Photo-Oxygenation as a New Therapeutic Strategy for Neurodegenerative Proteinopathies by Enhancing the Clearance of Amyloid Proteins

Alzheimer disease (AD) is associated with the aggregation of two amyloid proteins: tau and amyloid-β (Aβ). The results of immunotherapies have shown that enhancing the clearance and suppressing the aggregation of these two proteins are effective therapeutic strategies for AD. We have developed photocatalysts that attach oxygen atoms to Aβ and tau aggregates via light irradiation. Photo-oxygenation of these amyloid aggregates reduced their neurotoxicity by suppressing their aggregation both in vitro and in vivo. Furthermore, photo-oxygenation enhanced the clearance of Aβ in the brain and microglial cells. Here, we describe the effects of photo-oxygenation on tau and Aβ aggregation, and the potential of photo-oxygenation as a therapeutic strategy for AD, acting via microglial clearance.

Association with sagittal alignment and osteoporosis-related fractures in outpatient women with osteoporosis

The baseline sagittal vertical axis (SVA) and pelvic tilt (PT) are independent risk factors of osteoporosis-related fractures in women with osteoporosis. We clarified the SVA and PT to predict the incidence of osteoporosis-related fractures.

PURPOSE

Sagittal alignment with osteoporosis women deteriorates with advancing age and sagittal alignment may indicate osteoporosis-related fractures in the future. However, whether the sagittal alignment predicts future osteoporosis-related fracture in patients with osteoporosis has not been clarified. We aimed to investigate the association between sagittal alignment and future osteoporosis-related fractures.

METHODS

This was a retrospective cohort study. Of the 313 participants (mean follow-up period, 2.9 years), 236 were included in the analysis. At baseline, we measured bone mineral density (BMD) of the lumbar spine and the femoral neck, sagittal vertical axis (SVA), thoracic kyphosis, pelvic incidence minus lumbar lordosis, sacral slope, pelvic tilt (PT), geriatric locomotive function scale (GLFS), two-step value, and stand-up test. The information on medications and the duration of treatment were reviewed from the medical records. Additionally, participants reported their history of falls at baseline. Multiple logistic regression analysis was used to determine the association of future osteoporosis-related fracture, and adjusted Odds ratios (OR) and 95% confidence interval (CI) were calculated with all predictors as covariates. All continuous variables were calculated using standardized OR (sOR).

RESULTS

Osteoporosis-related fractures occurred in 33 of 313 participants (10.5%). Multiple logistic regression analysis showed that a history of falls (OR =4.092, 95% CI: 1.029-16.265, p =0.045), SVA (sOR =4.228, 95% CI: 2.118-8.439, p <0.001), and PT (sOR =2.497, 95% CI: 1.087-5.733, p =0.031) were independent risk factors for future osteoporosis-related fractures.

CONCLUSIONS

This study revealed the SVA and PT to predict osteoporosis-related fractures.

TRIAL REGISTRATION NUMBER AND DATE OF REGISTRATION

UMIN000036516 (April 1, 2019).

A Catalytic Alkylation of Ketones via sp3 C-H Bond Activation

We identified a ternary hybrid catalyst system composed of an acridinium photoredox catalyst, a thiophosphoric imide (TPI) catalyst, and a titanium complex catalyst that promoted an intermolecular addition reaction of organic molecules with various ketones through sp³ C-H bond activation. The thiyl radical generated via single-electron oxidation of TPI by the excited photoredox catalyst abstracted a hydrogen atom from organic molecules such as toluene, benzyl alcohol, alkenes, aldehydes, and THF. The thus-generated carbon-centered radical species underwent addition to ketones and aldehydes. This intrinsically unfavorable step was promoted by single-electron reduction of the intermediate alkoxy radical by catalytically generated titanium(III) species. This reaction provided an efficient and straightforward route to a broad range of tertiary alcohols and was successfully applied to late-stage functionalization of drugs or their derivatives. The proposed mechanism was supported by both experimental and theoretical studies.

A Germanium Catalyst Accelerates the Photoredox α-C(sp3)-H Alkylation of Primary Amines

Site-selective C(sp³)-H functionalizations using photoredox catalysis (PC) and hydrogen atom transfer (HAT) catalysis have received increasing attention. Here, we report a Ph₂GeCl₂ cocatalyst that greatly improves the yield of α-C(sp³)-H alkylation of primary amines catalyzed by a PC-HAT hybrid system. The α-position of the amino group selectively reacted even when weaker C-H bonds existed in the substrates. This finding may help the design of a novel site-selective hybrid catalysis.

