A specific diagnostic metabolome signature in adult IgA vasculitis.

INTRODUCTION: IgA vasculitis diagnosis relies primarily on clinical features and is confirmed by pathological findings. To date, there is no reliable noninvasive diagnostic biomarker. OBJECTIVE: We aimed to explore the baseline serum metabolome of adult patients with IgA vasculitis to identify potential diagnostic biomarkers. METHODS: We performed a study comparing the serum metabolome of patients with IgA vasculitis to that of patients with inflammatory condition, namely spondyloarthritis. Serum analyses were performed by high-performance liquid chromatography-mass spectrometry. RESULTS: Fifty-five patients with IgA vasculitis and 77 controls with spondyloarthritis (age- and sex-matched) were included in this study. The median age of IgA vasculitis patients was 53 years. Two-thirds of patients were female (n = 32). At the time of vasculitis diagnosis, 100% of patients had skin involvement and 69% presented with glomerulonephritis (n = 38). Joint and digestive involvement were observed in 56% (n = 31) and 42% (n = 23) of patients. Four discriminative metabolites between the two groups were identified: 1-methyladenosine, L-glutamic acid, serotonin, and thymidine. The multivariate model built from the serum metabolomes of patients with IgA vasculitis and spondyloarthritis revealed an accuracy > 90%. As this model was significant according to the permutation test (p < 0.01), independent validation showed an excellent predictive value of the test set: sensitivity 98%; specificity 98%, positive predictive value 97% and negative predictive value 98%. CONCLUSION: To our knowledge, this study is the first to use the metabolomic approach for diagnostic purposes in adult IgA vasculitis, highlighting a specific diagnostic metabolome signature.

Pharmacometabolomics applied to low-dose interleukin-2 treatment in amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a devastating motor neuron disease. The immunosuppressive functions of regulatory T lymphocytes (Tregs) are impaired in ALS, and correlate to disease progression. The phase 2a IMODALS trial reported an increase in Treg number in ALS patients following the administration of low-dose (ld) interleukin-2 (IL-2). We propose a pharmacometabolomics approach to decipher metabolic modifications occurring in patients treated with ld-IL-2 and its relationship with Treg response. Blood metabolomic profiles were determined on days D1, D64, and D85 from patients receiving 2 MIU of IL-2 (n = 12) and patients receiving a placebo (n = 12). We discriminated the three time points for the treatment group (average error rate of 42%). Among the important metabolites, kynurenine increased between D1 and D64, followed by a reduction at D85. The percentage increase of Treg number from D1 to D64, as predicted by the metabolome at D1, was highly correlated with the observed value. This study provided a proof of concept for metabolic characterization of the effect of ld-IL-2 in ALS. These data could present advances toward a personalized medicine approach and present pharmacometabolomics as a key tool to complement genomic and transcriptional data for drug characterization, leading to systems pharmacology.

Corneal nerves and amyotrophic lateral sclerosis: an in vivo corneal confocal imaging study.

OBJECTIVES: Amyotrophic lateral sclerosis (ALS) is a severe motor neuron disorder. Diagnosis is challenging due to its clinical heterogeneity and the absence of definitive diagnostic tools, leading to delays averaging between 9.1 and 27 months. In vivo corneal confocal microscopy, assessing the sub-basal nerve plexus of the cornea, has been proposed as a potential biomarker for ALS. We aimed to determine whether the assessment of corneal nerves using in vivo confocal microscopy can serve as an imaging biomarker for ALS. METHODS: A single-centre prospective case-control study was conducted in France from September 2021 to March 2023 including patients with ALS according to the revised EI Escorial criteria. The corneal sub-basal nerve plexus was analysed using in vivo confocal microscopy. An automated algorithm (ACCMetrics) was used to evaluate corneal parameters: nerve fibre density, nerve branch density, nerve fibre length, nerve fibre area, nerve total branch density, nerve fibre width, and nerve fractal dimension. RESULTS: Twenty-two patients with ALS and 30 controls were included. No significant differences were found between ALS and control groups for all corneal parameters (p > 0.05). Corneal sensitivity did not differ between groups, and no correlation was identified between corneal nerve parameters and ALS disease duration, severity and rate of progression (p > 0.05). CONCLUSIONS: The present study does not support the use of in vivo corneal confocal microscopy as an early diagnostic or prognostic tool for ALS. Further research, especially longitudinal investigations, is needed to understand any potential corneal innervation changes as ALS progresses.

The effect of pH alterations on TDP-43 in a cellular model of amyotrophic lateral sclerosis.

