Targeting Neuroinflammation by Pharmacologic Downregulation of Inflammatory Pathways Is Neuroprotective in Protein Misfolding Disorders

Abstract

Neuroinflammation plays a crucial role in the development of neurodegenerative protein misfolding disorders. This category of progressive diseases includes, but is not limited to, Alzheimer's disease, Parkinson's disease, and prion diseases. Shared pathogenesis involves the accumulation of misfolded proteins, chronic neuroinflammation, and synaptic dysfunction, ultimately leading to irreversible neuronal loss, measurable cognitive deficits, and death. Presently, there are few to no effective treatments to halt the advancement of neurodegenerative diseases. We hypothesized that directly targeting neuroinflammation by downregulating the transcription factor, NF-κB, and the inflammasome protein, NLRP3, would be neuroprotective. To achieve this, we used a cocktail of RNA targeting therapeutics (SB_NI_112) shown to be brain-penetrant, nontoxic, and effective inhibitors of both NF-κB and NLRP3. We utilized a mouse-adapted prion strain as a model for neurodegenerative diseases to assess the aggregation of misfolded proteins, glial inflammation, neuronal loss, cognitive deficits, and lifespan. Prion-diseased mice were treated either intraperitoneally or intranasally with SB_NI_112. Behavioral and cognitive deficits were significantly protected by this combination of NF-κB and NLRP3 downregulators. Treatment reduced glial inflammation, protected against neuronal loss, prevented spongiotic change, rescued cognitive deficits, and significantly lengthened the lifespan of prion-diseased mice. We have identified a nontoxic, systemic pharmacologic that downregulates NF-κB and NLRP3, prevents neuronal death, and slows the progression of neurodegenerative diseases. Though mouse models do not always predict human patient success and the study was limited due to sample size and number of dosing methods utilized, these findings serve as a proof of principle for continued translation of the therapeutic SB_NI_112 for prion disease and other neurodegenerative diseases. Based on the success in a murine prion model, we will continue testing SB_NI_112 in a variety of neurodegenerative disease models, including Alzheimer's disease and Parkinson's disease.

Targeted-Neuroinflammation Mitigation Using Inflammasome-Inhibiting Nanoligomers is Therapeutic in an Experimental Autoimmune Encephalomyelitis Mouse Model

“…This is highly significant because so far, NF-κB1 has been considered an “undruggable” target, , and these results further highlight the advantages of the Nanoligomer targeting approach as opposed to traditional small-molecules and antibody-based therapeutic discovery. Further, other potential targets that could be synergistic with this key transcription factor, NF-κB1, were screened: (1) combination of NF-κB1 and TNF receptor (TNFR1) downregulator (SB_NI_111 or renamed as NI111); and (2) combination of NF-κB1 and NLRP3 inflammasome downregulator (SB_NI_112 or renamed as NI112) . These were termed as Nanoligomer combinations NI111 and NI112, respectively, and subsequently screened in the human brain organoid model ( in vitro ) and EAE model for MS ( in vivo ), to assess their preclinical efficacy for MS treatment and identify molecular mechanisms that can be neuro- and myelin-protective.…”

“…Since IL-6 is involved in a number of biological functions in immunity, tissue regeneration, and metabolism, − due to potential for side-effects in further screening, our algorithm , identified NF-κB1 as the top target. We will conduct additional safety–toxicity assessment using animal models, − before prioritizing and further testing of IL-6 inhibiting Nanoligomer. Therefore, after screening several targets to identify key nodes involved in the downregulation of neurotoxic chronic inflammasome activation, NF-κB1 was identified as the key single target that could restore innate immune response to the nonactivated state.…”

“…Nanoligomers were specifically designed and synthesized (Sachi Bio) following established methods detailed in published references. − The Nanoligomers are composed of an antisense peptide nucleic acid (PNA) − , conjugated to a gold nanoparticle. − The 17-base-long PNA sequence was selected to optimize solubility and specificity, targeting the start codon regions of nfkb1 (Sequence: AGTGGTACCGTCTGCTA) and nlrp3 (Sequence: CTTCTACTGCTCACAGG), within the Mouse genome (GCF_000001635.27), identified using our bioinformatics toolbox . Various PNA sequences were screened for their solubility, self-complementing sequences, and potential off-target interactions within the mouse genome (GCF_000001635.27).…”

“…The Nanoligomer therapeutic platform generates gold nanoparticle-bound peptide nucleic acid (PNA) molecules to regulate any desired gene in a safe, effective, and targeted manner. − PNAs demonstrate strong hybridization and specificity to their targets compared to naturally occurring RNA or DNA, and they exhibit no known enzymatic cleavage, leading to increased stability in human blood serum and mammalian cellular extracts . These advantages make PNAs a promising choice for expression-modifying therapeutics.…”

“…Nanoligomers designed to inhibit the translation of target mRNAs simply bind the mRNA which prevents access to ribosomes. The low K D (∼5 nM ,, ), high binding specificity, minimal off-targeting, , high safety profile, lack of any immunogenic response or accumulation in first pass organs, absence of any observable histological damage to organs even for long (>15–20 weeks) treatments, − and facile delivery to the brain to counter neuroinflammation , make Nanoligomers and specifically the NI112 cocktail a safe and targeted approach to mitigate neuropathological microglial and astrocytic activation.…”