Amyloid-ß specific regulatory T cells attenuate Alzheimer's disease pathobiology in APP/PS1 mice.

BACKGROUND: Regulatory T cells (Tregs) maintain immune tolerance. While Treg-mediated neuroprotective activities are now well-accepted, the lack of defined antigen specificity limits their therapeutic potential. This is notable for neurodegenerative diseases where cell access to injured brain regions is required for disease-specific therapeutic targeting and improved outcomes. To address this need, amyloid-beta (Aß) antigen specificity was conferred to Treg responses by engineering the T cell receptor (TCR) specific for Aß (TCRAß). The TCRAb were developed from disease-specific T cell effector (Teff) clones. The ability of Tregs expressing a transgenic TCRAß (TCRAß -Tregs) to reduce Aß burden, transform effector to regulatory cells, and reverse disease-associated neurotoxicity proved beneficial in an animal model of Alzheimer's disease. METHODS: TCRAß -Tregs were generated by CRISPR-Cas9 knockout of endogenous TCR and consequent incorporation of the transgenic TCRAb identified from Aß reactive Teff monoclones. Antigen specificity was confirmed by MHC-Aß-tetramer staining. Adoptive transfer of TCRAß-Tregs to mice expressing a chimeric mouse-human amyloid precursor protein and a mutant human presenilin-1 followed measured behavior, immune, and immunohistochemical outcomes. RESULTS: TCRAß-Tregs expressed an Aß-specific TCR. Adoptive transfer of TCRAß-Tregs led to sustained immune suppression, reduced microglial reaction, and amyloid loads. 18F-fluorodeoxyglucose radiolabeled TCRAß-Treg homed to the brain facilitating antigen specificity. Reduction in amyloid load was associated with improved cognitive functions. CONCLUSIONS: TCRAß-Tregs reduced amyloid burden, restored brain homeostasis, and improved learning and memory, supporting the increased therapeutic benefit of antigen specific Treg immunotherapy for AD.

Immune senescence in aged APP/PS1 mice.

Objectives: To evaluate the linkage between age and deficits in innate and adaptive immunity which heralds both Alzheimer's disease (AD) onset and progression. The pathobiological events which underlie and tie these outcomes remain not fully understood. Methods: To investigate age-dependent immunity in AD, we evaluated innate and adaptive immunity in coordinate studies of regulatory T cell (Treg) function, T cell frequencies, and microglial integrity. These were assessed in blood, peripheral lymphoid tissues, and the hippocampus of transgenic (Tg) amyloid precursor protein/presenilin 1 (APP/PS1) against non-Tg mice. Additionally, immune arrays of hippocampal tissue were performed at 4, 6, 12, and 20 months of age. Results: APP/PS1 mice showed progressive impairment of Treg immunosuppressive function with age. There was partial restoration of Treg function in 20-month-old mice. Ingenuity pathway analyses of hippocampal tissues were enriched in inflammatory, oxidative, and cellular activation pathways that paralleled advancing age and AD-pathobiology. Operative genes in those pathways included, but were not limited to triggering receptor on myeloid cells 1 (TREM1), T helper type 1 (Th1), and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathways. Interleukin-17 (IL-17), nitric oxide, acute phase, and T cell receptor signaling pathways were also perturbed. Significant inflammation was observed at 6- and 12-months. However, at 20-months, age associated partial restoration of Treg function reduced inflammatory phenotype. Conclusions: Impaired Treg function, inflammation and oxidative stress were associated with AD pathology. Age associated partial restoration of Treg function in old mice reduced the hippocampal inflammatory phenotype. Restoring Treg suppressive function can be a therapeutic modality for AD.

Multipolymer microsphere delivery of SARS-CoV-2 antigens.