Amyotrophic Lateral Sclerosis (ALS) is the most common neurodegenerative disease affecting motor neurons. The pathophysiology of ALS is not well understood but TDP-43 proteinopathy (aggregation and mislocalization) is one of the major phenomena described. Several factors can influence TDP-43 behavior such as mild pH alterations that can induce conformational changes in recombinant TDP-43, increasing its propensity to aggregate. However to our knowledge, no studies have been conducted yet in a cellular setting, in the context of ALS. We therefore tested the effect of cellular pH alterations on the localization, aggregation, and phosphorylation of TDP-43. HEK293T cells overexpressing wildtype TDP-43 were incubated for 1 h with solutions of different pH (6.4, 7.2, and 8). Incubation of cells for 1 h in solutions of pH 6.4 and 8 led to an increase in TDP-43-positive puncta. This was accompanied by the mislocalization of TDP-43 from the nucleus to the cytoplasm. Our results suggest that small alterations in cellular pH affect TDP-43 and increase its mislocalization into cytoplasmic TDP-43-positive puncta, which might suggest a role of TDP-43 in the response of cells to pH alterations.

Neutrophil to Lymphocyte Ratio as a Prognostic Marker in Amyotrophic Lateral Sclerosis.

Amyotrophic lateral sclerosis (ALS) is the most common neurodegenerative motor neuron disease and remains misunderstood with a difficult diagnosis and prognosis. The implication of the immune system is recognized in ALS pathophysiology, hence the interest in leucocyte count as lymphocytes and neutrophils. The neutrophil-to-lymphocyte ratio (NLR) has recently been used as a prognosis factor to assess the progression of ALS. Thus, the aim of this study was to analyze the evolution of the NLR during disease evolution in a French cohort of ALS patients and its relation with survival. In this monocentric retrospective study, clinical parameters and NLR were collected in ALS patients followed at the University Hospital of Tours (France). ALS patients were subdivided into three groups regarding their NLR value at inclusion: group 1 (NLR < 2); group 2 (NLR: 2-3); group 3 (NLR > 3). A comparison of qualitative and quantitative clinical and biological variables between NLR groups was performed. Then, Cox regressions were carried out to determine the association of NLR with survival. We observed a significant correlation of NLR with ALSFRS-r score (p < 0.0001) and with vital forced capacity (p = 0.0004) at inclusion. We observed that increased NLR at diagnosis is associated with decreased ALS patients' survival.

No evidence for systemic low-grade inflammation in adult patients with early-treated phenylketonuria: The INGRAPH study.

The question of an increased cardiovascular risk has been recently raised in adults with phenylketonuria (PKU). As low-grade systemic inflammation increases cardiovascular risk, the INGRAPH study aimed to evaluate low-grade inflammation in adult PKU patients compared to healthy controls and to determine the potential influence of Phe-controlled diet on inflammation. Twenty early-treated adult PKU patients, including a subgroup of 15 classical PKU patients, and 20 healthy volunteers were included. PKU patients and healthy subjects were matched on age, sex and body mass index class. Plasma concentrations of CRP, IFNg, IL1a, IL1b, IL2, IL6, IL10, and TNFα were measured in PKU patients and compared to controls. Plasma CRP was not different in the PKU group as compared to controls. No significant differences were observed between the two groups concerning plasma cytokines concentrations. Plasma CRP and cytokine profile were not different between "on diet" and "off diet" PKU patients. All these results were similar considering only the classical PKU subgroup. No differences were shown in plasma CRP and pro-inflammatory cytokines between adult PKU patients and healthy controls. Further studies are needed, including more patients and extensive characterization of systemic low-grade inflammation, as cardiovascular risk appears to be a new concern in adult PKU population.

Joint manifestations revealing inborn metabolic diseases in adults: a narrative review.

Inborn metabolic diseases (IMD) are rare conditions that can be diagnosed during adulthood. Patients with IMD may have joint symptoms and the challenge is to establish an early diagnosis in order to institute appropriate treatment and prevent irreversible damage. This review describes the joint manifestations of IMD that may be encountered in adults. The clinical settings considered were arthralgia and joint stiffness as well as arthritis. Unspecific arthralgias are often the first symptoms of hereditary hemochromatosis, chronic low back pain may reveal an intervertebral disc calcification in relation with alkaptonuria, and progressive joint stiffness may correspond to a mucopolysaccharidosis or mucolipidosis. Gaucher disease is initially revealed by painful acute attacks mimicking joint pain described as "bone crises". Some IMD may induce microcrystalline arthropathy. Beyond classical gout, there are also gouts in connection with purine metabolism disorders known as "enzymopathic gouts". Pyrophosphate arthropathy can also be part of the clinical spectrum of Gitelman syndrome or hypophosphatasia. Oxalate crystals arthritis can reveal a primary hyperoxaluria. Destructive arthritis may be indicative of Wilson's disease. Non-destructive arthritis may be seen in mevalonate kinase deficiency and familial hypercholesterolemia.

