Biology subjects

Ricciotti, E.

Publications and source records attributed to Ricciotti, E..

8 recordsLinked to original sources

bioRxiv2025

Sources of non-uniform coverage in short-read RNA-Seq data

The origin of several normal cellular functions and related abnormalities can be traced back to RNA splicing. As such, RNA splicing is currently the focus of a vast array of studies. To quantify the transcriptome, short-read RNA-Seq remains the standard assay. The primary technical artifact of RNA-Seq library prep, which severely interferes with analysis, is extreme non-uniformity in coverage across transcripts. This non-uniformity is present in both bulk and single-cell RNA-Seq and is observed even when the sample contains only full-length transcripts. This issue dramatically affects the accuracy of isoform-level quantification of multi-isoform genes. Understanding the sources of this non-uniformity is critical to developing improved protocols and analysis methods. Here, we explore eight potential sources of non-uniformity. We demonstrate that it cannot be explained by one factor alone. We performed targeted experiments to investigate the effect of fragment length, PCR ramp rate, and ribosomal depletion. We assessed existing data sets with varying sample quality, PCR cycle number, reverse transcriptase, and technical or biological replicates. We found evidence that interference of reverse transcription by secondary structure is unlikely to be the major contributing factor, that rRNA pull-down methods do not cause non-uniformity, that PCR ramp rate does not substantially impact non-uniformity, and that shorter fragments do not reduce non-uniformity. All these findings contradict prior publications or recommendations.

bioinformatics↗

bioRxiv2024

Metabolomic Response to Non-Steroidal Anti-Inflammatory Drugs

Non-steroidal anti-inflammatory drugs (NSAIDs) are popular choices for the mitigation of pain and inflammation; however, they are accompanied by side effects in the gastrointestinal and cardiovascular systems. We compared the effects of naproxen, a traditional NSAID, and celecoxib, a cyclooxygenase -2 (Cox-2) inhibitor, in humans. Our findings showed a decrease in tryptophan and kynurenine levels in plasma of volunteers treated with naproxen. We further validated this result in mice. Additionally, we find that the depression of tryptophan was independent of both Cox-1 and Cox-2 inhibition, but rather was due to the displacement of bound tryptophan by naproxen. Supplementation of tryptophan in naproxen-treated mice rescued fecal blood loss and inflammatory gene expression driven by IL-1{beta} in the heart.

systems biology↗

bioRxiv2024

Concomitant suppression of COX-1 and COX-2 is insufficient to induce enteropathy associated with chronic NSAID use

Nonsteroidal anti-inflammatory drugs (NSAIDs) are the most widely used medications for the management of chronic pain; however, they are associated with numerous gastrointestinal (GI) adverse events. Although many mechanisms have been suggested, NSAID-induced enteropathy has been thought to be primarily due to inhibition of both cyclooxygenases (COX) -1 and -2, which results in suppression of prostaglandin synthesis. Yet surprisingly, we found that concomitant postnatal deletion of Cox-1 and -2 over 10 months failed to cause intestinal injury in mice unless they were treated with naproxen or its structural analog, phenylpropionic acid, which is not a COX inhibitor. Cox double knockout mice exhibit a distinct gut microbiome composition and cohousing them with controls rescues their dysbiosis and delays the onset of NSAID-induced GI bleeding. In both the UK Biobank and All of Us human cohorts, coadministration of antibiotics with NSAIDs is associated with an increased frequency of GI bleeding. These results show that prostaglandin suppression plays a trivial role in NSAID-induced enteropathy. However, Cox deletion causes dysbiosis of the gut microbiome that amplifies the enteropathic response to NSAIDs.

pharmacology and toxicology↗

bioRxiv2024

Cyclooxygenase-2 disruption predisposes to heart failure with preserved ejection fraction

