COVID-19: Study Maps How a Patient’s Immune System Fights Back
Researchers have mapped immune responses from one of Australia's first COVID-19 patients, showing the body's ability to fight the virus and recover from the infection. The study shows how the immune system of an otherwise healthy person was able to fight the virus, within days. 
 
Published in Nature Medicine, researchers, from the University of Melbourne at the Peter Doherty Institute for Infection and Immunity in Australia, have found that while some people who have contracted COVID-19 experience serious symptoms, others are able to recover after a fairly short period of time. 
 
Using information about one of Australia’s first COVID-19 patients, they were able to conduct a comprehensive case study. The female patient was experiencing mild-to-moderate symptoms of the infection when she sought care; but was noted to be healthy in all other respects. This was the reason researchers first became interested in finding out how an otherwise healthy adult’s immune system is able to react to an infection with new virus. 
 
“We showed that even though COVID-19 is caused by a new virus, in an otherwise healthy person, a robust immune response across different cell types was associated with clinical recovery, similar to what we see in influenza,” says the study’s co-author Prof Katherine Kedzierska.
 
“This is an incredible step forward in understanding what drives recovery of COVID-19. People can use our methods to understand the immune responses in larger COVID-19 cohorts, and also understand what’s lacking in those who have fatal outcomes,” she adds. 
The patient had sought specialised care four days after the onset of viral infection symptoms. These symptoms included lethargy, a sore throat, a dry cough, pleuritic chest pain, some shortness of breath and a fever. She was discharged from the hospital and entered herself into self-isolation for 11 days, after the onset of symptoms, and was found to be symptom-free by day 13. 
 
For the study, researchers analysed blood samples that healthcare professionals had collected from the patient on four different occasions—on days 7, 8, 9 and 20, following the onset of symptoms. 
 
“We looked at the whole breadth of the immune response in this patient using the knowledge we have built over many years of looking at immune responses in patients hospitalised with influenza,” explains the study’s co-author Dr Oanh Nguyen.
 
They found that during day-7 to day-9 following the onset of symptoms, there was an increase in immunoglobulins, the most common type of antibodies, rushing to fight the virus. This increase in immunoglobulins persisted up to day-20 after the onset of symptoms, according to the analysis. 
 
At day-7 today-9 following the symptom onset, a large number of specialised helper T-cells, killer T-cells and B-cells—all of which are crucial immune cells -- were also active in the patient’s blood samples. This suggested that the patient’s body had been using many different ‘weapons’ effectively against the virus.
 
“Three days after the patient was admitted, we saw large populations of several immune cells, which are often a tell-tale sign of recovery during seasonal influenza infection, so we predicted that the patient would recover in 3 days, which is what happened,” notes Dr Nguyen. 
 
The researchers also report that their investigation’s efficient timelines are much owed to the fact that the patient had enrolled into Sentinel Travellers and Research Preparedness for Emerging Infectious Disease (SETREP-ID). This is a research platform from the Peter Doherty Institute for Infection and Immunity. 
 
“When COVID-19 emerged, we already had ethics and protocols in place so we could rapidly start looking at the virus and immune system in great detail,” says study’s co-author Dr Irani Thevarajan, praising the importance of SETREP-ID. It has already been established at a number of Melbourne hospitals and the researchers are now planning to roll out SETREP-ID as a national study. 
 
“We hope to now expand our work nationally and internationally to understand why some people die from COVID-19, and build further knowledge to assist in the rapid response of COVID-19 and future emerging viruses,” Dr Thevarajan added. 
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    Eating Eggs Moderately Does Not Increase Risk of Cardiovascular Disease, Finds Study
    Although eggs are an affordable source of high-quality protein, iron and unsaturated fatty acids, their cholesterol content has always given them a bad reputation. The association of egg consumption and cardiovascular disease risk has been a topic of intense debate over the past decade. However, now egg lovers can rejoice once again.
     
    A massive new meta-analysis suggests that consumption of one egg per day may not increase the risk of cardiovascular disease. The data analysed for this study was collected over a period of three decades and has been published in the scientific journal The BMJ. Researchers, including those from Harvard University in the US, analysed health data of 173,563 women and 90,214 men who were free of cardiovascular heat disease, type-2 diabetes and cancer. 
     
    For the study, researchers used repeated measures of diet and followed it up over a period of 32 years to gain a detailed picture of potentially confounding lifestyle factors such as correlation of high body mass index (BMI) and red meat consumption. In this process, they managed to conduct the largest meta-analysis of this topic, including 28 prospective cohort studies, with up to 1.7 million participants. 
     