Increased acylcarnitines in infant heart failure indicate fatty acid oxidation inhibition: towards therapeutic options?

AIMS: Heart failure in adults is characterized by reduction of long-chain fatty acid oxidation in favour of carbohydrate metabolism. This adaptive phenomenon becomes maladaptive because energy conversion decreases and lipid toxic derivatives known to impair cardiac function are accumulating. No data are available concerning metabolic modification in heart failure in children. METHODS AND RESULTS: In order to evaluate the fatty acid oxidation in children suffering from heart failure, acylcarnitine profiles on dried blood spots were obtained from children under 16 years old with dilated cardiomyopathy and clinical heart failure (DCM-HF) and control children. Nine children were included in the DCM-HF group and eight in the control group. Acylcarnitine profiles revealed a significant 3.1-fold increase of total acylcarnitines (sum of C3 to C18 acylcarnitine species) in DCM-HF children compared with controls. This result persisted considering the sum of long-chain acylcarnitines (sum of C14 to C18 species), medium-chain acylcarnitines (sum of C8 to C12 species), and short-chain acylcarnitines (sum of C3 to C6 species), respectively, 2.0-, 2.6-, and 1.9-fold increase compared with the control group. A significant linear correlation was found between left ventricular dilatation or ejection fraction and acylcarnitines accumulation. Finally, acylcarnitine ratio C16OH/C16 and C18OH/C18 enhanced in the DCM-HF group, suggesting a diminution of the long-chain hydroxyl acyl-CoA dehydrogenase activity. CONCLUSIONS: Our results suggest down-regulation of fatty acid oxidation in children with heart failure. Such lipidomic alteration could worsen heart function and may suggest considering a metabolic treatment of heart failure in children.

Implication of Central Nervous System Barrier Impairment in Amyotrophic Lateral Sclerosis: Gender-Related Difference in Patients.

Central nervous system (CNS) barrier impairment has been reported in amyotrophic lateral sclerosis (ALS), highlighting its potential significance in the disease. In this context, we aim to shed light on its involvement in the disease, by determining albumin quotient (QAlb) at the time of diagnosis of ALS in a large cohort of patients. Patients from the university hospital of Tours (n = 307) were included in this monocentric, retrospective study. In total, 92 patients (30%) had elevated QAlb levels. This percentage was higher in males (43%) than in females (15%). Interestingly, QAlb was not associated with age of onset, age at sampling or diagnostic delay. However, we found an association with ALS functional rating scale-revised (ALSFRS-r) at diagnosis but this was significant only in males. The QAlb levels were not linked to the presence of a pathogenic mutation. Finally, we performed a multivariate survival analysis and found that QAlb was significantly associated with survival in male patients (HR = 2.3, 95% CI = 1.2-4.3, p = 0.009). A longitudinal evaluation of markers of barrier impairment, in combination with inflammatory biomarkers, could give insight into the involvement of CNS barrier impairment in the pathogenesis of the disease. The gender difference might guide the development of new drugs and help personalise the treatment of ALS.

Evaluation of arterial blood gas parameters as prognostic markers in amyotrophic lateral sclerosis.

BACKGROUND: Forced vital capacity (FVC) remains difficult to determine for some patients suffering from amyotrophic lateral sclerosis (ALS) due to the rapid progression of the disease. Arterial blood gas (ABG) parameters could represent a valuable alternative. The aim of this study was therefore to evaluate the correlation between ABG parameters and FVC, along with the prognostic ability of ABG parameters, in a large cohort of ALS patients. METHODS: ALS patients (n=302) with FVC and ABG parameters available at diagnosis were included. Correlations between ABG parameters and FVC were evaluated. Cox regression was then carried out to determine the association of each parameter (ABG and clinical data) with survival. Finally, receiver operating characteristic (ROC) curves were built to predict the survival of ALS. RESULTS: Bicarbonates (HCO3 - ), oxygen partial pressure (pO2 ), carbon dioxide partial pressure (pCO2 ), base excess (BE), oxygen saturation and oxyhemoglobin were significantly correlated with FVC both in patients with spinal or bulbar onset. Univariate Cox regression showed that HCO3 - and BE were associated with survival but only in spinal forms. ABG parameters predicted the survival of ALS with a similar performance to FVC, HCO3 - being the parameter with the highest area under the curve. CONCLUSIONS: Our results suggest that there is an interest in conducting a longitudinal evaluation throughout disease progression to confirm the equal performances of FVC and ABG. This study highlights the benefits of performing ABG analysis that could be used as an interesting alternative to FVC when spirometry cannot be performed.

