A novel biomarker associated with distress in humans: calcium-binding protein, spermatid-specific 1 (CABS1)

Abstract

Calcium-binding protein spermatid-specific 1 (CABS1) is expressed in the human submandibular gland and has an anti-inflammatory motif similar to that in submandibular rat 1 in rats. Here, we investigate CABS1 in human saliva and its association with psychological and physiological distress and inflammation in humans. Volunteers participated across three studies: 1) weekly baseline measures; 2) a psychosocial speech and mental arithmetic stressor under evaluative threat; and 3) during academic exam stress. Salivary samples were analyzed for CABS1 and cortisol. Additional measures included questionnaires of perceived stress and negative affect; exhaled nitric oxide; respiration and cardiac activity; lung function; and salivary and nasal inflammatory markers. We identified a CABS1 immunoreactive band at 27 kDa in all participants and additional molecular mass forms in some participants. One week temporal stability of the 27-kDa band was satisfactory (test-retest reliability estimate = 0.62-0.86). Acute stress increased intensity of 18, 27, and 55 kDa bands; 27-kDa increases were associated with more negative affect and lower heart rate, sympathetic activity, respiration rate, and minute ventilation. In both acute and academic stress, changes in 27 kDa were positively associated with salivary cortisol. The 27-kDa band was also positively associated with VEGF and salivary leukotriene B4 levels. Participants with low molecular weight CABS1 bands showed reduced habitual stress and negative affect in response to acute stress. CABS1 is readily detected in human saliva and is associated with psychological and physiological indicators of stress. The role of CABS1 in inflammatory processes, stress, and stress resilience requires careful study.

Keywords: acute and chronic stress; anti-inflammatory activity; calcium-binding protein spermatid-specific 1; cortisol; negative affect; saliva; submandibular rat 1.

Fig. 1.

CABS1 is detected in saliva at varying molecular weights among different individuals and stress conditions. A representative Western blot showing CABS1 detected in saliva from 3 different individuals across 3 studies. Lane 1 contains human submandibular gland (SMG) as a normalization control. Lanes 2–5 contain saliva samples collected weekly over 4 wk from 1 participant in study 1 (multiple baseline assessment). Lanes 6–11 contain saliva samples collected at 6 time points (−15 and −0 m are prestress; +0, +15, +30, and +45 m are poststress) from 1 participant during study 2 (acute laboratory stress). Lanes 12–14 contain saliva samples collected at 3 time points (pre is before exams begin; early and late are during exams) from 1 participant in study 3 (final exam stress). All lanes were loaded with 25 μg protein, and all immunoreactive band intensity values were normalized to the 27-kDa band in SMG.

Fig. 2.

CABS1 band of 27 kDa for individual participants across 5 weekly baseline assessments.

Fig. 3.

CABS1 band of 27 kDa during the laboratory stress assessment protocol with the Trier Social Stress Test. **P < 0.01 relative to measurement at 0 min before stress (−0 min).

Fig. 4.

CABS1 band of 27 kDa for individual participants during low stress and final exam stress periods.

Fig. 5.

Effects of the Trier Social Stress Test on levels of CABS1 bands of 18, 15, and 12 kDa for 5 individual participants.

Fig. 6.

A: changes in negative affect [PANAS negative-affect subscale (ΔPANAS neg)] in response to the Trier Social Stress Test in those with (n = 5) and without (n = 11) additional CABS1 bands at 18, 15, and/or 12 kDa. ***P < 0.001. B: perceived Stress Scale (PSS) scores in those with (n = 6) and without (n = 24) additional CABS1 bands at 18 and/or 12 kDa in study 1. †P < 0.10. C: PSS scores in those with (n = 5) and without (n = 11) additional CABS1 bands at 18, 15, and/or 12 kDa in study 2. *P < 0.05.