Effective antigen delivery facilitates antiviral vaccine success defined by effective immune protective responses against viral exposures. To improve severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) antigen delivery, a controlled biodegradable, stable, biocompatible, and nontoxic polymeric microsphere system was developed for chemically inactivated viral proteins. SARS-CoV-2 proteins encapsulated in polymeric microspheres induced robust antiviral immunity. The viral antigen-loaded microsphere system can preclude the need for repeat administrations, highlighting its potential as an effective vaccine. STATEMENT OF SIGNIFICANCE: Successful SARS-CoV-2 vaccines were developed and quickly approved by the US Food and Drug Administration (FDA). However, each of the vaccines requires boosting as new variants arise. We posit that injectable biodegradable polymers represent a means for the sustained release of emerging viral antigens. The approach offers a means to reduce immunization frequency by predicting viral genomic variability. This strategy could lead to longer-lasting antiviral protective immunity. The current proof-of-concept multipolymer study for SARS-CoV-2 achieve these metrics.

Monocyte biomarkers define sargramostim treatment outcomes for Parkinson's disease.

BACKGROUND: Dysregulation of innate and adaptive immunity heralds both the development and progression of Parkinson's disease (PD). Deficits in innate immunity in PD are defined by impairments in monocyte activation, function, and pro-inflammatory secretory factors. Each influences disease pathobiology. METHODS AND RESULTS: To define monocyte biomarkers associated with immune transformative therapy for PD, changes in gene and protein expression were evaluated before and during treatment with recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF, sargramostim, Leukine® ). Monocytes were recovered after leukapheresis and isolation by centrifugal elutriation, before and 2 and 6 months after initiation of treatment. Transcriptome and proteome biomarkers were scored against clinical motor functions. Pathway enrichments from single cell-RNA sequencing and proteomic analyses from sargramostim-treated PD patients demonstrate a neuroprotective signature, including, but not limited to, antioxidant, anti-inflammatory, and autophagy genes and proteins (LRRK2, HMOX1, TLR2, TLR8, RELA, ATG7, and GABARAPL2). CONCLUSIONS: This monocyte profile provides an "early" and unique biomarker strategy to track clinical immune-based interventions, but requiring validation in larger case studies.

Development of an extended half-life GM-CSF fusion protein for Parkinson's disease.

Transformation of CD4+ T cell effector to regulatory (Teff to Treg) cells have been shown to attenuate disease progression by restoring immunological balance during the onset and progression of neurodegenerative diseases. In our prior studies, we defined a safe and effective pathway to restore this balance by restoring Treg numbers and function through the daily administration of the cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF). These studies were conducted as a proof-of-concept testing in Parkinson's disease (PD) preclinical models and early phase I clinical investigations. In both instances, they served to ameliorate disease associated signs and symptoms. However, despite the recorded efficacy, the cytokine's short half-life, low bioavailability, and injection site reactions proved to be limitations for any broader use. To overcome these limitations, mRNA lipid nanoparticles encoding an extended half-life albumin-GM-CSF fusion protein were developed for both mouse (Msa-GM-CSF) and rat (Rsa-GM-CSF). These formulations were tested for immunomodulatory and neuroprotective efficacy using 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and human wild-type alpha-synuclein (αSyn) overexpression preclinical models of PD. A single dose of the extended half-life mouse and rat mRNA lipid nanoparticles generated measurable GM-CSF plasma cytokine levels up to four days. Increased Treg frequency and function were associated with a resting microglial phenotype, nigrostriatal neuroprotection, and restoration of brain tissue immune homeostasis. These findings were substantively beyond the recorded efficacy of daily recombinant wild-type GM-CSF with a recorded half-life of six hours. Mechanistic evaluation of neuropathological transcriptional profiles performed in the disease-affected nigral brain region demonstrated an upregulation of neuroprotective CREB and synaptogenesis signaling and neurovascular coupling pathways. These findings highlight the mRNA-encoded albumin GM-CSF fusion protein modification linked to improvements in therapeutic efficacy. The improvements achieved were associated with the medicine's increased bioavailability. Taken together, the data demonstrate that mRNA LNP encoding the extended half-life albumin-GM-CSF fusion protein can serve as a benchmark for PD immune-based therapeutics. This is especially notable for improving adherence of drug regimens in a disease-affected patient population with known tremors and gait abnormalities.