Sonoporation of the Round Window Membrane on a Sheep Model: A Safety Study.

Sonoporation using microbubble-assisted ultrasound increases the permeability of a biological barrier to therapeutic molecules. Application of this method to the round window membrane could improve the delivery of therapeutics to the inner ear. The aim of this study was to assess the safety of sonoporation of the round window membrane in a sheep model. To achieve this objective, we assessed auditory function and cochlear heating, and analysed the metabolomics profiles of perilymph collected after sonoporation, comparing them with those of the control ear in the same animal. Six normal-hearing ewes were studied, with one sonoporation ear and one control ear for each. A mastoidectomy was performed on both ears. On the sonoporation side, Vevo MicroMarker® microbubbles (MBs; VisualSonics-Fujifilm, Amsterdam, The Netherlands) at a concentration of 2 × 108 MB/mL were locally injected into the middle ear and exposed to 1.1 MHz sinusoidal ultrasonic waves at 0.3 MPa negative peak pressure with 40% duty cycle and 100 µs interpulse period for 1 min; this was repeated three times with 1 min between applications. The sonoporation protocol did not induce any hearing impairment or toxic overheating compared with the control condition. The metabolomic analysis did not reveal any significant metabolic difference between perilymph samples from the sonoporation and control ears. The results suggest that sonoporation of the round window membrane does not cause damage to the inner ear in a sheep model.

Time for optimism in amyotrophic lateral sclerosis.

BACKGROUND AND PURPOSE: Amyotrophic lateral sclerosis (ALS) is among the most common motor neuron diseases in adults. Nevertheless, ALS remains fatal, despite decades of research and clinical trials, which has led to negative conclusions until recently in regard to four specific treatments. It is well known that we can learn from failures, and we consider that the time has come to present positive insight on this disease. METHODS: We did a literature search using PubMed and Scopus for articles published in English from 1 January 2016, to 30 June 2022 dealing with "amyotrophic lateral sclerosis", diagnosis, treatment, and biomarkers. RESULTS: A comprehensive review of the literature on diagnosis, monitoring, and treatment of this condition showed convincing evidence that we are now able to diagnose earlier as well as to better monitor and treat ALS. CONCLUSIONS: Although ALS is often difficult to diagnose and remains incurable, there are many indications that an optimistic view of ALS management in the coming years is now realistic.

Study of Ubiquitin Pathway Genes in a French Population with Amyotrophic Lateral Sclerosis: Focus on HECW1 Encoding the E3 Ligase NEDL1.

The ubiquitin pathway, one of the main actors regulating cell signaling processes and cellular protein homeostasis, is directly involved in the pathophysiology of amyotrophic lateral sclerosis (ALS). We first analyzed, by a next-generation sequencing (NGS) strategy, a series of genes of the ubiquitin pathway in two cohorts of familial and sporadic ALS patients comprising 176 ALS patients. We identified several pathogenic variants in different genes of this ubiquitin pathway already described in ALS, such as FUS, CCNF and UBQLN2. Other variants of interest were discovered in new genes studied in this disease, in particular in the HECW1 gene. We have shown that the HECT E3 ligase called NEDL1, encoded by the HECW1 gene, is expressed in neurons, mainly in their somas. Its overexpression is associated with increased cell death in vitro and, very interestingly, with the cytoplasmic mislocalization of TDP-43, a major protein involved in ALS. These results give new support for the role of the ubiquitin pathway in ALS, and suggest further studies of the HECW1 gene and its protein NEDL1 in the pathophysiology of ALS.

Salivary metabolome indicates a shift in tyrosine metabolism in patients with burning mouth syndrome: a prospective case-control study.

