The aorta and the large conductive arteries are immunoprivileged tissues and are protected against inflammatory attack. A breakdown of the immunoprivilege leads to autoimmune vasculitis, such as giant cell arteritis (GCA), in which CD8+ T regulatory (Treg) cells fail to contain CD4+ T cells and macrophages, resulting in the formation of tissue-destructive granulomatous lesions. Here, we report that the molecular defect of malfunctioning CD8+ Treg cells lies in aberrant NOTCH4 signaling that deviates endosomal trafficking and minimizes exosome production. By transcriptionally controlling the profile of RAB GTPases, NOTCH4 signaling restricted membrane translocation and vesicular secretion of the enzyme NADPH oxidase 2 (NOX2). Specifically, NOTCH4hiCD8+ Treg cells increased RAB5A and RAB11A expression and suppressed RAB7A, culminating in the accumulation of early and recycling endosomes and trapping of NOX2 in an intracellular, non-secretory compartment. RAB7AloCD8+ Treg cells failed in the surface translocation and the exosomal release of NOX2. NOTCH4hi RAB5Ahi RAB7Alo RAB11Ahi CD8+ Treg cells left adaptive immunity unopposed, enabling a breakdown in tissue tolerance and aggressive vessel wall inflammation. Inhibiting NOTCH4 signaling corrected the defect and protected arteries from inflammatory insult. The study implicates NOTCH4-dependent transcriptional control of RAB proteins and intracellular vesicle trafficking in autoimmune disease and in vascular inflammation.
View details for DOI 10.1172/JCI136042
View details for PubMedID 32960812
Over the past decades, tumor-resident immune cells have been extensively studied to dissect their biological functions and clinical roles. Tumor-infiltrating CD8+ T cells, because of their cytotoxic and killing ability, have been under the spotlight for a long time, whereas CD4+ T cells are considered just a supporting actor in the field of cancer immunotherapy. Until recently, accumulating evidence has demonstrated the ability of CD4+ T cells in eradicating solid tumors, and their functions in mediating antitumor immunity have been investigated in various orientations. In this review, we highlight the pivotal role of CD4+ T cells in eliciting vigorous antitumor immune responses, summarize key signaling axes and molecular networks behind these antitumor functions, and also propose possible targets and promising strategies which might translate into more efficient immunotherapies against human cancers.
View details for DOI 10.1016/j.bbcan.2020.188439
View details for PubMedID 32980465
Rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) are relatively common autoimmune diseases, often considered prototypic examples for how protective immunity switches to destructive immunity. The autoantigens recognized in RA and SLE are distinct, clinical manifestations are partially overlapping. A shared feature is the propensity of the adaptive immune system to respond inappropriately, with T cell hyper-responsiveness a pinnacle pathogenic defect. Upon antigen recognition, T cells mobilize a multi-pranged metabolic program, enabling them to massively expand and turn into highly mobile effector cells. Current evidence supports that T cells from patients with RA or SLE adopt metabolic programs different from healthy T cells, in line with the concept that autoimmune effector functions rely on specified pathways of energy sensing, energy generation and energy utilization. Due to misrouting of the energy sensor AMPK, RA T cells have a defect in balancing catabolic and anabolic processes and deviate towards a cell-building program. They supply biosynthetic precursors by shunting glucose away from glycolytic breakdown towards the pentose phosphate pathway and upregulate lipogenesis, enabling cellular motility and tissue invasiveness. Conversely, T cells from SLE patients are committed to high glycolytic flux, overusing the mitochondrial machinery and imposing oxidative stress. Typically, disease-relevant effector functions in SLE are associated with inappropriate activation of the key metabolic regulator mTORC1. Taken together, disease-specific metabolic signatures in RA and SLE represent vulnerabilities that are therapeutically targetable to suppress pathogenic immune responses.
