Is the presence of Propionibacterium acnes bad for skin?
Many people think that we get pimples when the body secretes a large amount of sebum. However, even if there is a large amount of sebum secretion, pimples are not developed unless sebum accumulates in the pores. The role of sebum is to prevent water evaporation from the skin and to protect the skin from external stimuli. The skin gets dry in a sebum- deficient condition. In addition, there are many people who think that “It is better to kill Propionibacterium acnes which is a cause of acne.” Since Propionibacterium acnes is one of the indigenous bacteria on the skin, just killing it brings adverse effects to the skin. It also contributes to keep the bacterial balance of the skin surface. Recent studies have shown that there are also many Propionibacterium acnes on the skin of people who do not have acne. Researchers believe that there are strains that cause acne and others that don’t even though they are in the same Propionibacterium (*1, *2).
Both sebum and Propionibacterium acnes are necessary compounds and bacteria for the skin, but why do they cause acne? In fact, the cause of acne can be due to the process where the corneum at the exit of the pores becomes thick (chyperplasia of corneum). When the corneum becomes too thick, the pores tend to be blocked which in turn makes the sebum to get stuck in the pores. This process encourages excessive propagation of bad acne bacteria which use the sebum in the clogged pores as their nutrient source. Then, inflammation occurs and acne gets more severe. In other words, it is important to balance the system in the body such as hormones that affect the sebum secretion and hypertrophy of pores, and immunity that affects the activity of acne bacteria in order to solve acne problems. We need to pay attention to the high level of stress, lack of sleep or exercise and unbalanced diet because these factors can deteriorate the balance of the body systems and eventually cause acne.
Credit to: Muneaki Takahata Ph.,D.
*1: Journal of Investigative Dermatology 133, 2152-2160 (2013)
*2: Scientific Reports (2016)