Chloroquine Research Articles

A novel 4-aminoquinoline chemotype with multistage antimalarial activity and lack of cross-resistance with PfCRT and PfMDR1 mutants

Artemisinin-based combination therapy (ACT) is the mainstay of effective treatment of Plasmodium falciparum malaria. However, the long-term utility of ACTs is imperiled by widespread partial artemisinin resistance in Southeast Asia and its recent emergence in parts of East Africa. This underscores the need to identify chemotypes with new modes of action (MoAs) to circumvent resistance to ACTs. In this study, we characterized the asexual blood stage antiplasmodial activity and resistance mechanisms of LDT-623, a 4-aminoquinoline (4-AQ). We also detected LDT-623 activity against multiple stages (liver schizonts, stage IV-V gametocytes, and ookinetes) of Plasmodium’s life cycle, a feature unlike other 4-AQs such as chloroquine (CQ) and piperaquine (PPQ). Using heme fractionation profiling and drug uptake studies in PfCRT-containing proteoliposomes, we observed inhibition of hemozoin formation and PfCRT-mediated transport, which constitute characteristic features of 4-AQs’ MoA. We also found minimal cross-resistance to LDT-623 in a panel of mutant pfcrt or pfmdr1 lines, but not the PfCRT F145I mutant that is highly resistant to PPQ resistance yet is very unfit. No P. falciparum parasites were recovered in an in vitro resistance selection study, suggesting a high barrier for resistance to emerge. Finally, a competitive growth assay comprising >50 barcoded parasite lines with mutated resistance mediators or major drug targets found no evidence of cross-resistance. Our findings support further exploration of this promising 4-AQ.

Optimization of loop mediated isothermal amplification assay (LAMP) for detection of chloroquine resistance in P. vivax malaria

Chloroquine is still used as a first-line treatment for uncomplicated Plasmodium vivax malaria in India and resistance to this therapy can act as a major hurdle for malaria elimination. It is difficult to monitor drug-efficacy and drug resistance through in vivo and in vitro studies in case of Plasmodium vivax so analysis of molecular markers serves as an important tool to track resistance. Molecular methods that are currently in use for detecting single nucleotide polymorphisms in resistant genes including Polymerase chain reaction (PCR), Realtime-Polymerase chain reaction require highly sophisticated labs and are time consuming. So, with this background the study has been designed to optimize Loop Mediated Isothermal Amplification Assay to detect single nucleotide polymorphisms in chloroquine resistance gene of Plasmodium vivax in field settings. Eighty-eight Plasmodium vivax positive samples were collected. Pvmdr1 gene was amplified for all the samples and sequenced. Obtained sequences were analyzed for the presence of single nucleotide polymorphisms in the target gene. Further Loop Mediated Isothermal Amplification Assay primer sets were designed for the target mutants and the assay was optimized. Clinical as well as analytical sensitivity and specificity for the assay was calculated. Double mutants with variations at T958M and F1076L were detected in 100% of the Plasmodium vivax clinical isolates with haplotype M958 Y976 Y1028 L1076. Designed primers for Loop Mediated Isothermal Amplification Assay successfully detected both the mutants (T958M and F1076L) in 100% of the isolates and do not show cross-reactivity with other strains. So, the assay was 100% sensitive and specific for detecting single nucleotide polymorphisms in the target Pvmdr1 gene. Limit of detection was found to be 0.9 copies/µl and lowest DNA template concentration detected by designed assay was 1.5 ng/µL. Observed prevalence of single nucleotide polymorphisms in Pvmdr 1 gene is indicating a beginning of trend towards chloroquine resistance in Plasmodium vivax. The present study optimized LAMP for detecting single nucleotide polymorphisms in Plasmodium vivax cases in field settings, thus would help in finding significant hubs of emerging chloroquine drug resistance and ultimately helping in the management of suitable antimalarial drug policy.

A histomorphometric study to evaluate the therapeutic effects of biosynthesized silver nanoparticles on the kidneys infected with Plasmodium chabaudi.

The study aimed to verify the pathogenic malarial kidney infections and histopathological pictures in mice infected with Plasmodium chabaudi using Indigofera oblongifolia leaf extract silver nanoparticles (IOLEAgNPs). Fifty healthy adult female mice C57BL/6 were used. Animals were divided into five groups, with each group of ten mice. The first control non-infected group was given distilled water for 7 days. The second group was orally given 50 mg/kg of IOLEAgNPs. The third, fourth, and fifth groups were injected intraperitoneally with 105 parasitized erythrocytes of P. chabaudi. After 1 h, the fourth group received 50 mg/kg of IOLEAgNPs, while the fifth group orally received 10 mg/kg chloroquine phosphate. The histopathology of the kidney was studied by routine histology method with hematoxylin-eosin staining. The kidney revealed cerebral microvessel congestion, hemorrhages, and necrosis. Cast formation, glomerulonephritis, tubular necrosis, and congestion were observed in the kidney cortex. Consequently, the targeted medical IOLEAgNPs reduced this degeneration impact on renal tissue. Proven that plant-source synthesized IOLEAgNPs play a preventive role as antimalarial agents in female mice infected with P. chabaudi.

The protective effect of carbamazepine on acute lung injury induced by hemorrhagic shock and resuscitation in rats.

