Alex Birk Nielsen

Over the past two decades, numerous highly effective biological treatments have been developed for patients with moderate-to-severe psoriasis. As a result of more effective therapies, treatment goals have shifted from a 50% to a 90% reduction in psoriasis area and severity index. Although randomized controlled trials provide some insight, they often include only a subset of patients, have short durations, and do not compare different treatments. Many patients respond well to these new treatments; however, some do not respond at all, whereas others experience a loss of effectiveness after an initial response. No definitive guidelines on the best time to start treatment or on how to choose the most suitable treatment for an individual patient have yet been established. Furthermore, it remains uncertain whether optimal treatment or specific therapy reduces the risk of developing comorbidities. Real-world data have revealed adverse effects, such as tuberculosis reactivation with tumor necrosis factor inhibitors, worsening of inflammatory bowel disease with interleukin-17 inhibitors, and potential cardiovascular events associated with particularly interleukin-12/23 inhibition. Studies from both clinical trials and real-world settings have also shown that patients with high body mass index, smokers, older individuals, and those with prior biological treatments tend to have poorer treatment outcomes. Recently, studies have indicated that genetic markers such as HLA-C*06:02, initial treatment response, and post-initiation drug concentration levels can predict treatment response. The integration of genetic markers, clinical data, and advanced technologies may aid in developing more personalized treatment plans for patients in the future.

Accumulating evidence supports the association between altered salivary microbiota and inflammatory diseases. The existing literature on the salivary microbiota in patients with psoriasis is limited. However, differences in the prevalence of Candida species and abundance of several bacterial taxa in saliva have been found between patients and controls. This study aimed to investigate the differences in the composition and functional potential of salivary microbiota in patients with psoriasis compared to their cohabiting partners and healthy controls. Samples from 115 of 123 individuals qualified for statistical analysis: patients with psoriasis who did not receive systemic anti-psoriatic treatment (n=47); cohabiting partners (n=21); and age-, sex-, and BMI-matched healthy controls (n=47). One saliva sample was collected from each participant and analysed by shotgun metagenomic sequencing. A difference in the α-diversity of bacterial species was observed exclusively between patients and controls, with a lower diversity in patients (p=0.041). Variation in bacterial composition (β-diversity) was influenced by smoking (p=0.001) and diet (p=0.025) but not by group status. Using a linear regression model adjusted for smoking and diet, we identified four bacterial classes and five species that were significantly different between the patient, partner, and control groups. One Kyoto Encyclopedia of Genes and Genomes module differed significantly between patients with psoriasis and their partners. No differences in Candida species or abundance were found among the three groups. Comparison of salivary microbiota at the levels of bacterial diversity, composition, and predicted function indicated that psoriasis cases are characterised by dysbiosis.