IgA-dependent mechanism of sleep fragmentation accelerated atherosclerosis
Poster #: 127
Session/Time: B
Author:
Basudha Habisyasi, MS
Mentor:
Elena Galkina, PhD
Research Type: Basic Science
Abstract
INTRODUCTION:
Atherosclerosis is a disease of large and medium-sized vessels, characterized by dyslipidemia, vascular dysfunction, foam cell formation and chronic inflammation. B cells play a subset-specific role in atherogenesis, with a complex role of immunoglobulins (Ig) where some are protective and others are pathogenic. IgA is the predominant Ig at mucosal sites, defending against pathogens and maintaining mucosal homeostasis. Pathologically, circulating IgA immune complexes can drive inflammation and tissue injury in chronic inflammatory diseases. Sleep fragmentation (SF), a common consequence of contemporary lifestyles, disrupts immune homeostasis, promotes systemic inflammation and accelerates atherosclerosis. To date, the role of IgA in atherogenesis and in SF-accelerated atherosclerosis remains unclear. Here, we investigate how disturbed sleep supports gut-associated inflammation and suppresses IgA production, thereby triggering the release of lipopolysaccharide (LPS) into circulation. Conversely, bone marrow-released IgA activates myeloid cells, which, in turn, play a key role in the formation of accelerated vulnerable plaques.
METHODS:
12-week-old apolipoprotein E deficient (Apoe-/-) mice were assigned to SF or activity control (AC) groups and fed High-fat diet (HFD). Atherosclerotic lesions in the aorta were measured as percent of total aorta via Oil Red-O staining (ORO). Dihydroethidine staining was used to measure reactive oxygen species (ROS) levels in the small intestines. Immune phenotyping of the aorta and gut was assessed by flow cytometry. IgA deficient low-density lipoprotein-deficient receptor (Iga-/-Ldlr-/-) mice and control Ldlr-/- mice were fed a HFD for 16 weeks to induce hyperlipidemia and atherogenesis. Plaque burden in the aorta and brachiocephalic artery (BCA) was measured by ORO staining and BCA grading. Oxidized-LDL (oxLDL) was pre-incubated with mouse IgA or human IgA and treated with mouse peritoneal macrophages (MFs) and human IgA and oxLDL was pre-incubated and treated with human monocytic THP-1 cells, to measure oxLDL uptake by MFs and MF activation.
RESULTS:
SF promoted atherosclerosis with accelerated lesion development in the BCA of HFD-fed, Apoe-/- mice. SF increased ROS production and interferon gamma (IFNg) expression but reduced IgA+ B cell frequency and tight junction protein 1 (Tjp1) expression in the small intestines of HFD-fed Apoe-/- mice. Furthermore, SF and HFD-feeding increased circulating LPS and ROS levels in Apoe-/- mice. IgA deficiency (Iga-/-Ldlr-/-) attenuated plaque burden in the aorta and BCA with reduced aortic leukocyte content of HFD-fed mice compared to controls (Ldlr-/-). Mouse or human IgA pre-incubated with oxLDL diminished oxLDL uptake while enhancing the activation of mouse MFs, reflected by MHCII and CD63 upregulation. Similarly, human IgA attenuated oxLDL uptake and elevated mitochondrial superoxide (mitoSOX) levels in THP-1 cells.
CONCLUSION:
SF exacerbates systemic inflammation and atherosclerotic plaque burden, potentially through dysregulated gut immunity and integrity as evidenced by increased intestinal ROS production and reduced Tjp1 expression and IgA+ B cell presence with concurrent elevated circulating LPS and ROS levels. IgA can bind to oxLDL and prevents its uptake by MFs and supports MF activation. Unexpectedly, IgA deficiency reduces atherosclerotic plaque burden. Taken together this data shows that IgA may play a complex role in SF accelerated atherosclerosis by supporting gut health and modulating myeloid cell activation.
Atherosclerosis is a disease of large and medium-sized vessels, characterized by dyslipidemia, vascular dysfunction, foam cell formation and chronic inflammation. B cells play a subset-specific role in atherogenesis, with a complex role of immunoglobulins (Ig) where some are protective and others are pathogenic. IgA is the predominant Ig at mucosal sites, defending against pathogens and maintaining mucosal homeostasis. Pathologically, circulating IgA immune complexes can drive inflammation and tissue injury in chronic inflammatory diseases. Sleep fragmentation (SF), a common consequence of contemporary lifestyles, disrupts immune homeostasis, promotes systemic inflammation and accelerates atherosclerosis. To date, the role of IgA in atherogenesis and in SF-accelerated atherosclerosis remains unclear. Here, we investigate how disturbed sleep supports gut-associated inflammation and suppresses IgA production, thereby triggering the release of lipopolysaccharide (LPS) into circulation. Conversely, bone marrow-released IgA activates myeloid cells, which, in turn, play a key role in the formation of accelerated vulnerable plaques.
METHODS:
12-week-old apolipoprotein E deficient (Apoe-/-) mice were assigned to SF or activity control (AC) groups and fed High-fat diet (HFD). Atherosclerotic lesions in the aorta were measured as percent of total aorta via Oil Red-O staining (ORO). Dihydroethidine staining was used to measure reactive oxygen species (ROS) levels in the small intestines. Immune phenotyping of the aorta and gut was assessed by flow cytometry. IgA deficient low-density lipoprotein-deficient receptor (Iga-/-Ldlr-/-) mice and control Ldlr-/- mice were fed a HFD for 16 weeks to induce hyperlipidemia and atherogenesis. Plaque burden in the aorta and brachiocephalic artery (BCA) was measured by ORO staining and BCA grading. Oxidized-LDL (oxLDL) was pre-incubated with mouse IgA or human IgA and treated with mouse peritoneal macrophages (MFs) and human IgA and oxLDL was pre-incubated and treated with human monocytic THP-1 cells, to measure oxLDL uptake by MFs and MF activation.
RESULTS:
SF promoted atherosclerosis with accelerated lesion development in the BCA of HFD-fed, Apoe-/- mice. SF increased ROS production and interferon gamma (IFNg) expression but reduced IgA+ B cell frequency and tight junction protein 1 (Tjp1) expression in the small intestines of HFD-fed Apoe-/- mice. Furthermore, SF and HFD-feeding increased circulating LPS and ROS levels in Apoe-/- mice. IgA deficiency (Iga-/-Ldlr-/-) attenuated plaque burden in the aorta and BCA with reduced aortic leukocyte content of HFD-fed mice compared to controls (Ldlr-/-). Mouse or human IgA pre-incubated with oxLDL diminished oxLDL uptake while enhancing the activation of mouse MFs, reflected by MHCII and CD63 upregulation. Similarly, human IgA attenuated oxLDL uptake and elevated mitochondrial superoxide (mitoSOX) levels in THP-1 cells.
CONCLUSION:
SF exacerbates systemic inflammation and atherosclerotic plaque burden, potentially through dysregulated gut immunity and integrity as evidenced by increased intestinal ROS production and reduced Tjp1 expression and IgA+ B cell presence with concurrent elevated circulating LPS and ROS levels. IgA can bind to oxLDL and prevents its uptake by MFs and supports MF activation. Unexpectedly, IgA deficiency reduces atherosclerotic plaque burden. Taken together this data shows that IgA may play a complex role in SF accelerated atherosclerosis by supporting gut health and modulating myeloid cell activation.