Salivary thioredoxin-1 as a non-invasive redox biomarker in oral diseases

Table 1 Molecular actions of thioredoxin-1 and their relevance in oral diseases

Molecular function of thioredoxin-1	Associated pathway or target	Biological effect	Relevance in oral diseases
Antioxidant activity	Reactive oxygen species scavenging pathways	Reduction of oxidative stress and maintenance of redox balance	Protection against periodontal tissue destruction and oxidative cellular injury
Redox regulation	Nuclear factor kappa B and activator protein-1 signaling pathways	Regulation of inflammatory cytokine production and inflammatory signaling	Contribution to chronic inflammation in periodontal diseases
Inhibition of apoptosis	Apoptosis signal-regulating kinase 1 pathway	Prevention of programmed cell death and promotion of cell survival	Survival of dysplastic and malignant cells in oral lesions
Support of DNA synthesis and repair	Ribonucleotide reductase pathway	Promotion of cellular proliferation and genomic maintenance	Facilitation of progression in oral potentially malignant disorders and oral squamous cell carcinoma
Promotion of angiogenesis	Redox-sensitive angiogenic signaling pathways	Formation of new blood vessels and enhancement of tumor microenvironment	Tumor progression and metastatic potential in oral squamous cell carcinoma
Extracellular signaling activity	Cytokine-like immunomodulatory pathways	Regulation of immune and inflammatory responses	Basis for its detectability and utility as a salivary biomarker