Perilipin 2–positive mononuclear phagocytes accumulate in the diabetic retina and promote PPARγ-dependent vasodegeneration
Guillaume Blot, Rémi Karadayi, Lauriane Przegralek, Thérèse-Marie Sartoris, Hugo Charles-Messance, Sébastien Augustin, Pierre Negrier, Frédéric Blond, Frida Paulina Muñiz-Ruvalcaba, David Rivera-de la Parra, Lucile Vignaud, Aude Couturier, José-Alain Sahel, Niyazi Acar, Aida Jimenez-Corona, Cécile Delarasse, Yonathan Garfias, Florian Sennlaub, Xavier Guillonneau
Guillaume Blot, Rémi Karadayi, Lauriane Przegralek, Thérèse-Marie Sartoris, Hugo Charles-Messance, Sébastien Augustin, Pierre Negrier, Frédéric Blond, Frida Paulina Muñiz-Ruvalcaba, David Rivera-de la Parra, Lucile Vignaud, Aude Couturier, José-Alain Sahel, Niyazi Acar, Aida Jimenez-Corona, Cécile Delarasse, Yonathan Garfias, Florian Sennlaub, Xavier Guillonneau
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Research Article Inflammation Ophthalmology

Perilipin 2–positive mononuclear phagocytes accumulate in the diabetic retina and promote PPARγ-dependent vasodegeneration

Abstract

Type 2 diabetes mellitus (T2DM), characterized by hyperglycemia and dyslipidemia, leads to nonproliferative diabetic retinopathy (NPDR). NPDR is associated with blood-retina barrier disruption, plasma exudates, microvascular degeneration, elevated inflammatory cytokine levels, and monocyte (Mo) infiltration. Whether and how the diabetes-associated changes in plasma lipid and carbohydrate levels modify Mo differentiation remains unknown. Here, we show that mononuclear phagocytes (MPs) in areas of vascular leakage in DR donor retinas expressed perilipin 2 (PLIN2), a marker of intracellular lipid load. Strong upregulation of PLIN2 was also observed when healthy donor Mos were treated with plasma from patients with T2DM or with palmitate concentrations typical of those found in T2DM plasma, but not under high-glucose conditions. PLIN2 expression correlated with the expression of other key genes involved in lipid metabolism (ACADVL, PDK4) and the DR biomarkers ANGPTL4 and CXCL8. Mechanistically, we show that lipid-exposed MPs induced capillary degeneration in ex vivo explants that was inhibited by pharmaceutical inhibition of PPARγ signaling. Our study reveals a mechanism linking dyslipidemia-induced MP polarization to the increased inflammatory cytokine levels and microvascular degeneration that characterize NPDR. This study provides comprehensive insights into the glycemia-independent activation of Mos in T2DM and identifies MP PPARγ as a target for inhibition of lipid-activated MPs in DR.

Authors

Guillaume Blot, Rémi Karadayi, Lauriane Przegralek, Thérèse-Marie Sartoris, Hugo Charles-Messance, Sébastien Augustin, Pierre Negrier, Frédéric Blond, Frida Paulina Muñiz-Ruvalcaba, David Rivera-de la Parra, Lucile Vignaud, Aude Couturier, José-Alain Sahel, Niyazi Acar, Aida Jimenez-Corona, Cécile Delarasse, Yonathan Garfias, Florian Sennlaub, Xavier Guillonneau

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Figure 2

PA stimulation triggers the expression of key DR markers by MPs.

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PA stimulation triggers the expression of key DR markers by MPs. (A) Sch...
(A) Schematic representation of Mo isolation, treatment, and preparation. (B–D) Chromatographic analysis of FA chain composition after BSA (n = 3) or PA (n = 3) treatment. (B) Mean percentage of PA (C16:0) chains relative to total FAs. P s were calculated using Welch’s t test. (C) Mean percentage of monounsaturated FAs (MUFAs), polyunsaturated FAs (PUFAs), and saturated FAs (SFAs) (minus PA). (D) Mean percentage of ω−3 and ω–6 PUFAs. (C and D) P values were calculated using multiple Welch’s t tests corrected for multiple comparisons using the Holm-Šidák method. (E) Heatmap representation of the percentage of individual FA chains relative to total FA chains (minus PA). (F) RT-qPCR quantification of PLIN2 after treatment with BSA (n = 4), PA (n = 4), or PACH3 (n = 4). P values were determined by 1-way Welch’s ANOVA (P = 0.0021) followed by Dunnett’s T3 multiple-comparison test. (G–I) RNA-Seq transcriptomics analysis after BSA (n = 3) or PA (n = 3) treatment. (G) Scatter plot of the mean TPM value for all transcripts detected after BSA (x axis) or PA (y axis) treatment. The red and blue dots represent transcripts upregulated with a log2 FC of 4 or higher or a log2 FC of 4 or lower. (H) Heatmap representation of the log2 variance stabilizing transformation (vst) of the top 10 upregulated and downregulated transcripts. (I) GO enrichment analysis representing the fold enrichment of the 528 transcripts with a log2 FC of 2 or higher; red dots represent pathways related to lipid metabolism. Numbers in parenthesis represents the number of genes regulated by PA stimulation. Resp., response; Neg., negative; reg., regulator; act. activation; lipoprot., lipoprotein; Cell., cellular; stim., stimulation; Pos., positive; org., organization; diff., differentiation; drvd, derived. (J) Heatmap representation of the log2 vst of transcripts with a log2 FC of 4 or higher and belonging to the GO pathway “fatty acid metabolic process.” (K) Schematic representation of the biological function of the markers selected as a signature of lipid exposure.