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Risk factors for COVID-19-related mortality in people with type 1 and type 2 diabetes in England: a population-based cohort study.
Holman, N, Knighton, P, Kar, P, O'Keefe, J, Curley, M, Weaver, A, Barron, E, Bakhai, C, Khunti, K, Wareham, NJ, et al
The lancet. Diabetes & endocrinology. 2020;8(10):823-833
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Diabetes, cardiovascular disease, and hypertension are the most common chronic conditions predisposing people to severe COVID-19 disease. The aim of this population-based cohort study, using data from 98% of general practices in England, was to investigate the associations between various risk factors, including poor blood sugar control, and COVID-19-related deaths in people with type 1 and type 2 diabetes. Between Feb 16 and May 11, 2020, 1604 people with type 1 diabetes and 36 291 people with type 2 diabetes died from all causes, of which almost 30% had COVID-19 listed on the death certificate, either a primary underlying or secondary cause of death. Male gender, age and being of Black or Asian ethnicity were associated with an increased mortality from COVID-19. Poor blood sugar control, as determined by HbA1C, prior to infection was strongly associated with COVID-19-related death, independent of other risk factors. Obesity (BMI of 30 or over) as well as being underweight were also significantly associated with COVID-19 mortality. The authors discuss that people with diabetes are at increased risk of many serious infections and that high blood glucose levels are known to impair immunity and may amplify the hyperimmune response associated with severe COVID-19.
Abstract
BACKGROUND Diabetes has been associated with increased COVID-19-related mortality, but the association between modifiable risk factors, including hyperglycaemia and obesity, and COVID-19-related mortality among people with diabetes is unclear. We assessed associations between risk factors and COVID-19-related mortality in people with type 1 and type 2 diabetes. METHODS We did a population-based cohort study of people with diagnosed diabetes who were registered with a general practice in England. National population data on people with type 1 and type 2 diabetes collated by the National Diabetes Audit were linked to mortality records collated by the Office for National Statistics from Jan 2, 2017, to May 11, 2020. We identified the weekly number of deaths in people with type 1 and type 2 diabetes during the first 19 weeks of 2020 and calculated the percentage change from the mean number of deaths for the corresponding weeks in 2017, 2018, and 2019. The associations between risk factors (including sex, age, ethnicity, socioeconomic deprivation, HbA1c, renal impairment [from estimated glomerular filtration rate (eGFR)], BMI, tobacco smoking status, and cardiovascular comorbidities) and COVID-19-related mortality (defined as International Classification of Diseases, version 10, code U07.1 or U07.2 as a primary or secondary cause of death) between Feb 16 and May 11, 2020, were investigated by use of Cox proportional hazards models. FINDINGS Weekly death registrations in the first 19 weeks of 2020 exceeded the corresponding 3-year weekly averages for 2017-19 by 672 (50·9%) in people with type 1 diabetes and 16 071 (64·3%) in people with type 2 diabetes. Between Feb 16 and May 11, 2020, among 264 390 people with type 1 diabetes and 2 874 020 people with type 2 diabetes, 1604 people with type 1 diabetes and 36 291 people with type 2 diabetes died from all causes. Of these total deaths, 464 in people with type 1 diabetes and 10 525 in people with type 2 diabetes were defined as COVID-19 related, of which 289 (62·3%) and 5833 (55·4%), respectively, occurred in people with a history of cardiovascular disease or with renal impairment (eGFR <60 mL/min per 1·73 m2). Male sex, older age, renal impairment, non-white ethnicity, socioeconomic deprivation, and previous stroke and heart failure were associated with increased COVID-19-related mortality in both type 1 and type 2 diabetes. Compared with people with an HbA1c of 48-53 mmol/mol (6·5-7·0%), people with an HbA1c of 86 mmol/mol (10·0%) or higher had increased COVID-19-related mortality (hazard ratio [HR] 2·23 [95% CI 1·50-3·30, p<0·0001] in type 1 diabetes and 1·61 [1·47-1·77, p<0·0001] in type 2 diabetes). In addition, in people with type 2 diabetes, COVID-19-related mortality was significantly higher in those with an HbA1c of 59 mmol/mol (7·6%) or higher than in those with an HbA1c of 48-53 mmol/mol (HR 1·22 [95% CI 1·15-1·30, p<0·0001] for 59-74 mmol/mol [7·6-8·9%] and 1·36 [1·24-1·50, p<0·0001] for 75-85 mmol/mol [9·0-9·9%]). The association between BMI and COVID-19-related mortality was U-shaped: in type 1 diabetes, compared with a BMI of 25·0-29·9 kg/m2, a BMI of less than 20·0 kg/m2 had an HR of 2·45 (95% CI 1·60-3·75, p<0·0001) and a BMI of 40·0 kg/m2 or higher had an HR of 2·33 (1·53-3·56, p<0·0001); the corresponding HRs for type 2 diabetes were 2·33 (2·11-2·56, p<0·0001) and 1·60 (1·47-1·75, p<0·0001). INTERPRETATION Deaths in people with type 1 and type 2 diabetes rose sharply during the initial COVID-19 pandemic in England. Increased COVID-19-related mortality was associated not only with cardiovascular and renal complications of diabetes but, independently, also with glycaemic control and BMI. FUNDING None.
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Coronavirus disease 2019 (COVID-19) and obesity. Impact of obesity and its main comorbidities in the evolution of the disease.
Cornejo-Pareja, IM, Gómez-Pérez, AM, Fernández-García, JC, Barahona San Millan, R, Aguilera Luque, A, de Hollanda, A, Jiménez, A, Jimenez-Murcia, S, Munguia, L, Ortega, E, et al
European eating disorders review : the journal of the Eating Disorders Association. 2020;28(6):799-815
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The Covid-19 pandemic has caused thousands of deaths worldwide. Being obese is associated with worse outcomes following infection with Covid-19. This review aimed to summarise the data available on the relationship between Covid-19 and obesity, and explored some of the possible reasons for this relationship. The researchers found that obesity is an independent and strong risk factor for severe infection, Intensive Care Unit (ICU) admission and death. The impact of obesity might be of particular relevance in males and in younger individuals. Long‐term complications of Covid‐19 could also be more frequent and severe in obese subjects. There are many potential mechanisms that could explain this relationship. These include the effects of obesity and related diseases such as diabetes, high blood pressure and heart disease on the immune system, lung function, vitamin D deficiency and male hormones. The researchers also discussed the possibility of fat cells acting as a possible reservoir for Covid-19 infection. Research into Covid-19 is still at a very early stage and more studies are needed.
Abstract
The COVID-19 pandemic is posing a great challenge worldwide. Its rapid progression has caused thousands of deaths worldwide. Although multiple aspects remain to be clarified, some risk factors associated with a worse prognosis have been identified. These include obesity and some of its main complications, such as diabetes and high blood pressure. Furthermore, although the possible long-term complications and psychological effects that may appear in survivors of COVID-19 are not well known yet, there is a concern that those complications may be greater in obese patients. In this manuscript, we review some of the data published so far and the main points that remain to be elucidated are emphasized.
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Stratifying cellular metabolism during weight loss: an interplay of metabolism, metabolic flexibility and inflammation.
Tareen, SHK, Kutmon, M, de Kok, TM, Mariman, ECM, van Baak, MA, Evelo, CT, Adriaens, ME, Arts, ICW
Scientific reports. 2020;10(1):1651
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Obesity is a public health concern as it has been linked to cardiovascular diseases, type 2 diabetes and metabolic syndrome. The aim of this study was to identify and analyse expression profiles of individuals clustered by cellular metabolism centring on metabolic flexibility. This study clustered gene expression samples from a weight loss study (Yoyo study’ - Clinical Trial ID: NCT01559415) into two clusters, based on 291 genes associated with cellular metabolic fexibility. The study covers two diets: a low-calorie diet (LCD) and a very low-calorie diet (VLCD). All the participants of the study were Caucasian with a BMI between 28kg/m2 and 35 kg/m2, aged between 32 and 67 years old. Findings showed that the majority of the individuals had their metabolism associated genes downregulated after weight loss and weight maintenance, but also had an upregulation of immune system associated genes. Furthermore, individuals who had changed their metabolic profiles in response to caloric restriction had a significant retention of lost weight compared to individuals which had not changed their cluster membership. Authors conclude that their findings indicate possible cross-talk between cellular metabolism and inflammation.
