| 英文摘要 | Infectious diarrhea is a global health problem that affects more than a billion people and leads to half a million deaths in children annually ([ 1 ][1]). Among diarrhea-inducing viruses, rotavirus is one of the most important pathogens. Although a rotavirus vaccine has been licensed since 2006 and is part of the standard vaccination plan in more than 100 countries, there are differences in efficacy, particularly in developing countries ([ 2 ][2]). Therefore, it is critical to understand how rotavirus induces such extreme diarrhea episodes in infants and young children so as to provide new therapeutic approaches. On page 930 of this issue, Chang-Graham et al . ([ 3 ][3]) provide evidence in human and simian cells that intercellular signaling from rotavirus-infected cells to neighboring noninfected cells ultimately leads to diarrhea. This study shows that diarrhea can be controlled not by targeting the pathogen but by interfering with the intercellular messengers that drive pathology.
In infectious-disease research, two populations of cells should be distinguished: the infected cells and the noninfected neighboring cells (also called bystander cells). In rotavirus-induced pathogenesis, it has been suspected that bystander cells participate in life-threatening diarrhea by responding to viral and/or cellular factors that are secreted by infected cells ([ 4 ][4], [ 5 ][5]). Chang-Graham et al. showed that upon rotavirus infection of human intestinal epithelial cells, both infected cells and bystander cells display increases in intracellular Ca2++, released from the endoplasmic reticulum, that propagates to adjacent cells through paracrine signaling to form intercellular calcium waves (ICWs). These ICWs have been described to be responsible for the spatial coordination of cellular functions ([ 6 ][6]). However, the importance of ICWs in the development of diarrhea during rotavirus infection is currently unknown.
The virally encoded nonstructural protein 4 (NSP4) is responsible for the induction of intracellular Ca2++ waves in rotavirus-infected cells ([ 7 ][7]), likely acting as a “pore” protein mediating Ca2++ release from the endoplasmic reticulum ([ 8 ][8]). This protein exists in two forms: an intracellular form in the rotavirus-infected cells and a secreted virotoxin form. Thus, NSP4 has been the usual suspect for the onset and development of disease ([ 9 ][9]). However, Chang-Graham et al. showed that although NSP4 was critical for the initial increase in intracellular Ca2++ in infected cells, it was not required for ICW propagation to bystander cells. Instead, they identified adenosine diphosphate (ADP) as the extracellular messenger responsible for the development of ICWs. Release of nucleotides in the extracellular milieu induces ICWs ([ 10 ][10]). The authors showed that ADP released by infected cells acts on bystander cells through specific purinergic receptors to induce Ca2++ release in those cells. These findings are consistent with the central role of purinergic receptors and extracellular nucleotides in regulating gut homeostasis and communication between the intestinal epithelium and the microbial content of the gastrointestinal tract ([ 11 ][11]).
![Figure][12]
Rotavirus-induced diarrhea
After rotavirus infection, nonstructural protein 4 (NSP4) induces intracellular Ca2+ waves that mediate the release of adenosine diphosphate (ADP). ADP activates purinergic receptors on bystander cells, which leads to diarrhea. ADP also activates phospholipase C and release of inositol trisphosphate (IP3), which amplifies intracellular and intercellular Ca2+ waves.
GRAPHIC: V. ALTOUNIAN/ SCIENCE
In addition to inducing ICWs, ADP-mediated signaling also induced the production of cellular factors (such as serotonin) that are responsible for the development of the rotavirus-associated pathology (see the figure). Serotonin is a neurotransmitter that bridges communication between the gut and the enteric nervous system. The intestinal epithelium is the largest producer of serotonin in the body, and as such, rotavirus infection of the intestinal epithelium and activation of the bystander cells induces a signaling storm that drives severe water loss.