Recent Progress in Chromium-Mediated Carbonyl Addition Reactions

Organochromium(III) species are versatile nucleophiles in complex molecule synthesis due to their high functional group tolerance and chemoselectivity for aldehydes. Traditionally, carbonyl addition reactions of organochromium(III) species were performed through reduction of organohalides either using stoichiometric chromium(II) salts or catalytic chromium salts in the presence of stoichiometric reductants [such as Mn(0)]. Recently, alternative methods emerged involving organoradical formation from readily available starting materials (e.g., N-hydroxyphthalimide esters, alkenes, and alkanes), followed by trapping the radical with stoichiometric or catalytic chromium(II) salts. Such methods, especially using catalytic chromium(II) salts, will lead to the development of sustainable chemical processes minimizing salt wastes and number of synthetic steps. In this review, methods for generation of organochromium(III) species for addition reactions to carbonyl compounds, classified by nucleophiles are described.

1 Introduction

2 Alkylation

2.1 Branch-Selective Reductive Alkylation of Aldehydes Using Unactivated Alkenes

2.2 Linear-Selective Alkylation of Aldehydes

2.2.1 Catalytic Decarboxylative Alkylation of Aldehydes Using NHPI ­Esters

2.2.2 Catalytic Reductive Alkylation of Aldehydes Using Unactivated Alkenes

2.2.3 Alkylation of Aldehydes via C(sp3)–H Bond Functionalization of Unactivated Alkanes

2.3 Catalytic α-Aminoalkylation of Carbonyl Compounds

3 Allylation

3.1 Catalytic Allylation of Aldehydes via Three-Component Coupling

3.2 Catalytic Allylation of Aldehydes via C(sp3)–H Bond Functionalization of Alkenes

4 Propargylation: Catalytic Propargylation of Aldehydes via Three-Component Coupling

5 Conclusion

Identification of a Self-Photosensitizing Hydrogen Atom Transfer Organocatalyst System

We developed organocatalyst systems to promote the cleavage of stable C-H bonds, such as formyl, α-hydroxy, and benzylic C-H bonds, through a hydrogen atom transfer (HAT) process without the use of exogenous photosensitizers. An electronically tuned thiophosphoric acid, 7,7'-OMe-TPA, was assembled with substrate or co-catalyst N-heteroaromatics through hydrogen bonding and π-π interactions to form electron donor-acceptor (EDA) complexes. Photoirradiation of the EDA complex induced stepwise, sequential single-electron transfer (SET) processes to generate a HAT-active thiyl radical. The first SET was from the electron-rich naphthyl group of 7,7'-OMe-TPA to the protonated N-heteroaromatics and the second proton-coupled SET (PCET) from the thiophosphoric acid moiety of 7,7'-OMe-TPA to the resulting naphthyl radical cation. Spectroscopic studies and theoretical calculations characterized the stepwise SET process mediated by short-lived intermediates. This organocatalytic HAT system was applied to four different carbon-hydrogen (C-H) functionalization reactions, hydroxyalkylation and alkylation of N-heteroaromatics, acceptorless dehydrogenation of alcohols, and benzylation of imines, with high functional group tolerance.

Titanium(IV) Chloride-Catalyzed Photoalkylation via C(sp3)-H Bond Activation of Alkanes

Despite the sophistication of C-H functionalization as one of the most powerful tools in organic synthesis, methodology for performing hydrogen-atom transfer of unactivated alkanes remains rather scarce. Herein, we describe chlorine radical-catalyzed C(sp³)-H photoalkylation using titanium(IV) chloride via a ligand-to-metal charge transfer process. Enabled by the unique properties of this abundant metal salt, the reaction not only effected the coupling of various alkanes with radical acceptors but also was shown to be applicable to direct photoalkylation of aromatic ketones.

Photo-Oxygenation: An Innovative New Therapeutic Approach Against Amyloidoses

Many types of amyloidoses are pathologically characterized by the deposition of amyloid, which is comprised of fibrils formed by abnormally aggregated proteins, in various peripheral tissues and the central nervous system (CNS). Neurodegenerative disorders, such as Alzheimer disease (AD), Parkinson disease (PD), frontotemporal dementia (FTD), and amyotrophic lateral sclerosis (ALS), are well-known CNS amyloidoses that are characterized by amyloid deposition both inside and outside of cells. The amyloidogenic proteins of each disease have distinct primary sequences, and they normally function as soluble proteins. However, these proteins all aggregate and form amyloid with a common intermolecular tertiary structure, namely, a cross-β-sheet structure, finally leading to the onset of each disease. Therefore, inhibition of the aggregation of amyloid proteins or efficient clearance of the already formed amyloids are thought to be promising therapeutic strategies against amyloidoses.

