Type I Diabetes Pathoetiology and Pathophysiology: Roles of the Gut Microbiome, Pancreatic Cellular Interactions, and the ‘Bystander’ Activation of Memory CD8<sup>+</sup> T Cells
Type 1 diabetes mellitus (T1DM) arises from the failure of pancreatic β-cells to produce adequate insulin, usually as a consequence of extensive pancreatic β-cell destruction. T1DM is classed as an immune-mediated condition. However, the processes that drive pancreatic β-cell apoptosis remain to be...
| Main Author: | |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2023-02-01
|
| Series: | International Journal of Molecular Sciences |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1422-0067/24/4/3300 |
| _version_ | 1797620601608732672 |
|---|---|
| author | George Anderson |
| author_facet | George Anderson |
| author_sort | George Anderson |
| collection | DOAJ |
| description | Type 1 diabetes mellitus (T1DM) arises from the failure of pancreatic β-cells to produce adequate insulin, usually as a consequence of extensive pancreatic β-cell destruction. T1DM is classed as an immune-mediated condition. However, the processes that drive pancreatic β-cell apoptosis remain to be determined, resulting in a failure to prevent ongoing cellular destruction. Alteration in mitochondrial function is clearly the major pathophysiological process underpinning pancreatic β-cell loss in T1DM. As with many medical conditions, there is a growing interest in T1DM as to the role of the gut microbiome, including the interactions of gut bacteria with <i>Candida albicans</i> fungal infection. Gut dysbiosis and gut permeability are intimately associated with raised levels of circulating lipopolysaccharide and suppressed butyrate levels, which can act to dysregulate immune responses and systemic mitochondrial function. This manuscript reviews broad bodies of data on T1DM pathophysiology, highlighting the importance of alterations in the mitochondrial melatonergic pathway of pancreatic β-cells in driving mitochondrial dysfunction. The suppression of mitochondrial melatonin makes pancreatic β-cells susceptible to oxidative stress and dysfunctional mitophagy, partly mediated by the loss of melatonin’s induction of PTEN-induced kinase 1 (PINK1), thereby suppressing mitophagy and increasing autoimmune associated major histocompatibility complex (MHC)-1. The immediate precursor to melatonin, <i>N</i>-acetylserotonin (NAS), is a brain-derived neurotrophic factor (BDNF) mimic, via the activation of the BDNF receptor, TrkB. As both the full-length and truncated TrkB play powerful roles in pancreatic β-cell function and survival, NAS is another important aspect of the melatonergic pathway relevant to pancreatic β-cell destruction in T1DM. The incorporation of the mitochondrial melatonergic pathway in T1DM pathophysiology integrates wide bodies of previously disparate data on pancreatic intercellular processes. The suppression of <i>Akkermansia muciniphila</i>, <i>Lactobacillus johnsonii</i>, butyrate, and the shikimate pathway—including by bacteriophages—contributes to not only pancreatic β-cell apoptosis, but also to the bystander activation of CD8<sup>+</sup> T cells, which increases their effector function and prevents their deselection in the thymus. The gut microbiome is therefore a significant determinant of the mitochondrial dysfunction driving pancreatic β-cell loss as well as ‘autoimmune’ effects derived from cytotoxic CD8<sup>+</sup> T cells. This has significant future research and treatment implications. |
| first_indexed | 2024-03-11T08:43:57Z |
| format | Article |
| id | doaj.art-61085c2548d54bbfbf3dcd107a3d7389 |
| institution | Directory Open Access Journal |
| issn | 1661-6596 1422-0067 |
| language | English |
| last_indexed | 2024-03-11T08:43:57Z |
| publishDate | 2023-02-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | International Journal of Molecular Sciences |