ABSTRACT: The pathophysiology of primary burning mouth syndrome (BMS) remains controversial. Targeted analyses or "omics" approach of saliva provide diagnostic or pathophysiological biomarkers. This pilot study's primary objective was to explore the pathophysiology of BMS through a comparative analysis of the salivary metabolome among 26 BMS female cases and 25 age- and sex-matched control subjects. Secondary objectives included comparative analyses of inflammatory cytokines, neuroinflammatory markers, and steroid hormones among cases and control subjects, and among BMS patients according to their clinical characteristics. Salivary metabolome, neuroinflammatory markers, cytokines, and steroids were, respectively, analysed by liquid chromatography coupled with mass spectrometry, ELISA and protease activity assay, and multiparametric Luminex method. Among the 166 detected metabolites, univariate analysis did not find any discriminant metabolite between groups. Supervised multivariate analysis divided patients into 2 groups with an accuracy of 60% but did not allow significant discrimination (permutation test, P = 0.35). Among the metabolites contributing to the model, 3 belonging to the tyrosine pathway ( l -dopa, l -tyrosine, and tyramine) were involved in the discrimination between cases and control subjects, and among BMS patients according to their levels of pain. Among the detectable molecules, levels of cytokines, steroid hormones, and neuroinflammatory markers did not differ between cases and control subjects and were not associated with characteristics of BMS patients. These results do not support the involvement of steroid hormones, inflammatory cytokines, or inflammatory neurogenic mediators in the pathophysiology of pain in BMS, whereas the observed shift in tyrosine metabolism may indicate an adaptative response to chronic pain or an impaired dopaminergic transmission.

Comparison between PFN1 and SOD1 mutations in amyotrophic lateral sclerosis.

BACKGROUND: The objective of this study was to characterize the prototypical phenotype of patients with amyotrophic lateral sclerosis (ALS) associated with PFN1 mutations in profilin 1 (PFN1) and to determine clinical indications to test for mutations in this gene. MATERIAL AND METHODS: The phenotype of three relatives carrying the M114V PFN1 mutation are detailed here and are compared with those of patients with ALS linked to PFN1 previously reported in the literature. RESULTS: In this pedigree and in the literature, the main clinical findings which best describe familial ALS linked to PFN1 might be the following characteristics: pedigrees over five cases, age of onset around 50 years, site of onset systematically lower limbs and the absence of cognitive impairment. CONCLUSION: First, the infrequent incidence of patients with ALS linked to PFN1 mutation supports the pursuit of a precise characterization of the phenotype linked to PFN1 mutations. Then, the numerous similarities between the phenotype amongst patients linked to SOD1 and PFN1 mutations and between histological features amongst both mice models prompts a review of the current ALS classifications, taking into consideration both phenotype and genotype.

Validation of metabolomic and lipidomic analyses of human tears using ultra-high-performance liquid chromatography tandem mass spectrometry.

To facilitate application in ophthalmological and systemic diseases, there is a need to standardize preanalytical and analytical steps for metabo-lipidomics in human tears. We assessed different methods for each step of the workflow, from sampling to omics profiles acquisition, to provide the largest metabo-lipidomic coverage with the most robust analytical criteria in human tears. We compared reproducibility according to different extraction methods, two sampling techniques, three volumes (2 µL, 5 µL, 10 µL) and eye laterality using ultra-high-performance liquid chromatography coupled with tandem high-resolution mass spectrometry for metabolomic and lipidomic application. The effect of age on the tear metabo-lipidome was also investigated in healthy subjects. The extraction method using methanol/water provided the best results for Schirmer strip metabolomics, while Folch extraction was superior for lipidomics, whatever the sampling method used. When comparing both sampling methods, microcapillary glass tube was superior to Schirmer strip for metabolomics but comparable for lipidomics. The 5 µL volume provided a satisfying metabo-lipidomic coverage. There was no significant difference in tear metabo-lipidome between both eyes in healthy subjects. While most metabolites and lipids where not influenced by age, the phenylalanine-tyrosine-tryptophan pathway, aminoacyl t-RNA biosynthesis, and alanine-aspartate-glutamate metabolism were the 3 principal pathways associated with the 15 most variable metabolites according to age. The current findings will contribute to improve metabo-lipidomic workflow in human tears for the identification of new biomarkers. Preanalytical and analytical standardization is mandatory in order to perform better between-study comparisons and increase the chances of transferring laboratory findings into clinical practice.

Sweet ending: When genetics prevent a dramatic CDG diagnostic mistake.