Abstract
Obesity is a global epidemic, contributing significantly to chronic non-communicable diseases, such as type 2 diabetes mellitus, cardiovascular diseases and metabolic syndrome. Metabolic flexibility, the ability of organisms to switch between metabolic substrates, is found to be impaired in obesity, possibly contributing to the development of chronic illnesses. Several studies have shown the improvement of metabolic flexibility after weight loss. In this study, we have mapped the cellular metabolism of the adipose tissue from a weight loss study to stratify the cellular metabolic processes and metabolic flexibility during weight loss. We have found that for a majority of the individuals, cellular metabolism was downregulated during weight loss, with gene expression of all major cellular metabolic processes (such as glycolysis, fatty acid β-oxidation etc.) being lowered during weight loss and weight maintenance. Parallel to this, the gene expression of immune system related processes involving interferons and interleukins increased. Previously, studies have indicated both negative and positive effects of post-weight loss inflammation in the adipose tissue with regards to weight loss or obesity and its co-morbidities; however, mechanistic links need to be constructed in order to determine the effects further. Our study contributes towards this goal by mapping the changes in gene expression across the weight loss study and indicates possible cross-talk between cellular metabolism and inflammation.
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A randomized, phase 1, placebo-controlled trial of APG-157 in oral cancer demonstrates systemic absorption and an inhibitory effect on cytokines and tumor-associated microbes.
Basak, SK, Bera, A, Yoon, AJ, Morselli, M, Jeong, C, Tosevska, A, Dong, TS, Eklund, M, Russ, E, Nasser, H, et al
Cancer. 2020;126(8):1668-1682
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APG-157 is a botanical drug containing multiple polyphenols that delivers the active components to oromucosal tissues near the tumour target. APG-157 slowly disintegrates in the oral cavity over 15 to 20 minutes to release the drug substance. The drug substance is a precise, rational combination of multiple molecules derived from Curcuma longa wherein curcumin is the principal component. The main aim of this study was to determine the pharmacokinetics and safety of the orally delivered pastille (APG-157) when used by normal subjects and patients with cancer. This study is a randomised, double-blind, placebo-controlled trial. A total of 32 subjects were enrolled, and 25 completed the study (13 normal individuals and 12 patients with oral cancer). Results demonstrated that transoral APG-157 treatment leads to systemic absorption of curcumin and its analogs. There was a statistically significant concentration reduction in inflammatory cytokines and Bacteroides species noted in the salivary cells. Pre-treatment and post-treatment tumour samples from patients with cancer demonstrated T-cell recruitment to the tumour microenvironment. Authors conclude that APG-157 is absorbed well, reduces inflammation, and attracts T-cells to the tumour thus, it can be potentially used in combination with immunotherapy drugs. Furthermore, a long-term evaluation of immune checkpoint blockade with and without APG-157 could provide a clear understanding of the usefulness of APG-157 as either an adjuvant or neoadjuvant therapeutic agent for patients with advanced or recurrent head and neck cancer.
