Since the Middle East respiratory syndrome coronavirus (MERS-CoV) first emerged in Saudi Arabia in 2012, there have been more than 2,400 confirmed cases of the infection, resulting in greater than 800 deaths - an alarming fatality rate of 35 percent. For this reason, researchers have been eager to identify any risk factors that contribute to the development of severe or lethal disease. Current clinical evidence points to diabetes as a major risk factor in addition to other comorbidities including kidney disease, heart disease, and lung disease.
MERS virus, Middle-East Respiratory Syndrome coronavirus in human lungs, 3D illustration - Image Credit: Kateryna Kon/ Shutterstock
People who have diabetes may have worse symptoms. A team of researchers at the University of Maryland School of Medicine and the Johns Hopkins University School of Medicine may have found the answer to why diabetic patients have worse symptoms of lung disease. Understanding how diabetes affects MERS-CoV is important to formulate better diagnostics and therapeutics for them.
The researchers have shown how diabetes can contribute to mortality from severe lung infection, and the discovery can shed light on why other respiratory diseases, such as pneumonia or flu, can affect those with diabetes more severely.
Lung sections from 21 days after infection with MERS-CoV in normal mice (left) and diabetic mice (right). We find that normal mice resolve the inflammation faster than diabetic mice leading to prolonged weight loss and disease in the diabetic mice. Image Credit: University of Maryland School of Medicine
Diabetes may prolong the inflammatory response
The study, published in the Journal of Clinical Investigation Insights, showed the link between diabetes and MERS-CoV in laboratory mice. The team found that the mice with diabetes had prolonged and delayed inflammatory response in the respiratory tract, compared to the healthy controls. Interestingly, mice with diabetes had reduced amounts of inflammatory cytokines, macrophages, and T cells.
"Understanding how diabetes contributes to disease severity following MERS-CoV infection in this context is critical. Our next step is to determine what drives the altered immune response in diabetics and how to reverse those effects with therapeutics for the treatment of patients,” Dr. Matthew Frieman, associate professor of microbiology and immunology, said in a statement.
The investigators used a model wherein mice were made susceptible to MERS-CoV, through the expression of human DPP4 and type 2 diabetes. The mice were given a high-fat diet to induce type 2 diabetes, and when these mice were infected by the virus, they had longer severe disease duration and delayed recovery.
Understanding how diabetes affects MERS-CoV
When the tissues were examined, the analysis revealed that mice with diabetes had delayed inflammation, spanning 21 days after the infection. The data gathered shows that type 2 diabetes patients might have worse symptoms, delayed recovery, the disease is more severe due to a dysregulated immune response.
“Our current model to study diabetes and MERS-CoV infection provides the opportunity to investigate a wide variety of questions, such as the contribution of age to disease severity in diabetic mice, how anti-T2D drugs affect pathogenesis and disease outcome, and the efficacy of current therapeutics and vaccines in the context of diabetes,” the researchers wrote in the paper.
“This model is a stepping-stone in understanding how diabetes affects MERS-CoV pathogenesis and how to effectively develop therapeutics and vaccines for this high-need population,” they added.
What is MERS-CoV and how to prevent it
The Middle East Respiratory Syndrome Coronavirus (MERS-CoV) is a potentially fatal lung disease. It affects the respiratory system and can lead to serious complications. There are many ways to prevent the spread of the infection:
- Practice proper hand hygiene by washing your hands with soap and water.
- Avoid contact with farm and domesticated animals, including camels.
- Practice proper cough etiquette by covering your nose and mouth when coughing or sneezing.
- Avoid contact with patients infected with the virus. If you have respiratory disease, make sure to wear a mask and stay home as much as possible.
- For health workers, always follow infection control protocols.
If you suspect that you have the infection, visit your doctor immediately.
Kulcsar, K.A, et al. (2019) Comorbid diabetes results in immune dysregulation and enhanced disease severity following MERS-CoV infection. Journal of Clinical Investigation Insight. doi.org/10.1172/jci.insight.131774. https://insight.jci.org/articles/view/131774