SIB# 445- Metabolic Syndrome- Lessons from the pandemic

 

The Study: Metabolic Syndrome and Viral Pathogenesis: Lessons from Influenza and Coronaviruses.

  

Overview:  This paper is a summary review of the relationship between metabolic dysregulation and the body’s auto immune responses. It is of timely interest to anyone interested in better understanding the relationship between viral infection and the increased risks attributable to the ongoing, worldwide epidemic of metabolic syndrome…a cluster of serious health conditions which is almost entirely manageable with simple changes in lifestyle.

  

Key Points: 

  • Metabolic syndrome (MetS) is a cluster of metabolic disorders that can lead to serious deterioration of health. 

  • The key features of Metabolic Syndrome are abdominal obesity, insulin resistance (pre diabetes), Type 2 Diabetes, Hypertension (high blood pressure) and hyperlipidemia (abnormal cholesterol or triglyceride levels). Presence of any three is diagnostic.

  •  Recent work has shown how Metabolic Syndrome allows viruses to re engineer the cells of infected patients so as to allow for enhanced virus replication. 

  • The metabolically challenged patient also provides a host environment in which viruses are able to more easily evade the body’s normal autoimmune responses.   

  • Although most of us are familiar with the increased risk factors posed by various comorbidities like obesity and diabetes, we are probably less familiar with the specific ways in which underlying metabolic disease actually influences the course of viral infections. 

OBESITY: 

  • Obesity is a worldwide epidemic and is implicated in the development of type 2 diabetes (T2DM), stroke, heart disease and high blood pressure. 

  • Obesity is strongly linked to chronic low grade inflammation created by the secretion of cytokines (think “cytokine storm” here) from excess fat tissue.  

  • Chronic state of inflammation “dampens antiviral immune responses” and results in a more severe progression. 

  • Obesity is also linked to aggravated lung inflammation and contributes to increased disease severity in respiratory infections.  

  • Obese patients have been shown to shed more virus over a longer period of time than non obese adults. 

  • Obesity has also been shown to promote “the emergence of more-pathogenic viral variants”. 

  • Obesity also has been shown to double “the risk of developing influenza virus infection and influenza-like illness” despite receiving vaccination for seasonal influenza and appearing to generate a robust antibody response.  

  • “Among hospitalized patients with confirmed SARS-CoV-2 infection, almost 50% were considered obese and were admitted into intensive care requiring mechanical ventilation.”

    HYPERLIPIDEMIA: 

  • “ The accumulation of lipids can be exploited by viruses for lipid raft formation to enhance viral entry, replication, and progeny release”

  • “Upregulated lipid metabolism may provide more opportunities for the virus to hijack host cells to complete its replication cycle.”

     

HYPERTENSION: 

  • One study in Wuhan reported that nearly 20% of hospitalizd COVID-19 patients suffered documented heart damage. Of these, more than 50% had a prior history of hypertension. 

 

TYPE 2 DIABETES: 

  • Type 2 diabetes impairs host immunity, enhances the severity of influenza virus infection and death, triples the rate of hospitalization and quadruples the likelihood of ICU admission.

  • Glucose intolerance and insulin resistance “alter the cytokine milieu and contribute to a chronic state of metainflammation.” 

  • “A recent study of 174 patients with diabetes who had confirmed COVID-19 found that these patients were at a significantly higher risk for severe pneumonia than nondiabetic patients.”

     

Author’s Conclusions: The increasing prevalence of metabolic syndrome is a major public health issue. Over the years, humans have adopted sedentary lifestyles, and dietary patterns have shifted to excessive food consumption and poor nutrition. Impaired immune responses and chronic inflammation in metabolically diseased microenvironments provide the ideal conditions for viral exploitation of host cells and enhanced viral pathogenesis.

 Reviewer's Comments: This study documents the role of Metabolic Syndrome in the recent pandemic. However, the problem is much farther reaching. Metabolic Syndrome now affects up to 31% of all people worldwide, is associated with a doubling of heart disease, cerebrovascular disease and a 1.5 fold increase in the risk of all-cause mortality. Up to 40 million children under age 5 are now considered seriously overweight or obese. The worst tragedy is that this disease is almost entirely manageable with simple changes in diet and lifestyle. I can think of no profession better suited to guide patients through the journey to better metabolic health than ours.

 Reviewer:  Mark R. Payne DC

 

 Reference: Smith M, Honce R, Shultz-Cherry S.  Metabolic Syndrome and Viral Pathogenesis: Lessons from Influenza and Coronaviruses J Virol. 2020 Sep; 94(18): e00665-20. Published online 2020 Aug 31. 

 Link to Abstract: https://pubmed.ncbi.nlm.nih.gov/32661141/

 Link to Full Text: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7459568/

 

Mark R. Payne DC