Abstract
BACKGROUND Although curcumin's effect on head and neck cancer has been studied in vitro and in vivo, to the authors' knowledge its efficacy is limited by poor systemic absorption from oral administration. APG-157 is a botanical drug containing multiple polyphenols, including curcumin, developed under the US Food and Drug Administration's Botanical Drug Development, that delivers the active components to oromucosal tissues near the tumor target. METHODS A double-blind, randomized, placebo-controlled, phase 1 clinical trial was conducted with APG-157 in 13 normal subjects and 12 patients with oral cancer. Two doses, 100 mg or 200 mg, were delivered transorally every hour for 3 hours. Blood and saliva were collected before and 1 hour, 2 hours, 3 hours, and 24 hours after treatment. Electrocardiograms and blood tests did not demonstrate any toxicity. RESULTS Treatment with APG-157 resulted in circulating concentrations of curcumin and analogs peaking at 3 hours with reduced IL-1β, IL-6, and IL-8 concentrations in the salivary supernatant fluid of patients with cancer. Salivary microbial flora analysis showed a reduction in Bacteroidetes species in cancer subjects. RNA and immunofluorescence analyses of tumor tissues of a subject demonstrated increased expression of genes associated with differentiation and T-cell recruitment to the tumor microenvironment. CONCLUSIONS The results of the current study suggested that APG-157 could serve as a therapeutic drug in combination with immunotherapy. LAY SUMMARY Curcumin has been shown to suppress tumor cells because of its antioxidant and anti-inflammatory properties. However, its effectiveness has been limited by poor absorption when delivered orally. Subjects with oral cancer were given oral APG-157, a botanical drug containing multiple polyphenols, including curcumin. Curcumin was found in the blood and in tumor tissues. Inflammatory markers and Bacteroides species were found to be decreased in the saliva, and immune T cells were increased in the tumor tissue. APG-157 is absorbed well, reduces inflammation, and attracts T cells to the tumor, suggesting its potential use in combination with immunotherapy drugs.
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'The long tail of Covid-19' - The detection of a prolonged inflammatory response after a SARS-CoV-2 infection in asymptomatic and mildly affected patients.
Doykov, I, Hällqvist, J, Gilmour, KC, Grandjean, L, Mills, K, Heywood, WE
F1000Research. 2020;9:1349
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‘Long COVID’ or the persistence of symptoms after SARS-CoV-2 infection, such as fatigue, is becoming increasingly common. As the emergence of the virus is still relatively recent in research terms, little is known about the long-term impact of the viruses infection. This study sought to generate further insights into the management and diagnostic of long COVID, by assessing a range of inflammatory markers from blood serum samples. Examined were 10 samples of health care workers with previous asymptomatic or moderate SARS-CoV-2 infections, compared to 10 samples of SARS-CoV-2 naive health care workers. The serum was analyzed by mass spectrometry using a customized panel of the 96 immune response associated proteins. Despite being mild to moderate cases, the results showed that even 40-60 days after infection, significant disturbance in the immune systems inflammatory response could be observed. Particularly markers that reflect anti-inflammatory pathways and mitochondrial stress. The study highlighted six of the most noteworthy proteins and included a brief description of their role. The authors suggest that analysing proteins by using targeted proteomic technology, could serve as a cost-effective strategy to further investigate the changes in inflammatory responses post SARS-CoV-2 infection. Which could help to aid the identification of potential treatment targets in the future. Relevant findings from this small study for clinical practice are that even mild to moderate SARS-CoV-2 infection can alter the inflammatory responses for months afterwards.
Abstract
'Long Covid', or medical complications associated with post SARS-CoV-2 infection, is a significant post-viral complication that is being more and more commonly reported in patients. Therefore, there is an increasing need to understand the disease mechanisms, identify drug targets and inflammatory processes associated with a SARS-CoV-2 infection. To address this need, we created a targeted mass spectrometry based multiplexed panel of 96 immune response associated proteins. We applied the multiplex assay to a cohort of serum samples from asymptomatic and moderately affected patients. All patients had tested positive for a SARS-CoV-2 infection by PCR and were determined to be subsequently positive for antibodies. Even 40-60 days post-viral infection, we observed a significant remaining inflammatory response in all patients. Proteins that were still affected were associated with the anti-inflammatory response and mitochondrial stress. This indicates that biochemical and inflammatory pathways within the body can remain perturbed long after SARS-CoV-2 infections have subsided even in asymptomatic and moderately affected patients.
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The COVID-19 Pandemic: a Call to Action to Identify and Address Racial and Ethnic Disparities.
