Neutrophil reverse migration from liver fuels neutrophilic inflammation to tissue injury in Nonalcoholic Steatohepatitis

Abstract

Inflammation is a hallmark in the progression of nonalcoholic fatty liver disease (NAFLD) to nonalcoholic steatohepatitis (NASH). Patients with NAFLD are characterized by a chronic low-grade systemic metabolic inflammation (i.e., metainflammation), which contributes to exacerbated however dysfunctional immune response. Neutrophils play an important pathological role in NAFLD progression to NASH; however, how NASH and associated chronic systemic inflammation impact overall the neutrophil response to injury is completely unexplored. Here, we investigated how neutrophil response to tissue injury is altered by the presence of NASH. We used a diet-induced NASH zebrafish model combined with tailfin transection in transgenic zebrafish larvae to study neutrophilic inflammation. Live non-invasive confocal microscopy was used to investigate neutrophil recruitment to tailfin injury through time. Photoconvertion of neutrophils at the liver area followed by time-lapse microscopy was performed to evaluate the migration of neutrophils from liver to tailfin injury. Metformin and Pentoxifylline were used to pharmacologically reduce NASH and liver inflammation. We found that larvae with NASH display systemic inflammation and increased myelopoiesis. NASH larvae display a dysfunctional and exacerbated neutrophil response to tailfin injury, characterized by increased neutrophil recruitment, and delayed resolution of inflammation. Interestingly, we showed that neutrophils undergo reverse migration from the NASH liver to the wounded tailfin area. Finally, pharmacological treatment of NASH with Pentoxifylline and Metformin significantly reduced systemic chronic inflammation and the exacerbated recruitment of neutrophils to tissue injury. Taken together, our findings suggest that NASH exacerbates neutrophilic inflammation probably via neutrophil priming at the liver, which can further undergo reverse migration and respond to secondary inflammatory triggers such as tissue injury. Reverse migration of primed neutrophils from the liver might be an important mechanism that fuels the exacerbated neutrophil response observed in NASH conditions and associated metainflammation contributing to poor prognosis and increasing death in patients with metabolic syndrome.

A zebrafish xenotransplant model of anaplastic thyroid cancer to study the tumor microenvironment and innate immune cell interactionsin vivo

“…All experiments were replicated independently two to three times (N) with multiple samples in each replicate (n). For analysis of mass volume/area, vessel volume/area, and PIP-Fucci cell phases an unpaired Mann-Whitney T-test was performed on GraphPad Prism version 9.3 (10). For mass to vessel volume correlation a Pearson correlation was performed using GraphPad Prism version 9.3.…”

“…To quantify neutrophil recruitment to the tumor area and neutrophil infiltration of the tumor, the larval tumor area was imaged as previously described and reconstructed using IMARIS Bitplane Software (Version 9.9.1/10.1) rendering mode and the total number of cancer cells were automatically counted using IMARIS spots function (10). All neutrophils in the FOV (field of view) were counted and neutrophils in the tumor were isolated and counted.…”

Cisplatin Toxicity Causes Neutrophil-Mediated Inflammation in Zebrafish Larvae

“…Images were captured using the ZEISS Axio Zoom.V16 microscope. The larvae were classified as none, mild, or severe for systemic inflammation based on the criteria described in Table 2 [59].…”