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Raybuck AL, Lee K, Cho SH, Li J, Thomas JW, Boothby MR. mTORC1 as a cell-intrinsic rheostat that shapes development, preimmune repertoire, and function of B lymphocytes. FASEB J 2019; 33:13202-13215. [PMID: 31533002 PMCID: PMC6894075 DOI: 10.1096/fj.201900069r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 08/19/2019] [Indexed: 11/11/2022]
Abstract
Ample evidence indicates that nutrient concentrations in extracellular milieux affect signaling mediated by environmental sensor proteins. For instance, the mechanistic target of rapamycin (mTOR) is reduced during protein malnutrition and is known to be modulated by concentrations of several amino acids when in a multiprotein signaling complex that contains regulatory-associated protein of mTOR. We hypothesized that a partial decrease in mTOR complex 1 (mTORC1) activity intrinsic to B-lineage cells would perturb lymphocyte development or function, or both. We show that a cell-intrinsic decrease in mTORC1 activity impacted developmental progression, antigen receptor repertoire, and function along the B lineage. Thus, preimmune repertoires of B-lineage cells were altered in the marrow and periphery in a genetic model of regulatory-associated protein of mTOR haplo-insufficiency. An additional role for mTORC1 was revealed when a B-cell antigen receptor transgene was found to circumvent the abnormal B-cell development: haploinsufficient B cells were profoundly impaired in responses to antigen in vivo. Collectively, our findings indicate that mTORC1 serves as a rheostat that shapes differentiation along the B lineage, the preimmune repertoire, and antigen-driven selection of mature B cells. The findings also reveal a range in the impact of this nutrient sensor on activity-response relationships for distinct endpoints.-Raybuck, A. L., Lee, K., Cho, S. H., Li, J., Thomas, J. W., Boothby, M. R. mTORC1 as a cell-intrinsic rheostat that shapes development, preimmune repertoire, and function of B lymphocytes.
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Affiliation(s)
- Ariel L. Raybuck
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Keunwook Lee
- Department of Biomedical Science, Hallym University, Chuncheon, Gangwon-do, South Korea
| | - Sung Hoon Cho
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation (VI4), Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Jingxin Li
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - James W. Thomas
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Mark R. Boothby
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation (VI4), Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
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Briet F, Jeejeebhoy KN. Effect of hypoenergetic feeding and refeeding on muscle and mononuclear cell activities of mitochondrial complexes I--IV in enterally fed rats. Am J Clin Nutr 2001; 73:975-83. [PMID: 11333853 DOI: 10.1093/ajcn/73.5.975] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Previous studies suggested that cell energetics are altered by malnutrition. OBJECTIVE We hypothesized that nutritional manipulations influence mitochondrial enzyme activities of the electron transport chain in both skeletal muscle and blood mononuclear cells. DESIGN After a gastrostomy tube was inserted, 44 rats were randomly assigned to 1 of 4 experimental groups: control fed (CF; 364 kJ/d for 7 d), hypoenergetic fed (HF; 92 kJ/d for 7 d), hypoenergetic protein refed (HPR; 92 kJ/d for 7 d and then 129 kJ/d for 1 d), and hypoenergetic glucose refed (HGR; 92 kJ/d for 7 d and then 129 kJ/d for 1 d). The protein and glucose contents of the liquid formulas were different for the HPR and HGR groups. After mitochondria were isolated from the soleus muscle, the activities of complexes I--IV were measured spectrophotometrically. Because of the lack of available tissue, only the activity of complex I was measured in the mononuclear cell extract. RESULTS The recovery of complex activities in the CF and HF groups was not significantly different in the mitochondrial fraction of the soleus muscle. Compared with that in the CF group, the activities of complexes I--III in the mitochondrial fraction of the soleus muscle and the activity of complex I in mononuclear cells were significantly lower in the HF group. The activities of complexes I--III in the mitochondrial fraction of the soleus muscle and the activity of complex I in mononuclear cells were significantly higher in the HPR than in the HF group. The activity of complex IV was generally not affected by nutritional manipulations. CONCLUSION Malnutrition decreases activities of mitochondrial complexes, which are restored by protein but not glucose refeeding.