Protective Effect of CP690550 in MPTP-Induced Parkinson's Like Behavioural, Biochemical and Histological Alterations in Mice.

Janus-activated kinases (JAKs) are well known to play a physiological as well as pathological role in several disease conditions such as autoimmune disorders. The present study evaluated the therapeutic potential of CP690550 (pan-JAK inhibitor) in 1-methyl-4-phenyl-1,2,3,6-tertahydropyridine (MPTP) model of Parkinson's disease. Intrastriatal administration of MPTP (30 micromol in 2 microl) produced a significant alteration in behavioural (bar test and block test). Biochemical investigations in serum and brain homogenate revealed a significant alteration in the JAK-mediated cytokine levels. MPTP administration also showed significant imbalance of inflammatory (increased TNF-α, IL-6 and NF-κb) versus anti-inflammatory cytokines (decreased IL-10 levels). MPTP-treated brain sections revealed alteration in the tissue architecture as well as undifferentiated bodies of varying contour and lesions. Chronic administration of CP690550 (3 and 10 mg/kg, po) for 7 days significantly reversed the behavioural, biochemical and histological alterations induced by MPTP. In conclusion, the findings of the present study govern the possible therapeutic potential of CP690550 in MPTP-treated mice and thus highlight the therapeutic potential of JAK inhibitors in treatment of Parkinson's disease.

Europium-Doped Cerium Oxide Nanoparticles for Microglial Amyloid Beta Clearance and Homeostasis.

Alzheimer's disease (AD) is the most common neurodegenerative disorder. Pathologically, the disease is characterized by the deposition of amyloid beta (Aß) plaques and the presence of neurofibrillary tangles. These drive microglia neuroinflammation and consequent neurodegeneration. While the means to affect Aß plaque accumulation pharmacologically was achieved, how it affects disease outcomes remains uncertain. Cerium oxide (CeO2) reduces Aß plaques, oxidative stress, inflammation, and AD signs and symptoms. In particular, CeO2 nanoparticles (CeO2NPs) induce free-radical-scavenging and cell protective intracellular signaling. This can ameliorate the pathobiology of an AD-affected brain. To investigate whether CeO2NPs affect microglia neurotoxic responses, a novel formulation of europium-doped CeO2NPs (EuCeO2NPs) was synthesized. We then tested EuCeO2NPs for its ability to generate cellular immune homeostasis in AD models. EuCeO2NPs attenuated microglia BV2 inflammatory activities after Aß1-42 exposure by increasing the cells' phagocytic and Aß degradation activities. These were associated with increases in the expression of the CD36 scavenger receptor. EuCeO2NPs facilitated Aß endolysosomal trafficking and abrogated microglial inflammatory responses. We posit that EuCeO2NPs may be developed as an AD immunomodulator.

Prodrug Therapies for Infectious and Neurodegenerative Diseases.

Prodrugs are bioreversible drug derivatives which are metabolized into a pharmacologically active drug following chemical or enzymatic modification. This approach is designed to overcome several obstacles that are faced by the parent drug in physiological conditions that include rapid drug metabolism, poor solubility, permeability, and suboptimal pharmacokinetic and pharmacodynamic profiles. These suboptimal physicochemical features can lead to rapid drug elimination, systemic toxicities, and limited drug-targeting to disease-affected tissue. Improving upon these properties can be accomplished by a prodrug design that includes the careful choosing of the promoiety, the linker, the prodrug synthesis, and targeting decorations. We now provide an overview of recent developments and applications of prodrugs for treating neurodegenerative, inflammatory, and infectious diseases. Disease interplay reflects that microbial infections and consequent inflammation affects neurodegenerative diseases and vice versa, independent of aging. Given the high prevalence, personal, social, and economic burden of both infectious and neurodegenerative disorders, therapeutic improvements are immediately needed. Prodrugs are an important, and might be said a critical tool, in providing an avenue for effective drug therapy.

