Decreased Peripheral Blood Natural Killer Cell Count in Untreated Juvenile Dermatomyositis Is Associated with Muscle Weakness

• Published in: International journal of molecular sciences Vol. 25; no. 13; p. 7126
• Main Authors: Khojah, Amer, Pachman, Lauren M, Bukhari, Ameera, Trinh, Chi, Morgan, Gabrielle, Pandey, Surya, Le Poole, I Caroline, Klein-Gitelman, Marisa S
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 28.06.2024
• Subjects: Adolescent; Autoimmune diseases; Biopsy; CD56 Antigen - metabolism; Cells; Child; Child, Preschool; Cytotoxicity; Dermatomyositis - blood; Dermatomyositis - immunology; Dermatomyositis - pathology; Disease; disease activity scores; Enzymes; Family medical history; Female; Humans; Interferon; juvenile dermatomyositis; Killer Cells, Natural - immunology; Killer Cells, Natural - metabolism; Lymphocyte Count; Male; Muscle Weakness - blood; natural killer cell; Pathophysiology; Patients; Perforin - metabolism; perforin expression; perforin expression; natural killer cell; disease activity scores; juvenile dermatomyositis
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms25137126

Juvenile Dermatomyositis (JDM) is the most common inflammatory myopathy in pediatrics. This study evaluates the role of Natural Killer (NK) cells in Juvenile Dermatomyositis (JDM) pathophysiology. The study included 133 untreated JDM children with an NK cell count evaluation before treatment. NK cell subsets (CD56 vs. CD 56 ) were examined in 9 untreated children. CD56 and perforin were evaluated in situ in six untreated JDM and three orthopedic, pediatric controls. 56% of treatment-naive JDM had reduced circulating NK cell counts, designated "low NK cell". This low NK group had more active muscle disease compared to the normal NK cell group. The percentage of circulating CD56 NK cells was significantly lower in the NK low group than in controls (0.55% vs. 4.6% < 0.001). Examination of the untreated JDM diagnostic muscle biopsy documented an increased infiltration of CD56 and perforin-positive cells ( = 0.023, = 0.038, respectively). Treatment-naive JDM with reduced circulating NK cell counts exhibited more muscle weakness and higher levels of serum muscle enzymes. Muscle biopsies from treatment-naive JDM displayed increased NK cell infiltration, with increased CD56 and perforin-positive cells.