The inclusion criteria for this study were patients aged 18 to 75 years with a confirmed diagnosis of psoriasis by a dermatologist or psoriatic arthritis by a rheumatologist. Patients with active infections or suspected malignancies were excluded.

A total of 40 patients with psoriasis, with or without psoriatic arthritis, were enrolled from multiple centers in Taiwan. All participants were recruited from the outpatient clinics of either the Department of Allergy, Immunology, and Rheumatology or the Department of Dermatology in tertiary hospitals across Taiwan.

Participants were randomly assigned to one of two groups:

Prescreen Strategy-Based Biologics Selection Group

Standard-Based Biologics Selection Group

Patients will be followed up at weeks 4, 8, 12, 24, 32, 40, 48, 56, 64, and 72. Follow-up may be extended up to 3 years if necessary.

Clinical assessments will include:

Primary endpoints: PASI (Psoriasis Area and Severity Index), painful joint count, swollen joint count, and DAPSA (Disease Activity in Psoriatic Arthritis) score.

Secondary endpoints: DLQI (Dermatology Life Quality Index), BSA (Body Surface Area), pruritus score, and internal carotid artery thickness measured at 6 months, 1 year, and 2 years.

To prepare the PBMC (peripheral blood mononuclear cell) culture, 16 mL of peripheral blood is collected from each patient using sodium citrate tubes (Vacutainer CPT, BD Biosciences, Franklin Lakes, NJ, USA). PBMCs are isolated by centrifugation at 1800 × g for 20 minutes at room temperature with the brake turned off, resulting in the separation of plasma, PBMCs, gel plugs, and red blood cell (RBC) layers.

The isolated PBMCs are washed with phosphate-buffered saline (PBS) and then cultured in RPMI-1640 medium supplemented with 10% fetal bovine serum (FBS) and 1% penicillin/streptomycin at 37 °C in a 5% CO₂ incubator.

A total of 6 × 10⁵ cells/mL are seeded into 12-well plates and treated for 24 hours under the following conditions:

Control

Streptococcus pyogenes only

S. pyogenes + adalimumab (4 μg/mL)

S. pyogenes + golimumab (0.5 μg/mL)

S. pyogenes + certolizumab (20 μg/mL)

S. pyogenes + ustekinumab (0.25 μg/mL)

S. pyogenes + ixekizumab (3.5 μg/mL)

S. pyogenes + secukinumab (16.7 μg/mL or 34 μg/mL)

S. pyogenes + guselkumab (1.2 μg/mL)

S. pyogenes + risankizumab (2 μg/mL)

Culture supernatants are collected for subsequent cytokine measurement. The concentrations of biological agents used correspond to the trough serum concentrations at steady state as indicated in the pharmacokinetic sections of reference data. The two concentrations of secukinumab (16.7 μg/mL and 34 μg/mL) reflect the two common clinical doses of 150 mg and 300 mg per month, respectively.

Cytokine Analysis

Cytokine levels are measured in the collected supernatants using a protein multiplex immunoassay system (Bio-Plex Cytokine Array System, Bio-Rad Laboratories, Hercules, CA, USA). The following cytokines and chemokines are analyzed:

IL-1β, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12, IL-13, IL-17A, IFN-γ, TNF-α, monocyte chemoattractant protein-1 (MCP-1), macrophage inflammatory proteins (MIP-1α and MIP-1β), platelet-derived growth factor-BB (PDGF-BB), and chemokine (CC motif) ligand 5 (RANTES).

Screening Method for Biologic Agents

RANTES Exclusion First, biologics that induce a RANTES level ≥1.5 times higher than that of S. pyogenes-only treatment are excluded.

Scoring System for Biologic Selection in Psoriasis

Remaining biologics are categorized into three grades based on biomarker levels:

IFN-γ

IL-17A

IFN-γ/IL-4

IFN-γ/IL-13

IL-17A/IL-4

IL-17A/IL-13

Grade 1 (Most appropriate): Lowest biomarker values

Grade 2 (Possibly appropriate): Intermediate values

Grade 3 (Not recommended): Highest values

Each grade is subdivided into a, b, and c groups:

Lower values within a grade are ranked as a, followed by b, then c

Scoring is as follows:

1. a = +3, 1b = +2, 1c = +1.5
2. a = +1, 2b = +0.5, 2c = 0
3. a = -0.5, 3b = -1, 3c = -1.5

The total score for each biologic is the sum of individual biomarker scores. Based on total scores:

High score = Most appropriate

Medium score = Possibly appropriate

Low score = Not recommended

Scoring for Psoriatic Arthritis (PsA)

For PsA, biologics are selected based on the lowest RANTES, MCP-1 and IFN-γ levels:

Grade 1 (Most appropriate): Lowest biomarker values Grade 2 (Possibly appropriate): Intermediate values Grade 3 (Not recommended): Highest values RANTES: 2+, 1+, 0 MCP-1: 1+, 0.5+, 0 IFN-γ: 1+, 0.5+, 0 The final score is the sum of RANTES MCP-1 and IFN-γ scores. Biologics with the lowest total scores are preferred.

Patient Assignment in Strategic Group

Biologics from the "most appropriate" group are selected for each patient in the strategic group. The following clinical indicators are monitored over time:

Absolute PASI

Tender joint count

Swollen joint count

DAPSA score

DLQI

Internal carotid artery intima thickness

Follow-up Timeline

Clinical assessments: Weeks 0, 2, 4, 12, 24, and 48

Intima thickness: Weeks 0 and 48

Outcome Comparison Outcomes between the strategic selection group and standard care group are compared at Weeks 24 and 48, with extended follow-up up to 5 years. Primary outcomes include PASI and DLQI scores.

Statistical Analysis

All statistical analyses are conducted using SPSS version 22 (IBM, Armonk, NY, USA). Demographic and clinical characteristics, as well as outcome measures (PASI, joint counts, DAPSA, DLQI, and carotid intima thickness), are analyzed using the Mann-Whitney U test and Spearman's rho correlation.

Data are presented as mean ± standard deviation. Two-sided p values < 0.05 are considered statistically significant.

Inclusion Criteria:

• Healthy subjects
• Psoriasis patients
• Psoriatic arthritis patients
• Agree to provide a blood sample

Exclusion Criteria:

• A current history of cancer,
• Recent hospitalization for infection or current antibiotic treatment
• HIV infection.

only IPD used in the results publication