Knoevenagel Condensation between 2-Methyl-thiazolo[4,5-b]pyrazines and Aldehydes

Knoevenagel condensation, an olefin-forming reaction from active methyl/methylene-containing compounds and aldehydes, is a fundamental and useful synthetic method. Benzothiazoles are, however, out of the scope of Knoevenagel condensation. Here, we report that Knoevenagel condensation between aldehydes and 2-methyl-thiazolo[4,5-b]pyrazines (MeTPy), a fused ring structure comprising pyrazine and thiazole, proceeded smoothly, despite minor structural differences from benzothiazoles. This finding will be useful for short synthesis of MeTPy-containing functional molecules, such as a tau probe analog 1.

Antibody mimetic drug conjugate manufactured by high-yield Escherichia coli expression and non-covalent binding system

Antibody-drug conjugates (ADCs) are a major therapeutic tool for the treatment of advanced cancer. Malignant cells in advanced cancer often display multiple genetic mutations and become resistant to monotherapy. Therefore, a therapeutic regimen that simultaneously targets multiple molecules with multiple payloads is desirable. However, the development of ADCs is hampered by issues in biopharmaceutical manufacturing and the complexity of the conjugation process of low-molecular-weight payloads to biologicals. Here, we report antibody mimetic-drug conjugates (AMDCs) developed by exploiting the non-covalent binding property of payloads based on high-affinity binding of mutated streptavidin and modified iminobiotin. Miniprotein antibodies were fused to a low immunogenic streptavidin variant, which was then expressed in Escherichia coli inclusion bodies, solubilized, and refolded into functional tetramers. The AMDC developed against human epidermal growth factor receptor 2 (HER2) effectively killed cultured cancer cells using bis-iminobiotin conjugated to photo-activating silicon phthalocyanine. The HER2-targeting AMDC was also effective in vivo against a mouse KPL-4 xenograft model. This AMDC platform provides rapid, stable, and high-yield therapeutics against multiple targets.

Promotion in the Clearance of Aggregated Aβ In Vivo Using Amyloid Selective Photo-Oxygenation Technology

Alzheimer’s disease (AD) is characterized by the aggregation and deposition of 2 amyloid proteins: amyloid β peptide (Aβ) and tau protein. Immunotherapies using anti-Aβ antibodies to promote the clearance of aggregated Aβ have recently been highlighted as a promising disease-modifying approach against AD. However, immunotherapy has still some problems, such as low efficiency of delivery into the brain and high costs. We have developed the “amyloid selective photo-oxygenation technology” as a comparable to immunotherapy for amyloids. The photo-oxygenation can artificially attach the oxygen atoms to specific amino acids in amyloid proteins using photocatalyst and light irradiation. We revealed that in vivo photo-oxygenation for living AD model mice reduced the aggregated Aβ in the brain. Moreover, we also showed that microglia were responsible for this promoted clearance of photo-oxygenated Aβ from the brain. These results indicated that our photo-oxygenation technology has the potential as a disease-modifying therapy against AD to promote the degradation of amyloids, resulting in being comparable to immunotherapy. Here, we introduce our technology and its effects in vivo that we showed previously in Ozawa et al., Brain, 2021, as well as a further improvement towards non-invasive in vivo photo-oxygenation described in another publication Nagashima et al., Sci. Adv., 2021, as expanded discussion.

Protein Modification at Tyrosine with Iminoxyl Radicals

Post-translational modifications (PTMs) of proteins are a biological mechanism for reversibly controlling protein function. Synthetic protein modifications (SPMs) at specific canonical amino acids can mimic PTMs. However, reversible SPMs at hydrophobic amino acid residues in proteins are especially limited. Here, we report a tyrosine (Tyr)-selective SPM utilizing persistent iminoxyl radicals, which are readily generated from sterically hindered oximes via single-electron oxidation. The reactivity of iminoxyl radicals with Tyr was dependent on the steric and electronic demands of oximes; isopropyl methyl piperidinium oxime 1f formed stable adducts, whereas the reaction of tert-butyl methyl piperidinium oxime 1o was reversible. The difference in reversibility between 1f and 1o, differentiated only by one methyl group, is due to the stability of iminoxyl radicals, which is partly dictated by the bond dissociation energy of oxime O-H groups. The Tyr-selective modifications with 1f and 1o proceeded under physiologically relevant, mild conditions. Specifically, the stable Tyr-modification with 1f introduced functional small molecules, including an azobenzene photoswitch, to proteins. Moreover, masking critical Tyr residues by SPM with 1o, and subsequent deconjugation triggered by the treatment with a thiol, enabled on-demand control of protein functions. We applied this reversible Tyr modification with 1o to alter an enzymatic activity and the binding affinity of a monoclonal antibody with an antigen upon modification/deconjugation. The on-demand ON/OFF switch of protein functions through Tyr-selective and reversible covalent-bond formation will provide unique opportunities in biological research and therapeutics.