View details for DOI 10.20900/immunometab20200017
View details for PubMedID 32477606
Autoimmune T cells in rheumatoid arthritis (RA) have a defect in mitochondrial oxygen consumption and ATP production. Here, we identified suppression of the GDP-forming ? subunit of succinate-CoA ligase (SUCLG2) as an underlying abnormality. SUCLG2-deficient T cells reverted the tricarboxylic acid (TCA) cycle from the oxidative to the reductive direction, accumulated ?-ketoglutarate, citrate, and acetyl-CoA (AcCoA), and differentiated into pro-inflammatory effector cells. In AcCoAhi RA T cells, tubulin acetylation stabilized the microtubule cytoskeleton and positioned mitochondria in a perinuclear location, resulting in cellular polarization, uropod formation, T cell migration, and tissue invasion. In the tissue, SUCLG2-deficient T cells functioned as cytokine-producing effector cells and were hyperinflammatory, a defect correctable by replenishing the enzyme. Preventing T cell tubulin acetylation by tubulin acetyltransferase knockdown was sufficient to inhibit synovitis. These data link mitochondrial failure and AcCoA oversupply to autoimmune tissue inflammation.
View details for DOI 10.1016/j.cmet.2020.10.025
View details for PubMedID 33264602
View details for Web of Science ID 000507466903359
View details for Web of Science ID 000507466905047
In the autoimmune disease rheumatoid arthritis (RA), CD4+ Tcells promote pro-inflammatory effector functions by shunting glucose away from glycolysis and ATP production. Underlying mechanisms remain unknown, and here we implicate the DNA repair nuclease MRE11A in the cells' bioenergetic failure. MRE11A deficiency in RA Tcells disrupted mitochondrial oxygen consumption and suppressed ATP generation. Also, MRE11A loss of function caused leakage of mitochondrial DNA (mtDNA) into the cytosol, triggering inflammasome assembly, caspase-1 activation, and pyroptotic cell death. Caspase-1 activation was frequent in lymph-node-residing Tcells in RA patients. Invivo, pharmacologic and genetic inhibition of MRE11A resulted in tissuedeposition of mtDNA, caspase-1 proteolysis, andaggressive tissue inflammation. Conversely, MRE11A overexpression restored mitochondrial fitness and shielded tissue from inflammatory attack. Thus, the nuclease MRE11A regulates a mitochondrial protection program, and MRE11A deficiency leads to DNA repair defects, energy production, and failure and loss of tissue homeostasis.
View details for DOI 10.1016/j.cmet.2019.06.016
View details for PubMedID 31327667
N-myristoyltransferase (NMT) attaches the fatty acid myristate to the N-terminal glycine of proteins to sort them into soluble and membrane-bound fractions. Function of the energy-sensing AMP-activated protein kinase, AMPK, is myristoylation dependent. In rheumatoid arthritis (RA), pathogenic T cells shift glucose away from adenosine tri-phosphate production toward synthetic and proliferative programs, promoting proliferation, cytokine production, and tissue invasion. We found that RA T cells had a defect in NMT1 function, which prevented AMPK activation and enabled unopposed mTORC1 signaling. Lack of the myristate lipid tail disrupted the lysosomal translocation and activation of AMPK. Instead, myristoylation-incompetent RA T cells hyperactivated the mTORC1 pathway and differentiated into pro-inflammatory TH1 and TH17 helper T cells. In vivo, NMT1 loss caused robust synovial tissue inflammation, whereas forced NMT1 overexpression rescued AMPK activation and suppressed synovitis. Thus, NMT1 has tissue-protective functions by facilitating lysosomal recruitment of AMPK and dampening mTORC1 signaling.
View details for PubMedID 30718913
Rheumatoid arthritis (RA) is a prototypic autoimmune disease manifesting as chronic inflammation of the synovium and leading to acceleration of cardiovascular disease and shortening of life expectancy. The basic defect causing autoimmunity has remained elusive, but recent insights have challenged the notion that autoantigen is the core driver.Emerging data have added metabolic cues involved in the proper maintenance and activation of immune cells as pathogenic regulators. Specifically, studies have unveiled metabolic pathways that enforce T cell fate decisions promoting tissue inflammation; including T cell tissue invasiveness, T cell cytokine release, T cell-dependent macrophage activation and inflammatory T cell death. At the center of the metabolic abnormalities lies the mitochondria, which is consistently underperforming in RA T cells. The mitochondrial defect results at least partially from insufficient DNA repair and leads to lipid droplet accumulation, formation of invasive membrane ruffles, inflammasome activation and pyroptotic T cell death.T cells in patients with RA, even naïve T cells never having been involved in inflammatory lesions, have a unique metabolic signature and the changes in intracellular metabolites drive pathogenic T cell behavior. Recognizing the role of metabolic signals in cell fate decisions opens the possibility for immunomodulation long before the end stage synovial inflammation encountered in clinical practice.