    During the follow-up period, there were 14,806 cases of cardiovascular disease, including 9,010 cases of coronary heart disease and 5,903 cases of stroke. Most people ate between one to five eggs per week and those with a higher egg intake had a higher BMI, were less likely to be treated with statins and ate more red meat. After adjusting for age, lifestyle and dietary factors, no association was found between egg intake and risk of cardiovascular disease. 
     
    The results supported the finding that moderate egg consumption is not associated with increased risk of heart disease in Americans and Europeans. However, researchers observed moderate egg consumption was associated with a slightly lower cardiovascular disease risk in Asian populations. This may be due to the fact that eggs are consumed in a variety of dishes in Asian cultures. 
     
    “Recent studies reignited the debated on this controversial topic, but our study provides compelling evidence supporting the lack of an appreciable association between moderate egg consumption and cardiovascular disease,” said lead author Dr Jean-Philippe Drouin-Chartier.
     
    It is also important to note that, while moderate egg consumption can be part of a healthy eating pattern, it is not essential. “There is a range of other foods that can be included in a healthy breakfast, such as whole grain toast, plain yogurt and fruits,” said Dr Shilpa Bhupathiraju, research scientist at the Harvard Chan School Department of Nutrition and associate epidemiologist at Brigham and Women’s Hospital.
     
    Readers should be aware that this was an observational study and, as such, cannot establish cause. The study’s authors have also pointed to some limitations, including the fact that the participants of the study were health professionals and, therefore, the findings may not be reflective of the general population. 
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    Eating Less Slows Down Ageing
    Want to live longer? The secret to a long life lies in restricting intake of calories, a new study has found. Eating less, or restricting intake of calories, reduces levels of inflammation throughout body, delays the onset of age-related diseases and increases survival. 
     
    This new study, published in the journal Cell, brings us one step closer to living a long life, by elucidating the underlying mechanisms. Researchers have found that ageing causes a functional decline in tissues throughout the body that may be delayed by caloric restriction.
     
    For years, science has shown that restricting the number of calories ingested, while maintaining overall nutrition, is a health-promoting habit. “We already knew that calorie restriction increases life span, but now we’ve shown all the changes that occur at a single-cell level to cause that,” said Dr Juan Carlos Izpisua Belmonte, a senior author of the study.
     
    For the study, researchers recorded and analysed the effects of caloric restriction on individual cells in rats. They considered 56 rats that were put on a diet with 30% fewer calories, compared to standard rat diets, from the age of 18 months to 27 months. In terms of human age, this corresponds to the period between 50 years and 70 years. 
     
    They extracted almost 170,000 cells of 40 different types, from the rats, in two stages - at the beginning of the study and at its end. These cells came from fat tissues, liver, kidney, aorta, skin, bone marrow, brain and muscle. In each of the cells that was taken from the animals, the genes were sequenced so that the impact of the dietary restriction on their expression levels could be identified. The scientists also examined the overall composition of the cell types found in any type of tissue before and after the experiment. Finally, they made a comparison of the changes in old and young mice on the standard versus calorie-restricted diet.
     
    They found that there were many changes occurring with age in the rats on a standard diet that failed to make their appearance in the cells taken from rats on calorie-restricted diet. In fact, the tissues and cells in the old rats fed a calorie restricted diet were very similar to those from the younger rats. There was an overall reduction of 57% in the age-related changes in the cell composition in rats on a calorie-restricted diet. 
     
    The cells and tissues that were turned down low included those that regulate immune function, inflammation and fat metabolism. In almost all the tissues, there was a markedly increased number of immune cells with age which was absent in the calorie restricted rats. Especially in the metabolically active type of fat called brown fat, calorie restriction suppressed gene expression related to inflammatory activity, to the level more typical of young rats. This means that age-related inflammation can be regulated by this lifestyle modification.  
     
    “People say that ‘you are what you eat’, and we’re finding that to be true in lots of ways,” says Dr Concepcion Rodriguez Esteban, another of the paper’s authors and a staff researcher at Salk’s Gene Expression Laboratory. “The state of your cells as you age clearly depends on your interactions with your environment, which includes what and how much you eat.” 
     
    The research team is now trying to utilise this information to discover ageing drug targets and implement strategies towards increasing life and health span.
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