Blocking interferon γ reduces expression of chemokines CXCL9, CXCL10 and CXCL11 and decreases macrophage infiltration in ex vivo cultured arteries from patients with giant cell arteritis

Abstract

Background Interferon γ (IFNγ) is considered a seminal cytokine in the pathogenesis of giant cell arteritis (GCA), but its functional role has not been investigated. We explored changes in infiltrating cells and biomarkers elicited by blocking IFNγ with a neutralising monoclonal antibody, A6, in temporal arteries from patients with GCA. Methods Temporal arteries from 34 patients with GCA ( positive histology) and 21 controls were cultured on 3D matrix (Matrigel) and exposed to A6 or recombinant IFNγ. Changes in gene/protein expression were measured by qRT-PCR/western blot or immunoassay. Changes in infiltrating cells were assessed by immunohistochemistry/immunofluorescence. Chemotaxis/ adhesion assays were performed with temporal arteryderived vascular smooth muscle cells (VSMCs) and peripheral blood mononuclear cells (PBMCs). Results Blocking endogenous IFNγ with A6 abrogated STAT-1 phosphorylation in cultured GCA arteries. Furthermore, selective reduction in CXCL9, CXCL10 and CXCL11 chemokine expression was observed along with reduction in infiltrating CD68 macrophages. Adding IFNγ elicited consistent opposite effects. IFNγ induced CXCL9, CXCL10, CXCL11, CCL2 and intracellular adhesion molecule-1 expression by cultured VSMC, resulting in increased PBMC chemotaxis/adhesion. Spontaneous expression of chemokines was higher in VSMC isolated from GCA-involved arteries than in those obtained from controls. Incubation of IFNγ-treated control arteries with PBMC resulted in adhesion/infiltration by CD68 macrophages, which did not occur in untreated arteries. Conclusions Our ex vivo system suggests that IFNγ may play an important role in the recruitment of macrophages in GCA by inducing production of specific chemokines and adhesion molecules. Vascular wall components (ie, VSMC) are mediators of these functions and may facilitate progression of inflammatory infiltrates through the vessel wall.

Interleukin 12 and interleukin 23 play key pathogenic roles in inflammatory and proliferative pathways in giant cell arteritis

“…IFN-γ is increased in GCA plasma and TABs and persists despite clinically efficacious treatment 12 33. Culturing normal TAs with recombinant IFN-γ results in macrophage infiltration, while blockade of IFN-γ ameliorates macrophage infiltration, GC formation and chemokine secretion 33. IL-17A is increased at both gene and protein levels in TABs from patients with GCA and correlates with the acute-phase response 14 34 35.…”

Ustekinumab inhibits Th1 and Th17 polarisation in a patient with giant cell arteritis

“…Recent advances in the pathophysiology of GCA showed that CD4+ T cells are recruited in the arterial wall and polarised into Th1 and Th17 cells,2 3 the latter being sensitive to GC-mediated suppression, whereas Th1 response persists in GC-treated patients,2 which triggers the recruitment of macrophages4 and could be implicated in the occurrence of relapses when GC are tapered. Interleukin (IL)-12 and IL-23 are two cytokines involved in Th1 and Th17 polarisations, respectively 5.…”

Giant Cell Arteritis: From Pathogenesis to Therapeutic Management

“…Also, GCA macrophages are highly efficient in producing the IFN-γ–dependent chemokines CXCL9, 10 and 11 [20]. A recent study has confirmed that GCA Mo are responsive to these chemokines, placing the T cell product IFN-γ into a key position in organizing the cellular recruitment into the arterial wall [21]. Immunohistochemical examination of tissue-residing Mo has revealed that macrophage activation patterns in GCA and primary angiitis of the central nervous system (PACNS) are fundamentally different [22].…”