Lung specific homing of diphenyleneiodonium chloride improves pulmonary fibrosis by inhibiting macrophage M2 metabolic program.

INTRODUCTION: Pulmonary fibrosis (PF) is a fatal disease with a variable and unpredictable course. Effective clinical treatment for PF remains a challenge due to low drug accumulation in lungs and imbalanced polarization of pro/anti-fibrotic macrophages. OBJECTIVES: To identify the alteration of immunometabolism in the pulmonary macrophages and investigate the feasibility of specific inhibition of M2 activation of macrophages as an effective anti-PF strategy in vivo. METHODS: The high-content screening system was used to select lung-specific homing compounds that can modulate macrophage polarization. Imaging mass spectrometry (IMS) conjugated with chemical proteomics approach was conducted to explore the cells and proteins targeted by diphenyleneiodonium chloride (DPI). A bleomycin-induced fibrotic mouse model was established to examine the in vivo effect of DPI. RESULTS: Pulmonary macrophages of PF at late stage exhibited predominantly the M2 phenotype with decreased glycolysis metabolism. DPI was demonstrated to inhibit profibrotic activation of macrophages in the preliminary screening. Notably, IMS conjugated with chemical proteomics approach revealed DPI specifically targeted pulmonary macrophages, leading to the efficient protection from bleomycin-induced pulmonary fibrosis in mice. Mechanistically, DPI upregulated glycolysis and suppressed M2 programming in fibrosis mice, thus resulting in pro-fibrotic cytokine inhibition, hydroxyproline biosynthesis, and collagen deposition, with a concomitant increase in alveolar airspaces. CONCLUSIONS: DPI mediated glycolysis in lung and accordingly suppressed M2 programming, resulting in improved lung fibrosis.

Mitochondrial metabolism mediated macrophage polarization in chronic lung diseases.

As the first line of defence in the lung, alveolar macrophage contributes to maintaining lung immune homoeostasis. Characterized by the heterogeneity and plasticity, macrophages polarize into two pro-inflammatory and anti-inflammatory phenotypes regarding the biological and pathological environment. In the past decade, numerous studies have revolutionized the relationship between cellular metabolism and macrophage functions. Mitochondria dysfunctions, which results in altered cellular metabolic profile, were observed in the alveolar macrophages during chronic lung diseases. In addition, alveolar macrophages adapt metabolic reprogramming to produce an immune response against the pathogens. Here, we outline the role of mitochondria in the development of macrophage phenotypes and functions and highlight the mitochondrial dysfunction in the setting of chronic lung diseases. Lastly, we emphasize the therapeutic relevance of targeting metabolic pathways in alveolar macrophages, which may shed light on developing novel strategies against chronic lung diseases.

The Association of Residence Permits on Utilization of Health Care Services by Migrant Workers in China.

Due to the limitations in the verifiability of individual identity, migrant workers have encountered some obstacles in access to public health care services. Residence permits issued by the Chinese government are a solution to address the health care access inequality faced by migrant workers. In principle, migrant workers with residence permits have similar rights as urban locals. However, the validity of residence permits is still controversial. This study aimed to examine the impact of residence permits on public health care services. Data were taken from the China Migrants Dynamic Survey (CMDS). Our results showed that the utilization of health care services of migrant workers with residence permits was significantly better than others. However, although statistically significant, the substantive significance is modest. In addition, megacities had significant negative moderating effects between residence permits and health care services utilization. Our research results emphasized that reforms of the household registration system, taking the residence permit system as a breakthrough, cannot wholly address the health care access inequality in China. For developing countries with uneven regional development, the health care access inequality faced by migrant workers is a structural issue.