View details for DOI 10.1097/BOR.0000000000000683
View details for PubMedID 31895885
Protein nitrosylation is a ubiquitous post-translational modification in almost all biological systems. However, its function on stem cell biology is so far incompletely understood. Here, we demonstrated that peroxiredoxin 2 (Prdx-2) nitrosylation was involved in cardiomyocyte differentiation of mouse embryonic stem (ES) cells induced by S-nitrosoglutathione (GSNO). We found that temporary GSNO exposure could promote ES cell-derived cardiomyogenesis. Using a stable isotope labeling by amino acids in cell culture (SILAC)-based proteomics approach, coupled with biotin switch technique, a total of 104 nitrosylated proteins were identified. Specifically, one of the antioxidant enzymes, Prdx-2, was abundantly nitrosylated and temporarily reduced in antioxidant activity, causing transient endogenous hydrogen peroxide (H2O2) accumulation and subsequent X-box binding protein-1s/phosphatidylinositol 3-kinase pathway activation. The present study reveals the mechanism in which GSNO favors cardiomyocyte differentiation. Prdx-2 nitrosylation could be a potent strategy to affect the pluripotent stem cell-derived cardiomyogenesis.
View details for DOI 10.1016/j.freeradbiomed.2016.05.025
View details for PubMedID 27261193
Aristolochic acid I (AAI) existing in plant drugs from Aristolochia species is an environmental human carcinogen associated with urothelial cancer. Although gene association network analysis demonstrated gene expression profile changes in the liver of human TP53 knock-in mice after acute AAI exposure, to date, whether AAI causes hepatic tumorigenesis is still not confirmed. Here, we show that hepatic premalignant alterations appeared in canines after a 10-day AAI oral administration (3 mg/kg/day). We observed c-Myc oncoprotein and oncofetal RNA-binding protein Lin28B overexpressions accompanied by cancer progenitor-like cell formation in the liver by AAI exposure. Meanwhile, we found that forkhead box O1 (FOXO1) was robustly phosphorylated, thereby shuttling into the cytoplasm of hepatocytes. Furthermore, utilizing microarray and qRT-PCR analysis, we confirmed that microRNA expression significantly dysregulated in the liver treated with AAI. Among them, we particularly focused on the members in let-7 miRNAs and miR-23a clusters, the downstream of c-Myc and IL6 receptor (IL6R) signaling pathway linking the premalignant alteration. Strikingly, when IL6 was added in vitro, IL6R/NF-?B signaling activation contributed to the increase of FOXO1 phosphorylation by the let-7b inhibitor. Therefore, it highlights the new insight into the interplay of the network in hepatic tumorigenesis by AAI exposure, and also suggests that anti-premalignant therapy may be crucial for preventing AAI-induced hepatocarcinogenesis.
View details for DOI 10.1158/1940-6207.CAPR-15-0339
View details for Web of Science ID 000373446500007
View details for PubMedID 26851235
It is well accepted that junctophilin (JPHs) isoforms act as a physical bridge linking plasma membrane and endoplasmic reticulum (ER) for channel crosstalk in excitable cells. Our purpose is to investigate whether JPHs are involved in the proper communication between Ca(2+) influx and subsequent Ca(2+) amplification in pancreatic beta cells, thereby participating in regulating insulin secretion. The expression of JPH isoforms was examined in human and mouse pancreatic tissues, and JPH3 expression was found in both the beta cells. In mice, knockdown of Jph3 (si-Jph3) in islets decreased glucose-stimulated insulin secretion (GSIS) accompanied by mitochondrial function impairment. Si-Jph3 lowered the insulin secretory response to Ca(2+) signaling in the presence of glucose, and reduced [Ca(2+)]c transient amplitude triggered by caffeine. Si-Jph3 also attenuated mitofusin 2 expression, thereby disturbing the spatial organization of ER-mitochondria contact in islets. These results suggest that the regulation of GSIS by the KATP channel-independent pathways is partly impaired due to decrease of JPH3 expression in mouse islets. JPH3 also binds to type 2 ryanodine receptors (RyR2) in mouse and human pancreatic tissues, which might contribute to Ca(2+) release amplification in GSIS. This study demonstrates some previously unrecognized findings in pancreatic tissues: (1) JPH3 expresses in mouse and human beta cells; (2) si-Jph3 in mouse primary islets impairs GSIS in vitro; (3) impairment in GSIS in si-Jph3 islets is due to changes in RyR2-[Ca(2+)]c transient amplitude and ER-mitochondria contact.
