bims-imseme Biomed News
on Immunosenescence and T cell metabolism
Issue of 2022‒05‒15
seven papers selected by
Pierpaolo Ginefra
Ludwig Institute for Cancer Research

  1. Nat Aging. 2022 Mar;2(3): 231-242
      Impaired T cell immunity with aging increases mortality from infectious disease. The branching of Asparagine-linked glycans is a critical negative regulator of T cell immunity. Here we show that branching increases with age in females more than males, in naïve more than memory T cells, and in CD4+ more than CD8+ T cells. Female sex hormones and thymic output of naïve T cells (TN) decrease with age, however neither thymectomy nor ovariectomy altered branching. Interleukin-7 (IL-7) signaling was increased in old female more than male mouse TN cells, and triggered increased branching. N-acetylglucosamine, a rate-limiting metabolite for branching, increased with age in humans and synergized with IL-7 to raise branching. Reversing elevated branching rejuvenated T cell function and reduced severity of Salmonella infection in old female mice. These data suggest sex-dimorphic antagonistic pleiotropy, where IL-7 initially benefits immunity through TN maintenance but inhibits TN function by raising branching synergistically with age-dependent increases in N-acetylglucosamine.
    Keywords:  Immunosenescence; N-acetyglucosamine; N-glycan branching; N-glycosylation; T cell, infection; aging; immunity; interleukin-7
  2. FASEB J. 2022 May;36 Suppl 1
      CD4 T cell differentiation to pro-inflammatory and immunosuppressive subsets requires distinct metabolic pathways. Pro-inflammatory CD4 subsets rely on glycolysis, while immunosuppressive (Treg cells) subsets, require functional mitochondria for their differentiation and function. Previous studies have shown that binge alcohol (ethanol, EtOH) administration increased Tbet-expressing (Th1) and decreased FOXP3-expressing (Treg) CD4 T cells in the colons of mice. We tested the hypothesis that EtOH dysregulates normal CD4 T cell differentiation, after stimulation, by impairing mitochondrial homeostasis. Human naïve CD4 T cells were isolated from buffy coats from blood bank donors (N = 6) using MACS sorting. Cells were stimulated using anti-CD3-coated dishes in the presence of anti-CD28 and IL-12, and exposed to EtOH (0 and 50 mM) for 3 days. Mitochondrial content was measured with Mitotracker Deep Red. Gene expression indicative of: autophagosome formation (ATG5, ATG7, ATG13, MAP1LC3B, BECN1, BNIP3L, ULK1), mitophagy (PINK1, PRKN),mitochondrial fusion (MFN1, MFN2, OPA1), mitochondrial fission (MFFand FIS1), and mitochondrial biogenesis (PPARC1A, PPARC1B, TFAM) was determined by RT2 profiler arrays. EtOH-treated CD4 T cells had increased mitochondrial content (p = 0.0008) with Tregs accounting for the greatest increase in mitochondria (p = 0.04). There was a main effect of stimulation (p < 0.05) to increase ATG5, ATG13, MAP1LC3B, BECN1, BNIP3L, ULK1, MFF, PPARC1B, and TFAM, and a main effect of EtOH (p < 0.05) to increase PINK1 and decrease ATG7. There was a main effect of both EtOH and stimulation (p < 0.05) to increase MFN2, and OPA1.Taken together, these results indicate that EtOH increases mitochondrial content in Treg cells and dysregulates mitochondrial gene expression important for mitochondrial repair and mitophagy. These EtOH-mediated alterations in gene expression could result in an inability of CD4 T cells to maintain mitochondrial homeostasis and remove damaged mitochondria that is required for normal differentiation and function of anti-inflammatory Treg cells.
  3. Cells. 2022 Apr 25. pii: 1454. [Epub ahead of print]11(9):
      The manufacture of efficacious CAR T cells represents a major challenge in cellular therapy. An important aspect of their quality concerns energy production and consumption, known as metabolism. T cells tend to adopt diverse metabolic profiles depending on their differentiation state and their stimulation level. It is therefore expected that the introduction of a synthetic molecule such as CAR, activating endogenous signaling pathways, will affect metabolism. In addition, upon patient treatment, the tumor microenvironment might influence the CAR T cell metabolism by compromising the energy resources. The access to novel technology with higher throughput and reduced cost has led to an increased interest in studying metabolism. Indeed, methods to quantify glycolysis and mitochondrial respiration have been available for decades but were rarely applied in the context of CAR T cell therapy before the release of the Seahorse XF apparatus. The present review will focus on the use of this instrument in the context of studies describing the impact of CAR on T cell metabolism and the strategies to render of CAR T cells more metabolically fit.
