There is unmet need for additional biomarkers to better select patients with non-small cell lung cancer (NSCLC) that are likely to benefit from immunotherapy in order to improve patient outcomes, reduce patient toxicity, and relieve the growing burden of healthcare costs. In this issue of the JCI, Hayashi and colleagues evaluated soluble forms of the immune checkpoint molecules PD-L1, PD-1, and CTLA-4 in the plasma of patients with advanced NSCLC who had been treated with anti-PD-1/L1 therapy. The findings suggest that these soluble immune-checkpoint factors may provide a complementary biomarker to PD-L1 IHC, although application into the clinic may not be straightforward.

Mutations in genes encoding chromatin modifiers are enriched among mutations causing intellectual disability. The continuing development of the brain postnatally, coupled with the inherent reversibility of chromatin modifications, may afford an opportunity for therapeutic intervention following a genetic diagnosis. Development of treatments requires an understanding of protein function and models of the disease. Here, we provide a mouse model of Say-Barber-Biesecker-Young-Simpson syndrome (SBBYSS) (OMIM 603736) and demonstrate proof-of-principle efficacy of postnatal treatment. SBBYSS results from heterozygous mutations in the KAT6B (MYST4/MORF/QFK) gene and is characterized by intellectual disability and autism-like behaviors. Using human cells carrying SBBYSS-specific KAT6B mutations and Kat6b heterozygous mice (Kat6b+/-), we showed that KAT6B deficiency caused a reduction in histone H3 lysine 9 acetylation. Kat6b+/- mice displayed learning, memory, and social deficits, mirroring SBBYSS individuals. Treatment with a histone deacetylase inhibitor, valproic acid, or an acetyl donor, acetyl-carnitine (ALCAR), elevated histone acetylation levels in the human cells with SBBYSS mutations and in brain and blood cells of Kat6b+/- mice and partially reversed gene expression changes in Kat6b+/- cortical neurons. Both compounds improved sociability in Kat6b+/- mice, and ALCAR treatment restored learning and memory. These data suggest that a subset of SBBYSS individuals may benefit from postnatal therapeutic interventions.

Hypothermia is commonly used to protect donor hearts during transplantation. However, patients transplanted with aged donor hearts still have severe myocardial injury and decreased survival rates, but the underlying mechanism remains unknown. Because aged hearts are not considered suitable for donation, the number of patients awaiting heart transplants is increasing. In this study, we examined whether hypothermic cardioprotection was attenuated in aged donor hearts during transplantation and evaluated potential therapeutic targets. Using a rat heart transplantation model, we found that hypothermic cardioprotection was impaired in aged donor hearts but preserved in young donor hearts. RNA-Seq showed that cold-inducible RNA-binding protein (Cirbp) expression was decreased in aged donor hearts, and these hearts showed severe ferroptosis after transplantation. The young donor hearts from Cirbp-KO rats exhibited attenuated hypothermic cardioprotection, but Cirbp overexpression in aged donor hearts ameliorated hypothermic cardioprotection. Cardiac proteomes revealed that dihydroorotate dehydrogenase (DHODH) expression was significantly decreased in Cirbp-KO donor hearts during transplantation. Consequently, DHODH-mediated ubiquinone reduction was compromised, thereby exacerbating cardiac lipid peroxidation and triggering ferroptosis after transplantation. A cardioplegic solution supplemented with CIRBP agonists improved hypothermic cardioprotection in aged donor hearts, indicating that this method has the potential to broaden the indications for using aged donor hearts in transplantation.

Stromal interaction molecule 1 (STIM1) is a Ca2+ sensor located in the sarcoplasmic reticulum (SR) of skeletal muscle, where it is best known for its role in store-operated Ca2+ entry (SOCE). Genetic syndromes resulting from STIM1 mutations are recognized as a cause of muscle weakness and atrophy. Here, we focused on a gain-of-function mutation that occurs in humans and mice (STIM1+/D84G mice), in which muscles exhibited constitutive SOCE. Unexpectedly, this constitutive SOCE did not affect global Ca2+ transients, SR Ca2+ content, or excitation-contraction coupling (ECC) and was therefore unlikely to underlie the reduced muscle mass and weakness observed in these mice. Instead, we demonstrate that the presence of D84G STIM1 in the nuclear envelope of STIM1+/D84G muscle disrupted nuclear-cytosolic coupling, causing severe derangement in nuclear architecture, DNA damage, and altered lamina A-associated gene expression. Functionally, we found that D84G STIM1 reduced the transfer of Ca2+ from the cytosol to the nucleus in myoblasts, resulting in a reduction of [Ca2+]N. Taken together, we propose a novel role for STIM1 in the nuclear envelope that links Ca2+ signaling to nuclear stability in skeletal muscle.

