Risk of Neuroinflammatory Diseases Among New Recipients of Biologic and Targeted Synthetic Disease-Modifying Antirheumatic Drugs.

OBJECTIVE: Neuroinflammatory adverse events have been observed among new users of tumor necrosis factor (TNF) inhibitors. No studies to date have compared the real-world risk of TNFs with other new users of biologic or targeted synthetic disease-modifying antirheumatic drugs (b/tsDMARDs). The objective of this study is to describe the risk of neuroinflammatory disease after initiation b/tsDMARDs. METHODS: This new user comparative effectiveness cohort study used a large US-based electronic health records database to describe the unadjusted incidence of neuroinflammatory adverse events over a 3-year period. The cohort included patients with rheumatoid arthritis, psoriasis, psoriatic arthritis, ankylosing spondylitis, Crohn's disease, or ulcerative colitis initiating treatment with a TNF inhibitor (n = 93,661) or other b/tsDMARD (n = 38,354). RESULTS: Among 132,015 patients included in the analysis, the most common first biologic agent was a TNF inhibitor; the unadjusted incidence of neuroinflammatory events was numerically lower among new users of TNF inhibitors (incidence 1.34 per 1,000 patient-years) as compared with the combined non-TNF group (1.69 per 1,000 patient-years). There was no significant association between TNF exposure and neuroinflammatory events as compared with the combined non-TNF b/tsDMARDs overall (hazard ratio 1.01; 95% confidence interval 0.75-1.36) and within each disease group. CONCLUSION: The overall risk of neuroinflammatory events among new users of TNF inhibitors did not differ substantially as compared with new users of other b/tsDMARDs. Meta-analyses of randomized trials should be conducted to corroborate these findings, which may be affected by channeling bias.

Mechanism of liponecrosis, a distinct mode of programmed cell death.

An exposure of the yeast Saccharomyces cerevisiae to exogenous palmitoleic acid (POA) elicits "liponecrosis," a mode of programmed cell death (PCD) which differs from the currently known PCD subroutines. Here, we report the following mechanism for liponecrotic PCD. Exogenously added POA is incorporated into POA-containing phospholipids that then amass in the endoplasmic reticulum membrane, mitochondrial membranes and the plasma membrane. The buildup of the POA-containing phospholipids in the plasma membrane reduces the level of phosphatidylethanolamine in its extracellular leaflet, thereby increasing plasma membrane permeability for small molecules and committing yeast to liponecrotic PCD. The excessive accumulation of POA-containing phospholipids in mitochondrial membranes impairs mitochondrial functionality and causes the excessive production of reactive oxygen species in mitochondria. The resulting rise in cellular reactive oxygen species above a critical level contributes to the commitment of yeast to liponecrotic PCD by: (1) oxidatively damaging numerous cellular organelles, thereby triggering their massive macroautophagic degradation; and (2) oxidatively damaging various cellular proteins, thus impairing cellular proteostasis. Several cellular processes in yeast exposed to POA can protect cells from liponecrosis. They include: (1) POA oxidation in peroxisomes, which reduces the flow of POA into phospholipid synthesis pathways; (2) POA incorporation into neutral lipids, which prevents the excessive accumulation of POA-containing phospholipids in cellular membranes; (3) mitophagy, a selective macroautophagic degradation of dysfunctional mitochondria, which sustains a population of functional mitochondria needed for POA incorporation into neutral lipids; and (4) a degradation of damaged, dysfunctional and aggregated cytosolic proteins, which enables the maintenance of cellular proteostasis.