Dimethyl Fumarate Prevents HIV-Induced Lysosomal Dysfunction and Cathepsin B Release from Macrophages

Abstract

HIV-associated neurocognitive disorders (HAND) are prevalent despite combined antiretroviral therapy, affecting nearly half of HIV-infected patients worldwide. During HIV infection of macrophages secretion of the lysosomal protein, cathepsin B, is increased. Secreted cathepsin B has been shown to induce neurotoxicity. Oxidative stress is increased in HIV-infected patients, while antioxidants are decreased in monocytes from patients with HIV-associated dementia (HAD). Dimethyl fumarate (DMF), an antioxidant, has been reported to decrease HIV replication and neurotoxicity mediated by HIV-infected macrophages. Thus, we hypothesized that DMF will decrease cathepsin B release from HIV-infected macrophages by preventing oxidative stress and enhancing lysosomal function. Monocyte-derived macrophages (MDM) were isolated from healthy donors, inoculated with HIV-1 and treated with DMF following virus removal. After 12 days post-infection, HIV-1 p24 and total cathepsin B levels were measured from HIV-infected MDM supernatants using ELISA; intracellular reactive oxygen and nitrogen species (ROS/RNS) were measured from MDM lysates, and functional lysosomes were assessed using a pH-dependent lysosomal dye. Neurons were incubated with serum-free conditioned media from DMF-treated MDM and neurotoxicity was determined using TUNEL assay. Results indicate that DMF reduced HIV-1 replication and cathepsin B secretion from HIV-infected macrophages in a dose-dependent manner. Also, DMF decreased intracellular ROS/RNS levels, and prevented HIV-induced lysosomal dysfunction and neuronal apoptosis. In conclusion, the improvement in lysosomal function with DMF treatment may represent the possible mechanism to reduce HIV-1 replication and cathepsin B secretion. DMF represents a potential therapeutic strategy against HAND.

Cannabinoid receptor type 2 agonist JWH-133 decreases cathepsin B secretion and neurotoxicity from HIV-infected macrophages

“…3). In a recent study, we demonstrated that CATB secretion from HIV-infected MDM was associated with oxidative stress 9 . Additionally, in recent studies we have demonstrated that MDM cultures with increased CATB secretion after HIV infection induce significant neuronal apoptosis, whereas MDM cultures with decreased CATB secretion after HIV infection fails to induce significant neuronal apoptosis (Zenon et al, in press).…”

“…We hypothesize that the intracellular mechanism by which JWH-133 decreases CATB secretion from HIV-infected macrophages after activation of CB2R is by reducing oxidative stress. This hypothesis is formulated based on a recent study in our laboratory in which we demonstrated that dimethyl fumarate, an antioxidant, decreases oxidative stress and CATB secretion from HIV-infected MDM 9 . Moreover, CB2R activation inhibits oxidative stress in macrophages 50 – 52 .…”

“…MDM viability was assessed at day 13pi, as previously described by our laboratory 9 . In summary, we used 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay (Sigma; St Louis, MO), following manufacturer instructions.…”

Potential pharmacological approaches for the treatment of HIV-1 associated neurocognitive disorders

“…Primary cultures of rat astrocytes exposed to gp120 [118] Not HIV patients on stable cART [258] HIV+ patients with HAND [259,260] IFN therapy IFNβ Primary human fetal microglia infected with HIV-1 [270] Transgenic gp120 mice [271] Rat cerebrocortical cultures exposed to gp120 [271] B18R Not evaluated to date HIVE SCID mice [187,278,279] Fumaric acid derivatives Monomethyl fumarate Primary human astrocytes cocultured with HIV-1 transduced monocytoid cells [339] Not evaluated to date DMF HIV-1 infected human monocytes [281] Not evaluated to date Primary rat neurons exposed to HIV-1 infect human monocytes [281,340] Human neuronal cells exposed to HIV infected human macrophages and neuroblastoma cells [285] and pioglitazone have been clinically proven as effective treatments for type 2 diabetes [221]. There is ample evidence suggesting that targeting the PPAR family is neuroprotective in several animal models of neurological disorders [222][223][224].…”

“…One of the most recent studies investigating DMF and its possible role in treating HAND looks at lysosomal dysfunction and the release of neurotoxic cathepsin B from infected macrophages. Increased cathepsin B release has been evidenced in HIV-infected macrophages and promotes neuronal apoptosis [ 282 – 284 ] and infected macrophages treated with DMF showed decreases in HIV-1 replication, cathepsin B secretion and ROS/RNS production [ 285 ]. DMF has consistently shown evidence of reducing HIV-1 replication in macrophages and inhibiting the release of neurotoxic compounds in vitro, but conflicting results on neuronal cell viability prevents a definitive conclusion of DMF’s role in HAND therapy.…”