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Affiliation(s)
- F Briet
- Department of Medicine, University of Toronto, Ontario, Canada
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Konno A, Utsuyama M, Kurashima C, Kasai M, Kimura S, Hirokawa K. Effects of a protein-free diet or food restriction on the immune system of Wistar and Buffalo rats at different ages. Mech Ageing Dev 1993; 72:183-97. [PMID: 8196423 DOI: 10.1016/0047-6374(93)90099-d] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The effects of a protein-free diet or food restriction on the immune system were examined in two rat strains, Wistar and Buffalo, in different age-groups. Unlike Wistar rats, Buffalo rats have an unusually hyperplastic thymus and a large number of peripheral T cells. The protein-free diet (PFD) in rats resulted in marked thymic involution together with a reduction of splenic T cells, both in number and in antibody response to sheep red blood cells. The depressive effect of the PFD on the immune system was more serious in young immature rats than in older rats, but less serious in Buffalo rats having enhanced T cell functions regardless of age. Thymic involution was also accelerated in both strains of rats by feeding them a restricted amount of the control diet containing well-balanced nutrients (food restriction, FR). In the FR experiment, no significant change was observed in immune functions of Wistar rats. A slight reduction was observed in the immune functions of Buffalo rats with FR, but absolute levels were distinctly higher in Buffalo rats than in Wistar rats even after FR. These results suggested (1) that the thymic function is sensitive to protein deficiency; (2) that a well-balanced dietary condition is necessary for immunological maturation in the early stage of life and preservation of immune functions at older age; (3) that animals having higher immune functions are more resistant to malnutrition than ordinary ones.
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Affiliation(s)
- A Konno
- Department of Pathology, Tokyo Metropolitan Institute of Gerontology, Japan
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Tetzlaff CL, Carlomagno MA, McMurray DN. Reduced dietary protein content suppresses infection with Babesia microti. Med Microbiol Immunol 1988; 177:305-15. [PMID: 3216813 DOI: 10.1007/bf02389902] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The influence of acute dietary protein restriction on the development of Babesia microti infection in the mouse model was investigated. Female mice consuming a diet either devoid of protein or adequate with respect to protein were infected with B. microti-parasitized erythrocytes and sacrificed 7 days later. Absence of dietary protein resulted in a delay in the onset of infection and a significantly reduced peak parasitemia. Non-specific antibody responses to heterologous erythrocytes and specific anti-babesial antibody titers were impaired in mice consuming the protein-free diets, suggesting that the enhanced resistance to experimental babesiosis observed in protein-malnourished mice is not an antibody-mediated phenomenon. In addition, protein-malnourished mice did not demonstrate significantly lower concentrations of the serum complement component, C3, which has been implicated as a participant in the invasion process of host erythrocytes by parasites. Serum C3 levels were significantly reduced in infected mice consuming both diets. The mechanism by which acute protein deprivation protects mice against lethal babesiosis remains to be determined.
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Affiliation(s)
- C L Tetzlaff
- Department of Medical Microbiology and Immunology, College of Medicine, Texas A&M University, College Station 77843
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Menge H, Germer CT, Stössel R, Simes G, Hahn H, Riecken EO. Pathogenesis of the mucosal hyperplasia in self-filling blind loops of rat jejunum: a morphometric study in germ free animals. Gut 1987; 28 Suppl:175-80. [PMID: 3319809 PMCID: PMC1434550 DOI: 10.1136/gut.28.suppl.175] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Bacterial overgrowth and high intraluminal concentrations of deconjugated bile acids are thought to be responsible for mucosal hyperplasia in self-filling blind loops of rat jejunum. To investigate this hypothesis further we have assessed the three dimensional architecture of these loops created in germ free animals without or with di- or mono-association of different bacterial species. It was found that mucosal hyperplasia develops in the absence of any bacterial contamination and that bacterial association does not lead to a more pronounced mucosal proliferation. This implies that other mechanisms provoke this morphological phenomenon. Increased bulk contents in these loops or immunological events are probably the most likely explanation.
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Affiliation(s)
- H Menge
- Klinikum Steglitz, Abteilung für innere Medizin mit Schwerpunkt Gastroenterologie, Freie Universität, Berlin, FRG
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Carlomagno MA, Coghlan LG, McMurray DN. Chronic zinc deficiency and listeriosis in rats: acquired cellular resistance and response to vaccination. Med Microbiol Immunol 1986; 175:271-80. [PMID: 3093828 DOI: 10.1007/bf02126048] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The functional significance of zinc deficiency on primary and secondary host responses to infection with a facultative intracellular pathogen was studied in specific pathogen free rats. Groups of female rats fed either a low zinc or normal diet for 8 or 10 weeks were infected with Listeria monocytogenes five days prior to sacrifice. Zinc-deficient rats demonstrated thymic atrophy, reduced delayed hypersensitivity responses to listeria antigen, and impaired lymphocyte response of spleen cells to phytohemagglutinin, but not to Concanavalin A. Separate groups of zinc-deficient or control rats were vaccinated with viable L. monocytogenes 10 days prior to respiratory challenge. Vaccination resulted in successful control of bacteria in both dietary groups.
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