sensitivity to neonicotinoids after frequent or
long-term exposure ( 27, 32).
Defining the thresholds below which neonicotinoids would not even have a sublethal effect
under chronic exposure is much more difficult
than assessing levels corresponding to short-term acute toxicity. Therefore, the proportion
of samples that may affect bees cannot be
ascertained based on current knowledge, but
this study shows that pollinators are globally
exposed to neonicotinoids, partly at concentrations shown to be harmful to bees. The fact
that 45% of our samples showed multiple contaminations is worrying and indicates that bee
populations throughout the world are exposed
to a cocktail of neonicotinoids. The effects of exposure to multiple pesticides, which have only
recently started to be explored ( 35), are suspected
to be stronger than the sum of individual effects ( 18). This worldwide description of the
situation should be useful for decision-makers
to reconsider the risks and benefits of using
neonicotinoids and provides scientists an inventory of the most frequent combinations of
neonicotinoids found in honey (table S9). We
urge national agriculture authorities to make
the quantities of neonicotinoids and other pesticides used on their territories publicly available
and also professionally available to epidemiologists at a much higher geographical resolution to
enable correlative studies between local events
and pesticide load.
REFERENCES AND NOTES
1. N. Simon-Delso et al., Environ. Sci. Pollut. Res. 22, 5–34
2. F. Sánchez-Bayo, K. Goka, D. Hayasaka, Front. Environ. Sci. 4,
3. J. M. Bonmatin et al., Environ. Sci. Pollut. Res. 22, 35–67
4. F. Sánchez-Bayo et al., Environ. Int. 89-90, 7–11 (2016).
5. G. Di Prisco et al., Proc. Natl. Acad. Sci. U.S.A. 110,
6. M. Henry et al., Science 336, 348–350 (2012).
7. B. A. Woodcock et al., Nat. Commun. 7, 12459 (2016).
8. P. R. Whitehorn, S. O’Connor, F. L. Wackers, D. Goulson,
Science 336, 351–352 (2012).
9. L. W. Pisa et al., Environ. Sci. Pollut. Res. 22, 68–102
10. T. C. Van Dijk, M. A. Van Staalduinen, J. P. Van der Sluijs,
PLOS ONE 8, e62374 (2013).
11. C. A. Hallmann, R. P. B. Foppen, C. A. M. van Turnhout,
H. de Kroon, E. Jongejans, Nature 511, 341–343 (2014).
12. D. Gibbons, C. Morrissey, P. Mineau, Environ. Sci. Pollut. Res.
22, 103–118 (2015).
13. N. Hoshi et al., Biol. Pharm. Bull. 37, 1439–1443 (2014).
14. M. Tomizawa, J. E. Casida, Toxicol. Appl. Pharmacol. 169,
15. K. H. Harada et al., PLOS ONE 11, e0146335 (2016).
16. L. Wang et al., Environ. Sci. Technol. 49, 14633–14640
17. M. Chagnon et al., Environ. Sci. Pollut. Res. 22, 119–134
18. J. P. van der Sluijs et al., Environ. Sci. Pollut. Res. 22, 148–154
19. L. Furlan, D. Kreutzweiser, Environ. Sci. Pollut. Res. 22, 135–147
20. C. D. Michener, The Social Behavior of the Bees (Belknap Press,
ed. 1, 1974).
21. S. S. Greenleaf, N. M. Williams, R. Winfree, C. Kremen,
Oecologia 153, 589–596 (2007).
22. A. David et al., Environ. Int. 88, 169–178 (2016).
23. M. Gbylik-Sikorska, T. Sniegocki, A. Posyniak, J. Chromatogr.
B Analyt. Technol. Biomed. Life Sci. 990, 132–140 (2015).
24. G. Codling, Y. Al Naggar, J. P. Giesy, A. J. Robertson,
Chemosphere 144, 2321–2328 (2016).
25. T. Blacquière, G. Smagghe, C. A. M. van Gestel, V. Mommaerts,
Ecotoxicology 21, 973–992 (2012).
