Baricitinib reverses HIV-associated neurocognitive disorders in a SCID mouse model and reservoir seeding in vitro

Abstract

Background: Since HIV-associated neurocognitive disorders (HANDs) occur in up to half of HIV-positive individuals, even with combined antiretroviral therapy (cART), adjunctive therapies are needed. Chronic CNS inflammation contributes to HAND and HIV encephalitis (HIVE). Baricitinib is a JAK 1/2 inhibitor approved in the USA, EU, and Japan for rheumatoid arthritis, demonstrating potent inhibition of IL-6, D-dimer, CRP, TNF-α, IFN-α/β, and other pro-inflammatory cytokines.

Methods: Our modified murine HAND model was used to evaluate the ability of baricitinib to cross the blood-brain barrier (BBB) and modulate monocyte/macrophage-driven HAND. Severity of HAND was measured by assessing cognitive performance of low- and high-dose baricitinib treated versus untreated HAND mice. The severity of brain neuroinflammation was evaluated in these mouse groups after flow cytometric analyses. We also assessed the ability of baricitinib to block events in myeloid and lymphoid cells in vitro that may undergird the persistence of HIV in the central nervous system (CNS) in primary human macrophages (Mϕ) and lymphocytes including HIV replication, HIV-induced activation, reservoir expansion, and reservoir maintenance.

Results: In vivo, both doses of 10 and 50 mg/kg qd baricitinib crossed the BBB and reversed behavioral abnormalities conferred by HIV infection. Moreover, baricitinib significantly reduced HIV-induced neuroinflammation marked by glial activation: activated microglia (MHCII⁺/CD45⁺) and astrogliosis (GFAP). Baricitinib also significantly reduced the percentage of p24+ human macrophages in mouse brains (p < 0.05 versus HAND mice; t test). In vitro, baricitinib significantly reduced markers of persistence, reservoir size, and reseeding in Mϕ.

Conclusion: These results show that blocking the JAK/STAT pathway reverses cognitive deficits and curtails inflammatory markers in HAND in mice. Our group recently reported safety and tolerability of ruxolitinib in HIV-infected individuals (Marconi et al., Safety, tolerability and immunologic activity of ruxolitinib added to suppressive ART, 2019), underscoring potential safety and utility of JAK inhibitors for additional human trials. The data reported herein coupled with our recent human trial with JAK inhibitors provide compelling preclinical data and impetus for considering a trial of baricitinib in HAND individuals treated with cART to reverse cognitive deficits and key events driving viral persistence.

Keywords: Baricitinib; HIV-associated neurocognitive disorders; JAK inhibitor; Mononuclear phagocytes; Neuroinflammation; Object recognition testing.

Fig. 1

Schematic diagram showing the SCID mouse HAND model and ORT paradigm used

Fig. 2

Pharmacokinetics of baricitinib in mice plasma or brains. Baricitinib concentrations in plasma (a, ng/mL) and brain (b, ng/g tissue), versus time after single SC of 10 (black circles) or 50 (red triangles) mg/kg. Each data point represents a mouse. Dashed curves were plotted through the averaged data from each time point

Fig. 3

Baricitinib reverses behavioral abnormalities conferred by HIV in vivo. Discrimination index for novel object testing on days 5 and 6 (5 min delay or 2 h delay, a and b respectively) demonstrates that HAND (HIV) mice (untreated) cannot discriminate novel versus familiar object. However, uninfected control mice can discriminate. Day 12 and 13 ORT data demonstrate that uninfected mice can discriminate between novel and familiar objects; HIV infection significantly reduces ability of mice to discriminate between novel and familiar objects (c, d). Ten milligrams per kilogram and 50 mg/kg baricitinib restore the ability to discriminate to the level of the control mice (c, d). *p < 0.01, **p < 0.001. HAND (HIV) mice were compared to sham controls, and treated groups were compared to HAND (HIV) group

Fig. 4

HIV induction of activation markers in vivo. Experimental mice were separated into four groups: control, HIV-infected, HIV-infected treated with low-dose baricitinib (10 mg/kg), and HIV-infected treated with high-dose baricitinib (50 mg/kg). Mice were sacrificed 14 days after infection, and brain samples were homogenized and assessed for encephalitis markers and viral protein using flow cytometry. a CD45/MHCII double staining as mononuclear phagocyte activation markers. b Activated p24+ human macrophages. c Activated astrocytes. **p < 0.001

Fig. 5

Correlation analysis of inflammatory markers with discrimination index and between different inflammatory markers. a–c Linear regression plots show correlations of discrimination index with different inflammatory markers. a Correlation of discrimination index with mononuclear cell activation markers with viral burden (b) and with astrogliosis marker (c). d–f Correlations between different inflammatory markers as well as viral burden. d Viral burden and mononuclear cell activation. e Astrogliosis and mononuclear cell activation. f Viral burden and astrogliosis

Fig. 6

Baricitinib blocks reservoir establishment, maintenance, and expansion in primary human T cells and macrophages. Baricitinib demonstrates nanomolar inhibition of HIV replication in primary human macrophages and T cells, block of HIV-induced activation in macrophages, and HIV reactivation in T cells and macrophages (a). The concentrations that confer these anti-HIV effects are within the steady-state concentration range for approved doses of baricitinib in humans (b). Individual dose responses for data reported appear in Additional file 1: Figure S1