How does the immune system affect the skin

The immune system protects skin by regulating bacteria and responding to injuries. For example, neutrophils increase 50-fold in wounds within 24 hours, aiding repair.

Protección contra patógenos

The immune system acts as the first layer of protection to the body, the skin, against harmful pathogens. A few studies estimated that the skin hosts approximately 1.5 trillion microorganisms—namely, bacteria, viruses, and fungi. A strong immune system keeps the balance with these microorganisms, which it does not allow to overgrow into harmful species. It is estimated, for instance, that Staphylococcus aureus colonizes in 20-30% of the general population; a competent immune response, however, ensures that the bacteria do not infect the individual. In the event such defenses fail, these types of bacteria will readily penetrate the skin to cause infection, as evidenced by the facility with which infectious disease takes hold without a properly functioning immune system. Regarding comparative age-related changes, skin defenses in younger adults tend to be more resilient compared to older adults. Indeed, one publication in Immunology Today estimated that skin of individuals above 65 years had a 30% increased pathogen colonization compared to their younger counterparts. He termed this age-related decline as immunosenescence, which impairs the capacity of skin to fend off common cutaneous infections, such as fungal or bacterial ones. Skin infections occur in as many as 40% of nursing home residents over age 70, a finding that nicely illustrates how age-related immune changes can make older adults more susceptible to skin problems. This difference, in healthy maintenance of the skin across the lifespan, directly reflects the impact of immune efficiency on the skin’s ability to effectively fight off pathogens. Hygiene and skin care habits may also affect the immunological health of the skin. For example, the overuse of antimicrobial soaps can result in an imbalance of the skin microbiome. It is important to state that it has been estimated that individuals who apply antibacterial soaps daily have a 25% increased risk of developing dry skin and cracks on the skin, conditions that give way to new infections since bacteria can cross the skin barrier much more easily. Conversely, subjects using milder cleansers with a consideration for microbiome preservation show better balance and as such have up to 15% reductions in pathogen colonization. These data underpin the importance of skin care routines in a mindful way to support the protective role of the immune system.