Atopic dermatitis (AD) is a recurrent, chronic, and inflammatory skin disease, which processes with severe itchiness. It often coexists with different atopic diseases. The number of people suffering from AD is relatively high. Epidemiological research demonstrates that 15–30% of children and 2–10% adults suffer from AD. The disease has significant negative social and economic impacts, substantially decreasing the quality of life of the patients and their families. Thanks to enormous progress in science and technology, it becomes possible to recognise complex genetic, immunological, and environmental factors and epidermal barrier defects that play a role in the pathogenesis of AD. We hope that the new insight on cytokines in AD will lead to new, individualised therapy and will open different therapeutic possibilities. In this article, we will focus on the cytokines, interleukin (IL)-17, IL-19, IL-33, and TSLP (thymic stromal lymphopoietin), which play a significant role in AD pathogenesis and may become the targets for future biologic therapies in AD. It is believed that the new era of biological drugs in AD will give a chance for patients to receive more successful treatment.

Psoriasis (PsO) is a chronic, immune-mediated, inflammatory skin disease associated in most cases with pruritus. Chemokines seem to play a significant role in PsO pathogenesis. The aim of the study was to analyse serum concentrations of CCL2/MCP-1, CCL3/MIP-1α, CCL4/MIP-1β, CCL5/RANTES, CCL17/TARC, CCL18/PARC, CCL22/MDC and CXCL8/IL-8, and their correlation with PsO severity and pruritus intensity. The study included 60 PsO patients and 40 healthy volunteers. Serum concentrations of six (CCL2/MCP-1, CCL3/MIP-1α, CCL5/RANTES, CCL17/TARC, CCL18/PARC and CCL22/MDC) out of eight analysed chemokines were significantly elevated in PsO patients; however, they did not correlate with disease severity. The serum level of CCL5/RANTES was significantly higher in patients with the psoriasis area and severity index (PASI) ≥ 15 (p = 0.01). The serum concentration of CCL17/TARC correlated positively with pruritus assessed using the visual analogue scale (VAS) (R = 0.47; p = 0.05). The study indicated CCL17/TARC as a potential biomarker of pruritus intensity in PsO patients. Chemokines appear to be involved in the development of PsO systemic inflammation. Further detailed studies on the interactions between chemokines, proinflammatory cytokines and immune system cells in PsO are required to search for new targeted therapies.

Interleukin 35 (IL-35), a new member of the IL-12 family of heterodimeric cytokines, could induce two different types of regulatory cells including regulatory T and B cells such as IL-35-induced regulatory T cells and IL-10-producing regulatory B cells (IL-10+Bregs), and IL-35-producing regulatory B cells (IL-35+Bregs). These cells appear to play an important role in modulating the immune system in numerous diseases. Several findings suggested that the expression of IL-35 is dysregulated in many autoimmune, inflammatory, and allergic diseases. Due to the functions of IL-35, it seems that this cytokine may act as an efficient therapeutic strategy for numerous conditions including atopic dermatitis (AD). We aimed to provide a comprehensive overview of the role of IL-35 in modulating the immune system. Additionally, we highlight IL-35 as a specific immunological target, discuss its possible involvement in the pathogenesis of AD, and hypothesize that IL-35 may become a novel target for the treatment of AD. However, further studies are required to evaluate this hypothesis.

Recent studies have indicated a key role of the impaired suppressive capacity of regulatory T cells (Tregs) in psoriasis (PsO) pathogenesis. However, the genetic background of Treg dysfunctions remains unknown. The aim of this study was to evaluate the association of PsO development with selected single nucleotide polymorphisms (SNPs) of genes in which protein products play a significant role in the regulation of differentiation and function of Tregs. There were three study groups in our research and each consisted of different unrelated patients and controls: 192 PsO patients and 5605 healthy volunteers in the microarray genotyping group, 150 PsO patients and 173 controls in the ARMS–PCR method group, and 6 PsO patients and 6 healthy volunteers in the expression analysis group. The DNA microarrays analysis (283 SNPs of 57 genes) and ARMS–PCR method (8 SNPs in 7 genes) were used to determine the frequency of occurrence of SNPs in selected genes. The mRNA expression of selected genes was determined in skin samples. There were statistically significant differences in the allele frequencies of four SNPs in three genes (TNF, IL12RB2, and IL12B) between early-onset PsO patients and controls. The lowest p-value was observed for rs3093662 (TNF), and the G allele carriers had a 2.73 times higher risk of developing early-onset PsO. Moreover, the study revealed significant differences in the frequency of SNPs and their influence on PsO development between early- and late-onset PsO. Based on the ARMS–PCR method, the association between some polymorphisms of four genes (IL4, IL10, TGFB1, and STAT3) and the risk of developing PsO was noticed. Psoriatic lesions were characterized with a lower mRNA expression of FOXP3, CTLA4, and IL2, and a higher expression of TNF and IL1A in comparison with unaffected skin. In conclusion, the genetic background associated with properly functioning Tregs seems to play a significant role in PsO pathogenesis and could have diagnostic value.

Interleukin 37 (IL-37) is a recently discovered member of the IL-1 cytokine family that appears to have anti-inflammatory and immunosuppressive effects in various diseases. IL-37 acts as a dual-function cytokine, exerting its effect extracellularly by forming a complex with the receptors IL-18 α (IL-18Rα) and IL-1R8 and transmitting anti-inflammatory signals, as well as intracellularly by interacting with Smad3, entering the nucleus, and inhibiting the transcription of pro-inflammatory genes. Consequently, IL-37 is linked to IL-18, which plays a role in the pathogenesis of atopic dermatitis (AD), consistent with our studies. Some isoforms of IL-37 are expressed by keratinocytes, monocytes, and other skin immune cells. IL-37 has been found to modulate the skewed T helper 2 (Th2) inflammation that is fundamental to the pathogenesis of AD. This review provides an up-to-date summary of the function of IL-37 in modulating the immune system and analyses its potential role in the pathogenesis of AD. Moreover, it speculates on IL-37’s hypothetical value as a therapeutic target in the treatment of AD.

The pathophysiology of atopic dermatitis (AD) is complex, multifactorial, and not fully understood. Genes encoding collagens, the most abundant proteins in the extracellular matrix (ECM), may play a potential role in the pathogenesis of AD. Our study aimed to estimate the associations between Col3A1/rs1800255, Col6A5 /29rs12488457, and Col8A1/rs13081855 polymorphisms and the occurrence, course, and features of AD in the Polish population. Blood samples were collected from 157 patients with AD and 111 healthy volunteers. The genotype distribution of the investigated collagens genes did not differ significantly between the AD and control subjects (p > 0.05). The AA genotype of Col3A1/rs1800255 was significantly associated with the occurrence of mild SCORAD (OR = 0.16; 95% Cl: 0.03–0.78; p = 0.02) and mild pruritus (OR = 18.5; 95% Cl: 3.48–98.40; p = 0.0006), while the GG genotype was significantly associated with severe SCORAD (OR = 6.6; 95% Cl: 1.23–32.35; p = 0.03). Regarding Col6A5/29rs12488457 polymorphism, the average SCORAD score was significantly lower in the group of patients with genotype AA than in patients with the AC genotype (39.8 vs. 53.4; p = 0.04). Nevertheless, both average SCORAD scores were high, and represent the moderate and severe grades of the diseases, respectively. The single nucleotide polymorphisms (SNPs) of COL3A1/ rs1800255 and Col6A5/29rs12488457 seem to be associated with AD courses and symptoms, suggesting new disease biomarkers. The modulation of collagens, the major component of the ECM, may serve as a therapeutic target of AD in the future.