Heat-killed probiotic regulates the body’s regulatory immunity to attenuate subsequent experimental autoimmune arthritis

•Pre-treating CIA mice with heat-killed L. reuteri reduced the severity of CIA.•Heat-killed L. reuteri might modulated serum IL-6 level to repress CIA development.•Tregs and IL-10-producing CD4 + T cells played a role in suppression of CIA response.•CD103+ DCs in MLN were expanded in recipients of heat-killed L. reuteri after CIA.•Treating with heat-killed L. reuteri did not provide benefits if CIA has emerged.