Health In Focus
  • Influenza (flu) is a viral infection affecting respiratory tract, caused by the Influenza virus.
  • Women in the reproductive age are more likely than men to suffer from complications of flu.
  • Female sex hormone progesterone may reduce lung inflammation and prevent flu complications.
  • Progesterone may find a novel role one day in treatment of flu in women.

Progesterone Role In Flu Infection - What Lab Studies Show

The effects of progesterone in keeping at bay the complications of influenza infection were studied by scientists at the Johns Hopkins University Bloomberg School of Public Health.
Female Sex Hormone May Be A Potential Treatment For Flu In Women

During their research, study leader Sabra L. Klein, PhD, an associate professor in the Bloomberg School's Department of Molecular Microbiology and Immunology, placed progesterone implants in one set of female mice and left other female mice without implants. Both sets of mice were then infected with influenza A virus. Though both groups of mice became ill, those which had progesterone implants had less lung inflammation, better lung function and the damage to their lung cells repaired more quickly. These effects were found to keep at bay the worst complications of flu.

How Progesterone May Reduce Flu Complications

The researchers discovered that progesterone increased the production of a protein called amphiregulin by the cells lining the lungs. Amphiregulin has a positive effect in improving lung function. Interestingly, when the scientists bred mice that were depleted of amphiregulin, the protective effects of progesterone were not present.

Klein says she was not surprised that progesterone lessened the inflammation and damage associated with the flu. What was surprising though, was to find that progesterone also helped induce repair.

When female mice (and possibly humans) become ill with the flu, their natural levels of progesterone fall. Women on hormonal contraceptives, whether it is a birth control pill, intrauterine device (IUD) or injection, maintain a steady level of progesterone which overrides the naturally occurring progesterone from the ovaries or what the virus takes away during infection.

Amphiregulin Facts

Amphiregulin is a protein belonging to the Epidermal Growth Factor (EGF) family. It interacts with the Epidermal growth factor receptor (EGFR) and aids the growth of normal epithelial cells.

Studies have shown that amphiregulin, produced by lung innate lymphoid cells (ILCs) can restore lung function, barrier integrity and repair of damaged respiratory tissues following influenza virus-induced damage.

Female sex hormones, estrogen and progesterone have been shown to induce amphiregulin expression to promote ductal development in the breast.

About Influenza

Influenza (flu) is a respiratory infection caused by the Influenza virus, affecting the nose, throat and lungs. It is characterized by fever with sore throat and cough, associated with tiredness and body pains. It is especially common during the winter months. The illness may be mild to severe in certain cases, occasionally causing death.

Complications of flu may typically occur in persons 65 years and older, persons with chronic conditions such as diabetes, asthma or heart disease, young children and pregnant women. They include
  • Superimposed bacterial pneumonia
  • Middle ear infections (otitis media)
  • Sinus infections
  • Dehydration (loss of body fluids, mostly water), and
  • Worsening of underlying diseases, such as congestive heart failure, diabetes and asthma.
Flu can be prevented by getting the flu shot (vaccination) every year. Other safety measures include covering coughs and sneezes, staying away from persons having the infection, and frequent handwashing to reduce the spread of germs that cause flu.

Why Progesterone Could Become A Potential Flu Treatment

According to the World Health Organization (WHO), more than 100 million young adult women around the world are on Progesterone-based contraception.

"Despite the staggering number of women who take this kind of birth control, very few studies are out there that evaluate the impact of contraceptives on how the body responds to infections beyond sexually-transmitted diseases", says Klein.

"Understanding the role that progesterone appears to play in repairing lung cells could really be important for women's health. When women go on birth control, they don't generally think about the health implications beyond stopping ovulation and it's important to consider them."

The World Health Organization (WHO) has already listed hormone based contraceptives as an essential medication due to the untold benefits these compounds could have on women's health by spacing the interval between pregnancies, with consequent decreased maternal deaths, and an improved outlook for babies and children.

Further Research

The mice in the initial study were given actual natural progesterone and not the synthetic form of the hormone, which is used in contraception. More recently, as part of their ongoing work, Klein and her team administered synthetic progesterone to mice and found a similar effect.

Klein says there is no scientific data until now that demonstrates whether progesterone in humans has any relationship to flu severity since no researcher has asked those questions so far. Following this study, Klein says researchers at the Johns Hopkins Center of Excellence for Influenza Research and Surveillance involved in flu surveillance have added questions about specific forms of birth control to their questionnaires in order to get a better idea of how effective this may be in protecting humans.

Going forward, Klein says, she and her colleagues are studying the exact mechanism of how progesterone could possibly increase the concentration of amphiregulin in the lungs. "We really want to understand from a therapeutic sense how this could potentially work in humans to keep women from experiencing complications from the flu," Klein says.

Source: Medindia

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