Commentary
Abstract
Patients with type 2 diabetes (T2D) fail to secrete insulin in response to increased glucose levels that occur with eating. Glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are two incretins secreted from gastrointestinal cells that amplify insulin secretion when glucose is high. In this issue of the JCI, Oduori et al. explore the role of ATP-sensitive K+ (KATP) channels in maintaining glucose homeostasis. In persistently depolarized β cells from KATP channel knockout (KO) mice, the researchers revealed a shift in G protein signaling from the Gs family to the Gq family. This shift explains why GLP-1, which signals via Gq, but not GIP, which signals preferentially via Gs, can effectively potentiate secretion in islets from the KATP channel–deficient mice and in other models of KATP deficiency, including diabetic KK-Ay mice. Their results provide one explanation for differential insulinotropic potential of incretins in human T2D and point to a potentially unifying model for T2D progression itself.
Authors
Colin G. Nichols, Nathaniel W. York, Maria S. Remedi
Abstract
Some germ cell tumors (GCTs) in men develop into hematologic malignancies; however, the clonal origins of such malignancies remain unknown. In this issue of the JCI, Taylor, Donoghue, et al. unravel the clonal relationship between primary mediastinal nonseminomas (PMNs) and hematologic somatic-type malignancies (HSTMs). Whole-exome sequencing was used to construct phylogenetic trees of the PMNs and the ensuing HSTM clones. HSTMs were derived from multiple distinct clones not detected within the PMNs. Clones from PMNs and HSTMs shared a common precursor, arguably an embryonal carcinoma cell resulting from a reprogrammed primordial germ cell from the thymus. Mutational and copy number variation analysis of a large cohort of patients with PMNs also demonstrated a high prevalence of TP53 mutations not found in testicular nonseminomas. These data likely explain why patients with PMNs are frequently resistant to platinum-based chemotherapy and provide TP53 mutations as potential targets.
Authors
J. Wolter Oosterhuis, Leendert H.J. Looijenga
Abstract
Identifying genes that result in monogenic diabetes can provide insights that can build a scientific foundation for precision medicine. At present, nearly 20% of neonatal diabetes cases have unknown causes. In this issue of the JCI, De Franco and Lytrivi et al. sequenced the genome of two probands with a rare neonatal diabetes subtype that also associated with microcephaly and epilepsy. The authors revealed mutations in the YIPF5 gene. YIPF5 resides in the Golgi apparatus and is thought to play a critical role in vesicular trafficking. Notably, disrupting YIPF5 in β cell–based models induced ER stress signaling and resulted in the accumulation of intracellular proinsulin. We believe that utilizing registries and biobanks to reveal other monogenic atypical forms of diabetes is an important approach to gaining insight and suggest that an insulin sensitizer may alleviate ER stress associated with YIPF5 disruption by decreasing the demand for insulin secretion.
Authors
Toni I. Pollin, Simeon I. Taylor
Abstract
The genetic factors that determine a patient’s risk for developing the acute respiratory distress syndrome (ARDS) remain understudied. In this issue of the JCI, Reilly and colleagues analyzed three cohorts of critically-ill patients and observed an association between the ABO allele A1 and the onset of moderate-severe ARDS. This association was most notable in patients with non-pulmonary sepsis (an indirect, vascular-targeted mechanism of lung injury) and persisted in patients who lacked epithelial expression of the A antigen, suggesting an endothelial mechanism of A1-associated ARDS susceptibility. Critically-ill patients with blood type A had increased circulating concentrations of endothelial-derived glycoproteins von Willebrand Factor and soluble thrombomodulin, and marginal lungs from blood type A donors were less likely to recover function during ex vivo perfusion. These findings implicate A antigen glycosylation of endothelial cells as a critical, genetically-determined risk factor for indirect lung injury that may contribute to the mechanistic heterogeneity of ARDS.
Authors
Alicia N. Rizzo, Eric P. Schmidt
Abstract
Ongoing observational clinical research has prioritized understanding the human immune response to the SARS-CoV-2 during the COVID-19 pandemic. Several recent studies suggest that immune dysregulation with early and prolonged adaptive immune system activation can result in cellular exhaustion. In this issue of the JCI, Files et al. compared cellular immune phenotypes during the first two months of COVID-19 in hospitalized and less severe, non-hospitalized patients. The authors utilized flow cytometry to analyze circulating peripheral blood mononuclear cells. Both patient-cohorts maintained B and T cell phenotypes consistent with activation and cellular exhaustion throughout the first two months of infection. Additionally, follow-up samples from the non-hospitalized patient cohort showed that activation markers and cellular exhaustion increased over time. These findings illustrate the persistent nature of the adaptive immune system changes that have been noted in COVID-19 and suggest longer-term effects that may shape the maintenance of immunity to SARS-CoV-2.
