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Genetically encoded biosensor for monitoring spatiotemporal dynamics of CCR2 ligands in culture and in vivo

Abstract

Chemokines regulate immune cell migration in development, homeostasis and inflammation, but the precise spatiotemporal pattern of chemokine release in vivo remains elusive due to the constraints of existing detection methodologies. Here, we report the engineering and characterization of a genetically encoded green fluorescent chemokine sensor, named CRAFi-CCR2, which utilizes the CCR2 receptor as a sensing moiety. In astrocytes, hCRAFi-CCR2, derived from the human CCR2B receptor, exhibited ~300% increase in fluorescence in response to mCCL2, with nanomolar affinity (2.5 nM). Activation of hCRAFi-CCR2 did not affect downstream signaling pathways, such as calcium mobilization and receptor internalization. Using this sensor, we performed 17–20 h of real-time imaging to observe endogenous mCCL2 release under inflammatory conditions, both in cell culture and in mice. In mouse brain, we observed spatial heterogeneity of CCL2 signal response on a scale of about 20–50 µm, highlighting the complexity of the immune system’s spatiotemporal signaling.

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Fig. 1: Development of the CCR2-based chemokine sensors.
Fig. 2: Characterization of hCRAFi-CCR2 in HEK cells.
Fig. 3: Characterization of hCRAFi-CCR2 in primary mouse neuronal and astrocyte cultures.
Fig. 4: Detection of endogenous CCR2 ligand release in cultured astrocytes stimulated with inflammatory stimuli.
Fig. 5: Detection of endogenous CCR2 ligands in the blood of mice stimulated with inflammatory stimuli.
Fig. 6: In vivo spatiotemporal dynamics of mCCL2 during LPS-evoked systemic inflammation and laser-induced ablation injury.

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Data availability

All essential raw datasets, including files for supplementary figures, the mass spectrometry proteomics data including raw datasets, and raw unprocessed images, are available at figshare via https://figshare.com/projects/CRAFi-CCR2/242891 (ref. 63). The rest of the files are available from the corresponding author upon request, as the total size of the files acquired for this study exceeds the 20-GB limit of the figshare repository. All plasmids used in this study are available from WeKwikGene (https://wekwikgene.wllsb.edu.cn/publications/1173; accession number 0001173-0001182) and Addgene. Source data are provided with this paper.

Code availability

Custom MATLAB codes used for data acquisition are available at https://github.com/MingCShare/xyzRegist/.

References

  1. Hughes, C. E. & Nibbs, R. J. B. A guide to chemokines and their receptors. FEBS J. 285, 2944–2971 (2018).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  2. Sokol, C. L. & Luster, A. D. The chemokine system in innate immunity. Cold Spring Harb. Perspect. Biol. 7, a016303 (2015).

    Article  PubMed  PubMed Central  Google Scholar 

  3. Proudfoot, AmandaE. I. Chemokine receptors: multifaceted therapeutic targets. Nat. Rev. Immunol. 2, 106–115 (2002).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  4. Dinarello, C. A. Immunological and inflammatory functions of the interleukin-1 family. Annu. Rev. Immunol. 27, 519–550 (2009).

    Article  CAS  PubMed  Google Scholar 

  5. Bradley, J. R. TNF-mediated inflammatory disease. J. Pathol. 214, 149–160 (2008).

    Article  CAS  PubMed  Google Scholar 

  6. Bours, M. J. L., Swennen, E. L. R., Di Virgilio, F., Cronstein, B. N. & Dagnelie, P. C. Adenosine 5′-triphosphate and adenosine as endogenous signaling molecules in immunity and inflammation. Pharmacol. Ther. 112, 358–404 (2006).

    Article  CAS  PubMed  Google Scholar 

  7. Tang, P. & Wang, J. M. Chemokines: the past, the present and the future. Cell. Mol. Immunol. 15, 295–298 (2018).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  8. Duan, L. et al. PDGFRβ cells rapidly relay inflammatory signal from the circulatory system to neurons via chemokine CCL2. Neuron 100, 183–200 (2018).

    Article  CAS  PubMed  Google Scholar 

  9. Van Steenwinckel, J. et al. CCL2 released from neuronal synaptic vesicles in the spinal cord is a major mediator of local inflammation and pain after peripheral nerve injury. J. Neurosci. 31, 5865–5875 (2011).

