Friday, July 13, 2012
If the hygiene hypothesis is correct, we might be able to control our immune system and prevent disease. Frequent interaction of children with the outside environment will allow them to contact various types of bacteria, thereby preventing allergic diseases. Furthermore, there are several reports that certain foods, including bacteria, work well with our body. For example yogurt, containing lactic acid bacteria, is believed to make us healthy and prevent diseases as these bacteria strengthen the immune system. This hypothesis is termed probiotics. However, the extent of protection that probiotics offer our body is still unclear. This is because we are already constantly exposed to various strains of bacteria present in our environment. Additionally, most of the available data demonstrating the benefits of bacteria to our body are claimed by companies producing fermented foods. Thus, this represents research conflicts that require further detailed investigation/experiements.
The immune system is a remarkably effective protection from bacterial infection. Therefore, disorders in the immune system can result in disease such as immunodeficiency, autoimmunity and hypersensitivity. Several genetic variations of important factors in immune system are associated to these diseases. However, the people with genetic variation induce not always these diseases. For example, allergic diseases are caused by inappropriate immunological responses to harmless antigens and genetic variations of immune system are associated to allergic disease, but not everyone who has the genetic variation become allergic disease. Thus the genetic variations affect to just prevalence of the disease and the other factors in our environment are also affect to develop the disease.
Once bacteria enters into our body, the cells within our body recognize the bacteria. The cells have several pattern recognition receptors, which recognize components that are conserved among broad groups of bacteria. For example, these receptors recognize bacteria specific DNA, RNA and bacterial cell walls, respectively, but do not recognize product from ourselves. There are more than 30 receptors at the surface and inside of the cells.
However, our immune system must destroy only pathogenic bacteria because our body originally has many non-pathogenic and useful bacteria. It is still unclear how our immune systems identify only pathogenic bacteria but not non-pathogenic bacteria, though both groups of bacteria have the same components recognized by pattern recognition receptors.
Bacteria are microorganisms that are ubiquitous in our environment including in our body, on food and in soil. Bacteria have a wide range of shapes, ranging from spheres to rods.
There are typically 40 million bacteria in a gram of soil, a million bacteria in a millilitre of fresh water and 10(15) bacteria that is ten times as many bacteria as human cells in the human body. In all, there are approximately 5×10(30) bacteria on Earth.
Most of the bacteria in our environment are harmless and important for our body. For example, they have roles to produce nutrients, protect from pathogens and help to establishment of our immune system. In addition, bacteria are important for the production of fermented food such as cheese and yogurt, as well as the manufacture of antibiotics and other chemicals. However, some of the bacteria are pathogenic and they attack our body. Therefore, our immune systems try to block these bacteria infecting us.
There are many bacteria in our environment such as in soil, on food and in our body. Most of bacteria in our environment are harmless and important for our body. However, some of them are pathogenic and attack our body, although, we usually do not become diseased because of our immune system. The immune system is one of the mechanisms within our body that protect against disease by killing bacteria and virus. Therefore, it is important to understand how our immune system interacts with bacteria.