Serum Biomarkers of Vascular Involvement in Childhood Uveitis

Abstract

Purpose: Nonanterior uveitis frequently involves the retinal vasculature; however, no molecular markers associated with the retinal vascular disease are currently known. In this study, we aimed to identify serum biomarker signatures associated with retinal vascular involvement in noninfectious pediatric uveitis.

Methods: We performed a 384-plex targeted proteomic analysis of serum samples of 154 noninfectious pediatric uveitis patients diagnosed with nonanterior uveitis (n = 74), idiopathic chronic anterior uveitis (iCAU, n = 36), or juvenile idiopathic arthritis-associated uveitis (JIA-U, n = 44), as well as 22 noninflammatory pediatric controls. Data on retinal vascular involvement (i.e., papillitis, cystoid macular edema, retinal vasculitis, or retinal capillary leakage on optical coherence tomography and/or fluorescein angiography) were used to stratify cases in the nonanterior uveitis group.

Results: In the analysis of nonanterior uveitis, we identified nine proteins significantly associated with retinal vascular involvement, including F13B, MYOM3, and PTPN9. These proteins were enriched through pathway enrichment analysis for the coagulation cascade. Comparing cases and controls, we identified 63 differentially expressed proteins, notably proteins involved in platelet biology and complement cascades, which could be primarily attributed to differences in serum proteomes between anterior uveitis and nonanterior uveitis groups.

Conclusions: Serum proteins related to the coagulation and complement cascade are associated with retinal vascular involvement in pediatric uveitis patients. Our results indicate involvement of mediators that could interact with the microcirculation in pediatric uveitis and might serve as potential biomarkers in personalized medicine in the future.

Translational relevance: Our targeted proteomics analysis in serum of pediatric uveitis patients indicates involvement of mediators that could interact with the microcirculation in pediatric uveitis and might serve as potential biomarkers in personalized medicine in the future.

Figure 1.

Serum proteome changes comparing pediatric controls (PCs, n = 22), nonanterior uveitis (NAU) patients (n = 74), idiopathic chronic anterior uveitis (iCAU) patients (n = 36), and juvenile idiopathic arthritis–associated uveitis (JIA-U) patients (n = 44). (A) Scatterplots for the top four differentially serum proteins (q < 0.05). NPX indicates normalized protein expression data from Olink. (B) Pathway enrichment analysis of the 63 differentially expressed proteins showing the top five using Reactome, with coloring based on the adjusted P values. (C) Heatmap of the 63 differentially expressed proteins between the controls and uveitis subtypes. The levels for each protein analyte are shown for each of the samples in the study and are color coded from low (cyan) to high (yellow).

Figure 2.

Serum proteome changes comparing anterior pediatric uveitis (n = 80) versus nonanterior pediatric uveitis (n = 74) patients. (A) Differential expression of serum proteins obtained from proximity extension assay (PEA) results. Differentially upregulated proteins are depicted in red, and downregulated proteins are depicted in blue. Proteins were analyzed using the likelihood ratio test adjusted for age and sex and followed by FDR multiple testing correction. The dotted line represents q = 0.05. NPX indicates normalized protein expression data from Olink. (B) Pathway enrichment analysis of the 63 differentially expressed proteins showing the top five using Reactome, with coloring based on the adjusted P values. (C) Heatmap of the 63 differentially expressed proteins between the anterior and nonanterior uveitis cases. The levels for each protein analyte are shown for each of the samples in the study and are color coded from low (cyan) to high (yellow). (D) Venn diagram showing overlapping and unique proteins in the four disease group comparisons (A) and the nonanterior versus nonanterior comparison.

Figure 3.

Serum proteome changes comparing pediatric nonanterior uveitis patients with active retinal vascular involvement (n = 48) and non-active retinal vascular involvement (n = 23). (A) Correlation plot showing the correlation between nine differentially expressed serum proteins obtained from PEA results using the likelihood ratio test adjusted for age, sex, and immunomodulatory treatment and followed by a relaxed FDR multiple testing correction (q < 0.1). (B) The overlapping serum proteins shown in a Venn diagram of three different group comparisons: A, pediatric controls compared to nonanterior uveitis, iCAU, and JIA-U; B, anterior compared to nonanterior uveitis; and C, retinal vascular involvement in nonanterior uveitis patients. (C) Scatterplots for the three unique serum proteins regarding retinal vascular involvement in children with nonanterior uveitis with q < 0.1, except for F13B, for which is q < 0.05. (D) Protein expressions with and without correction for the use of immunomodulatory treatment. NPX indicates normalized protein expression data from Olink.