We appreciate the interest and comments on our paper by Chisci et al. The points highlighted in the letter seek an explanation for gender-, physiological-, and environmental-dependent variations in oxidative stress (OS) in the study patients and their possible effects on the results.

Heat shock proteins (HSPs) play essential roles in biochemical processes. HSP70 coordinates and cooperates with other proteins to overcome mild stress in an organism at the cellular-local level. HSP70 has two isoforms: cognate-constitutive (HSC70) and inducible (HSP70). HSP70 but not HSC70 expression is induced when an organism is under stress. HSP70 acts locally and prevents induced OS. If HSP70 cannot overcome OS, then HSP70 activates apoptosis.

In our study, two different techniques were applied to the same individual within a 2-week time frame and we determined inducible HSP70 levels both at the protein and mRNA level. Please note that HSP70 acts locally, therefore OS is less likely to affect the results. Other factors such as local anaesthesia and/or anxiety are negligible since comparisons were made on the same patient.

The study sub-group, 13 female patients, consisted of younger women (patient age range 19–32 years). For this reason it is likely that no menopausal women were included in the sub-group. To the best of our knowledge no woman in the group was pregnant – we are extremely cautious about pregnant women and specifically ask individuals about their pregnancy status before performing any treatment in the clinic. As stated above, menstrual cycle phases and menopause may have no effect on HSP70 induction locally, but may have an effect on the HSC70 level. The average HSC70 fold increases in patients were similar in both genders in our study, supporting a lack of effect of OS-dependent factors on the reported results.

In conclusion, HSP70 may be used as a marker of stress in both males and females. Two different molecular techniques, the enzyme-linked immunosorbent assay (ELISA) and real-time reverse-transcription polymerase chain reaction (RT-qPCR), support the hypothesis, and the results correlate with each other.