GLP-1, the researchers explain, is a peptide, or amino acid chain, that increases insulin secretion. GLP-1 agonists help activate this process.

According to the researchers, GLP-1 agonists can help regulate the immune system by reducing systemic inflammation. Previous studies have shown that GLP-1 agonists inhibit tumor necrosis factor-alpha (TNF-alpha), the researchers report. TNF-alpha is a cytokine, or protein, involved in psoriatic disease inflammation.

Many biologic treatments for psoriasis, such as Enbrel (etanercept) and Humira (adalimumab), work by blocking TNF-alpha.

Type 2 diabetes, a comorbidity of psoriasis, is associated with inflammation, the researchers note. Previous research has found that obesity, a risk factor for type 2 diabetes and psoriasis, can lead to an increase in inflammation, because fat cells secrete pro-inflammatory cytokines.

In one study analyzed by the researchers, a patient taking both the GLP-agonist and Soriatane (acitretin), a systemic medication for psoriasis, experienced a reduction in psoriasis area and severity index score (PASI) from 14.2 to 7.6. Psoriasis disease severity is determined by assessing the degree of redness, shedding, plaque thickness and affected body surface area, degree of itching, and the impact of psoriasis on quality of life. Psoriasis with a PASI score under 10 is generally considered to be mild. In another study of seven patients with psoriasis, two experienced at least a 50 percent improvement in PASI score (known as PASI 50).

The therapy was well-tolerated by most patients, according to the researchers. In some cases, the researchers note, a patient’s psoriasis improved before the drug took effect as a diabetes medication, suggesting that it improves psoriasis by working directly on the immune system.

Three clinical trials have tested GLP-1 agonist therapy for psoriasis, according to the researchers. Two of these were for patients with psoriasis alone, and one was for patients with psoriasis and type 2 diabetes. Larger studies with longer follow-up periods are needed to explore whether GLP-1 agonist therapy could be an effective psoriasis treatment, the researchers conclude.