Selected Grantee Publications
Giardia Hinders Growth by Disrupting Nutrient Metabolism Independent of Inflammatory Enteropathy
Giallourou et al., Nature Communications. 2023.
https://www.nature.com/articles/s41467-023-38363-2
Giardia lamblia is one of the most common intestinal pathogens among children in low- and middle-income countries. Investigators performed translational investigations using the Malnutrition and Enteric Diseases (MAL-ED) male and female cohort, as well as mice of both sexes, to identify mechanistic pathways that might explain Giardia-induced effects on early childhood growth. They identified signatures in the urinary metabolome of young children, suggesting that host growth restriction during infection is mediated by dysregulated amino acid metabolism. Supported by ORIP (P40OD010995), NIAID, and NIDDK.
CD8+ T Cells Promote HIV Latency by Remodeling CD4+ T Cell Metabolism to Enhance Their Survival, Quiescence, and Stemness
Mutascio et al., Immunity. 2023.
https://www.doi.org/10.1016/j.immuni.2023.03.010
An HIV reservoir persists following antiretroviral therapy, representing the main barrier to an HIV cure. Using a validated in vitro model, investigators explored the mechanism by which CD8+ T cells promote HIV latency and inhibit latency reversal in HIV-infected CD4+ T cells. They reported that CD8+ T cells favor the establishment of HIV latency by modulating metabolic, stemness, and survival pathways that correlate with the downregulation of HIV expression and promote HIV latency. In future studies, comparative analyses may provide insight into common molecular mechanisms in the silencing of HIV expression by CD8+ T cells and macrophages, which can be applied to new intervention strategies that target the HIV reservoir. Supported by ORIP (P51OD011132, S10OD026799), NIAID, NIDDK, NIDA, NHLBI, and NINDS.
Hematopoietic Stem Cells Preferentially Traffic Misfolded Proteins to Aggresomes and Depend on Aggrephagy to Maintain Protein Homeostasis
Chua et al., Cell Stem Cell. 2023.
https://pubmed.ncbi.nlm.nih.gov/36948186/
Investigators studied the mechanism of hematopoietic stem cells (HSCs) being dependent on managing proteostasis. Their findings demonstrated that HSCs preferentially depend on aggrephagy, a form of autophagy, to maintain proteostasis. When aggrephagy is disabled, HSCs compensate by increasing proteasome activity, but proteostasis is ultimately disrupted as protein aggregates accumulate and HSC function is impaired. The investigators also showed that Bag3 deficiency blunts aggresome formation in HSCs, resulting in protein aggregate accumulation, myeloid-biased differentiation, and diminished self-renewal activity, thus demonstrating Bag3 as a regulator of HSC proteostasis. HSC aging is associated with loss of aggresomes and reduced autophagic flux. Protein degradation pathways are thus configured in young-adult HSCs to preserve proteostasis and fitness but become dysregulated during aging. Supported by ORIP (S10OD032316, S10OD021831), NCI, and NIDDK.
A Class of Anti-Inflammatory Lipids Decrease with Aging in the Central Nervous System
Tan et al., Nature Chemical Biology. 2023.
https://doi.org/10.1038/s41589-022-01165-6
Impaired lipid metabolism in the brain has been implicated in neurological disorders of aging, yet analyses of lipid pathway changes with age have been lacking. The researchers examined the brain lipidome of mice of both sexes across the lifespan using untargeted lipidomics. They found that 3-sulfogalactosyl diacylglycerols (SGDGs) are structural components of myelin and decline with age in the central nervous system. The researchers discovered that SGDGs also are present in male human and rhesus macaque brains, demonstrating their evolutionary conservation in mammals. The investigators showed that SGDGs possess anti-inflammatory activity, suggesting a potential role for this lipid class in age-related neurodegenerative diseases. Supported by ORIP (P51OD011092), NIA, NCI, NIDDK, and NINDS.
Prolonged Experimental CD4+ T-Cell Depletion Does Not Cause Disease Progression In SIV-Infected African Green Monkeys
Le Hingrat et al., Nature Communications. 2023.
https://www.nature.com/articles/s41467-023-36379-2
Chronically simian immunodeficiency virus (SIV)–infected African green monkeys (AGMs) partially recover mucosal CD4+ T cells, maintain gut integrity, and do not progress to AIDS. Investigators assessed the impact of prolonged, antibody-mediated CD4+ T cell depletion on gut integrity and natural history of SIV infection in AGMs. All circulating CD4+ T cells and more than 90% of mucosal CD4+ T cells were depleted. Plasma viral loads and cell-associated viral RNA in tissues were lower in CD4+-cell-depleted animals. CD4+-cell-depleted AGMs maintained gut integrity, controlled immune activation, and did not progress to AIDS. Therefore, CD4+ T cell depletion is not a determinant of SIV-related gut dysfunction when gastrointestinal tract epithelial damage and inflammation are absent, suggesting that disease progression and resistance to AIDS are independent of CD4+ T cell restoration in SIV-infected AGMs. Supported by ORIP (P40OD028116), NIAID, NIDDK, and NHLBI.
