Metabolic modeling of single Th17 cells reveals regulators of autoimmunity

Metabolism is a major regulator of immune cell function, but it remains difficult to study the metabolic status of individual cells. Here, we present Compass, an algorithm to characterize cellular metabolic states based on single-cell RNA sequencing and flux balance analysis. We applied Compass to associate metabolic states with T helper 17 (Th17) functional variability (pathogenic potential) and recovered a metabolic switch between glycolysis and fatty acid oxidation, akin to known Th17/regulatory T cell (Treg) differences, which we validated by metabolic assays. Compass also predicted that Th17 pathogenicity was associated with arginine and downstream polyamine metabolism. Indeed, polyamine-related enzyme expression was enhanced in pathogenic Th17 and suppressed in Treg cells. Chemical and genetic perturbation of polyamine metabolism inhibited Th17 cytokines, promoted Foxp3 expression, and remodeled the transcriptome and epigenome of Th17 cells toward a Treg-like state. In vivo perturbations of the polyamine pathway altered the phenotype of encephalitogenic T cells and attenuated tissue inflammation in CNS autoimmunity.

Abstract 2101: Targeting the root of cancer persister cells using an expressed barcode library

Despite a favorable initial response, many cancer patients will experience recurrence of disease within months or years after diagnosis. Recurrence largely arises as a result of the growth of residual cancer cells that remain after treatment. The ability of a subset of cells to survive is attributed frequently to genetic heterogeneity, however recently it was shown that in multiple cancer types relapse can arise due to the presence of persister cells. Persisters are a subpopulation of transiently drug-tolerant cells that are able to survive therapy through reversible, non-mutational mechanisms. Tumor dormancy, stochastic cell state shifts and stem cell-like populations are amongst the mechanisms hypothesized to underlie persister phenotype. However, given the lack of high-throughput methods to concurrently track cell state and lineage, it is not currently feasible to distinguish the relative contribution of each of these factors. To address this need, we generated the Watermelon library. The Watermelon library is a high-complexity expressed barcode library that enables simultaneous tracing of lineage as well as the transcriptional and proliferative state of each cell in the population during drug treatment. We have applied the watermelon system to study the mechanisms underlying the ability of a small population of cells to regain proliferative capacity under constant treatment with EGFR tyrosine kinase inhibitors. We combine time-lapse imaging with single-cell RNA sequencing to show that early drug-cyclers do not acquire a facilitating resistance mutation but rather transition to a new cell state. We find that this non-genetic drug-proliferative state is not restricted to a certain clonal lineage and can be reached by distinct transcriptional paths. We anticipate that this unique library, which can be applied to other systems, would facilitate a better understanding of the cellular and molecular pathways that affect non-inherited drug resistance.

Citation Format: Yaara Oren, Pratiksha Thakore, Mike S. Cuoco, Heidie Frisco Cabanos, Aaron Hata, Joan S. Brugge, Aviv Regev. Targeting the root of cancer persister cells using an expressed barcode library [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2101.

Central diabetes insipidus: A rare complication of IVH in a very low birth weight preterm infant

A 710 g male infant was born at a referring hospital at a gestational age of 23 weeks and 2 days via vaginal delivery and was transferred to our facility at 14 days of age. His delivery was complicated by the breech presentation with difficult head extraction. The infant's initial course was significant for respiratory distress syndrome, grade III-IV intraventricular hemorrhage (IVH), acute kidney injury, and large PDA. On the day of life 29, a gradual increase in serum sodium level refractory to increasing total fluid volume was noted. The combination of persistent hypernatremia (150-160 mmol/l), polyuria (8.4 ml/kg/hr), high plasma osmolality (323 mosm/kg), hyposthenuria (75 mosm/kg) and an undetectable serum ADH (<0.8 pg/ml) confirmed the diagnosis of central diabetes insipidus (CDI). Serum sodium and urine output decreased and urine osmolality increased after subcutaneous DDAVP administration.CDI is an uncommon cause of hypernatremia in the neonatal period. The diagnosis can be difficult as excessive urine output and high serum sodium can often be attributed to high insensible water loss in the extremely premature newborn. CDI in our patient was thought to be due to grade III-IV IVH complicated by post-hemorrhagic hydrocephalus.In conclusion, the diagnosis of central DI should be considered as a complication of severe IVH in the extremely premature neonate who demonstrates persistent hypernatremia, polyuria, decreased urine osmolality, and increased plasma osmolality. Serum ADH levels can be helpful in confirming the central origin of DI and subcutaneous desmopressin can be an effective treatment in the preterm infant.

A newer avenue for evaluation of thyroid dysfunction

Attempt has been made to rationalise the biochemical assessment of patients suspected to have thyroid dysfunction by introduction of a new rapid and supersensitive immunoradiometric assay (IRMA) for TSH. 294 patients were subjected to thyroid investigation viz; tT3, tT4 and TSH (IRMA). Of these, 51 (17.34%) were hypothyroid, 22 (7.48%) were hyperthyroid and 221 (75.1%) were euthyroid. The ratio of thyroid disorder in male to female was 1:3.38. In all patients with hyperthyroidism TSH (IRMA) was 0.05 to undetectable and it was more than 4.5 ulu/ml in hypothyroid patients. TSH (IRMA) was low in one euthyroid patient a 0.34% incidence of false negativity. In 2 patients with subclinical hyperthyroidism TSH (IRMA) was low while tT3 and tT4 were normal. TSH (IRMA) therefore may obviate the need for more time consuming and expensive TRH test and simplify the approach to thyroid function tests in patients suspected to have masked or overt hyperthyroidism.