miRNAs, Suicide, and Ketamine - Plasma Exosomal microRNAs as Novel Biomarkers for Suicidality and Treatment Outcome

Neural MicroRNAs (miRNAs) are responsive to environmental, synaptic, and pathological changes and can be actively secreted by cells such as exosomes from brain into blood. These exosomes bear cell-type specific surface markers. Using a neural specific surface marker, the investigators successfully isolated neural-derived exosomes and found that these exosomes are enriched with miRNAs/Messenger RNA (mRNAs) that are expressed in brain. Using this novel approach the investigators aim to examine whether neural derived exosomal miRNAs are differentially expressed that are specific to suicidal ideation or behavior, and which by affecting specific mRNA targets and pathways, are associated with suicidal behavior and response to ketamine.

The following groups of subjects will be examined: 1) major depressive disorder (MDD) with a recent suicide attempt (in past 2 weeks), 2) MDD with serious ideation (in the past 7 days) without recent suicide attempt (in the past 6 months), 3) MDD without clinically significant suicidal ideation (in the past 7 days) or suicide attempt in the past 6 months, and 4) healthy controls. Both suicidal and non-suicidal MDD will be given ketamine (0.5 mg/kg, IV) and blood will be drawn at pre-infusion, 30 minutes and 180 minutes post-infusion to measure changes in miRNAs. Healthy controls will have a one-time blood draw. The investigators also propose a parallel human postmortem brain study to examine whether changes in miRNAs in suicidality correspond to miRNA changes in brain by comparing dlPFC and hippocampus from MDD suicide, MDD non-suicide, and control subjects.

With this the investigators attempt to discover 1) whether suicidal ideation or behavior is associated with differences in the expression of specific miRNAs, 2) whether anti-suicidal/antidepressant effects of ketamine is associated with miRNAs changes, and 3) whether miRNA/mRNA-regulatory pathways contribute to suicide pathogenesis and treatment response. Our study will provide a novel avenue for the development of miRNAs as ''molecular tool'' to identify suicidality and treatment response and in generating target based therapies to treat this devastating disorder.

Inclusion criteria

• Age 18-65
• Physically healthy and capable of undergoing ketamine infusion
• Willing and able to provide informed consent
• Diagnosis of Major Depressive Episode (MDE) as determined by the Mini International Neuropsychiatric Interview (MINI) (MDD participants)
• Hamilton Depression Rating Scale (HAM-D) 21 score ≥ 16 (MDD participants)
• Suicide attempt occurred within past 2 weeks (MDD Participants with Suicide Attempt)
• For the time frame of the past 7 days, Columbia-Suicide Severity Rating Scale (C-SSRS) score ≥ 3 (MDD Participants without Suicide Attempt, with Suicidal Ideation)
• For the time frame of the past 7 days, C-SSRS score < 3 (MDD Participants without Suicide Attempt, without SUicidal Ideation)

Exclusion criteria

• Pregnancy or lactation
• Post-partum state (being within 2 months of delivery or miscarriage)
• Homicide risk as determined by clinical interview
• A lifetime history of psychotic disorder
• Any history of dissociation or dissociative disorder
• Bipolar disorder
• Pervasive developmental disorder
• Cognitive disorder
• Cluster A personality disorder
• Anorexia nervosa
• Treatment with one of the following medications, known to affect the glutamate-N-methyl-D-aspartate (NMDA) receptor system (specifically: lamotrigine, acamprosate, memantine, riluzole, or lithium)
• Alcohol or drug dependence (except nicotine and caffeine) within the last month or the use of any hallucinogen (except cannabis), including phencyclidine in the last month
• Any known hypersensitivity or serious adverse effect associated with ketamine treatment
• Any clinically-significant medication condition or therapy that would preclude treatment with ketamine, to include: Recent myocardial infarction
• Unstable angina
• Active neoplasm in the past 6 months
• Immunosuppressive or corticosteroid therapy within the last month, with the following exceptions: any inhaled, intranasal, topical or vaginal corticosteroids are allowed.
• Chemotherapy
• Head injury of loss of consciousness in the past 6 months
• If the subject reports any of the following disorders:

• Rheumatoid arthritis
• Lupus erythematosus
• Autoimmune hepatitis
• Autoimmune peripheral neuropathy
• Autoimmune pancreatitis
• Behcet's disease
• Chrohn's disease
• Autoimmune glomerulonephritis
• Grave's disease
• Guillain-Barre syndrome (if active)
• Hashimoto's thyroiditis
• Autoimmune polymyositis or polymyalgia (fibromyalgia is OK)
• Myasthenia gravis
• Narcolepsy
• Polyarteritis nodosa
• Scleroderma
• Sjogren's syndrome
• Transverse myelitis
• Wegener's granulomatosis
• HIstory of seizures (only childhood febrile seizures allowed)
• (HIV and Hepatitis are OK if stable)
• Systolic blood pressure > 150 and/or diastolic blood pressure >90 at screening
• A Corrected QT Interval (QTc) > 480 msec as determined by an ECG