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Ocular bacteria : A New Vision for Corneal Wound Healing
Corneal wounds or injuries on the transparent front part of the eye remains a serious health concern, as over one million Americans are affected by it. The wound healing depends on the body’s immune response that encourages tissue repair and reduces inflammation. During the process of healing, the eye is prone to infections and inflammation, which could further worsen the wound leading to more severe conditions such as nerve damage and vision loss. Due to this, scientists have been investigating various methods to effectively cure corneal wounds.
Currently corneal wounds are treated by delivering medication using methods such as injections and eye drops. Injections can be invasive and uncomfortable for the patient. Medications through eye drops are prone to getting washed away quickly through the tears produced by the eye. Hence, patients are expected to apply eye drops many times per day. In order to overcome these disadvantages, researchers have looked into treatments that are less invasive and allow the medicine to stay in the eye for prolonged durations without repeated application.
The human hosts multiple communities of microorganisms including bacteria, archaea, fungi, protists, and viruses on and inside the body. These microbial communities are termed as microbiomes and can be found in different parts of the body, including the skin, gut, eye etc. Many of these microbes are beneficial towards human health. As part of the ocular microbiome,a small number of bacteria have naturally colonised and reside on the surface of the eye.
Researchers have recently explored using eye colonising bacteria as a “live biotherapeutic product” (LBP). Live bacteria that are genetically engineered to produce a certain therapeutic product, is a type of LBP. Previously, LBPs have shown improvement in the treatment of conditions such as Crohn’s disease and irritable bowel syndrome. Following these successes, the researchers in this study decided to develop a LBP to heal eye injuries.
In this study, researchers chose Corynebacterium mastitidis (C. mast), a bacterium that naturally colonizes the eyes and skin as a candidate to develop a LBP for eye therapy. They genetically engineered C. mast by inserting a gene that produces interleukin-10 (IL-10), an anti-inflammatory protein. IL-10 helps in limiting an inflammatory response and promotes tissue repair. The researchers also designed the bacteria to secrete IL-10 so that the secreted IL-10 can directly interact with the cells on the eye surface for effective healing.
The engineered bacteria were introduced on the eye of mice with corneal wounds. After application, the engineered bacteria successfully colonised the corneal surface and sustained up to 12 weeks. During this period the bacteria naturally synthesized and released IL-10, which reduced inflammation. To compare the effectiveness of the LBP, wild type C. mast was also introduced on the eyes of mice with corneal damage. Corneal healing was sped up in mice with the engineered C. mast as compared to the mice with the wild type C.mast.
This study provides us with a new innovative method to treat eye injuries. In this case, the use of engineered C. mast as an LBP, overcomes the disadvantages linked with the frequent use of eye drops and invasive injections. Once the ocular LBP is introduced to the eye, it stably colonises the corneal surface and continuously secretes a steady amount of medicine required for healing. LBPs also lessens the cost of production, reduces discomfort and can be more effective than conventional treatments.
Although exciting, the research related to LBPs is still at its early stage and requires more testing to ensure effective treatment and safety of patients. Most of the research using LBPs have been tested in laboratory animals such as mice. Even though the physiology of our eyes are similar to rodents, there is still a need to verify the safety of genetically modified microbes in humans through clinical trials. There is a possibility that the use of engineered microbes could cause unforeseen side effects in later stages of treatment. Due to this, it is important to develop a way to control the growth and survival of engineered bacteria after being introduced to the patient. In the future, after proper clinical testing and precautions, genetically engineered bacteria could serve as a powerful tool for treating eye injuries and many other diseases.
Featured image: ChatGPT
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