Original Article
Myeloid Progenitor Inhibitory Factor-1 (CCL23) Inhibits Lung Leukocyte Recruitment in a Primate Cardiopulmonary Bypass-Induced Pulmonary Ischaemia Model

https://doi.org/10.1016/j.hlc.2022.11.017Get rights and content

Background

Bone marrow (BM)-derived polymorphonuclear leukocytes (PMNs) and monocytes (MO) induced by cardiopulmonary bypass (CPB) are highly proteolytic and cause postoperative lung injury. Although CCL23/Myeloid progenitor inhibitory factor-1 is a human CC chemokine with potent suppressor effects on myeloid progenitor cells, in vivo inhibitory effects on BM-derived leukocyte kinetics associated with CPB are unknown.

Methods

Two-hour CPB was surgically performed in cynomolgus monkeys and BM-derived leukocytes kinetics were monitored postoperatively by flow cytometry with 5’-bromo-2’-deoxyuridine (BrdU) and cytokine ELISA. Monkeys were given CCL23 (n=5) or saline (control, n=5) intravenously daily for 3 days before BrdU labelling and peripheral blood/bronchoalveolar lavage fluid (BALF) timepoint sampling to reveal BrdU-labelled cells. Levels of cytokines, CD11b, and L-selectin were considered leukocytic activation markers.

Results

The CCL23 treatment significantly prolonged BM transit of leukocytes (PMNs, 118.4±11.7–95.5±4.1 hours [control]; MO, 91.6±5.0–62.0±3.0 hours [control]) and reduced their alveolar appearance. The BM pool size of MO was decreased by CCL23 but PMNs were unaffected. CD11b, L-selectin expression of PMNs and MO during CPB, and post-surgical increases of interleukin (IL)-6, IL-8, TNF-α, MCP-1, and PMN elastase in the BALF were not suppressed.

Conclusions

CCL23 treatment slows turnover of PMN and MO progenitors in BM and suppresses their circulatory release and lung recruitment. CCL23 has inhibitory effects specifically on the CPB-induced BM response and could hold value for preventing CPB-induced lung injury.

Introduction

Bone marrow (BM)-derived leukocyte recruitment following cardiopulmonary bypass (CPB) chiefly contributes to postoperative lung injury. It has previously been shown that CPB accelerates polymorphonuclear leukocyte (PMN) and monocyte (MO) release from BM for recruitment to the lungs [1]. These CPB-induced, highly proteolytic, BM-derived leukocytes damage tissue more than their mature counterparts [1,2] as they sequester in the lungs and secrete pro-inflammatory proteins, including cytotoxic neutrophil elastase, which can cause severe tissue injury and subsequent multi-organ dysfunction [3,4]. In addition, they mediate release of inflammatory mediators from alveolar macrophages and lung epithelial cells to propagate further recruitment [3,[5], [6], [7]]. Therefore, prophylactic suppression of this inflammatory cascade could attenuate CPB-related lung injury. Mechanical filtration of leukocytes from the circulation after CPB reduces interleukin (IL)-6 and IL-8 but adds technical complexity [8] in contrast to endogenous, anti-PMN/leukocyte chemokines, such as CCL23, which can be precisely titrated [9].

CCL23, a 99-amino acid CC-motif chemokine—also known as myeloid progenitor inhibitory factor-1 (MPIF-1), macrophage inflammatory protein (MIP)-3, or CKb8—is expressed in the liver, lungs, pancreas, and BM tissues. Constitutively released by stimulated neutrophils [9] and MO-derived dendritic cells, but not macrophages or MO [10,11], CCL23 selectively recruits MO and resting T lymphocytes, inhibits proliferation of myeloid progenitor cells, and promotes angiogenesis [12,13] while possessing a dose-dependent, suppressive activity on granulocyte and monocyte lineages of the BM [11]. It predominantly binds to CC chemokine receptor (CCR)-1, which is broadly expressed in neutrophil progenitors (such as myeloblasts, promyelocytes, and myelocytes) within the BM [14]. As a previous study demonstrated that CCL23 mainly affects proliferating myeloid precursors, inhibiting production and release of both PMNs and MO in and from the BM [15], CCL23 is a probable regulator of the BM portion of the innate immune response.

This study hypothesised that CCL23 treatment would inhibit the release of PMNs and MO from BM, resulting in suppression of BM-derived leukocyte recruitment to the lungs in an established primate CPB model.

Section snippets

Experimental Animals

Ten healthy, young adult, male cynomolgus monkeys (Macaca fascicularis) (4–6 years old, 4.8±0.7 kg), born in the Tsukuba Primate Research Centre, were used as the non-human primate model. The study strictly adhered to the Rules for Animal Care and Management of the Tsukuba Primate Center [16] and to the Guiding Principles for Animal Experiments Using Nonhuman Primates formulated by the Primate Society of Japan [17]. The protocol, including ethical principles of laboratory animal care, was

Effect of CCL23 on Circulation

Table 1 shows perioperative details before, during, and after CPB. The preoperative CCL23 treatment did not change red blood cell, platelet, white blood cell (WBC), or PMN and monocyte counts compared with controls (Table 1 and Figure 1A). While the percentage of circulating band cells (non-segmented PMNs, a BM stimulation indicator) was elevated postoperatively, there were no significant between-group differences in temporal changes after CCL23 treatment (Figure 1B). Leukocyte counts were

Discussion

A primate-based study previously reported that CPB causes rapid release of PMNs and MO from the marrow, shortens their transit through BM, and further induces their migration into alveolar spaces after surgery [1]. It was also recently confirmed that accelerated release of and lung infiltration by new BM PMNs and MO are significantly suppressed by intraoperative administration of Sivelestat or Rolipram [7]; pharmacological control of this response is feasible to prevent CPB-induced lung injury.

Conclusions

This study investigated the effect of CCL23 on the BM response associated with CPB using an in vivo monkey model and showed that CCL23 treatment reduced the total pool size of MO in the marrow but did not affect PMNs. Accelerated release of BM PMNs and MO, as well as their recruitment into lung tissues, were also significantly downregulated. This suggests that CCL23 has potential to ameliorate CPB-induced, BM-derived leukocyte recruitment to the lungs by slowing the cell turnover cycle in the

Conflict of Interest

The authors declare no conflicts of interest.

Acknowledgements

The authors thank Shoko Sato for her excellent technical support. The authors also thank Yuko Katakai and Hiromi Ogawa at the Corporation for Production and Research of Laboratory Primates for their animal care and technical support. This work was supported by Grants-in-Aid for Scientific Research (grant number 16K15757 and 20H03778 to Dr. Goto) from the Japan Society for the Promotion of Science.

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