The human microbiome is a wide range of microorganisms residing in and on our body. The homeostasis between host immune system and the microbial environment allows mutual benefits and protection. Physiological bacterial colonization is essential for the establishment of organism immunity. The human microbiota ecosystem can be divided into several compartments, out of which intestinal flora strongly affects our health and plays a crucial role in the pathophysiology of many diseases. The gastrointestinal tract, being a major guardian of the immune system, maintains the homeostasis with the commensal microorganisms by tolerating the typical flora antigens. The dysbiosis may trigger an inflammatory response followed by tissue damage or autoimmune processes. The gut microbiome alterations are linked to the pathogenesis of the allergic, cardiovascular, gastrointestinal, metabolic, neurodevelopmental, psychiatric and neurodegenerative diseases and cancer. Moreover, there is increasing evidence connecting the skin condition with the gastrointestinal microbiome, which has been described as the skin–gut axis. The aim of this study was to review the literature regarding the role of the gut microbiome alterations in the pathogenesis of selected allergic and inflammatory skin diseases.

Psoriasis is a chronic inflammatory immune-mediated disorder associated and often coexisting with many other immune-related clinical conditions including those affecting the gastrointestinal tract. Data obtained from the reviewed literature suggest an association between psoriasis and pathologies of the oral cavity, both psoriasis-specific lesions, as well as non-specific, such as geographic tongue or fissured tongue. These findings show the importance of thorough examination of oral mucosa in psoriatic patients. Inflammatory bowel diseases (IBD) are also linked with psoriasis. Crohn’s disease and ulcerative colitis share a common genetic background, inflammatory pathways and have an evident iatrogenic anti-TNF treatment link, necessitating dermatological or gastroenterological care in patients with IBD or psoriasis, respectively, as well as treatment adjusted to manifestations. The presence of celiac disease-specific antibodies in psoriatic patients and their correlation with the severity of the disease show the association between these disorders. The linking pathogenesis comprises vitamin D deficiency, immune pathway, genetic background and increase in the intestinal permeability, which suggests a potential benefit from gluten-free diet among psoriatic patients. The link between psoriasis and non-alcoholic fatty liver disease implies screening patients for components of metabolic syndrome and lifestyle changes necessity. Some studies indicate increased prevalence of cancer in patients with psoriasis, probably due to negative influence of skin lesion impact on lifestyle rather than the role of psoriasis in carcinogenesis. However, there are no sufficient data to exclude such an oncogenic hit, which is yet to be confirmed. Therefore, all psoriasis-associated comorbidities establish the importance of a multidisciplinary approach in the treatment of these patients.

Systemic sclerosis (SSc) is a chronic, connective tissue disease with an autoimmune pattern characterized by inflammation, fibrosis and microcirculation changes leading to internal organs malfunctions. Recently, the presence of uncharacteristic gastrointestinal symptoms in the course of SSc has been underlined. The possible cause of such clinical presentation is the small intestinal bacterial overgrowth (SIBO). Nevertheless, these manifestations resulting from gastrointestinal tract hypomotility may occur in numerous disease entities. The systematic review of the literature was performed on MEDLINE database using the relevant MeSH terms including all sub-headings. After further investigation, the initial number of 56 records was limited to 7 results. The study analysis showed an increased presence of SIBO in 39% of patients suffering from SSc. The average SSc duration was longer in SSc patients with coexisting SIBO. SIBO remains a diagnostic and therapeutic challenge and therefore is a significant clinical problem among patients suffering from SSc.

Fecal calprotectin (FC) is a quick, cost-effective, and noninvasive test, which is used to diagnose patients with active inflammatory bowel diseases (IBD). Recent studies suggest the possible predictive role of FC in the diagnosis of small intestinal bacterial overgrowth (SIBO) in patients with systemic sclerosis (SSc). This study aimed to assess the predictive value of FC in SSc patients and its’ possible use as a SIBO marker. A total of 40 SSc patients and 39 healthy volunteers were enrolled in the study. All subjects completed questionnaires evaluating gastrointestinal symptoms, FC measurements, and lactulose hydrogen breath test (LHBT) assessing SIBO presence. After rifaximin treatment, patients with SIBO underwent the same diagnostic procedures. Significantly higher FC values were observed in the study group compared to controls (97 vs. 20 μg/g; p < 0.0001) and in SSc patients diagnosed with SIBO compared to SSc patients without SIBO (206 vs. 24 μg/g; p = 0.0010). FC turned out to be a sensitive (94.12%) and specific (73.68%) marker in the detection of SIBO in patients with SSc (AUC = 0.82, 95% CI = 0.66–0.93; p < 0.0001). Our study suggests the potential value of FC in SSc in detecting gastrointestinal impairment and its promising role as an additional diagnostic tool for SIBO.

No abstract