Role of oxidative stress in induction of trans-differentiation of neutrophils in patients with rheumatoid arthritis

Abstract

Rheumatoid arthritis (RA) is an autoimmune disorder whose etiopathology involves an interplay between genetic and environmental factors, with oxidative stress being a key contributory factor. This study aimed to establish the impact, if any, of an oxidative, pro-inflammatory milieu upon trans-differentiation of neutrophils and disease progression. In the synovial fluid (SF) and peripheral blood sourced from patients with RA (n = 40) along with healthy controls (n = 25), the proportion of neutrophil-dendritic (N-DC) cell hybrids, i.e. CD66b⁺/CD83⁺ was characterized in terms of their antigen presentation (HLA-DR, CD80, andCD86) and cell adhesion and migration (ICAM-1, VCAM-1, and CD62L) properties, along with their ability to generate reactive oxygen species (ROS). In the SF of RA cases, the raised levels of circulating and intra-neutrophilic pro-inflammatory cytokines/chemokines were accompanied by an enhanced proportion of CD66b⁺ neutrophils, that co-expressed features of antigen presenting cells (APCs) namely CD83, HLA-DR, CD80, CD86, ICAM-1, VCAM-1, and decreased CD62L. These N-DCs as compared to canonical neutrophils demonstrated a higher generation of ROS, and their frequency positively correlated with disease activity score (DAS28). An ex-vivo functional assay validated that oxidative stress supported trans-differentiation and could be attenuated by a free radical scavenger. Taken together, the pro-inflammatory microenvironment in the SF of patients with RA coupled with a higher generation of ROS promoted the trans-differentiation of neutrophils into N-DCs, suggesting the inclusion of anti-oxidants as an add-on therapeutic strategy to limit trans-differentiation.

Keywords:

• Neutrophil-dendritic cell hybrids
• pro-inflammatory cytokines
• oxidative stress
• reactive oxygen species
• rheumatoid arthritis

Disclosure statement

The authors report no conflicts of interest.

Additional information

Funding

The work received financial support from a JC Bose fellowship [Science Engineering Board, Govt. of India (JCB/2019/000043) MC] and technical support from Fund for Improvement of S&T infrastructure in Universities and Higher Educational Institutions (FIST) Program, Department of Science and Technology, Govt. of India, SR/FST/LS1-663/2016, and Department of Health Research, Govt. of India, “Establishment of Multidisciplinary Research Unit” no: V.25011/103/2016-HR.