Table 3.
Detailed characteristics of included studies considering mainly qualitative assessments of saliva.
| Author, Year | AITD Diagnosis | Type of Saliva and Method of Collection |
Centrifugation and Storing | Method of Analysis | Method of Salivation Assessment | Potential Salivary Biomarkers |
|---|---|---|---|---|---|---|
| Ford et al., 1997 [24] | GD | Stimulated saliva collected over a 5 min period during which the subject chewed raw gum (chicle) and spat into a plastic container | Lysozyme activity and total protein concentration determined on fresh specimens left at 5 °C overnight; other assays performed on specimens frozen at −70 °C up to 3 weeks | Protein assay kits based on the method of Bradford, Hitachi 717 random access analyser | Flow rate (mL/min) | Up: urate (p-value < 0.02), potassium (p-value < 0.01); down: total protein, calcium (p-value < 0.02), lactate dehydrogenase (p-value < 0.01) |
| Higashi et al., 2011 [25] | GD | Unstimulated saliva (ca. 1 mL) directly collected into a collecting tube; at least 1 h after any food intake | Stored below −15 °C until the analysis; after thawing, centrifuged at 1000× g for 10 min | Stable isotope-dilution liquid chromatography/tandem mass spectrometry method | NR | T4 |
| Morawska et al., 2021 [26] | HT | Unstimulated whole saliva collected into a centrifuge tube placed in a container with ice for 15 min, one day after blood collection and dental examination, between 7 a.m. and 9 a.m., on an empty stomach (last meal at least 10 h earlier) and did not perform any oral hygiene procedures on this day other than rinsing the mouth with water | Centrifuged for 20 min at 4 °C, 10,000× g, and frozen at −80 °C for no longer than 4 months, until assayed | Bio-Plex Pro Human Cytokine Assay (a multiplex assay based on magnetic beads) | Flow rate (mL/min) measured with a calibrated pipette | Cytokines: up: IL-3, IFN-γ, IL-5, IL-6, TNF-α, IL-12 (p40), HGF, IL-1α, IL-1β, IL-1RA, down: IL-8, IL-10; chemokines: up: CCL27/CTACK, CXCL1/Gro-α; growth factors: up: G-CSF, VEGF, TRIAL |
| Morawska et al., 2020 [27] | HT | Whole saliva unstimulated (for 15 min) and stimulated (after a 5 min break, for 5 min), collected via the spitting method into plastic centrifuge tubes placed in ice containers, between 8 a.m. and 10 a.m.; participants advised to refrain from consuming meals and drinks other than clean water, performing oral hygiene procedures for 2 h and taking any medications for 8 h; the first-minute sample discarded; stimulation triggered by dripping 100 μL 2% citric acid under the tongue every 20 s; to avoid oxidation, 0.5 M BHT added | Centrifuged for 20 min at 4 °C, 10,000× g, and frozen at −80 °C for no longer than 6 months, until assayed | Spectrophotometry, ELISA, colorimetry | Flow rate (mL/min) measured with a pipette calibrated to 0.1 mL | Up: total protein, IL-1β, CAT, Px, AGE, AOPP, LOOH, MDA (p-value < 0.0001); down: amylase, GSH, UA (p-value < 0.0001), SOD (p-value < 0.05, only unstimulated) |
| Pelewicz et al., 2020 [28] | GO | Using a Salivette® commercial device; at three time points: directly before administration of the 1st and 12th IVMP pulses and after the cessation of oral prednisone therapy, between 8:00 and 9:00 a.m. after fasting | Stored at −20 °C until analysis | A first-generation Elecsys® cortisol assay | NR | Cortisol (decreased after oral prednisone therapy) |
| Rao et al., 2010 [29] | HT | Unstimulated whole saliva collected by passive drooling into an ice-chilled polypropylene vial to a volume about 2 mL, at least 2 h after any food intake | Stored below −20 °C until the analyses | ELISA | NR | C-reactive protein (ns) |
| Tumilasci et al., 1996 [30] | GD, HT | Stimulated total parotid saliva obtained by use of a CarlsonCrittenden cannula after stimulation with a solution of citric acid 0.1 M for 3 min; between 08:00 and 09:00 a.m. after fasting | Frozen so the TRAb assay could be carried out monthly | TRAb receptor assay | Flow rate (mL/min) | TRAb |
| Van Herle et al., 1989 [31] | GD, HT | Unstimulated saliva from 2 to 10 mL in a clean disposable plastic container, from 5 to 30 min; patients asked to discard first salivary discharge 1 min after rinsing with water | After the collection immediately centrifugated at 10,000 rpm (5 min) and stored at −20 °C; immediately before the assays thawed and recentrifuged at 3500 rpm at 4 °C | Radioimmunoassay | NR | Tg and TgAb |
Legend: AITD, autoimmune thyroid disease; GD, Graves’ disease; HT, Hashimoto’s thyroiditis; GO, Graves’ orbitopathy; NR, not reported; T4, thyroxine; IL-3, interleukin 3; IFN-γ, interferon γ; IL-5, interleukin 5; IL-6, interleukin 6; TNF-α, tumour necrosis factor α; IL-12, interleukin 12; HGF, hepatocyte growth factor; IL-1α, interleukin 1α; IL-1β, interleukin 1β; IL-1RA, interleukin 1 receptor antagonist; IL-8, interleukin 8; IL-10, interleukin 10; CCL27/CTACK, c-c motif chemokine ligand 27/cutaneous T cell-attracting chemokine; CXCL1/Gro-α G-CSF, chemokine (C-X-C motif) ligand 1/granulocyte colony stimulating factor; VEGF, vascular endothelial growth factor; BHT, butylated hydroxytoluene; ELISA, enzyme-linked immunoassay; CAT, catalase; Px, peroxidase; AGE, advanced glycation end products; AOPP, advanced oxidation protein products; LOOH, lipid hydroperoxides; MDA, malondialdehyde; GSH, reduced glutathione; UA, uric acid; SOD, superoxide dismutase; IVMP, intravenous methylprednisolone; ns, non-significant; TRAb, thyrotropin receptor antibody; Tg, thyroglobulin; TgAb, thyroglobulin antibody.