| spelling | doaj.art-61085c2548d54bbfbf3dcd107a3d73892023-11-16T20:58:02ZengMDPI AGInternational Journal of Molecular Sciences1661-65961422-00672023-02-01244330010.3390/ijms24043300Type I Diabetes Pathoetiology and Pathophysiology: Roles of the Gut Microbiome, Pancreatic Cellular Interactions, and the ‘Bystander’ Activation of Memory CD8<sup>+</sup> T CellsGeorge Anderson0CRC Scotland & London, Eccleston Square, London SW1V 1PG, UKType 1 diabetes mellitus (T1DM) arises from the failure of pancreatic β-cells to produce adequate insulin, usually as a consequence of extensive pancreatic β-cell destruction. T1DM is classed as an immune-mediated condition. However, the processes that drive pancreatic β-cell apoptosis remain to be determined, resulting in a failure to prevent ongoing cellular destruction. Alteration in mitochondrial function is clearly the major pathophysiological process underpinning pancreatic β-cell loss in T1DM. As with many medical conditions, there is a growing interest in T1DM as to the role of the gut microbiome, including the interactions of gut bacteria with <i>Candida albicans</i> fungal infection. Gut dysbiosis and gut permeability are intimately associated with raised levels of circulating lipopolysaccharide and suppressed butyrate levels, which can act to dysregulate immune responses and systemic mitochondrial function. This manuscript reviews broad bodies of data on T1DM pathophysiology, highlighting the importance of alterations in the mitochondrial melatonergic pathway of pancreatic β-cells in driving mitochondrial dysfunction. The suppression of mitochondrial melatonin makes pancreatic β-cells susceptible to oxidative stress and dysfunctional mitophagy, partly mediated by the loss of melatonin’s induction of PTEN-induced kinase 1 (PINK1), thereby suppressing mitophagy and increasing autoimmune associated major histocompatibility complex (MHC)-1. The immediate precursor to melatonin, <i>N</i>-acetylserotonin (NAS), is a brain-derived neurotrophic factor (BDNF) mimic, via the activation of the BDNF receptor, TrkB. As both the full-length and truncated TrkB play powerful roles in pancreatic β-cell function and survival, NAS is another important aspect of the melatonergic pathway relevant to pancreatic β-cell destruction in T1DM. The incorporation of the mitochondrial melatonergic pathway in T1DM pathophysiology integrates wide bodies of previously disparate data on pancreatic intercellular processes. The suppression of <i>Akkermansia muciniphila</i>, <i>Lactobacillus johnsonii</i>, butyrate, and the shikimate pathway—including by bacteriophages—contributes to not only pancreatic β-cell apoptosis, but also to the bystander activation of CD8<sup>+</sup> T cells, which increases their effector function and prevents their deselection in the thymus. The gut microbiome is therefore a significant determinant of the mitochondrial dysfunction driving pancreatic β-cell loss as well as ‘autoimmune’ effects derived from cytotoxic CD8<sup>+</sup> T cells. This has significant future research and treatment implications.https://www.mdpi.com/1422-0067/24/4/3300type 1 diabetesmitochondriamelatonin<i>N</i>-acetylserotoninaryl hydrocarbon receptorTrkB |
| spellingShingle | George Anderson Type I Diabetes Pathoetiology and Pathophysiology: Roles of the Gut Microbiome, Pancreatic Cellular Interactions, and the ‘Bystander’ Activation of Memory CD8<sup>+</sup> T Cells International Journal of Molecular Sciences type 1 diabetes mitochondria melatonin <i>N</i>-acetylserotonin aryl hydrocarbon receptor TrkB |
| title | Type I Diabetes Pathoetiology and Pathophysiology: Roles of the Gut Microbiome, Pancreatic Cellular Interactions, and the ‘Bystander’ Activation of Memory CD8<sup>+</sup> T Cells |
| title_full | Type I Diabetes Pathoetiology and Pathophysiology: Roles of the Gut Microbiome, Pancreatic Cellular Interactions, and the ‘Bystander’ Activation of Memory CD8<sup>+</sup> T Cells |
| title_fullStr | Type I Diabetes Pathoetiology and Pathophysiology: Roles of the Gut Microbiome, Pancreatic Cellular Interactions, and the ‘Bystander’ Activation of Memory CD8<sup>+</sup> T Cells |
| title_full_unstemmed | Type I Diabetes Pathoetiology and Pathophysiology: Roles of the Gut Microbiome, Pancreatic Cellular Interactions, and the ‘Bystander’ Activation of Memory CD8<sup>+</sup> T Cells |
| title_short | Type I Diabetes Pathoetiology and Pathophysiology: Roles of the Gut Microbiome, Pancreatic Cellular Interactions, and the ‘Bystander’ Activation of Memory CD8<sup>+</sup> T Cells |
| title_sort | type i diabetes pathoetiology and pathophysiology roles of the gut microbiome pancreatic cellular interactions and the bystander activation of memory cd8 sup sup t cells |
| topic | type 1 diabetes mitochondria melatonin <i>N</i>-acetylserotonin aryl hydrocarbon receptor TrkB |
| url | https://www.mdpi.com/1422-0067/24/4/3300 |
| work_keys_str_mv | AT georgeanderson typeidiabetespathoetiologyandpathophysiologyrolesofthegutmicrobiomepancreaticcellularinteractionsandthebystanderactivationofmemorycd8supsuptcells |