    Article  PubMed  PubMed Central  Google Scholar 

  10. Mahajan, S. D., Schwartz, S. A. & Nair, M. P. N. Immunological assays for chemokine detection in In-vitro culture of CNS cells. Biol. Proced. Online 5, 90–102 (2003).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  11. McDonough, A. A., Veiras, L. C., Minas, J. N. & Ralph, D. L. Considerations when quantitating protein abundance by immunoblot. Am. J. Physiol. Cell Physiol. 308, C426–C433 (2015).

    Article  CAS  PubMed  Google Scholar 

  12. Maubert, M. A. et al. High-resolution mass spectrometry and partial de novo sequencing constitute a useful approach for determining the profile of chemokine secretion following the stimulation of human intestinal epithelial cells. Rapid Commun. Mass Spectrom. 27, 2179–2187 (2013).

    Article  CAS  PubMed  Google Scholar 

  13. Trenchevska, O. et al. Quantitative mass spectrometric immunoassay for the chemokine RANTES and its variants. J. Proteom. 116, 15–23 (2015).

    Article  CAS  Google Scholar 

  14. Sánchez-Tirado, E., Agüí, L., González-Cortés, A., Yáñez-Sedeño, P. & Pingarrón, J. M. Biodetection techniques for quantification of chemokines. Chemosensors 10, 294 (2022).

    Article  Google Scholar 

  15. Aydın, E. B. & Sezgintürk, M. K. Fabrication of electrochemical immunosensor for detection of interleukin 8 biomarker via layer-by-layer self-assembly process on cost-effective fluorine tin oxide electrode. Electroanalysis 33, 1596–1605 (2021).

    Article  Google Scholar 

  16. White, C. W., Kilpatrick, L. E., Pfleger, K. D. G. & Hill, S. J. A nanoluciferase biosensor to investigate endogenous chemokine secretion and receptor binding. iScience 24, 102011 (2021).

    Article  CAS  PubMed  Google Scholar 

  17. Wu, Z., Lin, D. & Li, Y. Pushing the frontiers: tools for monitoring neurotransmitters and neuromodulators. Nat. Rev. Neurosci. 23, 257–274 (2022).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  18. Singh, S., Anshita, D. & Ravichandiran, V. MCP-1: function, regulation, and involvement in disease. Int. Immunopharmacol. 101, 107598 (2021).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  19. Charo, I. F. et al. Molecular cloning and functional expression of two monocyte chemoattractant protein 1 receptors reveals alternative splicing of the carboxyl-terminal tails. Proc. Natl Acad. Sci. USA 91, 2752–2756 (1994).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  20. Wong, L. M. et al. Organization and differential expression of the human monocyte chemoattractant protein 1 receptor gene: evidence for the role of the carboxyl-terminal tail in receptor trafficking. J. Biol. Chem. 272, 1038–1045 (1997).

    Article  CAS  PubMed  Google Scholar 

  21. Piatkevich, K. D. et al. A robotic multidimensional directed evolution approach applied to fluorescent voltage reporters. Nat. Chem. Biol. 14, 352–360 (2018).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  22. Hall, S. E. et al. Elucidation of binding sites of dual antagonists in the human chemokine receptors CCR2 and CCR5. Mol. Pharmacol. 75, 1325–1336 (2009).

    Article  CAS  PubMed  Google Scholar 

  23. Weber, M. et al. Interstitial dendritic cell guidance by haptotactic chemokine gradients. Science 339, 328–332 (2013).

    Article  CAS  PubMed  Google Scholar 

  24. Berchiche, Y. A., Gravel, S. P., Pelletier, M. E., St-Onge, G. & Heveker, N. Different effects of the different natural CC-chemokine receptor 2B (CCR2B) ligands on β-arrestin recruitment, Gαi signalling, and receptor internalization. Mol. Pharmacol. 79, 488–498 (2010).

    Article  PubMed  Google Scholar 

  25. Huma, Z. E. et al. Key determinants of selective binding and activation by the monocyte chemoattractant proteins at the chemokine receptor CCR2. Sci. Signal. 10, eaai8529 (2017).

    Article  PubMed  Google Scholar 

  26. Islam, S. A. et al. Mouse CCL8, a CCR8 agonist, promotes atopic dermatitis by recruiting IL-5+ TH2 cells. Nat. Immunol. 12, 167–177 (2011).

    Article  CAS  PubMed  Google Scholar 

  27. Chui, R. & Dorovini-Zis, K. Regulation of CCL2 and CCL3 expression in human brain endothelial cells by cytokines and lipopolysaccharide. J. Neuroinflammation 7, 1 (2010).

