Human Microbiome : When a Friend Becomes an Enemy

The microorganisms that inhabit humans are very diverse on different body sites and tracts. Each specific niche contains a unique composition of the microorganisms that are important for a balanced human physiology. Microbial cells outnumber human cells by tenfold and they function as an invisible organ that is called the microbiome. Excessive use of antibiotics and unhealthy diets pose a serious danger to the composition of the microbiome. An imbalance in the microbial community may cause pathological conditions of the digestive system such as obesity, cancer and inflammatory bowel disease; of the skin such as atopic dermatitis, psoriasis and acne and of the cardiovascular system such as atherosclerosis. An unbalanced microbiome has also been associated with neurodevelopmental disorders such as autism and multiple sclerosis. While the microbiome has a strong impact on the development of the host immune system, it is suspected that it can also be the cause of certain autoimmune diseases, including diabetes or rheumatoid arthritis. Despite the enormous progress in the field, the interactions between the human body and its microbiome still remain largely unknown. A better characterization of the interactions may allow for a deeper understanding of human disease states and help to elucidate a possible association between the composition of the microbiome and certain pathologies. This review focuses on general findings that are related to the area and provides no detailed information about the case of study. The aim is to give some initial insight on the studies of the microbiome and its connection with human health.Peer reviewe

Original paper Assessment of the sensory threshold in patients with atopic dermatitis and psoriasis

A b s t r a c t Introduction: Atopic dermatitis (AD) and psoriasis are chronic inflammatory skin diseases frequently accompanied by itching. The exact pathogenesis of dermatological pruritus remains unknown, but it is believed that altered skin innervation may play a role. Aim: The assessment of the sensory threshold in AD and psoriasis in relation to pruritus experienced by patients. Material and methods: A total of 18 subjects with AD, 20 with psoriasis and 49 healthy controls were exposed to alternating current generated by the current source. A selected preset of current frequencies (ranging from 5 Hz to 2000 Hz) allowed a selective stimulation of different nerve endings (Ab, Ad and C-type). Pruritus severity was measured with visual analogue scale (VAS) and an itch questionnaire developed in house. All results were analyzed statistically. Results: Sensory thresholds within the uninvolved skin of AD or psoriasis patients were significantly higher than in healthy volunteers (p < 0.001), and no significant differences were found between AD and psoriasis (p > 0.05). Similarly, sensory thresholds within the diseased skin of AD or psoriasis were significantly higher than in the normal skin (p < 0.01), and patients with psoriasis had also a significantly higher threshold than AD individuals (p < 0.05). The sensory threshold inversely correlated with pruritus severity in AD and psoriasis and the highest correlation was found for 5 Hz frequency predominantly stimulating C fibers (VAS: R = -0.32, p < 0.05; pruritus questionnaire: R = 0.54, p < 0.001). Conclusions: Evaluation of the sensory threshold may be a valuable tool for pruritus assessment, but further studies are still warranted