Interleukin-2 expands neuroprotective regulatory T cells in Parkinson's disease.

Background: Pharmacological approaches that boost neuroprotective regulatory T cell (Treg) number and function lead to neuroprotective activities in neurodegenerative disorders. Objectives: We investigated whether low-dose interleukin 2 (IL-2) expands Treg populations and protects nigrostriatal dopaminergic neurons in a model of Parkinson's disease (PD). Methods: IL-2 at 2.5 × 104 IU/dose/mouse was administered for 5 days. Lymphocytes were isolated and phenotype determined by flow cytometric analyses. To 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) intoxicated mice, 0.5 × 106 of enriched IL-2-induced Tregs were adoptively transferred to assess the effects on nigrostriatal neuron survival. Results: IL-2 increased frequencies of CD4+CD25+CD127lowFoxP3+ Tregs that express ICOS and CD39 in blood and spleen. Adoptive transfer of IL-2-induced Tregs to MPTP-treated recipients increased tyrosine hydroxylase (TH)+ nigral dopaminergic neuronal bodies by 51% and TH+ striatal termini by 52% compared to control MPTP-treated animal controls. Conclusions: IL-2 expands numbers of neuroprotective Tregs providing a vehicle for neuroprotection of nigrostriatal dopaminergic neurons in a pre-clinical PD model.

CD4+ effector T cells accelerate Alzheimer's disease in mice.

BACKGROUND: Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by pathological deposition of misfolded self-protein amyloid beta (Aß) which in kind facilitates tau aggregation and neurodegeneration. Neuroinflammation is accepted as a key disease driver caused by innate microglia activation. Recently, adaptive immune alterations have been uncovered that begin early and persist throughout the disease. How these occur and whether they can be harnessed to halt disease progress is unclear. We propose that self-antigens would induct autoreactive effector T cells (Teffs) that drive pro-inflammatory and neurodestructive immunity leading to cognitive impairments. Here, we investigated the role of effector immunity and how it could affect cellular-level disease pathobiology in an AD animal model. METHODS: In this report, we developed and characterized cloned lines of amyloid beta (Aß) reactive type 1 T helper (Th1) and type 17 Th (Th17) cells to study their role in AD pathogenesis. The cellular phenotype and antigen-specificity of Aß-specific Th1 and Th17 clones were confirmed using flow cytometry, immunoblot staining and Aß T cell epitope loaded haplotype-matched major histocompatibility complex II IAb (MHCII-IAb-KLVFFAEDVGSNKGA) tetramer binding. Aß-Th1 and Aß-Th17 clones were adoptively transferred into APP/PS1 double-transgenic mice expressing chimeric mouse/human amyloid precursor protein and mutant human presenilin 1, and the mice were assessed for memory impairments. Finally, blood, spleen, lymph nodes and brain were harvested for immunological, biochemical, and histological analyses. RESULTS: The propagated Aß-Th1 and Aß-Th17 clones were confirmed stable and long-lived. Treatment of APP/PS1 mice with Aß reactive Teffs accelerated memory impairment and systemic inflammation, increased amyloid burden, elevated microglia activation, and exacerbated neuroinflammation. Both Th1 and Th17 Aß-reactive Teffs progressed AD pathology by downregulating anti-inflammatory and immunosuppressive regulatory T cells (Tregs) as recorded in the periphery and within the central nervous system. CONCLUSIONS: These results underscore an important pathological role for CD4+ Teffs in AD progression. We posit that aberrant disease-associated effector T cell immune responses can be controlled. One solution is by Aß reactive Tregs.

Defining the Innate Immune Responses for SARS-CoV-2-Human Macrophage Interactions.

