Interleukin-10 reduces hyperalgesia and the level of Interleukin-1β in BALB/c mice infected with Leishmania major with no major effect on the level of Interleukin-6

Infection with a high dose of Leishmania major has been shown to induce hyperalgesia in BALB/c mice accompanied by a sustained upregulation of Interleukin-1β (IL-1β) and an early upregulation of Interleukin-6 (IL-6). On the other hand, Interleukin 10 (IL-10) has been demonstrated to be hypoalgesic in other models such as rats exposed to UV rays. In this study, we injected BALB/c mice with a high dose of Leishmania major and treated them with IL-10 (15 ng/animal) for six consecutive days. Hyperalgesia was assessed using thermal pain tests and the levels of IL-1β and IL-6 were also assessed at different post-infection days. Our results show that IL-10 can reduce the Leishmania major-induced hyperalgesia during the treatment period through a direct effect on the levels of IL-1β which seems to play an important role in this hyperalgesia induction since its level was reduced during the period of IL-10 injection and was increased again when this treatment was stopped. On the contrary IL-10 has no direct effect on the levels IL-6 which seems to have no direct role in the induced hyperalgesia.