Heart failure (HF) is one of the most strongly associated adverse cardiovascular events linked to the use of cyclooxygenase (COX)-2 selective and non-selective nonsteroidal anti-inflammatory drug (NSAID). Nevertheless, it remains uncertain whether NSAID exposure is more likely to lead to heart failure with reduced ejection fraction (HFrEF) or preserved ejection fraction (HFpEF). In adult mice, postnatal genetic deletion or pharmacological inhibition of COX-2 did not affect cardiac function. In contrast, aged female inducible COX-2 (iCOX-2) knockout (KO) mice displayed diastolic dysfunction, cardiac hypertrophy, pulmonary congestion, and elevated levels of plasma N-terminal pro B-type natriuretic peptide (BNP) when compared to age- and sex- matched controls, while their ejection fraction (EF) remained preserved ([≥] 50%). No such phenotype was observed in aged male iCox-2 KO mice. Aged female iCox-2 KO mice showed a shift from prostanoid to leukotriene biosynthesis, along with changes in the expression of mitochondrial genes and calcium-handling proteins in the myocardium. The ratio of phospholamban to SERCA2a was increased, indicating an inhibitory effect on SERCA2a activity, which may contribute to impaired myocardial relaxation. In larval zebrafish, COX-2 inhibition by celecoxib caused a modest yet significant reduction in heart rate and diastolic function, while EF was preserved. Additionally, celecoxib increased BNP expression and ventricular calcium transient amplitude. Diabetic patients in the Harvard-Partners electronic medical record exposed to NSAIDs selective for COX-2 inhibition were more strongly associated with an increased risk of HFpEF compared to HFrEF. Collectively, these findings indicate that COX-2 deletion or inhibition does not impair systolic cardiac function but instead leads to an HFpEF phenotype in mice, zebrafish, and humans. An imbalance in calcium handling may mediate the impairment of myocardial relaxation following COX-2 suppression. SummaryGenetic deletion or pharmacological inhibition of COX-2 results in heart failure with preserved ejection fraction across zebrafish, mice, and humans.

pharmacology and toxicology↗

bioRxiv2024

Disruption of the PGE2 synthesis / response pathway restrains atherogenesis in programmed cell death-1 (Pd-1) deficient hyperlipidemic mice

Immune checkpoint inhibitors (ICIs) that target programmed cell death 1 (PD-1) have revolutionized cancer treatment by enabling the restoration of suppressed T-cell cytotoxic responses. However, resistance to single-agent ICIs limits their clinical utility. Combinatorial strategies enhance their antitumor effects, but may also enhance the risk of immune related adverse effects of ICIs. Prostaglandin (PG) E2, formed by the sequential action of the cyclooxygenase (COX) and microsomal PGE synthase (mPGES-1) enzymes, acting via its E prostanoid (EP) receptors, EPr2 and EPr4, promotes lymphocyte exhaustion, revealing an additional target for ICIs. Thus, COX inhibitors and EPr4 antagonists are currently being combined with ICIs potentially to enhance antitumor efficacy in clinical trials. However, given the cardiovascular (CV) toxicity of COX inhibitors, such combinations may increase the risk particularly of CV AEs. Here, we compared the impact of distinct approaches to disruption of the PGE2 synthesis /response pathway - global or myeloid cell specific depletion of mPges-1 or global depletion of Epr4 - on the accelerated atherogenesis in Pd-1 deficient hyperlipidemic (Ldlr-/-) mice. All strategies restrained the atherogenesis. While depletion of mPGES-1 suppresses PGE2 biosynthesis, reflected by its major urinary metabolite, PGE2 biosynthesis was increased in mice lacking EPr4, consistent with enhanced expression of aortic Cox-1 and mPges-1. Deletions of mPges-1 and Epr4 differed in their effects on immune cell populations in atherosclerotic plaques; the former reduced neutrophil infiltration, while the latter restrained macrophages and increased the infiltration of T-cells. Consistent with these findings, chemotaxis by bone-marrow derived macrophages from Epr4-/- mice was impaired. Epr4 depletion also resulted in extramedullary lymphoid hematopoiesis and inhibition of lipoprotein lipase activity (LPL) with coincident spelenomegaly, leukocytosis and dyslipidemia. Targeting either mPGES-1 or EPr4 may restrain lymphocyte exhaustion while mitigating CV irAEs consequent to PD-1 blockade.

pharmacology and toxicology↗

bioRxiv2020

Sex dependent compensatory mechanisms to preserve blood pressure homeostasis in PGI2 receptor deficient mice

