Investigation Explores Relationship Between Psoriasis and Autoimmune Disorders

Patients with psoriasis may be more likely to have additional autoimmune disorders, including vitiligo, diabetes, autoimmune thyroiditis, rheumatoid arthritis, and inflammatory bowel disease (IBD), according to study results published in Indian Dermatology Online Journal.

Although the exact etiology of psoriasis is unknown, genetic, metabolic, and immunologic mechanisms have all been implicated in the condition’s pathophysiology. Between 0.5% and 11.4% of individuals around the world are affected by psoriasis.

“Psoriasis, an immune-mediated inflammatory dermatosis…has been widely viewed as an autoimmune disease in view of flare-ups in psoriasis being triggered by bacterial microbiota by molecular mimicry,” the researchers explained. “The efficacy of various targeted therapies, both in psoriasis and other autoimmune disorders, further upholds this view.”

Because no autoantigens or self-reactive T cells that trigger psoriasis have been authenticated, the issue as to whether psoriasis ought to be considered a bona fide autoimmune disease remains. To better understand the profile of autoimmune disorders among Indian patients with psoriasis, the researchers recruited 80 consecutive patients with chronic plaque psoriasis from an outpatient clinic between 2017 and 2018.

Any patient taking systemic retinoids, corticosteroids, or other immunomodulator drugs in the last 3 months were excluded from the study. In addition, psoriasis severity was graded based on Psoriasis Area and Severity Index (PASI) scores (mild PASI < 6; moderate PASI = 6-12; and severe PASI > 12).

Biological data were gleaned from blood samples, measurements of antithyroid peroxidase (anti-TPO) antibodies and glycated hemoglobin, and other assessments. The majority of patients included were male (n = 57). The mean (SD) patient age was 42.04 (13.47) years, with a mean disease duration of 58.8 (60.6) months.

Analyses revealed:

• Mild to moderate and severe psoriasis were present in 86.3% and 13.8% of patients, respectively
• Psoriatic arthritis was present in 3.8% of patients, all of whom also had severe psoriasis
• 46.3% of patients had clinical and/or sero-abnormality suggestive of autoimmune disorders; 3.8%, vitiligo; 1.3%, type 1 diabetes; and 6.3%, type 2 diabetes
• Sero-positivity reflecting subclinical autoimmunity was noted for anti-CCP antibodies (2.5%), rheumatoid factor (2.5%), hypo- or hyper-thyroidism (8.8%), anti-TPO antibodies (5.0%), anti–tissue-transglutaminase antibody (1.3%), antinuclear antibody (in 5.0%), anti-dsDNA antibody (in 2.5%), and anti-Ro antibody in 11.3% patients
• Elevated fecal calprotectin levels suggestive of IBD occurred in 11.2% of 27 patients

“Deranged thyroid status in 7 (8.8%) patients in this study was consistent with hyperthyroidism in 1 and hypothyroidism in 2 patients,” the authors wrote, while the “other 4 (5.0%) patients with euthyroid status had elevated anti-TPO antibodies indicating possible subclinical autoimmune thyroiditis.”

Because of the relatively small number of patients included in the study, future long-term investigations may be able to better delineate the role of these hormones in the etiopathogenesis of psoriasis as an autoimmune disorder, the researchers explained.

“The presence of clinical and laboratory abnormalities in patients with psoriasis reflects subtle autoimmunity or a predilection for isolated or multiple diseases within the psoriasis-associated autoimmunity spectrum, which may remain asymptomatic,” the authors concluded. “Screening for concurrent autoimmune disorders seems prudent for holistic management of patients with psoriasis.”

Reference

Vashist S, Mahajan VK, Mehta KS, et al. Association of psoriasis with autoimmune disorders: results of a pilot study. Indian Dermatol Online J. Published online September 19, 2020. doi:10.4103/idoj.IDOJ_648_19