Bacteria living on the surface of the skin helps in maintaining its healthy texture, says a new study.

“These germs are actually good for us,” said Richard L. Gallo, Professor of medicine and paediatrics, who also heads the University of California, San Diego (UCSD) dermatology division.

The study was done on mice and in human cell cultures, primarily performed by post-doctoral fellow Yu Ping Lai.

“The exciting implications of Lai’s work is that it provides a molecular basis to understand the ‘hygiene hypothesis’ and has uncovered elements of the wound repair response that were previously unknown,” said Gallo.

“This may help us devise new therapeutic approaches for inflammatory skin diseases,” he added.

The so-called hygiene hypothesis suggests that a lack of childhood exposure to infectious agents and germs increases our susceptibility to disease by changing how the immune system reacts to such bacterial invaders.

The hypothesis was first developed to explain why allergies like hay fever and eczema were less common in children from large families, who were presumably exposed to more infectious agents than others.

It is also used to explain the higher incidence of allergic diseases in industrialised countries, said an UCSD release.

The skin’s normal microflora - the microscopic and usually harmless bacteria that live on the skin - includes certain staphylococcal bacterial species that will induce an inflammatory response when they are introduced below the skin’s surface, but do not initiate inflammation when present on the epidermis, or outer layer of skin.

These findings were published online in Nature Medicine.

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