Glycogen storage disease type 1a (GSD1a) is caused by a congenital deficiency of glucose-6-phosphatase-α (G6Pase-α, encoded by G6PC), which is primarily associated with life-threatening hypoglycemia. Although strict dietary management substantially improves life expectancy, patients still experience intermittent hypoglycemia and develop hepatic complications. Emerging therapies utilizing new modalities such as adeno-associated virus and mRNA with lipid nanoparticles are under development for GSD1a but potentially require complicated glycemic management throughout life. Here, we present an oligonucleotide-based therapy to produce intact G6Pase-α from a pathogenic human variant, G6PC c.648G>T, the most prevalent variant in East Asia causing aberrant splicing of G6PC. DS-4108b, a splice-switching oligonucleotide, was designed to correct this aberrant splicing, especially in liver. We generated a mouse strain with homozygous knockin of this variant that well reflected the pathophysiology of patients with GSD1a. DS-4108b recovered hepatic G6Pase activity through splicing correction and prevented hypoglycemia and various hepatic abnormalities in the mice. Moreover, DS-4108b had long-lasting efficacy of more than 12 weeks in mice that received a single dose and had favorable pharmacokinetics and tolerability in mice and monkeys. These findings together indicate that this oligonucleotide-based therapy could provide a sustainable and curative therapeutic option under easy disease management for GSD1a patients with G6PC c.648G>T.

Long-term sequelae of SARS-CoV-2 infection, referred to as postacute sequelae of COVID-19 (PASC), involve many organs, including the cardiovascular, pulmonary, gastrointestinal, and neurological systems. The basis of PASC is not well understood, but one possible explanation is that the persistence of infectious virus or viral RNA or protein contributes to PASC. This is difficult to assess in patients because human tissue can only usually be assessed for virus or viral products at autopsy or by biopsy. Furthermore, it is not known if some SARS-CoV-2-infected cells survive the acute infection and contribute to long-term sequelae. To address this issue in mice, we used a lineage-tracing approach that allows longitudinal tracking of previously infected cells over several months (1, 2). For this purpose, two recombinant SARS-CoV-2 expressing cre recombinase and Venus fluorescent proteins were engineered using a previously described BAC reverse genetics system (3) (see Supplemental Methods; supplemental material available online with this article; https://doi.org/10.1172/JCI172659DS1). We used these viruses to infect mice expressing a loxP-flanked STOP cassette in the tdTomato gene driven by the Rosa26 promoter (Ai9 mice). Venus and Cre were linked by a 2A peptide (Venus-2a-Cre [V2C]), which after autocleavage resulted in the release of the two proteins (Figure 1A ). V2C was inserted into ancestral SARS-CoV-2 (Wuhan-Hu-1; rSARS2-WH-V2C), which cannot infect laboratory mice but can infect hACE2 transgenic (K18-hACE2) mice (4), and into mouse-adapted SARS2-N501Y MA30 (rSARS2-MA30-V2C), which infects all strains of laboratory mice (5). Venus facilitated identification of acutely infected cells (Figure 1 , B-D), while Cre expression resulted in permanent tdTomato labeling of cells that survive the acute infection (Figure 1, B and C ). rSARS2-WH-V2C and rSARS2-MA30-V2C were as virulent as control viruses in K18-hACE2/Ai9 and Ai9 mice, respectively (Figure 1E and Supplemental Table 1 ). Pathological changes in the lungs (degree of hemorrhage, edema, perivascular infiltrates) were consistent with virulence (Figure 1F and Supplemental Methods). Venus expression was detected between 1 and 5 days after infection (dpi), with peak expression found at 2 dpi. tdTomato cells were detected no earlier than 7 dpi. We detected no cells dually labeled with Venus and tdTomato after infection. We used this system to assess infection of several organs at 2 dpi as well as at 20 and 60 dpi, when infectious virus was no longer detected. For both experimental systems, we analyzed at least 5 mice and 10-20 slides per mouse. We found virus predominantly, if not solely, in the respiratory tract of all mice, including the lungs and nasal cavity (Figure 1G ). Analysis of mice at 2 dpi showed occasional virus-infected cells in the intestine but not in the brain, heart, spleen, or liver (Supplemental Table 2 ). The intestine was the only extrapulmonary organ in which infected cells could be detected at 2 dpi (Figure 1G and Supplemental Table 2 ). In the intestine, a common site of SARS-CoV-2 infection in patients (6), virus was detected in occasional, isolated cells, suggesting that infection was nonproductive or, if productive, spread to adjacent cells was inefficient.

BACKGROUNDProglucagon can be processed to glucagon-like peptide1 (GLP-1) within the islet, but its contribution to islet function in humans remains unknown. We sought to understand whether pancreatic GLP-1 alters islet function in humans and whether this is affected by type 2 diabetes.METHODSWe therefore studied individuals with and without type 2 diabetes on two occasions in random order. On one occasion, exendin 9-39, a competitive antagonist of the GLP-1 Receptor (GLP1R), was infused, while on the other, saline was infused. The tracer dilution technique ([3-3H] glucose) was used to measure glucose turnover during fasting and during a hyperglycemic clamp.RESULTSExendin 9-39 increased fasting glucose concentrations; fasting islet hormone concentrations were unchanged, but inappropriate for the higher fasting glucose observed. In people with type 2 diabetes, fasting glucagon concentrations were markedly elevated and persisted despite hyperglycemia. This impaired suppression of endogenous glucose production by hyperglycemia.CONCLUSIONThese data show that GLP1R blockade impairs islet function, implying that intra-islet GLP1R activation alters islet responses to glucose and does so to a greater degree in people with type 2 diabetes.TRIAL REGISTRATIONThis study was registered at ClinicalTrials.gov NCT04466618.FUNDINGThe study was primarily funded by NIH NIDDK DK126206. AV is supported by DK78646, DK116231 and DK126206. CDM was supported by MIUR (Italian Minister for Education) under the initiative "Departments of Excellence" (Law 232/2016).