    Keywords:  CAR; T cells; chimeric antigen receptor; metabolism; tonic signaling
  4. FASEB J. 2022 May;36 Suppl 1
      Previously we have found that T cells contribute to age-related large artery stiffness and impairments in endothelium dependent dilation. The thymus is an immunological organ that is responsible for the generation of new naïve T cells. A hallmark of T cell aging is a phenotypic shift from a naïve to a memory phenotype. In this study, we sought to determine 1) whether early life thymectomy at 3wks of age would induce an aged (memory) T cell phenotype and 2) that these alterations in T cell phenotype will result in arterial dysfunction in otherwise middle-aged mice. This study was approved by the institutional animal care and use committee at the University of Texas Arlington. Male C57BL6 mice underwent thymectomy (thymex; n=7-17) at 3wks of age or left with their thymus intact (control; n=7-17). At 9 months of age, doppler pulse wave velocity was used to assess large artery stiffness and following euthanasia, splenic, aortic, and mesenteric T cell phenotype was assessed using flow-cytometry and T cell proliferation was assessed in vitro. To assess endothelium-dependent dilation, second order mesenteric arteries were gently cleared of adipose and connective tissue and cannulated on the stage of a pressure myograph. Group differences were assessed by independent samples t-test or repeated measures ANOVA and Bonferroni post-hoc test. Data are presented as mean±SEM. Pulse wave velocity indicated that the thymex mice had significantly higher aortic stiffness (304.1±12.2 cm/s) compared to controls (270.2±13.8 cm/s; p=0.05). Flow cytometry results (expressed as thymex vs control) demonstrate that the spleen (CD4:79.4±5, 55.4±7.6 %memory; p=0.01; CD8: 72.2±2.4, 44.8±6.7 %memory; p=0.0008), aorta (CD4: 63.4±5.2, 34.6±6.5 %memory; p=0.001; CD8: 64.5±4, 30.6±2.4 %memory; p=<0.0001), and mesentery (CD4: 68.3±5.6,44.2±6.5 %memory; p=0.006; CD8: 47.1±6.1, 31.6±5.7 %memory; p=0.04) all exhibited a greater proportion (relative to all immune cells) of memory CD4+ (helper T) and CD8+ (cytotoxic T) T cells in the thymex animals compared to controls which is consistent with chronological aging. The after 96 hours in culture cell proliferation was blunted in both the CD4+ (45142±7214.4 cells) and CD8+ (50285.7±7870.7 cells) cells from the thymex mice compared to the control mice (CD4: 75428.6±3652.5 cells; p=0.0023; CD8: 81142.9±2756.9 cells; p=0.0025), which is also consistent with an aged T cell phenotype. Finally, the thymex mice exhibited significantly blunted endothelium dependent dilation in response to 10-4 --M acetylcholine (46.1±6.99 % dilation) compared to controls (71.5±5%; p=0.005). Assessing dilation in the presence of L-NAME revealed a significant blunting of nitric oxide bioavailability in arteries from thymex mice (33.91±8.2% NO dependent dilation) compared to controls (55.7±8.5%; p=0.05). In conclusion, these results indicate that early-life thymectomy results in T cell aging as well as arterial dysfunction in otherwise middle-aged mice. These observations suggest that aged T cells alone can drive age-related dysfunction independent of the age of the arteries.
  5. FASEB J. 2022 May;36 Suppl 1
      NAD+ is an essential coenzyme found in all living cells. NAD+ concentrations decline during aging, but whether this reflects impaired production or accelerated consumption remains unclear. Here we employed isotope tracing and mass spectrometry to probe NAD+ metabolism across tissues in aged mice. In 25-month-old mice, we observe modest tissue NAD+ depletion (median decrease ~30%) without significant changes in circulating NAD+ precursors. Isotope tracing showed unimpaired synthesis of circulating nicotinamide from tryptophan, and maintained flux of circulating nicotinamide into tissue NAD+ pools. Although absolute NAD+ biosynthetic flux was maintained in most tissues of aged mice, fractional tissue NAD+ labeling from infused labeled nicotinamide was modestly accelerated, consistent with increased activity of NAD+ consuming enzymes. Long-term calorie restriction partially mitigated age-associated NAD+ decline despite decreasing NAD+ synthesis, suggesting that calorie restriction reduces NAD+ consumption. Acute inflammatory stress induced by LPS decreased NAD+ by impairing synthesis in both young and aged mice. Thus, age-related decline in NAD+ is relatively subtle and driven by increased NAD+ consumer activity rather than impaired production.
  6. Science. 2022 May 12. eabo0510
      Single-cell genomics studies have decoded the immune-cell composition of several human prenatal organs but were limited in understanding the developing immune system as a distributed network across tissues. We profiled nine prenatal tissues combining single-cell RNA sequencing, antigen-receptor sequencing, and spatial transcriptomics to reconstruct the developing human immune system. This revealed the late acquisition of immune effector functions by myeloid and lymphoid cell subsets and the maturation of monocytes and T cells prior to peripheral tissue seeding. Moreover, we uncovered system-wide blood and immune cell development beyond primary hematopoietic organs, characterized human prenatal B1 cells, and shed light on the origin of unconventional T cells. Our atlas provides both valuable data resources and biological insights that will facilitate cell engineering, regenerative medicine, and disease understanding.