Host innate immune response follows severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, and it is the driver of the acute respiratory distress syndrome (ARDS) amongst other inflammatory end-organ morbidities. Such life-threatening coronavirus disease 2019 (COVID-19) is heralded by virus-induced activation of mononuclear phagocytes (MPs; monocytes, macrophages, and dendritic cells). MPs play substantial roles in aberrant immune secretory activities affecting profound systemic inflammation and end-organ malfunctions. All follow the presence of persistent viral components and virions without evidence of viral replication. To elucidate SARS-CoV-2-MP interactions we investigated transcriptomic and proteomic profiles of human monocyte-derived macrophages. While expression of the SARS-CoV-2 receptor, the angiotensin-converting enzyme 2, paralleled monocyte-macrophage differentiation, it failed to affect productive viral infection. In contrast, simple macrophage viral exposure led to robust pro-inflammatory cytokine and chemokine expression but attenuated type I interferon (IFN) activity. Both paralleled dysregulation of innate immune signaling pathways, specifically those linked to IFN. We conclude that the SARS-CoV-2-infected host mounts a robust innate immune response characterized by a pro-inflammatory storm heralding end-organ tissue damage.

Defining the Immune Responses for SARS-CoV-2-Human Macrophage Interactions.

Host innate immune response follows severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, and it is the driver of the acute respiratory distress syndrome (ARDS) amongst other inflammatory end-organ morbidities. Such life-threatening coronavirus disease 2019 (COVID-19) is heralded by virus-induced activation of mononuclear phagocytes (MPs; monocytes, macrophages, and dendritic cells). MPs play substantial roles in aberrant immune secretory activities affecting profound systemic inflammation and end organ malfunctions. All follow an abortive viral infection. To elucidate SARS-CoV-2-MP interactions we investigated transcriptomic and proteomic profiles of human monocyte-derived macrophages. While expression of the SARS-CoV-2 receptor, the angiotensin-converting enzyme 2, paralleled monocyte-macrophage differentiation it failed to affect productive viral infection. In contrast, simple macrophage viral exposure led to robust pro-inflammatory cytokine and chemokine expression but attenuated type I interferon (IFN) activity. Both paralleled dysregulation of innate immune signaling pathways specifically those linked to IFN. We conclude that the SARS-CoV-2-infected host mounts a robust innate immune response characterized by a pro-inflammatory storm heralding consequent end-organ tissue damage.

A Role for Extracellular Vesicles in SARS-CoV-2 Therapeutics and Prevention.

Extracellular vesicles (EVs) are the common designation for ectosomes, microparticles and microvesicles serving dominant roles in intercellular communication. Both viable and dying cells release EVs to the extracellular environment for transfer of cell, immune and infectious materials. Defined morphologically as lipid bi-layered structures EVs show molecular, biochemical, distribution, and entry mechanisms similar to viruses within cells and tissues. In recent years their functional capacities have been harnessed to deliver biomolecules and drugs and immunological agents to specific cells and organs of interest or disease. Interest in EVs as putative vaccines or drug delivery vehicles are substantial. The vesicles have properties of receptors nanoassembly on their surface. EVs can interact with specific immunocytes that include antigen presenting cells (dendritic cells and other mononuclear phagocytes) to elicit immune responses or affect tissue and cellular homeostasis or disease. Due to potential advantages like biocompatibility, biodegradation and efficient immune activation, EVs have gained attraction for the development of treatment or a vaccine system against the severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) infection. In this review efforts to use EVs to contain SARS CoV-2 and affect the current viral pandemic are discussed. An emphasis is made on mesenchymal stem cell derived EVs' as a vaccine candidate delivery system.

Nanocarrier vaccines for SARS-CoV-2.

The SARS-CoV-2 global pandemic has seen rapid spread, disease morbidities and death associated with substantive social, economic and societal impacts. Treatments rely on re-purposed antivirals and immune modulatory agents focusing on attenuating the acute respiratory distress syndrome. No curative therapies exist. Vaccines remain the best hope for disease control and the principal global effort to end the pandemic. Herein, we summarize those developments with a focus on the role played by nanocarrier delivery.