    Article  PubMed  PubMed Central  Google Scholar 

  28. Thompson, W. L. & Van Eldik, L. J. Inflammatory cytokines stimulate the chemokines CCL2/MCP-1 and CCL7/MCP-7 through NFκB and MAPK dependent pathways in rat astrocytes. Brain Res. 1287, 47–57 (2009).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  29. Sierra-Filardi, E. et al. CCL2 shapes macrophage polarization by GM-CSF and M-CSF: identification of CCL2/CCR2-dependent gene expression profile. J. Immunol. 192, 3858–3867 (2014).

    Article  CAS  PubMed  Google Scholar 

  30. Cerri, C. et al. The chemokine CCL2 mediates the seizure-enhancing effects of systemic inflammation. J. Neurosci. 36, 3777–3788 (2016).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  31. Liu, J. et al. Screening cytokine/chemokine profiles in serum and organs from an endotoxic shock mouse model by LiquiChip. Sci. China Life Sci. 60, 1242–1250 (2017).

    Article  CAS  PubMed  Google Scholar 

  32. Renner, N. A., Ivey, N. S., Redmann, R. K., Lackner, A. A. & MacLean, A. G. MCP-3/CCL7 production by astrocytes: implications for SIV neuroinvasion and AIDS encephalitis. J. Neurovirol. 17, 146–152 (2011).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  33. Orchanian, S. B., Still, K., Harris, T. H. & Lodoen, M. B. Deficiency in astrocyte CCL2 production reduces neuroimmune control of Toxoplasma gondii infection. PLoS Pathog. 20, e1011710 (2024).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  34. Hasel, P., Rose, I. V. L., Sadick, J. S., Kim, R. D. & Liddelow, S. A. Neuroinflammatory astrocyte subtypes in the mouse brain. Nat. Neurosci. 24, 1475–1487 (2021).

    Article  CAS  PubMed  Google Scholar 

  35. Carpentier, P. A. et al. Differential activation of astrocytes by innate and adaptive immune stimuli. Glia 49, 360–374 (2005).

    Article  PubMed  Google Scholar 

  36. Rodgers, K. R., Lin, Y., Langan, T. J., Iwakura, Y. & Chou, R. C. Innate immune functions of astrocytes are dependent upon tumor necrosis factor-alpha. Sci. Rep. 10, 7047 (2020).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  37. Zhou, Y., Ling, E. A. & Dheen, S. T. Dexamethasone suppresses monocyte chemoattractant protein-1 production via mitogen activated protein kinase phosphatase-1 dependent inhibition of Jun N-terminal kinase and p38 mitogen-activated protein kinase in activated rat microglia. J. Neurochem. 102, 667–678 (2007).

    Article  CAS  PubMed  Google Scholar 

  38. Lu, Y. C., Yeh, W. C. & Ohashi, P. S. LPS/TLR4 signal transduction pathway. Cytokine 42, 145–151 (2008).

    Article  CAS  PubMed  Google Scholar 

  39. Kawai, T. & Akira, S. The role of pattern-recognition receptors in innate immunity: update on Toll-like receptors. Nat. Immunol. 11, 373–384 (2010).

    Article  CAS  PubMed  Google Scholar 

  40. Liu, S. et al. Hyperbaric oxygen alleviates the inflammatory response induced by LPS through inhibition of NF-κB/MAPKs-CCL2/CXCL1 signaling pathway in cultured astrocytes. Inflammation 41, 2003–2011 (2018).

    Article  CAS  PubMed  Google Scholar 

  41. Erickson, M. A. & Banks, W. A. Cytokine and chemokine responses in serum and brain after single and repeated injections of lipopolysaccharide: multiplex quantification with path analysis. Brain. Behav. Immun. 25, 1637–1648 (2011).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  42. Semple, B. D., Bye, N., Rancan, M., Ziebell, J. M. & Morganti-Kossmann, M. C. Role of CCL2 (MCP-1) in traumatic brain injury (TBI): evidence from severe TBI patients and CCL2−/− mice. J. Cereb. Blood Flow. Metab. 30, 769–782 (2010).

    Article  PubMed  Google Scholar 

  43. Chen, Y. et al. Spatiotemporally selective astrocytic ATP dynamics encode injury information sensed by microglia following brain injury in mice. Nat. Neurosci. 27, 1522–1533 (2024).