CD8+ Lymphocytes Do Not Impact SIV Reservoir Establishment under ART
Statzu et al., Nature Microbiology. 2023.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9894752/
The HIV-1 latent reservoir has been shown to persist following antiretroviral therapy (ART), but the mechanisms underlying the establishment and maintenance of the reservoir are not fully understood. Using rhesus macaques of both sexes, investigators examined the effects of CD8+ T cells on formation of the latent reservoir with simian immunodeficiency virus (SIV) infection. They found that CD8+ T cell depletion resulted in slower decline of viremia but did not change the frequency of infected CD4+ T cells in the blood or lymph nodes. Additionally, the size of the persistent reservoir was unchanged. These findings suggest that the viral reservoir is established largely independent of SIV-specific cytotoxic T lymphocyte control. Supported by ORIP (P51OD011132), NIAID, NCI, NIDDK, NIDA, NHLBI, and NINDS.
Human Hematopoietic Stem Cell Engrafted IL-15 Transgenic NSG Mice Support Robust NK Cell Responses and Sustained HIV-1 Infection
Abeynaike et al., Viruses. 2023.
https://www.mdpi.com/1999-4915/15/2/365
A major obstacle to human natural killer (NK) cell reconstitution is the lack of human interleukin‑15 (IL-15) signaling, as murine IL-15 is a poor stimulator of the human IL-15 receptor. Researchers show that immunodeficient NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice expressing a transgene encoding human IL-15 (NSG-Tg(IL-15)) have physiological levels of human IL-15 and support long-term engraftment of human NK cells when transplanted with human umbilical cord blood–derived hematopoietic stem cells (HSCs). These mice demonstrate robust and long-term reconstitution with human immune cells but do not develop graft-versus-host disease, allowing long-term studies of human NK cells. The HSC-engrafted mice can sustain HIV-1 infection, resulting in human NK cell responses. This work provides a robust novel model to study NK cell responses to HIV-1. Supported by ORIP (R24OD026440), NIAID, NCI, and NIDDK.
Elevated Transferrin Receptor Impairs T Cell Metabolism and Function in Systemic Lupus Erythematosus
Voss et al., Science Immunol. 2023.
https://www.science.org/doi/10.1126/sciimmunol.abq0178
Systemic lupus erythematosus (SLE) is an autoimmune disease in which dysfunctional T cells exhibit abnormalities in metabolism. Investigators performed a CRISPR screen to examine mechanisms associated with the role of excess iron in dysfunctional T cells. The transferrin receptor (CD71) was identified as differentially critical for Type 1 T helper cells and inhibitory for induced regulatory T cells. Activated T cells induced CD71 and iron uptake, which was exaggerated in SLE-prone T cells. Disease severity correlated with CD71 expression in cells from male and female patients with SLE, and blocking CD71 in vitro enhanced interleukin 10 secretion. These findings suggest that T cell iron uptake via CD71 contributes to T cell dysfunction and can be targeted to limit SLE-associated pathology. Supported by ORIP (S10OD030264), NIAID, NCI, and NIDDK.
Gut Microbiome Dysbiosis in Antibiotic-Treated COVID-19 Patients Is Associated with Microbial Translocation and Bacteremia
Bernard-Raichon et al., Nature Communications. 2022.
https://www.doi.org/10.1038/s41467-022-33395-6
The investigators demonstrated that SARS-CoV-2 infection induced gut microbiome dysbiosis in male mice. Samples collected from human COVID-19 patients of both sexes also revealed substantial gut microbiome dysbiosis. Analysis of blood culture results testing for secondary microbial bloodstream infections with paired microbiome data indicated that bacteria might translocate from the gut into the systemic circulation of COVID-19 patients. These results were consistent with a direct role for gut microbiome dysbiosis in enabling dangerous secondary infections during COVID-19. Supported by ORIP (S10OD021747), NCI, NHLBI, NIAID, and NIDDK.
Orthotopic Transplantation of the Full-Length Porcine Intestine After Normothermic Machine Perfusion
Abraham et al., Transplantation Direct. 2022.
https://www.doi.org/10.1097/TXD.0000000000001390
Successful intestinal transplantation currently is hindered by graft injury that occurs during procurement and storage, which contributes to postoperative sepsis and allograft rejection. Improved graft preservation could expand transplantable graft numbers and enhance post-transplant outcomes. Superior transplant outcomes recently have been demonstrated in clinical trials using machine perfusion to preserve the liver. The investigators report the development and optimization of machine perfusion preservation of small intestine and successful transplantation of intestinal allografts in a porcine model. Supported by ORIP (K01OD019911), NIAID, and NIDDK.