14 research outputs found
Roles of CXCL1 and CXCL2 on neutrophils during immune complex-mediated inflammation
No full textCXCR2 is a critical regulator of neutrophil migration, and has been proposed to play an important role in immune complex-mediated inflammation. In the mouse, major pro-inflammatory CXCR2 ligands include CXCL1/KC/GRO-α and CXCL2/MIP-2a/GRO-β, but their specific individual roles on neutrophils have remained largely unclear. We developed an intravital multiphoton microscopy model of the reverse passive Arthus reaction in the mouse ear skin that allowed us to image neutrophil interactions with immune complexes. In combination with other in vitro and in vivo assays, we discovered that both CXCL1 and CXCL2 played very similar roles on neutrophil activation, but CXCL2 was the major chemokine produced by the neutrophils in feed-forward and autocrine loops, whereas CXCL1, produced by sentinel cell types such as macrophages and endothelial cells, could enhance neutrophil CXCL2 production. Our study reveals the complexity of CXCR2 ligand crosstalk during immune complex-mediated inflammation, and elucidates an intriguing mechanism of neutrophil biology.
Keywords: neutrophil, immune complex, inflammation, CXCR2, CXCL1, CXCL2, in vivo imaging, multiphoton microscopyDoctor of Philosophy (SBS
Platelets as autonomous drones for hemostatic and immune surveillance
No full textPlatelets participate in many important physiological processes, including hemostasis and immunity. However, despite their broad participation in these evolutionarily critical roles, the anucleate platelet is uniquely mammalian. In contrast with the large nucleated equivalents in lower vertebrates, we find that the design template for the evolutionary specialization of platelets shares remarkable similarities with human-engineered unmanned aerial vehicles in terms of overall autonomy, maneuverability, and expendability. Here, we review evidence illustrating how platelets are uniquely suited for surveillance and the manner in which they consequently provide various types of support to other cell types.J.L. Li is supported by Agency for Science, Technology and Research funding. A. Zarbock is supported by Deutsche Forschungsgemeinschaft (ZA428/13-1 and INST211/604-2 A05). A. Hidalgo is supported by Plan Estatal de Investigación Científica y Técnica y de Innovación 2013–2016 (SAF2015-65607-R and PCIN-2014-103), Programa Estatal de I+D+i Orientada a los Retos de la Sociedad Retos Investigación I+D+i from MECI, and cofunding from Fondo Europeo de Desarrollo Regional. Centro Nacional de Investigaciones Cardiovasculares Carlos III is supported by the MECI and the Pro CNIC Foundation and is a Severo Ochoa Center of Excellence (MECI award SEV-2015-0505).S
Neutrophils Self-Regulate Immune Complex-Mediated Cutaneous Inflammation through CXCL2
No full textFull author list omitted for brevity. For the full list of authors, see article.Deposition of immune complexes (ICs) in tissues triggers acute inflammatory pathology characterized by massive neutrophil influx leading to edema and hemorrhage, and is especially associated with vasculitis of the skin, but the mechanisms that regulate this type III hypersensitivity process remain poorly understood. Here, using a combination of multiphoton intravital microscopy and genomic approaches, we re-examined the cutaneous reverse passive Arthus reaction and observed that IC-activated neutrophils underwent transmigration, triggered further IC formation, and transported these ICs into the interstitium, whereas neutrophil depletion drastically reduced IC formation and ameliorated vascular leakage in vivo. Thereafter, we show that these neutrophils expressed high levels of CXCL2, which further amplified neutrophil recruitment and activation in an autocrine and/or paracrine manner. Notably, CXCL1 expression was restricted to tissue-resident cell types, but IC-activated neutrophils may also indirectly, via soluble factors, modulate macrophage CXCL1 expression. Consistent with their distinct cellular origins and localization, only neutralization of CXCL2 but not CXCL1 in the interstitium effectively reduced neutrophil recruitment. In summary, our study establishes that neutrophils are able to self-regulate their own recruitment and responses during IC-mediated inflammation through a CXCL2-driven feed forward loop
Inducing Ischemia-reperfusion Injury in the Mouse Ear Skin for Intravital Multiphoton Imaging of Immune Responses
No full text10.3791/54956JOVE-JOURNAL OF VISUALIZED EXPERIMENTS201611
Inducing ischemia-reperfusion injury in the mouse ear skin for intravital multiphoton imaging of immune responses
No full textIschemia-reperfusion injury (IRI) occurs when there is transient hypoxia due to the obstruction of blood flow (ischemia) followed by a subsequent re-oxygenation of the tissues (reperfusion). In the skin, ischemia-reperfusion (IR) is the main contributing factor to the pathophysiology of pressure ulcers. While the cascade of events leading up to the inflammatory response has been well studied, the spatial and temporal responses of the different subsets of immune cells to an IR injury are not well understood. Existing models of IR using the clamping technique on the skin flank are highly invasive and unsuitable for studying immune responses to injury, while similar non-invasive magnet clamping studies in the skin flank are less-than-ideal for intravital imaging studies. In this protocol, we describe a robust model of non-invasive IR developed on mouse ear skin, where we aim to visualize in real-time the cellular response of immune cells after reperfusion via multiphoton intravital imaging (MP-IVM).Published versio
Co-option of neutrophil fates by tissue environments
No full textClassically considered short-lived and purely defensive leukocytes, neutrophils are unique in their fast and moldable response to stimulation. This plastic behavior may underlie variable and even antagonistic functions during inflammation or cancer, yet the full spectrum of neutrophil properties as they enter healthy tissues remains unexplored. Using a new model to track neutrophil fates, we found short but variable lifetimes across multiple tissues. Through analysis of the receptor, transcriptional, and chromatin accessibility landscapes, we identify varying neutrophil states and assign non-canonical functions, including vascular repair and hematopoietic homeostasis. Accordingly, depletion of neutrophils compromised angiogenesis during early age, genotoxic injury, and viral infection, and impaired hematopoietic recovery after irradiation. Neutrophils acquired these properties in target tissues, a process that, in the lungs, occurred in CXCL12-rich areas and relied on CXCR4. Our results reveal that tissues co-opt neutrophils en route for elimination to induce programs that support their physiological demands