    Article  CAS  PubMed  Google Scholar 

  44. Su, L., Shen, G. & Sun, L. Role of CXCL1 and CCL2 in patients with severe traumatic brain injury. Ann. Phys. Rehabil. Med. 61, e231 (2018).

    Article  Google Scholar 

  45. Feng, J. et al. A genetically encoded fluorescent sensor for rapid and specific in vivo detection of norepinephrine. Neuron 102, 745–761 (2019).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  46. Ulvmar, M. H. et al. The atypical chemokine receptor CCRL1 shapes functional CCL21 gradients in lymph nodes. Nat. Immunol. 15, 623–630 (2014).

    Article  CAS  PubMed  Google Scholar 

  47. Vaahtomeri, K., Moussion, C., Hauschild, R. & Sixt, M. Shape and function of interstitial chemokine CCL21 gradients are independent of heparan sulfates produced by lymphatic endothelium. Front. Immunol. 12, 630002 (2021).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  48. Batiuk, M. Y. et al. Identification of region-specific astrocyte subtypes at single cell resolution. Nat. Commun. 11, 1220 (2020).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  49. Panenka, W. et al. P2X7-like receptor activation in astrocytes increases chemokine monocyte chemoattractant protein-1 expression via mitogen-activated protein kinase. J. Neurosci. 21, 7135–7142 (2001).

    Article  PubMed  PubMed Central  Google Scholar 

  50. Shieh, C. H., Heinrich, A., Serchov, T., van Calker, D. & Biber, K. P2X7-dependent, but differentially regulated release of IL-6, CCL2, and TNF-α in cultured mouse microglia. Glia 62, 592–607 (2014).

    Article  PubMed  Google Scholar 

  51. Villette, V. et al. Ultrafast two-photon imaging of a high-gain voltage indicator in awake behaving mice. Cell 179, 1590–1608 (2019).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  52. Zhang, H. et al. Quantitative assessment of near-infrared fluorescent proteins. Nat. Methods 20, 1605–1616 (2023).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  53. Dou, Y. et al. Microglial migration mediated by ATP-induced ATP release from lysosomes. Cell Res. 22, 1022–1033 (2012).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  54. Hughes, C. S. et al. Single-pot, solid-phase-enhanced sample preparation for proteomics experiments. Nat. Protoc. 14, 68–85 (2018).

    Article  Google Scholar 

  55. Wu, Z. et al. A sensitive GRAB sensor for detecting extracellular ATP in vitro and in vivo. Neuron 110, 770–782 (2022).

    Article  CAS  PubMed  Google Scholar 

  56. Lagraoui, M. et al. Controlled cortical impact and craniotomy induce strikingly similar profiles of inflammatory gene expression, but with distinct kinetics. Front. Neurol. 3, 155 (2012).

  57. Xu, J. et al. Astrocyte-derived CCL2 participates in surgery-induced cognitive dysfunction and neuroinflammation via evoking microglia activation. Behav. Brain Res. 332, 145–153 (2017).

    Article  CAS  PubMed  Google Scholar 

  58. Davalos, D. et al. ATP mediates rapid microglial response to local brain injury in vivo. Nat. Neurosci. 8, 752–758 (2005).

    Article  CAS  PubMed  Google Scholar 

  59. Raduolovic, K., Mak’Anyengo, R., Kaya, B., Steinert, A. & Niess, J. H. Injections of lipopolysaccharide into mice to mimic entrance of microbial-derived products after intestinal barrier breach. J. Vis. Exp. 57610 (2018).

  60. Lubkowski, J. et al. The structure of MCP-1 in two crystal forms provides a rare example of variable quaternary interactions. Nat. Struct. Biol. 4, 64–69 (1997).

    Article  CAS  PubMed  Google Scholar 

  61. Oberthür, D. et al. Crystal structure of a mirror-image l-RNA aptamer (Spiegelmer) in complex with the natural l-protein target CCL2. Nat. Commun. 6, 6923 (2015).

    Article  PubMed  Google Scholar 

  62. Rodríguez-Frade, J. M. et al. The chemokine monocyte chemoattractant protein-1 induces functional responses through dimerization of its receptor CCR2. Proc. Natl Acad. Sci. USA 96, 3628–3633 (1999).

    Article  PubMed  PubMed Central  Google Scholar 

  63. Xiao, X. et al. Data source files for the manuscript "Genetically Encoded Biosensor for Monitoring Spatiotemporal Dynamics of CCR2 Ligands in Culture and In Vivo". figshare https://figshare.com/projects/CRAFi-CCR2/242891 (2025).

