Differential expression of IFN-α, IL-12 and BAFF on renal immune cells and its relevance to disease activity and treatment responsiveness in patients with proliferative lupus nephritis

Abstract

Objective: Since molecularly targeted therapies are emerging for treating lupus nephritis (LN), this study aimed to assess the immunohistochemical findings of the cytokines in renal tissue and their pathological and clinical relevance in LN.

Methods: Fifty patients with proliferative LN formed the case group; 5 with LN class II, IgA nephropathy and 10 with idiopathic haematuria were enrolled as controls. Immunohistochemical analysis for CD3, CD20, interferon (IFN)-α, interleukin (IL)-12/p40 and B-cell activating factor (BAFF) was performed by scoring the number of positive cells/area of the cortex. All immunohistochemical investigations were performed on formalin-fixed paraffin-embedded renal tissue. Proliferative LN cases were grouped by the dominant expression of IFN-α, IL-12/p40 and BAFF, and subsequently, clinicopathological features were compared.

Results: Clinical data of patients with proliferative LN included urine protein creatinine ratio, 2.2 g/gCre; anti-double-stranded DNA antibody, 200.9 IU/mL; total complement activity (CH50), 21.9 U/mL and SLE Disease Activity Index, 19.8 points. Proliferative LN cases, including class III (n=18) and IV (n=32), were classified into three subgroups according to the immunohistochemical score based on the dominancy of IFN-α (n=17), IL-12 (n=16) and BAFF group (n=17) proteins. Hypocomplementaemia and glomerular endocapillary hypercellularity were significantly increased in the IFN-α group, whereas chronic lesions were significantly higher in the IL-12 group (p<0.05). The IFN-α group had a poorer renal prognosis in treatment response after 52 weeks.

Conclusions: The immunohistochemistry (IHC) of IFN-α, IL-12 and BAFF for proliferative LN enabled grouping. Especially, the IFN-α and IL-12 groups showed different clinicopathological features and renal prognoses. The results indicated the possibility of stratifying cases according to the IHC of target molecules, which might lead to precision medicine.

Keywords: cytokines; lupus erythematosus, systemic; lupus nephritis.

Figure 1

Study design. BAFF, B-cell activating factor; IF, immunofluorescent; IFN, interferon; IL, interleukin; ISN/RPS, International Society of Nephrology/Renal Pathology Society; LN, lupus nephritis.

Figure 2

Immunofluorescence study of IFN-α, IL-12 and BAFF. (A) A representative immunofluorescence staining of human renal tissue for IFN-α, IL-12, BAFF and DAPI with composite multiplexed images in each group (scale bar: 50 μm). In the IFN-α-dominant group, IFN-α-positive cells increased (white arrow). IL-12-positive cells infiltrated in the IL-12-dominant group (white arrow), and BAFF-positive cells increased in the BAFF-dominant group (white arrow). (B) The graph shows the number of immunofluorescent positive cells/area of the cortex (mm²) in the following groups of patients with proliferative LN: IFN-α-dominant group (n=17), IL-12-dominant group (n=16) and BAFF-dominant group (n=17), LN class II group (n=5), IgA-GN group (n=5) and control group (n=10). Mean±SD shown. *P<0.05. BAFF, B-cell activating factor; DAPI, 4′,6-diamidino-2-phenylindole; GN, glomerulonephritis; IFN, interferon; IL, interleukin; LN, lupus nephritis.

Figure 3

Immunofluorescence study of CD3 and CD20 and light microscopic images (PAS and H&E staining). (A) A representative immunofluorescence staining of human renal tissue for CD3, CD20 and DAPI with composite multiplexed images in each group (scale bar: 50 μm). All six groups show CD3-positive T lymphocytes and CD20-positive B lymphocytes in the kidney tissue. (B) A representative light microscopic image stained by PAS and H&E. The IFN-α-dominant group shows increased glomerular active lesions, including segmental endocapillary hypercellularity and global wire-loop lesions. The IL-12-dominant group shows segmental sclerosis and fibrous adhesion to the Bowman’s capsule. The BAFF-dominant group shows segmental endocapillary hypercellularity. The LN class II group exhibits mesangial cell hypercellularity. The IgA group also shows fibrocellular crescent, and the control group exhibits minor glomerular abnormalities. (C) The number of immunofluorescent CD3-positive or CD20-positive cells/area of the cortex (mm²) in the six groups are not significantly different. Mean±SD shown. BAFF, B-cell activating factor; DAPI, 4′,6-diamidino-2-phenylindole; IFN, interferon; IL, interleukin; LN, lupus nephritis; PAS, periodic acid-Schiff.

Figure 4

Non-remission rate comparison in the IFN-a, IL-12 and BAFF groups 52 weeks after treatment. Non-remission rate in LUNAR (A), ACR (B), ALMS (C), BLISS-LN (D) criteria and non-achievement of UPCR <0.8 g/day (E) and PSL ≤7.5 mg (F). ACR, American College of Rheumatology; ALMS, Aspreva Lupus Management Study; BAFF, B-cell activating factor; BLISS-LN, Belimumab in Subjects with SLE-Lupus Nephritis; IFN, interferon; IL, interleukin; LUNAR, Lupus Nephritis Assessment with Rituximab; PSL, prednisolone; UPCR, urine protein creatinine ratio.