It has been unclear how a rotavirus infection that leads to very few infected cells (at least at the onset of infection) can lead to the severe pathology of loss of barrier function and excessive water loss. Similarly, it remained unexplained how severe diarrhea could be observed in patients before the noticeable loss of structural integrity of the intestinal epithelium. With the findings that bystander cells are the main players in rotavirus-induced diarrhea, the study of Chang-Graham et al. provides a unifying view of how rotavirus induces pathologies. In this model, a few infected cells can release extracellular messengers that activate bystander cells that will in turn induce complex signaling that leads to pathology and disease development. This intercellular activation allows signal amplification because one infected cell can activate many bystander cells. Chang-Graham et al. found that not all bystander cells were activated by ADP, which suggests that within an epithelium, a subpopulation of bystander cells are responsible for disease development. The origin for this heterogeneous response of bystander cells to the paracrine signal secreted by rotavirus-infected cells remains unknown. However, the identification of the molecular basis for this spatially restricted response could provide ideas for therapeutic approaches aimed to control water loss and inflammation.
The understanding of other enteric viruses is more limited. There is little knowledge of the molecular mechanisms by which enteric pathogens induce pathologies (inflammation, diarrhea, and vomiting). In the case of norovirus, only a few virus particles are sufficient to quickly induce severe diarrhea and vomiting. With the idea that severe pathology can develop in a bystander cell–dependent manner, despite only a few infected cells, perhaps research should also focus on bystander cells in the case of norovirus infection. Similarly, between 10 and 30% of coronavirus disease 2019 (COVID-19) patients have gastrointestinal symptoms ([ 12 ][13]), and there is evidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) replication in the human intestinal epithelium ([ 13 ][14], [ 14 ][15]). Although few infected cells have been detected in patient biopsies, bystander cells might be responsible for the gastrointestinal symptoms observed in COVID-19 patients.
Historically, infectious disease research has focused on the infected cell population because most analyses of host-pathogen interactions have been performed on bulk populations by using conditions in which most of the cells are infected by the pathogen of interest. With the development of single-cell methodologies, it is now possible to disentangle the participation of both the infected and noninfected bystander cells for the virus life cycle and induced pathologies. This will provide a better understanding of pathogenic mechanisms but also could provide new therapeutic targets to control the disease. This is exemplified by the study of Chang-Graham et al. , which showed that blocking the formation of ICWs in bystander cells, through the inhibition of P2Y purinoceptor 1 (P2Y1), resulted in a decrease of rotavirus-induced diarrhea severity in mice. As such, targeting the pathogen or the infected cells might not be the sole option to control infectious diseases and their induced pathologies.
1. [↵][16]1. World Health Organization
, “Diarrhoeal disease” (2017); .
2. [↵][17]1. E. Burnett et al
., Lancet Glob. Health. 8, e1195 (2020).
[OpenUrl][18]
3. [↵][19]1. A. L. Chang-Graham et al
., Science 370, eabc3621 (2020).
[OpenUrl][20][Abstract/FREE Full Text][21]
4. [↵][22]1. K. Hodges et al
., Gut Microbes. 1, 4 (2010).
[OpenUrl][23][CrossRef][24][PubMed][25]
5. [↵][26]1. K. Bányai et al
., Lancet. 392, 175 (2018).
[OpenUrl][27][CrossRef][28]
6. [↵][29]1. L. Leybaert et al
., Physiol. Rev. 92, 1359 (2012).
[OpenUrl][30][CrossRef][31][PubMed][32]
7. [↵][33]1. P. Tian et al
., J. Virol. 69, 5763 (1995).
[OpenUrl][34][Abstract/FREE Full Text][35]
8. [↵][36]1. T. Pham et al
., Sci. Rep. 7, 43487 (2017).
[OpenUrl][37][CrossRef][38]
9. [↵][39]1. L. Svensson,
2. U. Desselberger,
3. M. Estes,
4. H. Greenberg
1. N. P. Sastri et al
., in Viral Gastroenteritis, L. Svensson, U. Desselberger, M. Estes, H. Greenberg, Eds. (Academic Press, 2016), pp. 145–174.
10. [↵][40]1. Y. Osipchuk et al
., Nature. 359, 241 (1992).
[OpenUrl][41][CrossRef][42][PubMed][43]
11. [↵][44]1. A. Inami et al
., Int. J. Mol. Sci. 10.3390/ijms19082371 (2018).
12. [↵][45]1. L. Lin et al
., Gut. 69, 997 (2020).
[OpenUrl][46][Abstract/FREE Full Text][47]
13. [↵][48]1. M. M. Lamers et al
., Science 369, 50 (2020).