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Acknowledgements

We thank F. Li, S. Papadaki and Y. Y. Han from the laboratory of K.D.P. for their management support; Y. P. Gao, M. H. Liao, F. Xiao and L. M. Zheng, G.C. Fang from the Imaging Core at Westlake University for their technical support with the Nikon and Zeiss confocal microscopes; S. S. Liu from the Core Facilities at Zhejiang University School of Medicine for assistance with the two-photon microscope; F. Yang at Zhejiang University School of Medicine for support in generating the 3D model of hCRAFi-CCR2 sensor using AlphaFold2; M. Z. Fan and J. Hu from the Mass Spectrometry & Metabolomics Core Facility at Westlake University for assistance and discussion with LC–MS/MS analysis; D. Y. Gu from the Instrumentation and Service Center for Molecular Sciences at Westlake University for assistance with spectra measurement; and the Laboratory Animal Resources Center, Biomedical Research Core Facilities, Flow Cytometry Core, Westlake Center for Micro/Nano Fabrication. This work was supported by start-up funding from the Foundation of Westlake University, Westlake Laboratory of Life Sciences and Biomedicine, National Natural Science Foundation of China grants W2432024 and 32171093; and the ‘Pioneer’ and ‘Leading Goose’ R&D Program of Zhejiang 2024SSYS0031 (to K.D.P.), the Young Scientist Program of National Natural Science Foundation of China (grant 32100897 to X.X.), the National Natural Science Foundation of China (32371150 to M.J.) and STI2030-Major project 2021ZD0202200, Subject 2021ZD0202203 (to M.J.).

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Authors

Contributions

X.X. and K.D.P. initiated the project, made high-level designs and plans, and interpreted the data. X.X. developed the sensors with help from G.L. B.S. and X.X. developed the iDrug system. X.X. performed cell culture characterization. X.X. and Q.Q. performed affinity characterization. F.X. performed fast sensor kinetic measurements; X.G., X.S. and X.X. performed immunohistochemistry analysis. C.W., M.J., M.C. and X.X. performed two-photon in vivo experiments and analysis. X.X. and K.D.P., with help from M.J., wrote the manuscript. K.D.P. oversaw all aspects of the project.

Corresponding author

Correspondence to Kiryl D. Piatkevich.

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Competing interests

B.S. is the founder of CellSorter KFT, which is developing an automated micropipette. X.X. and K.D.P. are inventors on a patent application covering the design and application of the sensors. The other authors declare no competing interests.

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Nature Methods thanks the anonymous reviewers for their contribution to the peer review of this work. Primary Handling Editor: Nina Vogt, in collaboration with the Nature Methods team. Peer reviewer reports are available.

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Supplementary Information

Supplementary Notes 1–5, Supplementary Tables 1–4 and Supplementary Figs. 1–22.

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Supplementary Video 1

Drug-delivery system for PCR mutant library screening. To screen the variants efficiently and economically, we modified the CellSorter from cell picking into a drug-delivery system. During screening, cells were first imaged for 10–20 s to record the baseline fluorescence, and then the manipulator-guided glass pipette was lowered down into the well, 300–400 µm above the cells. Drugs were puffed to the cells through a 70-µm diameter glass capillary connected to the syringe pump, and time-lapse movies were recorded. This video shows how the manipulator-guided glass pipette moves from one well to another well to deliver drugs in an automatic mode.

Supplementary Video 2

Fluorescence response of hCRAFi-CCR2 sensor in HEK cells using the drug-delivery system. Images were acquired at 1 Hz.

Supplementary Video 3

In vivo two-photon imaging of the dynamics of fluorescence intensity for the hCRAFi-CCR2 sensor in mouse visual cortex after LPS challenge. The total time duration is 46 h. Images were acquired at 10-min intervals. Left, raw images showing the hCRAFi-CCR2 fluorescence intensity changes; right, calculated fluorescence response (∆F/F). Lines represent boundaries of the identified signal specific patches.

Supplementary Video 4

In vivo two-photon imaging of the dynamics of fluorescence intensity for hCRAFi-CCR2 sensor or null mutant in mouse visual cortex after laser-induced ablation. Images were acquired at 15-min intervals.

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Source Data Fig. 5

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Xiao, X., Wang, C., Guo, X. et al. Genetically encoded biosensor for monitoring spatiotemporal dynamics of CCR2 ligands in culture and in vivo. Nat Methods 22, 1731–1741 (2025). https://doi.org/10.1038/s41592-025-02742-y

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