Refresh your awareness! Can these common viruses help us suppress cancer?

When it comes to viruses, many people's best-selling impression is that they are harmful to human health and not beneficial. With the spread of cervical cancer vaccines, more and more people are beginning to understand that viral infections can also cause terrible cancers. In addition to the human papillomavirus (HPV) targeted by the cervical cancer vaccine, there are also common viruses that are also potential oncogens, such as hepatitis B virus (HBV).

However, a common class of viruses that live on our skin seems to produce not harm to human health, but benefits! According to a recent paper published in the leading academic journal Nature, scientists at the Massachusetts General Hospital Center for Oncology and Immunology have found that some "low-risk" HPVs appear to indirectly protect us from skin cancer.

According to the study authors, "This is evidence in both experimental models and humans that common viruses may have health benefits, and that this benefit is associated with cancer protection." ”

The first thing to note is that these low-risk types of HPV are different from the HPV targeted by the cervical cancer vaccine. To date, more than 170 known HPV types involve different clinical manifestations. Among them, only about 12 are classified as high-risk types, such as HPV16, 18, 6, 11, which are related to a variety of genital cancers, and some are related to head and neck cancer and oral cancer. Existing vaccines can help protect us against these malignancies.

In addition, there are many other types of HPV, such as those studied by Dr. Shawn Demehri and colleagues, which are common commensal viruses inside and on the surface of the human body and are considered to have a low risk of causing serious disease. The more common manifestations of these low-risk types of HPV on the skin are common warts, plantar warts, and flat warts. It is estimated that 1 in every 3 school-age children is infected with cutaneous HPV, which shows that infection is very common.

Past studies have suggested that widespread HPV infection with β subtypes in the population may be associated with the risk of some malignant skin cancers. In immunosuppressed patients, the risk of skin squamous cell carcinoma rises 100-fold. Naturally, some people speculate that the virus that has been latent in the human body for many years has become a carcinogen when the body's immunity is low?

　That's exactly the question the study is trying to answer. While multiple studies have attempted to prove a link between HPV infection and squamous cell carcinoma, none have been able to prove that HPV actually drives the development of these common skin cancers, the study authors said.

And the results of their experiments are exactly the opposite of what was previously suspected. Experiments using mouse models have shown that mice with intact immune systems that are naturally immune to HPV, as well as mice that are immune to T cell infusions, are able to fight skin cancer when exposed to ultraviolet radiation or chemicals known to cause skin cancer. That's because peptide molecules for HPV can induce T cells to develop an immune response. The activated T cells can effectively attack early-stage skin cancer cells.

In addition to animal experiments, the researchers also examined human skin cancer samples, analyzed the presence and activity of 25 known low-risk HPVs, and found that the viral activity and viral load in skin cancer cells were significantly lower than those in adjacent normal skin, "indicating strong immunoselectivity for virus-positive malignant cells."

For patients with suppressed immune systems, the risk of skin cancer is greatly increased, the researchers explain, because of the loss of immunity, not the carcinogenic effect of HPV.

Early skin cancer colonized by symbiotic HPV is like a warts for the immune system and can be effectively removed (Image source: Jon Messerschmidt) ▲ Early skin cancer colonized by symbiotic HPV is like a warts for the immune system and can be effectively removed (Image source: Jon Messerschmidt)

Based on these findings, the researchers propose that "the development of vaccines based on T cells targeting commensal HPV may provide an innovative way to enhance the skin's antiviral immunity and help prevent warts and skin cancer in high-risk groups." ”