[OpenUrl][49][Abstract/FREE Full Text][50]
14. [↵][51]1. M. L. Stanifer et al
., Cell Rep. 32, 107863 (2020).
[OpenUrl][52]
Acknowledgments: M.S. and S.B. are supported by research grants from the Deutsche Forschungsgemeinschaft: project nos. 415089553, 240245660, 278001972, and 272983813 to S.B. and 416072091 to M.S.
[1]: #ref-1
[2]: #ref-2
[3]: #ref-3
[4]: #ref-4
[5]: #ref-5
[6]: #ref-6
[7]: #ref-7
[8]: #ref-8
[9]: #ref-9
[10]: #ref-10
[11]: #ref-11
[12]: pending:yes
[13]: #ref-12
[14]: #ref-13
[15]: #ref-14
[16]: #xref-ref-1-1 "View reference 1 in text"
[17]: #xref-ref-2-1 "View reference 2 in text"
[18]: {openurl}?query=rft.jtitle%253DLancet%2BGlob.%2BHealth%26rft.volume%253D8%26rft.spage%253D1195e%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx
[19]: #xref-ref-3-1 "View reference 3 in text"
[20]: {openurl}?query=rft.jtitle%253DScience%26rft.stitle%253DScience%26rft.aulast%253DChang-Graham%26rft.auinit1%253DA.%2BL.%26rft.volume%253D370%26rft.issue%253D6519%26rft.spage%253Deabc3621%26rft.epage%253Deabc3621%26rft.atitle%253DRotavirus%2Binduces%2Bintercellular%2Bcalcium%2Bwaves%2Bthrough%2BADP%2Bsignaling%26rft_id%253Dinfo%253Adoi%252F10.1126%252Fscience.abc3621%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx
[21]: /lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6Mzoic2NpIjtzOjU6InJlc2lkIjtzOjE3OiIzNzAvNjUxOS9lYWJjMzYyMSI7czo0OiJhdG9tIjtzOjIyOiIvc2NpLzM3MC82NTE5LzkwOS5hdG9tIjt9czo4OiJmcmFnbWVudCI7czowOiIiO30=
[22]: #xref-ref-4-1 "View reference 4 in text"
[23]: {openurl}?query=rft.stitle%253DGut%2BMicrobes%26rft.aulast%253DHodges%26rft.auinit1%253DK.%26rft.volume%253D1%26rft.issue%253D1%26rft.spage%253D4%26rft.epage%253D21%26rft.atitle%253DInfectious%2Bdiarrhea%253A%2BCellular%2Band%2Bmolecular%2Bmechanisms.%26rft_id%253Dinfo%253Adoi%252F10.4161%252Fgmic.1.1.11036%26rft_id%253Dinfo%253Apmid%252F21327112%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx
[24]: /lookup/external-ref?access_num=10.4161/gmic.1.1.11036&link_type=DOI
[25]: /lookup/external-ref?access_num=21327112&link_type=MED&atom=%2Fsci%2F370%2F6519%2F909.atom
[26]: #xref-ref-5-1 "View reference 5 in text"
[27]: {openurl}?query=rft.jtitle%253DLancet%26rft.volume%253D392%26rft.spage%253D175%26rft_id%253Dinfo%253Adoi%252F10.1016%252FS0140-6736%252818%252931128-0%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx
[28]: /lookup/external-ref?access_num=10.1016/S0140-6736(18)31128-0&link_type=DOI
[29]: #xref-ref-6-1 "View reference 6 in text"
[30]: {openurl}?query=rft.jtitle%253DPhysiological%2BReviews%26rft.stitle%253DPhysiol.%2BRev.%26rft.aulast%253DLeybaert%26rft.auinit1%253DL.%26rft.volume%253D92%26rft.issue%253D3%26rft.spage%253D1359%26rft.epage%253D1392%26rft.atitle%253DIntercellular%2BCa2%252B%2BWaves%253A%2BMechanisms%2Band%2BFunction%26rft_id%253Dinfo%253Adoi%252F10.1152%252Fphysrev.00029.2011%26rft_id%253Dinfo%253Apmid%252F22811430%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx
[31]: /lookup/external-ref?access_num=10.1152/physrev.00029.2011&link_type=DOI
