Purpose: The vitreous proteome might provide an attractive gateway to discriminate between various uveitis aetiologies and gain novel insights into the underlying pathophysiological processes. Here, we investigated 180 vitreous proteins to discover novel biomarkers and broaden disease insights by comparing (1). primary vitreoretinal lymphoma ((P)VRL) versus other aetiologies, (2). sarcoid uveitis versus tuberculosis (TB)‐associated uveitis and (3). granulomatous (sarcoid and TB) uveitis versus other aetiologies.Methods: Vitreous protein levels were determined by proximity extension assay in 47 patients with intraocular inflammation and a prestudy diagnosis (cohort 1; training) and 22 patients with a blinded diagnosis (cohort 2; validation). Differentially expressed proteins identified by t‐tests on cohort 1 were used to calculate Youden’s indices. Pathway and network analysis was performed by ingenuity pathway analysis. A random forest classifier was trained to predict the diagnosis of blinded patients.Results: For (P)VRL stratification, the previously reported combined diagnostic value of IL‐10 and IL‐6 was confirmed. Additionally, CD70 was identified as potential novel marker for (P)VRL. However, the classifier trained on the entire cohort (cohort 1 and 2) relied primarily on the interleukin score for intraocular lymphoma diagnosis (ISOLD) or IL‐10/IL‐6 ratio and only showed a supportive role for CD70. Furthermore, sarcoid uveitis displayed increased levels of vitreous CCL17 as compared to TB‐associated uveitis.Conclusion: We underline the previously reported value of the ISOLD and the IL‐10/IL‐6 ratio for (P)VRL identification and present CD70 as a potentially valuable target for (P)VRL stratification. Finally, we also show that increased CCL17 levels might help to distinguish sarcoid uveitis from TB‐associated uveitis.

Objectives: To examine the relation between serum C1q levels and blood type‐1 interferon signature (type‐1 IFN signature) in active pulmonary tuberculosis (APTB) and to determine whether combined measurement of serum C1q and type‐1 IFN signature may add to the diagnosis of QuantiFERON‐positive (QFT⁺) patients with uveitis of unknown cause.Methods: C1q was determined (ELISA) in serum from two distinct Indonesian cohorts, and in total, APTB (n = 72), QFT⁺ uveitis of unknown aetiology (n = 58), QFT⁻ uveitis (n = 51) patients and healthy controls (HC; n = 73) were included. The type‐1 IFN signature scores were previously determined.Results: Serum C1q was higher in APTB than HC (P < 0.001). APTB patients with uveitis had higher serum C1q than APTB patients without uveitis (P = 0.0207). Serum C1q correlated inversely with type‐1 IFN signature scores in APTB (P = 0.0036, r² = 0.3526), revealing that these biomarkers for active TB disease can be mutually exclusive. Stratification of QFT⁺ patients with uveitis of unknown cause, by serum C1q and type‐1 IFN signature, yielded four groups with different likelihood of suffering from active TB uveitis.Conclusion: Serum C1q is elevated in APTB, especially in those cases with uveitis. We propose that combined measurement of blood type‐1 IFN signature and serum C1q may provide added value in the diagnosis of active TB disease. Combined measurement of type‐1 IFN signature and serum C1q in QFT⁺ patients without signs of active TB disease, but suffering from uveitis of unknown cause, may be of help to identify cases with low or high likelihood of having active TB uveitis, which may facilitate clinical management decisions.

In this study, we measured serum interferon (IFN) levels and activity in patients with sarcoidosis and tuberculosis (TB) with and without uveitis. We aimed to understand the role of IFN in the pathophysiology of both conditions and explore its potential as a discriminating marker for these clinically similar diseases. Sera from an Indonesian TB and a Dutch sarcoidosis cohort were used in the analysis. IFNα2 and IFNγ concentrations were measured using Simoa® and Luminex assays, respectively. Serum IFN activity was assessed by incubating THP-1 cells with patient serum and measuring IFN-stimulated gene transcription using qPCR. Anti-IFNα2 and IFNγ autoantibodies were detected via Luminex assay and tested for neutralizing capacity using a flow cytometry-based signal transducer and activator of transcription (STAT) 1 phosphorylation inhibition assay. IFNα2 was detected in 74 % and 64 % of patients with sarcoidosis and pulmonary TB, respectively, while IFNγ was found in 78 % and 23 % of patients with sarcoidosis and TB, respectively. For uveitis cases specifically, IFNα2 was detected in 85 % of sarcoid uveitis (SU) and 33 % of tubercular uveitis (TBU) cases. Similarly, IFNγ was detected in 69 % of SU and 17 % of TBU cases. IFNγ serum concentrations were higher in sarcoidosis than that in TB patients (p < 0.0001). Focusing on patients with uveitis, SU showed increased IFNα2 (p = 0.004) and IFNγ (p < 0.002) serum concentrations compared to that in TBU. Notably, TBU displayed significantly reduced IFNα2 concentrations compared to that in healthy controls (p = 0.006). These results align with the increased interferon stimulated gene (ISG) transcriptional upregulation observed in THP-1 cells stimulated with serum from patients with sarcoidosis. Elevated levels of non-neutralizing anti-IFN autoantibodies were observed in patients with TB; however, these levels were similar to those observed in geographically matched healthy Indonesian controls. Our results suggest decreased serum levels and activity of type I and II IFN in TB compared to those in sarcoidosis. This is indicative of distinct pathophysiological processes in these highly clinically similar diseases. We propose that the assessment of serum IFN levels and IFN activity has the potential to distinguish between sarcoidosis/SU and TB/TBU.

Meesilpavikkai K, et al. Immune Netw. 2025 Apr;25(2):e18. https://doi.org/10.4110/in.2025.25.e18

To explore the autoimmune component of sarcoid uveitis (SU) by analyzing serum anti-retinal antibodies (ARAs), identifying targeted retinal proteins, T- and B-cell receptor repertoires and HLA genotype. Material from 45 sarcoidosis patients with no presenting uveitis (SNPU) and 46 with SU was analyzed. Serum ARAs and targeted retinal layers were assessed using indirect immunofluorescence staining. HuScan analysis identified autoantibody-targeted linear epitopes. Validation included a bead-based assay for anti-Piccolo Presynaptic Cytomatrix Protein (PCLO) antibodies and an ELISpot assay for PCLO-reactive T-lymphocytes. T cell receptor beta (TCRB) and B cell receptor heavy (BCRH) repertoire analyses were performed using next-generation sequencing and HLA class II genotypes were determined by sequence-specific primer analysis. ARAs were more prevalent in SU patients than in SNPU patients (52 vs. 22 %, p = 0.003), with significant more reactivity against the nuclear retinal layer (32 vs. 7 %, p = 0.005). HuScan identified autoantibodies against three retinal proteins, including PCLO. Bead-based analysis showed higher anti-PCLO autoantibody levels in ARA-positive patients (median: 913.3 vs. 544.5, p = 0.035), and PCLO-directed T-lymphocytes were present in ARA-positive SU patients. Two TCRB clusters were identified in four unique ARA positive patients, while absent in ARA negative patients. No HLA allele association with ARA status could be detected. Our findings reveal an association between serum ARA-positivity and SU, suggesting a link to autoimmune processes. An humoral and cellular response against the retinal protein PCLO was identified, highlighting PCLO as a potential autoimmune target in ARA-positive patients. Additionally, specific TCRB clusters were found to correlate with ARA status.