiology. 2015;23(7):389-91. Epub 2015/06/14.
20. Green RM, Custovic A, Sanderson G, Hunter J, Johnston SL, Woodcock A. Synergism between allergens and viruses and risk of hospital admission with asthma: case-control study. BMJ. 2002;324(7340):763. Epub 2002/03/30.
21. Hammad H, Lambrecht BN. Dendritic cells and epithelial cells: linking innate and adaptive immunity in asthma. Nature reviews Immunology. 2008;8(3):193-204. Epub 2008/02/28.
22. Galli SJ, Tsai M, Piliponsky AM. The development of allergic inflammation. Nature. 2008;454(7203):445-54. Epub 2008/07/25.
23. Barrett NA, Austen KF. Innate cells and T helper 2 cell immunity in airway inflammation. Immunity. 2009;31(3):425-37. Epub 2009/09/22.
24. Kawakami T, Galli SJ. Regulation of mast-cell and basophil function and survival by IgE. Nature reviews Immunology. 2002;2(10):773-86. Epub 2002/10/03.
25. Miyazaki E, Nureki S, Fukami T, Shigenaga T, Ando M, Ito K, et al. Elevated levels of thymus- and activation-regulated chemokine in bronchoalveolar lavage fluid from patients with eosinophilic pneumonia. American journal of respiratory and critical care medicine. 2002;165(8):1125-31. Epub 2002/04/17.
26. Muir P, Kammerer U, Korn K, Mulders MN, Poyry T, Weissbrich B, et al. Molecular typing of enteroviruses: current status and future requirements. The European Union Concerted Action on Virus Meningitis and Encephalitis. Clinical microbiology reviews. 1998;11(1):202-27. Epub 1998/02/11.
27. Wong SS, Yip CC, Lau SK, Yuen KY. Human enterovirus 71 and hand, foot and mouth disease. Epidemiology and infection. 2010;138(8):1071-89. Epub 2010/01/09.
28. Schmidt NJ, Lennette EH, Ho HH. An apparently new enterovirus isolated from patients with disease of the central nervous system. The Journal of infectious diseases. 1974;129(3):304-9. Epub 1974/03/01.
29. Busse WW. The National Institutes of Allergy and Infectious Diseases networks on asthma in inner-city children: an approach to improved care. The Journal of allergy and clinical immunology. 2010;125(3):529-37; quiz 38-9. Epub 2010/03/17.
30. Khetsuriani N, Lu X, Teague WG, Kazerouni N, Anderson LJ, Erdman DD. Novel human rhinoviruses and exacerbation of asthma in children. Emerging infectious diseases. 2008;14(11):1793-6. Epub 2008/11/04.
31. Quintin J, Cheng SC, van der Meer JW, Netea MG. Innate immune memory: towards a better understanding of host defense mechanisms. Current opinion in immunology. 2014;29:1-7. Epub 2014/03/19.
32. Busse WW, Lemanske RF, Jr., Gern JE. Role of viral respiratory infections in asthma and asthma exacerbations. Lancet. 2010;376(9743):826-34. Epub 2010/09/08.
33. McGrath KW, Icitovic N, Boushey HA, Lazarus SC, Sutherland ER, Chinchilli VM, et al. A large subgroup of mild-to-moderate asthma is persistently noneosinophilic. American journal of respiratory and critical care medicine. 2012;185(6):612-9.
34. Irvin C, Zafar I, Good J, Rollins D, Christianson C, Gorska MM, et al. Increased frequency of dual-positive TH2/TH17 cells in bronchoalveolar lavage fluid characterizes a population of patients with severe asthma. The Journal of allergy and clinical immunology. 2014;134(5):1175-86 e7.
35. Miossec P, Kolls JK. Targeting IL-17 and TH17 cells in chronic inflammation. Nature reviews Drug discovery. 2012;11(10):763-76.
36. Virgin HW, Wherry EJ, Ahmed R. Redefining chronic viral infection. Cell. 2009;138(1):30-50.
37. Machiels B, Dourcy M, Xiao X, Javaux J, Mesnil C, Sabatel C, et al. A gammaherpesvirus provides protection against allergic asthma by inducing the replacement of resident alveolar macrophages with regulatory monocytes. Nature immunology. 2017;18(12):1310-20.
38. Holt PG, Haining S, Nelson DJ, Sedgwick JD. Origin and steady-state turnover of class II MHC-bearing dendritic cells in the epithelium of the conducting airways. Journal of immunology. 1994;153(1):256-61.
39. Bekkering S, Arts RJW, Novakovic B, Kourtzelis I, van der Heijden C, Li Y, et al. Metabolic Induction of Trained Immunity through the Mevalonate Pathway. Cell. 2018;172(1-2):135-46 e9. Epub 2018/01/13.
40. Christ A, Gunther P, Lauterbach MAR, Duewell P, Biswas D, Pelka K, et al. Western Diet Triggers NLRP3-Dependent Innate Immune Reprogramming. Cell. 2018;172(1-2):162-75 e14. Epub 2018/01/13.
41. Kaufmann E, Sanz J, Dunn JL, Khan N, Mendonca LE, Pacis A, et al. BCG Educates Hematopoietic Stem Cells to Generate Protective Innate Immunity against Tuberculosis. Cell. 2018;172(1-2):176-90 e19. Epub 2018/01/13.
42. Mitroulis I, Ruppova K, Wang B, Chen LS, Grzybek M, Grinenko T, et al. Modulation of Myelopoiesis Progenitors Is an Integral Component of Trained Immunity. Cell. 2018;172(1-2):147-61 e12. Epub 2018/01/13.
43. Kopf M, Nielsen PJ. Training myeloid precursors with fungi, bacteria and chips. Nature immunology. 2018;19(4):320-2. Epub 2018/03/23.