[32]: /lookup/external-ref?access_num=22811430&link_type=MED&atom=%2Fsci%2F370%2F6519%2F909.atom
[33]: #xref-ref-7-1 "View reference 7 in text"
[34]: {openurl}?query=rft.jtitle%253DJournal%2Bof%2BVirology%26rft.stitle%253DJ.%2BVirol.%26rft.aulast%253DTian%26rft.auinit1%253DP.%26rft.volume%253D69%26rft.issue%253D9%26rft.spage%253D5763%26rft.epage%253D5772%26rft.atitle%253DThe%2Brotavirus%2Bnonstructural%2Bglycoprotein%2BNSP4%2Bmobilizes%2BCa2%252B%2Bfrom%2Bthe%2Bendoplasmic%2Breticulum%26rft_id%253Dinfo%253Adoi%252F10.1128%252FJVI.69.9.5763-5772.1995%26rft_id%253Dinfo%253Apmid%252F7637021%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx
[35]: /lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6MzoianZpIjtzOjU6InJlc2lkIjtzOjk6IjY5LzkvNTc2MyI7czo0OiJhdG9tIjtzOjIyOiIvc2NpLzM3MC82NTE5LzkwOS5hdG9tIjt9czo4OiJmcmFnbWVudCI7czowOiIiO30=
[36]: #xref-ref-8-1 "View reference 8 in text"
[37]: {openurl}?query=rft.jtitle%253DSci.%2BRep%26rft.volume%253D7%26rft.spage%253D43487%26rft_id%253Dinfo%253Adoi%252F10.1038%252Fsrep43487%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx
[38]: /lookup/external-ref?access_num=10.1038/srep43487&link_type=DOI
[39]: #xref-ref-9-1 "View reference 9 in text"
[40]: #xref-ref-10-1 "View reference 10 in text"
[41]: {openurl}?query=rft.jtitle%253DNature%26rft.stitle%253DNature%26rft.aulast%253DOsipchuk%26rft.auinit1%253DY.%26rft.volume%253D359%26rft.issue%253D6392%26rft.spage%253D241%26rft.epage%253D244%26rft.atitle%253DCell-to-cell%2Bspread%2Bof%2Bcalcium%2Bsignals%2Bmediated%2Bby%2BATP%2Breceptors%2Bin%2Bmast%2Bcells.%26rft_id%253Dinfo%253Adoi%252F10.1038%252F359241a0%26rft_id%253Dinfo%253Apmid%252F1388246%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx
[42]: /lookup/external-ref?access_num=10.1038/359241a0&link_type=DOI
[43]: /lookup/external-ref?access_num=1388246&link_type=MED&atom=%2Fsci%2F370%2F6519%2F909.atom
[44]: #xref-ref-11-1 "View reference 11 in text"
[45]: #xref-ref-12-1 "View reference 12 in text"
[46]: {openurl}?query=rft.jtitle%253DGut%26rft_id%253Dinfo%253Adoi%252F10.1136%252Fgutjnl-2020-321013%26rft_id%253Dinfo%253Apmid%252F32241899%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx
[47]: /lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6NjoiZ3V0am5sIjtzOjU6InJlc2lkIjtzOjg6IjY5LzYvOTk3IjtzOjQ6ImF0b20iO3M6MjI6Ii9zY2kvMzcwLzY1MTkvOTA5LmF0b20iO31zOjg6ImZyYWdtZW50IjtzOjA6IiI7fQ==
[48]: #xref-ref-13-1 "View reference 13 in text"
[49]: {openurl}?query=rft.jtitle%253DScience%26rft_id%253Dinfo%253Adoi%252F10.1126%252Fscience.abc1669%26rft_id%253Dinfo%253Apmid%252F32358202%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx
[50]: /lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6Mzoic2NpIjtzOjU6InJlc2lkIjtzOjExOiIzNjkvNjQ5OS81MCI7czo0OiJhdG9tIjtzOjIyOiIvc2NpLzM3MC82NTE5LzkwOS5hdG9tIjt9czo4OiJmcmFnbWVudCI7czowOiIiO30=
[51]: #xref-ref-14-1 "View reference 14 in text"
[52]: {openurl}?query=rft.jtitle%253DCell%2BRep%26rft.volume%253D32%26rft.spage%253D107863%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx |
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