People with long Covid have distinct patterns of inflammation detectable in the blood which could potentially be targeted with immune therapies, the largest study of its kind has revealed.In an analysis of more than 650 people who had been hospitalised with severe Covid-19, patients with prolonged symptoms showed evidence of immune system activation. How this activation happened depended mainly on the type of symptoms they had, for example fatigue or brain fog.The research, led by Imperial College London, suggests that existing drugs which modulate the body’s immune system could be helpful in treating long Covid and should be investigated in future clinical trials. Around two million people in the UK are thought to have the condition, defined as the continuation or development of new symptoms three months after the initial infection, based on a recent study which found that one in 20 had persistent Covid symptoms.The new study, published in the journal Nature Immunology, is the latest research from two collaborations of UK-based academics. Researchers included 426 people who were experiencing long Covid who were compared with 233 people who were also hospitalised for Covid but who had fully recovered. The researchers took samples of blood plasma and measured 368 proteins known to be involved in inflammation and immune system modulation.They found that, relative to patients who had fully recovered, those with long Covid showed a pattern of immune system activation indicating inflammation of myeloid cells – a type of blood cell that originates in the bone marrow – and activation of a family of immune system proteins called the complement system, which consists of a cascade of linked proteins that are activated in response to infection or tissue damage. Overactivation of the complement system is known to be associated with many autoimmune and inflammatory conditions.Dr Felicity Liew, from Imperial College London’s National Heart & Lung Institute, said: “Our findings indicate that complement activation and myeloid inflammation could be a common feature of long Covid after hospitalisation, regardless of symptom type.“It is unusual to find evidence of ongoing complement activation several months after acute infection has resolved, suggesting that long Covid symptoms are a result of active inflammation. “However, we can’t be sure that this is applicable to all types of long Covid, especially if symptoms occur after non-hospitalised infection.”The researchers were also able to obtain comprehensive information about the range of symptoms that patients were experiencing, and which ones were most common. They found that certain groups of symptoms appeared to be associated with specific proteins.For example, people with gastrointestinal symptoms had increased levels of a marker called SCG3, which has previously been linked to impaired communication between the gut and the brain.Overall, there were five overlapping subtypes of long Covid with different immune signatures, despite some commonalities, namely: fatigue; cognitive impairment; anxiety and depression; cardiorespiratory; and gastrointestinal. The researchers said that these groups are not mutually exclusive, and people can fall between groups depending on their symptoms.Read NextThe research team said these long Covid subtypes seem to represent clear biological mechanisms of disease and highlight that different symptoms may have different underlying causes. They suggest this could be useful in designing clinical trials, especially for treatments that target immune responses and inflammation.Professor Peter Openshaw, also from Imperial and a lead investigator, said: “With one in 10 SARS-CoV-2 infections leading to long Covid and an estimated 65 million people around the world suffering from ongoing symptoms, we urgently need more research to understand this condition. At the moment, it’s very hard to diagnose and treat.“This study, which includes detailed clinical data on symptoms and a raft of inflammatory blood plasma markers, is an important step forward and provides crucial insights into what causes long Covid.”Kevin McConway, Emeritus Professor of Applied Statistics at The Open University, urged caution over whether the study would eventually lead to new treatments.He said: “Long Covid is an important health problem. It’s also clearly quite complicated – different people with long Covid report different patterns of symptoms, and there’s still a long way to go in the search for effective treatments… it’s important to mention that the new study does not itself provide any evidence on whether these drugs will actually be effective – we will need the trial results for that, and clinical trials take time.”
https://inews.co.uk/news/health/long-covid-telltale-trace-blood-targeted-treatment-2995954
Long Covid patients could get more targeted care due to ‘telltale’ traces in blood