Surface conjugation of EP67 to biodegradable nanoparticles increases the generation of long-lived mucosal and systemic memory T-cells by encapsulated protein vaccine after respiratory immunization and subsequent T-cell-mediated protection against respiratory infection.

Encapsulation of protein vaccines in biodegradable nanoparticles (NP) increases T-cell expansion after mucosal immunization but requires incorporating a suitable immunostimulant to increase long-lived memory T-cells. EP67 is a clinically viable, host-derived peptide agonist of the C5a receptor that selectively activates antigen presenting cells over neutrophils. We previously found that encapsulating EP67-conjugated CTL peptide vaccines in NP increases long-lived memory subsets of CTL after respiratory immunization. Thus, we hypothesized that alternatively conjugating EP67 to the NP surface can increase long-lived mucosal and systemic memory T-cells generated by encapsulated protein vaccines. We found that respiratory immunization of naïve female C57BL/6 mice with LPS-free ovalbumin (OVA) encapsulated in PLGA 50:50 NP (∼380 nm diameter) surface-conjugated with ∼0.1 wt% EP67 through 2 kDa PEG linkers (i) increased T-cell expansion and long-lived memory subsets of OVA323-339-specific CD4+ and OVA257-264-specific CD8a+ T-cells in the lungs (CD44HI/CD127/KLRG1) and spleen (CD44HI/CD127/KLRG1/CD62L) and (ii) decreased peak CFU of OVA-expressing L. monocytogenes (LM-OVA) in the lungs, liver, and spleen after respiratory challenge vs. encapsulation in unmodified NP. Thus, conjugating EP67 to the NP surface is one approach to increase the generation of long-lived mucosal and systemic memory T-cells by encapsulated protein vaccines after respiratory immunization.

Encapsulation of an EP67-Conjugated CTL Peptide Vaccine in Nanoscale Biodegradable Particles Increases the Efficacy of Respiratory Immunization and Affects the Magnitude and Memory Subsets of Vaccine-Generated Mucosal and Systemic CD8+ T Cells in a Diameter-Dependent Manner.

The diameter of biodegradable particles used to coencapsulate immunostimulants and subunit vaccines affects the magnitude of memory CD8+ T cells generated by systemic immunization. Possible effects on the magnitude of CD8+ T cells generated by mucosal immunization or memory subsets that potentially correlate more strongly with protection against certain pathogens, however, are unknown. In this study, we conjugated our novel host-derived mucosal immunostimulant, EP67, to the protective MCMV CTL epitope, pp89, through a lysosomal protease-labile double arginine linker (pp89-RR-EP67) and encapsulated in PLGA 50:50 micro- or nanoparticles. We then compared total magnitude, effector/central memory (CD127/KRLG1/CD62L), and IFN-γ/TNF-α/IL-2 secreting subsets of pp89-specific CD8+ T cells as well as protection of naive female BALB/c mice against primary respiratory infection with MCMV 21 days after respiratory immunization. We found that decreasing the diameter of encapsulating particle from ∼5.4 µm to ∼350 nm (i) increased the magnitude of pp89-specific CD8+ T cells in the lungs and spleen; (ii) partially changed CD127/KLRG1 effector memory subsets in the lungs but not the spleen; (iii) changed CD127/KRLG1/CD62L effector/central memory subsets in the spleen; (iv) changed pp89-responsive IFN-γ/TNF-α/IL-2 secreting subsets in the lungs and spleen; (v) did not affect the extent to which encapsulation increased efficacy against primary MCMV respiratory infection over unencapsulated pp89-RR-EP67. Thus, although not observed under our current experimental conditions with MCMV, varying the diameter of nanoscale biodegradable particles may increase the efficacy of mucosal immunization with coencapsulated immunostimulant/subunit vaccines against certain pathogens by selectively increasing memory subset(s) of CD8+ T cells that correlate the strongest with protection.