Laurencin, CT, McClinton, A
Journal of racial and ethnic health disparities. 2020;7(3):398-402
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The severe acute respiratory syndrome coronavirus 2 virus was first identified in late 2019 in Wuhan, China. Various unsubstantiated reports emerged declaring that the genetic constitution of Blacks or even the presence of melanin rendered Blacks immune to the virus. This study is a call of action which reviews preliminary data on race and ethnicity in the peer-reviewed literature for citizens in America affected by COVID-19. Findings demonstrate that communities of colour (Blacks) have a higher rate of infection and death in comparison to their population percentage in the state of Connecticut. However, authors are unable to draw conclusions since race and ethnicity data is missing and the data in this paper is the earliest data available. Therefore, the authors call for action to identify and address racial and ethnic health disparities in the COVID-19 crisis.
Abstract
The Coronavirus disease 2019 (COVID-19) pandemic has significantly impacted and devastated the world. As the infection spreads, the projected mortality and economic devastation are unprecedented. In particular, racial and ethnic minorities may be at a particular disadvantage as many already assume the status of a marginalized group. Black Americans have a long-standing history of disadvantage and are in a vulnerable position to experience the impact of this crisis and the myth of Black immunity to COVID-19 is detrimental to promoting and maintaining preventative measures. We are the first to present the earliest available data in the peer-reviewed literature on the racial and ethnic distribution of COVID-19-confirmed cases and fatalities in the state of Connecticut. We also seek to explode the myth of Black immunity to the virus. Finally, we call for a National Commission on COVID-19 Racial and Ethnic Health Disparities to further explore and respond to the unique challenges that the crisis presents for Black and Brown communities.
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Persistent fatigue following SARS-CoV-2 infection is common and independent of severity of initial infection.
Townsend, L, Dyer, AH, Jones, K, Dunne, J, Mooney, A, Gaffney, F, O'Connor, L, Leavy, D, O'Brien, K, Dowds, J, et al
PloS one. 2020;15(11):e0240784
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Tiredness is a common symptom of Covid-19; however, it is unknown if this fatigue persists once recovered. This observational study of 128 recovered Covid-19 patients aimed to determine if fatigue persisted after recovery and whether severity of disease could predict fatigue. The results showed that post Covid-19 fatigue was reported in more than half of the participants and was particularly pronounced in females and in those with depression. Severity of disease did not predict fatigue. It was concluded that fatigue appears to outlast infection and fatigue was independent of disease severity. This study could be used by health care practitioners to understand that fatigue is common even after recovery from Covid-19 infection and women and sufferers of depression are the most susceptible.
Abstract
Fatigue is a common symptom in those presenting with symptomatic COVID-19 infection. However, it is unknown if COVID-19 results in persistent fatigue in those recovered from acute infection. We examined the prevalence of fatigue in individuals recovered from the acute phase of COVID-19 illness using the Chalder Fatigue Score (CFQ-11). We further examined potential predictors of fatigue following COVID-19 infection, evaluating indicators of COVID-19 severity, markers of peripheral immune activation and circulating pro-inflammatory cytokines. Of 128 participants (49.5 ± 15 years; 54% female), more than half reported persistent fatigue (67/128; 52.3%) at median of 10 weeks after initial COVID-19 symptoms. There was no association between COVID-19 severity (need for inpatient admission, supplemental oxygen or critical care) and fatigue following COVID-19. Additionally, there was no association between routine laboratory markers of inflammation and cell turnover (leukocyte, neutrophil or lymphocyte counts, neutrophil-to-lymphocyte ratio, lactate dehydrogenase, C-reactive protein) or pro-inflammatory molecules (IL-6 or sCD25) and fatigue post COVID-19. Female gender and those with a pre-existing diagnosis of depression/anxiety were over-represented in those with fatigue. Our findings demonstrate a significant burden of post-viral fatigue in individuals with previous SARS-CoV-2 infection after the acute phase of COVID-19 illness. This study highlights the importance of assessing those recovering from COVID-19 for symptoms of severe fatigue, irrespective of severity of initial illness, and may identify a group worthy of further study and early intervention.
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Harnessing the immune system to overcome cytokine storm and reduce viral load in COVID-19: a review of the phases of illness and therapeutic agents.
Khadke, S, Ahmed, N, Ahmed, N, Ratts, R, Raju, S, Gallogly, M, de Lima, M, Sohail, MR
Virology journal. 2020;17(1):154
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Severe manifestations of COVID-19 infection and mortality are associated with a cytokine storm. This is an excessive inflammatory response to the infection leading to an overproduction of pro-inflammatory signalling molecules, which consequently contributes to tissue and organ damage. This literature review summarised current knowledge, as of June 2020, about virus-associated cytokine storm, virus-host interactions and immunological mechanism, to gain a better understanding of the phenomena observed in COVID-19 infections and devise better treatment strategies. The review briefly outlines the epidemiology of COVID-19, predictors of severity of disease, mode of transmission, testing, viral structure, mechanism of invasion of the host cell, replication and immune invasion and the progression of the four stages of the cytokine storm. The second part of the review discusses antiviral therapeutics of interest with a table summarising drugs, mechanism and available data. This article may be of interest to those who like to delve further into the mechanisms and immune components involved in a cytokine storm and gain an oversight of the pathways targeted by allopathic agents that have been put forward as treatment options.
Abstract
BACKGROUND Coronavirus disease 2019 (COVID-19) is caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2, previously named 2019-nCov), a novel coronavirus that emerged in China in December 2019 and was declared a global pandemic by World Health Organization by March 11th, 2020. Severe manifestations of COVID-19 are caused by a combination of direct tissue injury by viral replication and associated cytokine storm resulting in progressive organ damage. DISCUSSION We reviewed published literature between January 1st, 2000 and June 30th, 2020, excluding articles focusing on pediatric or obstetric population, with a focus on virus-host interactions and immunological mechanisms responsible for virus associated cytokine release syndrome (CRS). COVID-19 illness encompasses three main phases. In phase 1, SARS-CoV-2 binds with angiotensin converting enzyme (ACE)2 receptor on alveolar macrophages and epithelial cells, triggering toll like receptor (TLR) mediated nuclear factor kappa-light-chain-enhancer of activated B cells (NF-ƙB) signaling. It effectively blunts an early (IFN) response allowing unchecked viral replication. Phase 2 is characterized by hypoxia and innate immunity mediated pneumocyte damage as well as capillary leak. Some patients further progress to phase 3 characterized by cytokine storm with worsening respiratory symptoms, persistent fever, and hemodynamic instability. Important cytokines involved in this phase are interleukin (IL)-6, IL-1β, and tumor necrosis factor (TNF)-α. This is typically followed by a recovery phase with production of antibodies against the virus. We summarize published data regarding virus-host interactions, key immunological mechanisms responsible for virus-associated CRS, and potential opportunities for therapeutic interventions. CONCLUSION Evidence regarding SARS-CoV-2 epidemiology and pathogenesis is rapidly evolving. A better understanding of the pathophysiology and immune system dysregulation associated with CRS and acute respiratory distress syndrome in severe COVID-19 is imperative to identify novel drug targets and other therapeutic interventions.
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The Role of Bacteria and Its Derived Metabolites in Chronic Pain and Depression: Recent Findings and Research Progress.
Li, S, Hua, D, Wang, Q, Yang, L, Wang, X, Luo, A, Yang, C
The international journal of neuropsychopharmacology. 2020;23(1):26-41
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Depression is closely associated with chronic pain yet the connection between these comorbidities is ambiguous. Recent studies have shown alterations in the gut microbiome may contribute to cognitive dysfunction via the microbiota-gut-brain axis. The aim of this systematic review is to summarize the existing evidence of the role of the gut microbiome in chronic pain and depression and explore potential mechanisms of gut dysbiosis in the development of these conditions. This review found metabolic products from the gut microbiota can mediate neuro-inflammation and neuro-immunity pathways in pain and depression, and that dysbiosis in the gut may contribute to the cause of chronic pain and depression. The authors conclude the metabolic products from the gut bacteria offer new insights to the connection between the gut microbiota and mechanisms of pain and depression, while showing potential as a therapeutic target.
Abstract
BACKGROUND Chronic pain is frequently comorbid with depression in clinical practice. Recently, alterations in gut microbiota and metabolites derived therefrom have been found to potentially contribute to abnormal behaviors and cognitive dysfunction via the "microbiota-gut-brain" axis. METHODS PubMed was searched and we selected relevant studies before October 1, 2019. The search keyword string included "pain OR chronic pain" AND "gut microbiota OR metabolites"; "depression OR depressive disorder" AND "gut microbiota OR metabolites". We also searched the reference lists of key articles manually. RESULTS This review systematically summarized the recent evidence of gut microbiota and metabolites in chronic pain and depression in animal and human studies. The results showed the pathogenesis and therapeutics of chronic pain and depression might be partially due to gut microbiota dysbiosis. Importantly, bacteria-derived metabolites, including short-chain fatty acids, tryptophan-derived metabolites, and secondary bile acids, offer new insights into the potential linkage between key triggers in gut microbiota and potential mechanisms of depression. CONCLUSION Studying gut microbiota and its metabolites has contributed to the understanding of comorbidity of chronic pain and depression. Consequently, modulating dietary structures or supplementation of specific bacteria may be an available strategy for treating chronic pain and depression.
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Reductions in anti-inflammatory gut bacteria are associated with depression in a sample of young adults.
Liu, RT, Rowan-Nash, AD, Sheehan, AE, Walsh, RFL, Sanzari, CM, Korry, BJ, Belenky, P
Brain, behavior, and immunity. 2020;88:308-324
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Alterations to the gut microbiota may be associated with depression and anxiety disorders through a pathway known as the gut-brain axis. Inflammation may be the mediator between the two, as individuals with major depressive disorder (MDD) have reported high levels of inflammation, which the gut microbiota may have the capacity to protect against. This observational study of the gut microbiota of 90 young adults with MDD and 47 healthy controls aimed to determine the relationship between inflammatory gut microbiota and symptoms of depression. The results showed changes to several species of gut microbiota in those with MDD and that the level of change was related to MDD symptom severity. These changes were observed even in those taking psychotropic medications. Changes at the taxonomic level indicated that those with higher symptoms of depression had more pronounced differences compared with healthy controls. Although the observed differences were indicative of an inflammatory microbiome, no changes were observed in blood markers of inflammation between those individuals with MDD and healthy controls. It was concluded that the gut microbiome of individuals with MDD was different from healthy individuals in favour of an inflammatory environment. This study could be used by healthcare professionals to understand that the status of the gut microbiota may be an important measure in individuals with MDD and that a treatment plan to ensure gut health is considered may help with symptoms of depression.
Abstract
We assessed the gut microbiota of 90 American young adults, comparing 43 participants with major depressive disorder (MDD) and 47 healthy controls, and found that the MDD subjects had significantly different gut microbiota compared to the healthy controls at multiple taxonomic levels. At the phylum level, participants with MDD had lower levels of Firmicutes and higher levels of Bacteroidetes, with similar trends in the at the class (Clostridia and Bacteroidia) and order (Clostridiales and Bacteroidales) levels. At the genus level, the MDD group had lower levels of Faecalibacterium and other related members of the family Ruminococcaceae, which was also reduced relative to healthy controls. Additionally, the class Gammaproteobacteria and genus Flavonifractor were enriched in participants with MDD. Accordingly, predicted functional differences between the two groups include a reduced abundance of short-chain fatty acid production pathways in the MDD group. We also demonstrated that the magnitude of taxonomic changes was associated with the severity of depressive symptoms in many cases, and that most changes were present regardless of whether depressed participants were taking psychotropic medications. Overall, our results support a link between MDD and lower levels of anti-inflammatory, butyrate-producing bacteria, and may support a connection between the gut microbiota and the chronic, low-grade inflammation often observed in MDD patients.