Despite a range of treatments for posttraumatic stress disorder (PTSD), only a small proportion of patients reach full symptomatic remission. Recent developments in the field of neuroscience have been providing compelling evidence to suggest that neurobiological determinants might influence not only the emergence of PTSD, but also its resistance to treatment. Immune-inflammation regulatory processes were found to be active during recovery from PTSD, potentially through interactive relationship with the oxytocin secretion system. This innovative longitudinal study aims to examine the role of inflammatory biomarkers and their interactive effect with the oxytocin (OT) system on the development of PTSD and on treatment response among patients with PTSD symptoms undergoing psychotherapy treatment. Patients (N = 100) suffering from trauma-related distress will be recruited from the trauma clinic in Shalvata Mental Health Center. Participants will be followed for 12 weeks of once-a-week psychotherapy sessions. They will be measured for endogenous OT level and cytokines levels in saliva before and after sessions 1, 6, and 12, and will complete psychotherapy outcome self-report questionnaires following each of these sessions.