Peroxisome Proliferator-activated Receptor γ and Mitochondria: Drivers or Passengers on the Road to Pulmonary Hypertension?

Immuno-metabolic dendritic cell vaccine signatures associate with overall survival in vaccinated melanoma patients

Efficacy of cancer vaccines remains low and mechanistic understanding of antigen presenting cell function in cancer may improve vaccine design and outcomes. Here, we analyze the transcriptomic and immune-metabolic profiles of Dendritic Cells (DCs) from 35 subjects enrolled in a trial of DC vaccines in late-stage melanoma (NCT01622933). Multiple platforms identify metabolism as an important biomarker of DC function and patient overall survival (OS). We demonstrate multiple immune and metabolic gene expression pathway alterations, a functional decrease in OCR/OXPHOS and increase in ECAR/glycolysis in patient vaccines. To dissect molecular mechanisms, we utilize single cell SCENITH functional profiling and show patient clinical outcomes (OS) correlate with DC metabolic profile, and that metabolism is linked to immune phenotype. With single cell metabolic regulome profiling, we show that MCT1 (monocarboxylate transporter-1), a lactate transporter, is increased in patient DCs, as is glucose uptake and lactate secretion. Importantly, pre-vaccination circulating myeloid cells in patients used as precursors for DC vaccine generation are significantly skewed metabolically as are several DC subsets. Together, we demonstrate that the metabolic profile of DC is tightly associated with the immunostimulatory potential of DC vaccines from cancer patients. We link phenotypic and functional metabolic changes to immune signatures that correspond to suppressed DC differentiation.

The effects of lipoic acid on respiratory diseases

Respiratory diseases, including lung cancer, pulmonary fibrosis, asthma, and the recently emerging fatal coronavirus disease-19 (COVID-19), are the leading causes of illness and death worldwide. The increasing incidence and mortality rates have attracted much attention to the prevention and treatment of these conditions. Lipoic acid (LA), a naturally occurring organosulfur compound, is not only essential for mitochondrial aerobic metabolism but also shows therapeutic potential via certain pharmacological effects (e.g., antioxidative and anti-inflammatory effects). In recent years, accumulating evidence (animal experiments and in vitro studies) has suggested a role of LA in ameliorating many respiratory diseases (e.g., lung cancer, fibrosis, asthma, acute lung injury and smoking-induced lung injury). Therefore, this review will provide an overview of the present investigational evidence on the therapeutic effect of LA against respiratory diseases in vitro and in vivo. We also summarize the corresponding mechanisms of action to inspire further basic studies and clinical trials to confirm the health benefits of LA in the context of respiratory diseases.

Luteolin alleviates inflammation and autophagy of hippocampus induced by cerebral ischemia/reperfusion by activating PPAR gamma in rats

Background

Luteolin, a flavonoid compound with anti-inflammatory activity, has been reported to alleviate cerebral ischemia/reperfusion (I/R) injury. However, its potential mechanism remains unclear.

Methods

The binding activity of luteolin to peroxisome proliferator-activated receptor gamma (PPARγ) was calculated via molecular docking analysis. Rats were subjected to middle cerebral artery occlusion and reperfusion (MCAO/R). After reperfusion, vehicle, 25 mg/kg/d luteolin, 50 mg/kg/d luteolin, 10 mg/kg/d pioglitazone, 50 mg/kg/d luteolin combined with 10 mg/kg/d T0070907 (PPARγ inhibitor) were immediately orally treatment for 7 days. ELISA, TTC staining, H&E staining, immunohistochemistry, immunofluorescence and transmission electron microscope methods were performed to evaluate the inflammation and autophagy in damaged hippocampal region. The PPARγ, light chain 3 (LC3) B-II/LC3B-I and p-nuclear factor-κB (NF-κB) p65 proteins expression levels in damaged hippocampal region were analyzed.