Chemical catalyst-promoted photooxygenation of amyloid proteins

Misfolded proteins produce aberrant fibrillar aggregates, called amyloids, which contain cross-β-sheet higher order structures. The species generated in the aggregation process (i.e., oligomers, protofibrils, and fibrils) are cytotoxic and can cause various diseases. Interfering with the amyloid formation of proteins could be a drug development target for treating diseases caused by aberrant protein aggregation. In this review, we introduce a variety of chemical catalysts that oxygenate amyloid proteins under light irradiation using molecular oxygen as the oxygen atom donor (i.e., photooxygenation catalysts). Catalytic photooxygenation strongly inhibits the aggregation of amyloid proteins due to covalent installation of hydrophilic oxygen atoms and attenuates the neurotoxicity of the amyloid proteins. Recent in vivo studies in disease model animals using photooxygenation catalysts showed promising therapeutic effects, such as memory improvement and lifespan extension. Moreover, photooxygenation catalysts with new modes of action, including interference with the propagation of amyloid core seeds and enhancement in the metabolic clearance of amyloids in the brain, have begun to be identified. Manipulation of catalytic photooxygenation with secured amyloid selectivity is indispensable for minimizing the side effects in clinical application. Here we describe several strategies for designing catalysts that selectively photooxygenate amyloids without reacting with other non-amyloid biomolecules.

Siloxy Esters as Traceless Activators of Carboxylic Acids: Boron-Catalyzed Chemoselective Asymmetric Aldol Reaction*

The catalytic asymmetric aldol reaction is among the most useful reactions in organic synthesis. Despite the existence of many prominent reports, however, the late-stage, chemoselective, catalytic, asymmetric aldol reaction of multifunctional substrates is still difficult to achieve. Herein, we identified that in situ pre-conversion of carboxylic acids to siloxy esters facilitated the boron-catalyzed direct aldol reaction, leading to the development of carboxylic acid-selective, catalytic, asymmetric aldol reaction applicable to multifunctional substrates. Combining experimental and computational studies rationalized the reaction mechanism and led to the proposal of Si/B enediolates as the active species. The silyl ester formation facilitated both enolization and catalyst turnover by acidifying the α-proton of substrates and attenuating poisonous Lewis bases to the boron catalyst.

Cardio-renal protective effects of SGLT2 inhibitors in patients with type 2 diabetes mellitus and severely impaired renal function

Background

Prognostic impact of Sodium-Glucose Cotransporter 2 (SGLT2) inhibitors on cardiovascular and renal outcome was unknown in patients with type-2 diabetes mellitus (DM) and severely impaired renal function.

Methods

From July 2015 to December 2020, patients with type-2 DM who were taken SGLT2 inhibitors for more than six months were retrospectively screened. Patients with estimated glomerular filtration rate (eGFR) over 60ml/min/1.73m2 were excluded. We divided those patients into two groups by eGFR; less than 45ml/min/1,73m2 were group A and 46–60ml/min/m2 were group B. Randomly selected patients with DM not taking SGLT2 inhibitors and having severe renal dysfunction: eGFR less than 45ml/min/m2 (Group C) were set as controls. The primary outcome was a composite of cardiovascular/renal death, initiation of dialysis, doubling of the serum creatine level, decline in the eGFR more than 30%, nonfatal myocardial infraction, nonfatal stroke, and hospitalization for heart failure.

Results

Totally 418 patients were enrolled. Median age was 71 years (group A, n=106), 64 years (group B, n=115), and 77 years (group C, n=201) (p&lt;0.001). After median 24 months follow-up, primary endpoints were observed 24.5% in group A, 4.3% in group B, 36.8% in group C (p&lt;0.001). In Kaplan-Meier analysis, significantly lower incidence of primary endpoints were observed in SGLT2 groups (group A and B) than controls (p&lt;0.001, Figure 1). In patients with severe renal dysfunction, taking SGLT2 inhibitors tended to decrease future renal event (Figure 2). The incidence of SGLT2 related adverse events was not different between 2 groups (A and B).