Authors
Philip A. Mudd, Kenneth E. Remy
Abstract
Useful animal models of disease in neuroscience can make accurate predictions about a therapeutic outcome, a feature known as predictive validity. In this issue of the JCI, Knowland et al. provide an improved model to assess nicotinic acetylcholine receptor (nAChR) ligands for treating chronic pain. The authors identify two proteins, the voltage-dependent calcium channel auxiliary subunit BARP and the unfolded protein response sensor IRE1α, that are required for robust heterologous expression of α6β4, an nAChR subtype in dorsal root ganglia (DRG). This nAChR is a candidate for the analgesic effects of nicotine as well as the frog toxin epibatidine. Now researchers can efficiently screen for α6β4 nAChR–selective agonists using heterologous expression systems. Candidates that emerge will enable researchers to test the predictive validity of mouse models for chronic pain in the nAChR context. If all these steps work, one can envision a class of non-opioid nAChR-targeted analgesics for chronic pain.
Authors
Stephen Grant, Henry A. Lester
Abstract
Cytoplasmic aggregated proteins are a common neuropathological feature of neurodegenerative diseases. Cytoplasmic mislocalization and aggregation of TAR-DNA binding protein 43 (TDP-43) is found in the majority of patients with amyotrophic lateral sclerosis (ALS) and in approximately 50% of patients dying of frontotemporal lobar degeneration (FTLD). In this issue of the JCI, Prudencio, Humphrey, Pickles, and colleagues investigated the relationship of TDP-43 pathology with the loss of stathmin-2 (STMN2), an essential protein for axonal growth and maintenance. Comparing genetic, cellular, and neuropathological data from patients with TDP-43 proteinopathies (ALS, ALS–frontotemporal dementia [ALS-FTD], and FTLD-TDP-43 [FTLD-TDP]) with data from patients with non-TDP–related neurodegenerations, they demonstrate a direct relationship between TDP-43 pathology and STMN2 reduction. Loss of the normal transcription suppressor function of TDP-43 allowed transcription of an early termination cryptic axon, resulting in truncated, nonfunctional mRNA. The authors suggest that measurement of truncated STMN2 mRNA could be a biomarker for discerning TDP proteinopathies from other pathologies.
Authors
Jonathan D. Glass
Abstract
Human antibody responses to severe acute respiratory syndrome-associated coronavirus-2 (SARS-CoV-2) hold intense interest with research efforts directed at optimizing antibody-based interventions and monitoring immune status. By relating individual variations in antibody response to coronavirus disease 2019 (COVID-19) severity, beneficial antiviral immune responses may be identified in detail. In this issue of the JCI, Secchi and collaborators describe antibody response profiles in 509 COVID-19 patients from Italy during the 2020 pandemic. The research team found that multiple antibody types to multiple SARS-CoV-2 antigens developed over four weeks. Notably, IgG against the spike receptor binding domain (RBD) was predictive of survival and IgA against the viral spike protein (S protein) associated with rapid virologic clearance. These results may help guide selection of convalescent plasma, hyperimmune products, monoclonal antibodies, and vaccine strategies for COVID-19.
Authors
Jeffrey P. Henderson
Abstract
COVID-19 spans and wide range of symptoms, sometimes with profound immune system involvement. How immune cell subsets change during the disease course and with disease severity needs further study. While myeloid cells have been shown to initiate and maintain responses to pneumonia and lung inflammation, often playing a role in resolution, their involvement with COVID-19 remains unknown. In this issue of the JCI, Sánchez-Cerrillo and Pedro-Landete et al. investigated dendritic cells and monocytes from blood and bronchial secretions of patients with varying COVID-19 severity and with healthy controls. The authors conclude that circulating monocytes and DCs migrate from the blood into the inflamed lungs. While sampling differences in sex, collection timing, bacteria/fungal infection, and corticosteroid treatment limit interpretation, we believe that reprograming monocyte or macrophages by targeting immunometabolism, epigenetics, or the cytokine milieu holds promise in resolving lung-inflammation associated with COVID-19.
Authors
Franco R. D'Alessio, Nicola M. Heller
Abstract
Antiretroviral therapy (ART) generally reduces plasma HIV to undetectable levels, although virus persists in latently infected CD4+ T cells. In some individuals, viremia remains detectable despite adherence to ART and the absence of drug resistance mutations. In this issue of the JCI, Halvas et al. describe HIV RNA sequences from plasma of 8 donors with persistent viremia. Residual viremia was dominated by identical HIV-1 RNA sequences that remained relatively constant over 4 years. Plasma virus matched replication-competent virus cultured from CD4+ T cells. Integration site analysis confirmed the presence of large clones of infected cells. These results indicate that nonsuppressible viremia can be due to expanded clones of infected CD4+ T cells carrying replication-competent virus. The individuals described here represent extreme examples of a phenomenon that is seen in all infected individuals and that is a major barrier to curing HIV infection, the in vivo proliferation of latently infected cells.
Authors
Janet D. Siliciano, Robert F. Siliciano
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Copyright © 2021 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)