Herein, we described the case of a newborn male, from consanguineous parents, who developed, at day 11 of life, an obstructive hydrocephalus resulting from bilateral cerebellar hemorrhage without evident cause. Then, at 1 month, he developed a fulminant hepatitis with hyperammonia, hyperlactatemia and metabolic acidosis. Infectious and first line metabolic explorations were normal. Screening for congenital disorder of glycosylation (CDG) was performed using capillary electrophoresis and western blot of serum transferrin. Abnormal results were evocative of mannose-phosphate isomerase deficiency (MPI-CDG or CDG-Ib) as it can be responsible for fulminant hepatitis, digestive disease, developmental delay, and coagulopathy. However, trio whole exome sequencing revealed a pathogenic variant at the homozygous state in ALDOB, responsible for hereditary fructose intolerance (HFI), an inherited metabolic disorder with excellent prognosis under a fructose-free diet. HFI had not been previously evoked in view of the absence of diet diversification, but meticulous inquiry revealed that parents systematically added white sugar to the bottle milk of their child, unintentionally triggering potentially fatal HFI decompensations. Early genetic analysis upsetted both diagnosis and prognosis for this infant who had excellent development after fructose removal. This full-of-surprises diagnostic approach illustrates the importance of an integrative collaboration between clinicians, biochemists, and geneticists.

Clinical and biochemical footprints of inherited metabolic diseases. IX. Metabolic ear disease.

Damages to the ear are very diverse and can depend on the type of inherited metabolic diseases (IMD). Indeed, IMDs can affect all parts of the auditory system, from the outer ear to the central auditory process. We have identified 219 IMDs associated with various types of ear involvement which we classified into five groups according to the lesion site of the auditory system: congenital external ear abnormalities, acquired external ear abnormalities, middle ear involvement, inner ear or retrocochlear involvement, and unspecified hearing loss. This represents the ninth issue in a series of educational summaries providing a comprehensive and updated list of metabolic differential diagnoses according to system involvement.

Metabolomics as a Crucial Tool to Develop New Therapeutic Strategies for Neurodegenerative Diseases.

Neurodegenerative diseases (NDs), such as Alzheimer's (AD), Parkinson's (PD), and amyotrophic lateral sclerosis (ALS), share common pathological mechanisms, including metabolism alterations. However, their specific neuronal cell types affected and molecular biomarkers suggest that there are both common and specific alterations regarding metabolite levels. In this review, we were interested in identifying metabolite alterations that have been reported in preclinical models of NDs and that have also been documented as altered in NDs patients. Such alterations could represent interesting targets for the development of targeted therapy. Importantly, the translation of such findings from preclinical to clinical studies is primordial for the study of possible therapeutic agents. We found that N-acetyl-aspartate (NAA), myo-inositol, and glutamate are commonly altered in the three NDs investigated here. We also found other metabolites commonly altered in both AD and PD. In this review, we discuss the studies reporting such alterations and the possible pathological mechanism underlying them. Finally, we discuss clinical trials that have attempted to develop treatments targeting such alterations. We conclude that the treatment combination of both common and differential alterations would increase the chances of patients having access to efficient treatments for each ND.

Immediate-Early Modifications to the Metabolomic Profile of the Perilymph Following an Acoustic Trauma in a Sheep Model.

The pathophysiological mechanisms of noise-induced hearing loss remain unknown. Identifying biomarkers of noise-induced hearing loss may increase the understanding of pathophysiological mechanisms of deafness, allow for a more precise diagnosis, and inform personalized treatment. Emerging techniques such as metabolomics can help to identify these biomarkers. The objective of the present study was to investigate immediate-early changes in the perilymph metabolome following acoustic trauma. Metabolomic analysis was performed using liquid chromatography coupled to mass spectrophotometry to analyze metabolic changes in perilymph associated with noise-induced hearing loss. Sheep (n = 6) were exposed to a noise designed to induce substantial hearing loss. Perilymph was collected before and after acoustic trauma. Data were analyzed using univariate analysis and a supervised multivariate analysis based on partial least squares discriminant analysis. A metabolomic analysis showed an abundance of 213 metabolites. Four metabolites were significantly changed following acoustic trauma (Urocanate (p = 0.004, FC = 0.48), S-(5'-Adenosyl)-L-Homocysteine (p = 0.06, FC = 2.32), Trigonelline (p = 0.06, FC = 0.46) and N-Acetyl-L-Leucine (p = 0.09, FC = 2.02)). The approach allowed for the identification of new metabolites and metabolic pathways involved with acoustic trauma that were associated with auditory impairment (nerve damage, mechanical destruction, and oxidative stress). The results suggest that metabolomics provides a powerful approach to characterize inner ear metabolites which may lead to identification of new therapies and therapeutic targets.