Bacterial Enzymes Major Role on the Path to Universal Donor Blood

about 1 year ago

One major concern for me when I fall sick or I'm traveling is not getting blood if there is a need for a blood transfusion. At our hospital, we do not have lots of O- blood because of a lot of circumstances and the large one being it is not common. People who bring their wives who are close to the EDD would have to donate blood if their blood matches with theirs of their wives or would have to start procuring blood for cases where need might arise. The blood typeing thing might not be a problem to some, but it is sure a problem to others, especially people who have rarer blood then mine. This made me study to find out if scientists have been working on getting the O- blood group more available so as to help save lifes.

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This began when there was a report by the British medical journal on Blood Type A patients beginning to express the B blood type temporarily in patients with cancer in the stomach or intestine or with conditions where the gastrointestinal tract was affected. It was not really a deal to the world but scientists were eager.

In 1982, another intriguing case emerged, featuring an 86-year-old woman grappling with a urinary infection caused by E.coli. Surprisingly, this infection led to an abnormality in her blood group, temporarily acquiring the B antigen. Intriguingly, after her treatments, the acquired B antigen disappeared, raising questions about the underlying mechanisms.

Upon careful examination of these scenarios, researchers observed that the acquired blood antigen resulted from neither blood transfusion nor a direct genetic change. Instead, it pointed to the influence of neoplastic diseases or infections caused by Enterobacteriaceae bacteria. These bacteria possess the ability to adhere to specific blood types, altering them and effectively transforming one blood type into another. These revelations challenged the notion of immutable blood types and unveiled the potential for manipulation. So can this be done intentionally by scientists to solve the blood transfusion problem?

We need blood in our system and many people get blood transfusions on a regular but then the number of donors is quite small compared to the number of receivers, and the number of general donors O Rh- is very low, and this is causing a high demand for the universal blood. For easy understanding of the blood type system, we use both the Rhesus and the ABO blood type system, but the ABO is very important when talking about blood types. The ABO blood type system is determined by the presence of A and B antigens on the surface of the Red Blood Cells. This leads to the 4 types of blood groups that you know which are A, B, AB, and O.

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With Blood group O meaning they do not have any of the A and B antigens but only have the H antigen. A and B antigens use sugars on the RBC surface to identify foreign cells in the bloodstream, where the A and B antigens to the H antigen on the RBC with each type of blood having different sugar at the end of their chain. The A antigen has the N-acetyl-galactosamine, while the B antigen has Galactose. When a person has the A antigen, they have an antibody on type B blood cells and vice versa. So if there is a transfusion where a wrong type of RBC is introduced into a person, the antibodies in the recipient's blood would attack the RBC leading to agglutination, then hemolysis which can lead to death.

The Rh factor is another one where the blood can either be rhesus positive or negative, with negative being able to receive blood from only negative, while positive can receive blood from both positive and negative. With this, Blood Type O- is regarded as a universal donor but can only receive from O- types.

With this said, we can see the importance of having an O- blood type in cases of transfusion, and how scarce they are in comparison to other blood types. So with the bacterial change in blood type, scientists have begun working on being able to change a blood type to get a universal blood type that can be used on donors and it didn't start 10 years ago.

The scarcity of O- donors presents a pressing challenge in meeting the demand for compatible blood. As a result, scientists have diligently explored methods to transform other blood types into the universally compatible O blood type.

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Pioneering research, initiated by scientist Goldstein in 1982, sought to convert A, B, and AB blood types into the universal O blood type, suitable for blood donations. Initial attempts involved utilizing Alpha Galactosidase from green coffee beans to modify sugar molecules in the blood type chain. However, the enzyme's functionality at a low pH of 5.7 proved challenging, given RBCs' need to maintain a stable pH of 7.4. This procedure was going to work for B-type antigens and not A-type antigens because of the ability of the enzyme to cleave the galactose in the B antigen and not the N-acetyl galactosamine in the A antigen.

Fast forward to 2007, scientists began looking at bacterial and fungal enzymes that could cleave the sugar molecule in both the A and B blood types. Scientists found α-N-acetylgalactosaminidase enzyme from Elizabethkingia meningosepticum found in pond water, and α1,3-galactosidase from Bacteroides fragilis in the human gut, where enzymes α1,3-galactosidase could cleave the sugar in the B blood group at pH 7 while Elizabethkingia meningosepticum enzyme cleaves the sugar in A group blood. These enzymes were able to turn the blood groups to O blood type but this is not cost effective.

More recently, the integration of cutting-edge technology enabled the identification of additional bacterial enzymes from gut bacteria, providing a pathway to cleave sugar in type A Red Blood Cells. The combination of FpGalNAc deacetylase and FpGalactosaminidase from Flavonifractor plautii showcased promising results, effectively transforming both Type A and B blood into the universal O blood type.

This is not yet in commercial usage, but as research in this field continues to progress, having universally compatible donor bloods are inches closer to reality. This would help save lots of lifes, and people with blood group such as O negative like me will not have to worry getting blood at the hospital.