View details for DOI 10.1038/cddis.2016.179
View details for PubMedID 27336719
The in vitro predictive evaluation of chemical carcinogenicity based on hepatic premalignance has so far not been established. Here, we report a novel approach to investigate the premalignant events triggered by human carcinogen aristolochic acid I (AAI) in the liver-like tissue derived from mouse embryonic stem cells. By AAI exposure, the liver-like tissue exhibited the paracrine interleukin-6 phenotypic characteristics. Hepatocytes expressed STAT3/p-STAT3, c-Myc and Lin28B in parallel. Some of them displayed the dedifferentiation characteristics, such as full of ?-fetoprotein granules, increase in size, and nucleocytoplasmic shuttle of Oct4. When these cells were injected into mice, the xenografts mostly displayed the uniform area of hepatic-like tissue with malignant nuclei. The hepatic malignant markers, ?-fetoprotein, cytokeratin 7 and cytokeratin 19, were co-expressed in albumin-positive areas, respectively. In conclusion, we established an approach to predict the hepatic premalignance triggered by carcinogen AAI. This premalignant assay system might aid to evaluate the effects of potential carcinogens in liver, and probably to screen the protecting against hepatocarcinogenic efficacy of pharmaceuticals in vitro.
View details for DOI 10.18632/oncotarget.12424
View details for PubMedID 27713163
Latest information on COVID-19
Stanford Medicine is closely monitoring the outbreak of novel coronavirus (COVID-19). A new page is dedicated to the latest information and developments about COVID-19.
Racism and discrimination are direct affronts to Stanford Medicine?s values. Read our leaders? pledge on racial equity.
A leader in the biomedical revolution, Stanford Medicine has a long tradition of leadership in pioneering research, creative teaching protocols and effective clinical therapies.
An at-home COVID-19 test, designed by Stanford researchers to be easy to use and provide results within 30 minutes, will be the focus of a study funded by the Stanford Medicine Catalyst Program.
Our scientists have launched dozens of research projects as part of the global response to COVID-19. Some aim to prevent, diagnose and treat the disease; others aim to understand how it spreads and how people?s immune systems respond to it.
A subtype of a popular antibiotic could pose a smaller risk of hearing loss yet still be powerful at fighting off bacterial infections.
Lab scientists at Stanford Medicine are processing thousands of samples a day, fighting the coronavirus pandemic behind the scenes.
A look at Stanford Medicine?s response to the new coronavirus, as well as outside perspectives on the pandemic.
Latest information on COVID-19
Stanford Medicine is closely monitoring the outbreak of novel coronavirus (COVID-19). A new page is dedicated to the latest information and developments about COVID-19.
Racism and discrimination are direct affronts to Stanford Medicine?s values. Read our leaders? pledge on racial equity.
A leader in the biomedical revolution, Stanford Medicine has a long tradition of leadership in pioneering research, creative teaching protocols and effective clinical therapies.
An at-home COVID-19 test, designed by Stanford researchers to be easy to use and provide results within 30 minutes, will be the focus of a study funded by the Stanford Medicine Catalyst Program.
Our scientists have launched dozens of research projects as part of the global response to COVID-19. Some aim to prevent, diagnose and treat the disease; others aim to understand how it spreads and how people?s immune systems respond to it.
A subtype of a popular antibiotic could pose a smaller risk of hearing loss yet still be powerful at fighting off bacterial infections.
Lab scientists at Stanford Medicine are processing thousands of samples a day, fighting the coronavirus pandemic behind the scenes.
A look at Stanford Medicine?s response to the new coronavirus, as well as outside perspectives on the pandemic.
