Targeting the VEGFC–Macrophage Axis: Advances in NASH-Associated Hepatic Fibrosis Research

Study Background and Research Question

Non-alcoholic fatty liver disease (NAFLD), also termed metabolic dysfunction-associated fatty liver disease (MAFLD), has emerged as a leading cause of cirrhosis and hepatocellular carcinoma globally, with non-alcoholic steatohepatitis (NASH) representing a critical progressive stage characterized by steatosis, necroinflammation, and fibrotic remodeling. Despite increasing prevalence, the pathophysiological mechanisms underlying fibrogenesis in NASH remain incompletely elucidated, and targeted therapeutic options are limited.

Recent observations highlight vascular endothelial growth factor C (VEGFC) as a regulator of lymphangiogenesis and tissue remodeling. However, its specific role in hepatic fibrosis and the therapeutic potential of targeting the VEGFC–VEGFR-3 axis in NASH have not been fully explored. The reference study sought to determine whether downregulation of VEGFC could mediate protective effects against hepatic fibrosis, and to dissect the underlying cellular pathways, particularly involving hepatocyte–macrophage crosstalk (reference study).

Key Innovation from the Reference Study

The core innovation of this work is the identification and mechanistic dissection of a hepatocyte-derived VEGFC–macrophage regulatory axis that actively promotes hepatic inflammation and fibrogenesis in NASH. By combining pharmacological inhibition (using the selective VEGFR-3 inhibitor SAR131675), genetic knockout models, and clinical cohort analysis, the study demonstrates that attenuating VEGFC signaling can disrupt the recruitment and pro-fibrotic activation of hepatic macrophages, thereby mitigating disease progression.

This represents a significant advance in understanding the cellular drivers of NASH, as it connects VEGFC expression in hepatocytes to macrophage phenotypic switching and chemokine signaling, providing a rationale for anti-lymphangiogenic intervention strategies in metabolic liver disease.

Methods and Experimental Design Insights

The authors employed a multifaceted approach including in vivo, in vitro, and clinical analyses:

• Animal models: C57BL/6 mice were fed a high-fat diet (HFD) for 24 weeks to induce NASH-associated fibrosis. Treatment arms included low- and high-dose naringin (a known anti-fibrotic agent) and SAR131675, a selective ATP-competitive VEGFR-3 inhibitor, administered from week 9 to 24.
• Genetic models: Hepatocyte-specific Vegfc knockout mice (Vegfc^Hep-cKO) were generated by crossing Vegfc^flox/flox with Alb-CreERT2 mice, enabling assessment of hepatocyte-derived VEGFC in fibrogenesis.
• Clinical cohort: Serum VEGFC levels were measured in 165 patients with biopsy-proven NAFLD/NASH; hepatic expression data were validated using GEO datasets (GSE162694, GSE130970).
• Cellular assays: AML12 hepatocytes were treated with oleic acid, recombinant VEGFC, or subjected to Vegfc genetic modulation. Conditioned media from these cells were used to stimulate bone marrow-derived macrophages, evaluating effects on migration and phenotypic switching (Ly6C^high to Ly6C^low).

Pharmacological intervention with SAR131675 was chosen for its nanomolar potency and high selectivity for VEGFR-3, minimizing off-target effects (product information).

Core Findings and Why They Matter

Several pivotal discoveries emerged from this study:

• VEGFC upregulation in disease: Both clinical and preclinical data revealed elevated hepatic and serum VEGFC in NAFLD/NASH, implicating VEGFC as a marker and mediator of disease progression.
• Pharmacological and genetic inhibition attenuates fibrosis: Both naringin and SAR131675 reduced liver inflammation, collagen deposition, and markers of fibrosis in HFD-fed mice. Hepatocyte-specific Vegfc deletion produced similar protective effects, confirming the cell-autonomous role of VEGFC.
• Macrophage modulation: VEGFC promoted hepatic infiltration and pro-inflammatory polarization of Ly6C^high macrophages, partly via CCL2/CCR2 chemokine signaling. Suppression of VEGFC, either pharmacologically or genetically, reduced Ly6C^high monocyte infiltration and promoted phenotypic switching toward reparative Ly6C^low macrophages, associated with increased IL-10 and CX3CR1 expression.
• Mechanistic insights: In vitro, hepatocyte-derived VEGFC was necessary and sufficient to stimulate macrophage migration and block their transition to a reparative phenotype—a process reversed by VEGFR-3 inhibition or Vegfc knockout.

These findings collectively establish the VEGFC–VEGFR-3 pathway as a central driver of pro-fibrotic immune responses in NASH, and highlight the therapeutic potential of selective VEGFR-3 inhibition as an anti-lymphangiogenic and anti-angiogenic approach to halt fibrosis progression.

Protocol Parameters

• Animal model induction: High-fat diet for 24 weeks to induce NASH-like fibrosis.
• SAR131675 dosing: 30 mg/kg/day, administered from week 9 to 24 of HFD feeding.
• Genetic knockout induction: Tamoxifen-driven Cre activation in Vegfc^flox/flox x Alb-CreERT2 mice for hepatocyte-specific inactivation.
• In vitro macrophage stimulation: Conditioned medium from AML12 hepatocytes pretreated with oleic acid, recombinant VEGFC, or genetically modulated for Vegfc expression.

Comparison with Existing Internal Articles

The mechanistic focus on hepatic fibrosis and the VEGFC–macrophage axis in NASH distinguishes this reference from prior reviews and experimental studies of SAR131675. For example, a recent internal article contextualizes the significance of targeting the VEGFC–VEGFR-3 pathway in fibrosis models, but the current study extends these findings by directly linking VEGFC suppression to macrophage phenotypic shifts and inflammatory circuit disruption in a metabolic disease context. Other resources, such as mechanistic overviews of SAR131675, emphasize its anti-lymphangiogenic and anti-angiogenic properties in cancer and tissue remodeling, supporting the translational relevance of targeting VEGFR-3 in diverse pathological settings.

Collectively, these articles reinforce the position of SAR131675 as a versatile tool compound for dissecting VEGFR-3 signaling in both oncologic and fibrotic disease models, with the present study highlighting its specific utility in metabolic liver disease research.

Limitations and Transferability

Despite its comprehensive approach, the study has several limitations. The primary evidence derives from murine models, and although human cohort data support the clinical relevance of VEGFC upregulation, interspecies differences may affect transferability. The use of SAR131675 is limited to preclinical settings due to adverse metabolic effects observed in advanced testing (product information), and the long-term safety of VEGFR-3 inhibition in chronic liver disease remains to be established. Additionally, the complexity of the hepatic immune microenvironment and potential compensatory pathways may modulate therapeutic efficacy in clinical scenarios.

Nevertheless, the demonstration that both genetic and pharmacological targeting of hepatocyte-derived VEGFC can reverse key immunopathological events in NASH provides a robust rationale for further translational and mechanistic studies.

Research Support Resources

Researchers aiming to model or dissect the VEGFC–VEGFR-3 axis in hepatic fibrosis, inflammation, or metabolic disease can utilize SAR131675, a selective and ATP-competitive VEGFR-3 inhibitor (SKU B2301). Its potency and selectivity profile are well-suited for studies of lymphatic endothelial cell survival, macrophage migration, and anti-lymphangiogenic or anti-angiogenic compound screening. For detailed mechanistic insights and advanced protocol suggestions, see related internal reviews on the VEGFC–macrophage axis and SAR131675’s mechanistic applications.