Results

Luteolin showed good PPARγ activity according to docking score (score = − 8.2). Luteolin treatment downregulated the infarct area and the pro-inflammatory cytokines levels caused by MCAO/R injury. Moreover, luteolin administration ameliorated neuroinflammation and autophagy in damaged hippocampal region. Pioglitazone plays protective roles similar to luteolin. T0070907 concealed the neuroprotective roles of 50 mg/kg/d luteolin.

Conclusions

Luteolin exerts neuroprotective roles against inflammation and autophagy of hippocampus induced by cerebral I/R by activating PPARγ in rats.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-022-03652-8.

The pan-PPAR agonist lanifibranor reduces development of lung fibrosis and attenuates cardiorespiratory manifestations in a transgenic mouse model of systemic sclerosis

Background

The TβRII∆k-fib transgenic (TG) mouse model of scleroderma replicates key fibrotic and vasculopathic complications of systemic sclerosis through fibroblast-directed upregulation of TGFβ signalling. We have examined peroxisome proliferator-activated receptor (PPAR) pathway perturbation in this model and explored the impact of the pan-PPAR agonist lanifibranor on the cardiorespiratory phenotype.

Methods

PPAR pathway gene and protein expression differences from TG and WT sex-matched littermate mice were determined at baseline and following administration of one of two doses of lanifibranor (30 mg/kg or 100 mg/kg) or vehicle administered by daily oral gavage up to 4 weeks. The prevention of bleomycin-induced lung fibrosis and SU5416-induced pulmonary hypertension by lanifibranor was explored.

Results

Gene expression data were consistent with the downregulation of the PPAR pathway in the TβRII∆k-fib mouse model. TG mice treated with high-dose lanifibranor demonstrated significant protection from lung fibrosis after bleomycin and from right ventricular hypertrophy following induction of pulmonary hypertension by SU5416, despite no significant change in right ventricular systolic pressure.

Conclusions

In the TβRII∆k-fib mouse strain, treatment with 100 mg/kg lanifibranor reduces the development of lung fibrosis and right ventricular hypertrophy induced by bleomycin or SU5416, respectively. Reduced PPAR activity may contribute to the exaggerated fibroproliferative response to tissue injury in this transgenic model of scleroderma and its pulmonary complications.

Rats with a Human Mutation of NFU1 Develop Pulmonary Hypertension

NFU1 is a mitochondrial protein that is involved in the biosynthesis of iron-sulfur clusters, and its genetic modification is associated with disorders of mitochondrial energy metabolism. Patients with autosomal-recessive inheritance of the NFU1 mutation G208C have reduced activity of the respiratory chain Complex II and decreased levels of lipoic-acid-dependent enzymes, and develop pulmonary arterial hypertension (PAH) in ∼70% of cases. We investigated whether rats with a human mutation in NFU1 are also predisposed to PAH development. A point mutation in rat NFU1^G206C (human G208C) was introduced through CRISPR/Cas9 genome editing. Hemodynamic data, tissue samples, and fresh mitochondria were collected and analyzed. NFU1^G206C rats showed increased right ventricular pressure, right ventricular hypertrophy, and high levels of pulmonary artery remodeling. Computed tomography and angiography of the pulmonary vasculature indicated severe angioobliterative changes in NFU1^G206C rats. Importantly, the penetrance of the PAH phenotype was found to be more prevalent in females than in males, replicating the established sex difference among patients with PAH. Male and female homozygote rats exhibited decreased expression and activity of mitochondrial Complex II, and markedly decreased pyruvate dehydrogenase activity and lipoate binding. The limited development of PAH in males correlated with the preserved levels of oligomeric NFU1, increased expression of ISCU (an alternative branch of the iron-sulfur assembly system), and increased complex IV activity. Thus, the male sex has additional plasticity to overcome the iron-sulfur cluster deficiency. Our work describes a novel, humanized rat model of NFU1 deficiency that showed mitochondrial dysfunction similar to that observed in patients and developed PAH with the same sex dimorphism.