Inhibitors of microsomal prostaglandin E synthase-1 (mPges-1) are in the early phase of clinical development. Deletion of mPges-1 confers analgesia, restrains atherogenesis and fails to accelerate thrombogenesis, while suppressing prostaglandin (PG) E2, but increasing biosynthesis of prostacyclin (PGI2). In hyperlipidemic mice, this last effect represents the dominant mechanism by which mPges-1 deletion restrains thrombogenesis, while suppression of PGE2 accounts for its anti-atherogenic effect. However, the impact of mPges-1 depletion on blood pressure (BP) in this setting remains unknown. To address how differential effects on PGE2 and PGI2 might modulate salt-evoked BP responses in the absence of mPges-1, we generated mice lacking the I prostanoid (Ipr) receptor or mPges-1 on a hyperlipidemic background caused by deletion of the low density lipoprotein receptor (Ldlr KOs). Here, mPges-1 depletion significantly increased the BP response to salt loading in male Ldlr KO mice, whereas, despite the direct vasodilator properties of PGI2, Ipr deletion suppressed it. Furthermore, combined deletion of the Ipr abrogated the exaggerated BP response in male mPges-1 KO mice. Suppression of PGE2 biosynthesis was enough to explain the exaggerated BP response to salt loading by either mPges-1/Ldlr depletion or by an MPGES-1 inhibitor in mice expressing human mPGES-1. However, the lack of a hypertensive response to salt in Ipr-deficient mice was attributable to reactive activation of the atrial natriuretic peptide pathway. Interestingly, these unexpected BP phenotypes were not observed in female mice fed a high salt diet. This is attributable to the protective effect of estrogen in Ldlr KO mice and in Ipr /Ldlr DKOs. Thus, estrogen compensates for a deficiency in PGI2 to maintain BP homeostasis in response to high salt in hyperlipidemic female mice. In males, by contrast, augmented formation of ANP plays a similar compensatory role, restraining hypertension and oxidant stress in the setting of Ipr depletion. Hyperlipidemic males on a high salt diet might be at risk of a hypertensive response to mPGES-1 inhibitors.

pharmacology and toxicology↗

bioRxiv2018

Distinct vascular genomic response of proton and gamma radiation.

Purpose. The cardiovascular biology of proton radiotherapy is not well understood. We aimed to compare the genomic dose-response to proton and gamma radiation of the mouse aorta to assess whether their vascular effects may diverge.\n\nMaterials and methods. We performed comparative RNA sequencing of the aorta following (4 hrs) total-body proton and gamma irradiation (0.5 - 200 cGy whole body dose, 10 dose levels) of conscious mice. A trend analysis identified genes that showed a dose response.\n\nResults. While fewer genes were dose-responsive to proton than gamma radiation (29 vs. 194 genes; q-value [≤] 0.1), the magnitude of the effect was greater. Highly responsive genes were enriched for radiation response pathways (DNA damage, apoptosis, cellular stress and inflammation; p-value [≤] 0.01). Gamma, but not proton radiation induced additionally genes in vasculature specific pathways. Genes responsive to both radiation types showed almost perfectly superimposable dose-response relationships.\n\nConclusions. Despite the activation of canonical radiation response pathways by both radiation types, we detected marked differences in the genomic response of the murine aorta. Models of cardiovascular risk based on photon radiation may not accurately predict the risk associated with proton radiation.

systems biology↗

bioRxiv2018

Iso-relevance Functions - A Systematic Approach to Ranking Genomic Features by Differential Effect Size

It is common to measure large numbers of features to identify those differing between experimental conditions; for example using RNA-Seq to search for differentially expressed genes. Ranking by p-value allows for statistical control, but has well known issues: unreliability without many replicates; and significance of biologically irrelevant effect sizes. As a result prioritization is typically performed in conjunction with effect size; the canonical one being "fold-change" [Formula]. However fold-change has several issues: division by zero, sensitivity to small values in the denominator, insensitivity to magnitude (1 over 2 equals 100 over 200). To mitigate these problems adding 1 to all values is a widely used heuristic; which we show using real and simulated data is typically highly sub-optimal, while the value 20 is nearly optimal in all cases. From another point of view, adding a fixed "pseudocount" to all values is essentially re-defining effect size from fold-change to something else. To explore this further, we axiomatize the concept of effect size and use this mathematical framework to study the problem in general. We also present the remarkable finding that pseudocounts strike a balance between sorting by fold-change and sorting by difference. Therefore, optimization is equivalent to finding the most harmonious balance between these two extremes. Lastly, the framework is illustrated on a fundamentally different type of problem, that of ranking di-codons by their differential abundance in the ORFeome of different species, where p-values are unavailable and one must solve the problem directly with effect sizes.

bioinformatics↗