26. A. Jones, G. Turnbull, Pest Manag. Sci. 72, 1897–1900
27. C. Moffat et al., FASEB J. 29, 2112–2119 (2015).
28. M. J. Palmer et al., Nat. Commun. 4, 1634 (2013).
29. S. M. Williamson, G. A. Wright, J. Exp. Biol. 216, 1799–1807
30. R. J. Gill, O. Ramos-Rodriguez, N. E. Raine, Nature 491,
31. K. Tan et al., PLOS ONE 9, e102725 (2014).
32. C. Moffat et al., Sci. Rep. 6, 24764 (2016).
33. P. Jovanov et al., Talanta 111, 125–133 (2013).
34. A. M. Cimino, A. L. Boyles, K. A. Thayer, M. J. Perry, Environ.
Health Perspect. 125, 155–162 (2017).
35. D. Spurgeon et al., EFSA Support. Publ. 13, 1076E (2016).
The full data are provided in table S1. We thank L. Lachat and
A. Vallat for technical assistance; 100 volunteers who donated honey
samples; and F. Sanchez-Bayo, N. Simon Delso, L.-E. Perret-Aebi,
P. Vittoz, L.-F. Bersier, S. Gray, and two anonymous reviewers for
helpful comments on the manuscript.
Materials and Methods
Figs. S1 to S8
Tables S1 to S9
References ( 36–79)
4 April 2017; accepted 6 September 2017
Visualizing the function and fate of
neutrophils in sterile injury
Jing Wang,1,2, 3 Mokarram Hossain,1, 3 Ajitha Thanabalasuriar,1, 3 Matthias Gunzer, 4
Cynthia Meininger, 5† Paul Kubes1, 3, 6†‡
Neutrophils have been implicated as harmful cells in a variety of inappropriate
inflammatory conditions where they injure the host, leading to the death of the neutrophils
and their subsequent phagocytosis by monocytes and macrophages. Here we show that
in a fully repairing sterile thermal hepatic injury, neutrophils also penetrate the injury site
and perform the critical tasks of dismantling injured vessels and creating channels for
new vascular regrowth. Upon completion of these tasks, they neither die at the injury
site nor are phagocytosed. Instead, many of these neutrophils reenter the vasculature and
have a preprogrammed journey that entails a sojourn in the lungs to up-regulate CXCR4
(C-X-C motif chemokine receptor 4) before entering the bone marrow, where they
Sterile injury is a broad term covering many inflammatory diseases that occur in the ab- sence of microorganisms. Most of these are characterized by an essential inflammatory phase followed by a resolution phase, which
leads to homeostasis (1). Most studies, however,
use models of high-fat diet, smoking, ischemia-
reperfusion, toxic drugs, and autoimmune disorders,
all of which lack a resolution phase. In these mod-
els, neutrophils have been hypothesized to be in-
appropriately recruited and activated. They are
then thought to release a variety of proteases and
oxidants, which causes host-tissue injury (2, 3).
To date, the therapeutic strategy has been to in-
hibit the recruitment of neutrophils and thereby
allow for repair. However, this simplistic view
may be fundamentally flawed inasmuch as neu-
trophils are also recruited in huge numbers in
models of resolving sterile injury, where they
may play a critical role in the repair process ( 4).
Neutrophils are thought to die at sites of in-
flammation and then be phagocytosed by mono-
cytes and macrophages ( 5). In zebrafish embryos,
neutrophils migrate out of the vasculature to
sites of sterile injury but then immediately re-
enter the vasculature in a process termed reverse
migration ( 6). In mammalian systems, there is
growing evidence that neutrophils can at least
migrate into the subendothelial space adjacent
to the basement membrane of postischemic muscle
and then migrate back into the vasculature, travel-
ing to the lungs, where they cause injury ( 7, 8).
The function and fate of neutrophils in a sterile
injury model that leads to normal healthy repair
In a simple thermal hepatic injury model
(~0.02 mm3), an increase in neutrophil recruitment
1Department of Physiology and Pharmacology, University of
Calgary, Calgary, Alberta T2N 4N1, Canada. 2Division of
Inflammation Biology, Tokushima University, Tokushima
7708503, Japan. 3Calvin, Phoebe, and Joan Snyder Institute
for Chronic Diseases, University of Calgary, Calgary, Alberta
T2N 4N1, Canada. 4Institute for Experimental Immunology and
Imaging, University Hospital, University Duisburg–Essen, Essen
45147, Germany. 5Department of Medical Physiology, Texas
A&M University Health Science Center, Temple, TX 76504,
USA. 6Department of Microbiology and Infectious Diseases,
University of Calgary, Calgary, Alberta T2N 4N1, Canada.
*These authors contributed equally to this work. †These authors
contributed equally to this work. ‡Corresponding author. Email: