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Norlin AK, Walter S, Icenhour A, Keita ÅV, Elsenbruch S, Bednarska O, Jones MP, Simon R, Engström M. Fatigue in irritable bowel syndrome is associated with plasma levels of TNF-α and mesocorticolimbic connectivity. Brain Behav Immun 2021; 92:211-222. [PMID: 33249172 DOI: 10.1016/j.bbi.2020.11.035] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 10/17/2020] [Accepted: 11/23/2020] [Indexed: 02/06/2023] Open
Abstract
Irritable bowel syndrome (IBS) is a symptom-based disorder of gut-brain interactions generating abdominal pain. It is also associated with a vulnerability to develop extraintestinal symptoms, with fatigue often reported as one of the most disturbing. Fatigue is related to brain function and inflammation in several disorders, however, the mechanisms of such relations in IBS remain elusive. This study aimed to elucidate fatigue and its association with a resting state network of mesocorticolimbic regions of known importance in fatigue, and to explore the possible role of circulating TNF-α levels in IBS and healthy controls (HC). Resting state functional magnetic resonance imaging (fMRI) was conducted in 88 IBS patients and 47 HC of similar age and gender to investigate functional connectivity between mesocorticolimbic regions. Further, fatigue impact on daily life and plasma levels of the proinflammatory cytokine tumor necrosis factor-α (TNF-α), of known relevance to immune activation in IBS, were also measured. The selected mesocorticolimbic regions indeed formed a functionally connected network in all participants. The nucleus accumbens (NAc), in particular, exhibited functional connectivity to all other regions of interest. In IBS, fatigue impact on daily life was negatively correlated with the connectivity between NAc and dorsolateral prefrontal cortex bilaterally (left p = 0.019; right p = 0.038, corrected for multiple comparisons), while in HC, fatigue impact on daily life was positively correlated to the connectivity between the right NAc and anterior middle insula in both hemispheres (left p = 0.009; right p = 0.011). We found significantly higher levels of TNF-α in IBS patients compared to HC (p = 0.001) as well as a positive correlation between TNF-α and fatigue impact on daily life in IBS patients (rho = 0.25, p = 0.02) but not in HC (rho = -0.13, p = 0.37). There was no association between functional connectivity in the mesocorticolimbic network and plasma levels of TNF-α in either group In summary, this novel multimodal study provides the first evidence that the vulnerability to fatigue in IBS is associated with connectivity within a mesocorticolimbic network as well as immune activation. These findings warrant further investigation, both peripherally and potentially with measurements of central immune activation as well.
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Affiliation(s)
- Anna-Karin Norlin
- Department of Health, Medicine and Caring Sciences, Linköping University, Linköping, Sweden.
| | - Susanna Walter
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Adriane Icenhour
- Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköping Sweden; Institute of Medical Psychology and Behavioral Immunobiology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Åsa V Keita
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Sigrid Elsenbruch
- Department of Medical Psychology and Medical Sociology, Ruhr University Bochum, Bochum, Germany
| | - Olga Bednarska
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Michael P Jones
- Department of Psychology, Macquarie University, Sydney, Australia
| | - Rozalyn Simon
- Department of Health, Medicine and Caring Sciences, Linköping University, Linköping, Sweden; Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköping Sweden
| | - Maria Engström
- Department of Health, Medicine and Caring Sciences, Linköping University, Linköping, Sweden; Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköping Sweden
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