Conclusions

Even in patients with severe renal dysfunction, SGLT2 inhibitors would have cardio-renal protective effects without drug-related adverse effects.

Funding Acknowledgement

Type of funding sources: None.

Impact of polypharmacy on prognosis in patients with acute decompensated heart failure: from the CURE-HF registry

Background

Polypharmacy would be associated with poor prognosis in patients with heart failure (HF).

Methods

In 863 patients who discharged after treatment for HF were prospectively enrolled. Number of tablets prescribed at discharge was counted. Death, non-fatal myocardial infarction, non-fatal stroke, and hospitalization for HF were tracked.

Results

In our study cohort (median age, 78), 447 patients experienced adverse events during median 503 days follow-up. In Kaplan-Meier analysis, a greater number of prescribed tablets was associated with future adverse cardiac events in the crude population. Although patients with the greater number of non-HF medications showed worse outcome, those of HF medications were not associate with the outcome (Figure). Furthermore, the number of tablets was an independent predictor of future cardiovascular events after adjustment for age, gender, B-type natriuretic peptide, hemoglobin, albumin, estimated glomerular filtration rate, and left ventricular ejection fraction (HR 95% CI: 1.295 (1.066–1.573), p=0.009).

Conclusions

Polypharmacy was associated with poor prognosis. Although the numbers of tablets and non-HF medications were significantly associated with worse out come in HF patients, the number of HF medications was not.

Funding Acknowledgement

Type of funding sources: None.

Live-Cell Protein Modification by Boronate-Assisted Hydroxamic Acid Catalysis

Selective methods for introducing protein post-translational modifications (PTMs) within living cells have proven valuable for interrogating their biological function. In contrast to enzymatic methods, abiotic catalysis should offer access to diverse and new-to-nature PTMs. Herein, we report the boronate-assisted hydroxamic acid (BAHA) catalyst system, which comprises a protein ligand, a hydroxamic acid Lewis base, and a diol moiety. In concert with a boronic acid-bearing acyl donor, our catalyst leverages a local molarity effect to promote acyl transfer to a target lysine residue. Our catalyst system employs micromolar reagent concentrations and affords minimal off-target protein reactivity. Critically, BAHA is resistant to glutathione, a metabolite which has hampered many efforts toward abiotic chemistry within living cells. To showcase this methodology, we installed a variety of acyl groups in E. coli dihydrofolate reductase expressed within human cells. Our results further establish the well-known boronic acid-diol complexation as a bona fide bio-orthogonal reaction with applications in chemical biology and in-cell catalysis.

Large-Scale Prospective Genome-Wide Association Study of Oxaliplatin in Stage II/III Colon Cancer and Neuropathy

IMPORTANCE

The severity of oxaliplatin (L-OHP)-induced peripheral sensory neuropathy (PSN) exhibits substantial interpatient variability, and some patients suffer from long-term, persisting PSN.

OBJECTIVE

To identify single-nucleotide polymorphisms (SNPs) predicting L-OHP-induced PSN using a genome-wide association study (GWAS) approach.

DESIGN, SETTING, PARTICIPANTS

A large prospective GWAS including 1,379 patients with stage II/III colon cancer who received L-OHP-based adjuvant chemotherapy (mFOLFOX6/CAPOX) under the phase II (JOIN/JFMC41) or the phase III (ACHIVE/JFMC47) trial.

MAIN OUTCOMES AND MEASURES

First, GWAS comparison of worst grade PSN (grade 0/1 vs. 2/3) was performed. Next, to minimize the impact of ambiguity in PSN grading, extreme PSN phenotypes were selected and analyzed by GWAS. SNPs that could predict time to recovery from PSN were also evaluated. In addition, SNPs associated with L-OHP-induced allergic reactions (AR) and time to disease recurrence were explored.

RESULTS

No SNPs exceeded the genome-wide significance (p < 5.0 × 10^-8) in either GWAS comparison of worst grade PSN, extreme PSN phenotypes, or time to recovery from PSN. Association study focusing on AR or time to disease recurrence also failed to reveal any significant SNPs.

CONCLUSION AND RELEVANCE

Our results highlight the challenges of utilizing SNPs for predicting susceptibility to L-OHP-induced PSN in daily clinical practice.