Hemorrhagic shock and resuscitation (HSR) enhances the risk of acute lung injury (ALI). This study investigated the protective effect of carbamazepine (CBZ) on HSR-induced ALI in rats. Male Sprague-Dawley rats were allocated into five distinct groups through randomization: control (SHAM), saline + HSR (HSR), CBZ + HSR (CBZ/HSR), dimethyl sulfoxide (DMSO) + HSR (DMSO/HSR), and CBZ + chloroquine (CQ) + HSR (CBZ/CQ/HSR). Subsequently, HSR models were established. To detect tissue damage, we measured lung histological changes, lung injury scores, and wet/dry weight ratios. We measured neutrophil counts as well as assessed the expression of inflammatory factors using RT-PCR to determine the inflammatory response. We detected autophagy-related proteins LC3II/LC3I, P62, Beclin-1, and Atg12-Atg5 using western blotting. Pretreatment with CBZ improved histopathological changes in the lungs and reduced lung injury scores. The CBZ pretreatment group exhibited significantly reduced lung wet/dry weight ratio, neutrophil aggregation and number, and inflammation factor (TNF-α and iNOS) expression. CBZ changed the expression levels of autophagy-related proteins (LC3II/LC3I, beclin-1, Atg12-Atg5, and P62), suggesting autophagy activation. However, after injecting CQ, an autophagy inhibitor, the beneficial effects of CBZ were reversed. Taken together, CBZ pretreatment improved HSR-induced ALI by suppressing inflammation, at least in part, through activating autophagy. Thus, our study offers a novel perspective for treating HSR-induced ALI.

Autophagy activation ameliorates the fibrosis of trabecular meshwork cells induced by TGFβ2 through the promotion of fibrotic proteins degradation.

The level of transforming growth factor-beta2 (TGFβ2) is elevated in aqueous humor of partial glaucoma patients, and induced trabecular meshwork (TM) fibrosis, which could cause TM cells dysfunction and lead to intraocular pressure (IOP) elevation. Autophagy is a dynamic process of bulk degradation of organelles and proteins under stress condition, while its functions in fibrotic development remain controversial. Meanwhile, it is still unclear if activation of autophagy could ameliorate TGFβ2-induced fibrosis in TM cells. In this study, we demonstrated that autophagy activation with Rapamycin or Everolimus could ameliorate TM fibrosis induced by TGFβ2. We also proved that activation of autophagy may decrease TM cells fibrosis and reduce elevated IOP induced by TGFβ2 in vivo, while Rapamycin or Everolimus has no effect on TGFβ/Smad3 pathway activity and fibrotic genes expression. However, when Chloroquine phosphate blocks autophagy-lysosome pathway, the protective effect of Rapamycin or Everolimus on fibrosis was weakened. We established that autophagy activation ameliorates TM fibrosis through promoting fibrotic proteins degradation.

Synthesis and characterization of chloroquine-modified albumin-binding siRNA-lipid conjugates for improved intracellular delivery and gene silencing in cancer cells.

siRNA therapeutics have considerable potential as molecularly-targeted therapeutics in malignant disease, but identification of effective delivery strategies that mediate rapid intracellular delivery while minimizing toxicity has been challenging. Our group recently developed and optimized an siRNA conjugate platform termed "siRNA-L 2 ," which harnesses non-covalent association with endogenous circulating albumin to extend circulation half-life and achieve tumor-selective delivery without the use of traditional cationic lipids or polymers for transfection. To improve intracellular delivery and particularly the endosomal escape properties of siRNA-L 2 towards more efficient gene silencing, we report synthesis of siRNA-CQ-L 2 conjugates, in which chloroquine (CQ), an endosomolytic quinoline alkaloid, is covalently incorporated into the branching lipid tail structure. We accomplished this via synthesis of a novel CQ phosphoramidite, which can be incorporated into a modular siRNA-L 2 backbone using on-column solid-phase synthesis through use of asymmetric branchers with levulinyl-protected hydroxide groups that allow covalent addition of pendant CQ repeats. We demonstrate that siRNA-CQ-L 2 maintains the ability to non-covalently bind albumin, and with multiple copies of CQ, siRNA-CQ-L 2 mediates higher endosomal disruption, cellular uptake/retention, and reporter gene knockdown in cancer cells. Further, in mice, the addition of CQ did not significantly affect circulation kinetics nor organ biodistribution and did not produce hematologic or organ-level toxicity. Thus, controlled, multivalent conjugation of albumin-binding siRNA-L 2 to endosomolytic small molecule compounds holds promise in improving siRNA-L 2 knockdown potency while maintaining albumin-binding properties and overall safety.

In vivo efficacy of chloroquine plus primaquine combination therapy against uncomplicated Plasmodium vivax malaria in Limu Kossa District, Jimma Zone, Southwest Ethiopia.

Plasmodium vivaxis the second most common malaria parasite in Ethiopia. It has been treated with chloroquine (CQ) for the past seven decades. However, the emergence of CQ-resistant strains in the nation urged the Federal Ministry of Health of Ethiopia to review its national malaria treatment guideline in 2018.In the revised guideline, thefirst-line treatment for uncomplicatedP. vivaxinfection is a combination of CQ and primaquine (PQ). Thus, the present study was designed to evaluate the in vivo efficacy of CQ and PQ combination therapy against clinicalP. vivaxmono-infection in one of the malaria-endemic areas of Ethiopia. Anopen-label prospective clinical trialwas conducted in the Limmu Kossa District, Jimma zone, Southwest Ethiopia, from September 2023 to March 2024. A total of 108 patients were recruited for the study. All participants received treatment with CQ at a dosage of 25mg/kg over three days, followed by PQ at 0.25mg/kg for 14 consecutive days. Patients were monitored for 42days for any signs of treatment failure and malaria clinical symptoms, as per the World Health Organization (WHO) guidelines for anti-malarial drug evaluation. Additionally, haemoglobin (Hb) levels, body temperature,any adverse events, and signs of haemolysis were assessed.Data was analysed using R-software (version 4.0.0) and a significant level was considered at p < 0.05. The median age of the patients was 23years, ranging from 2.5 to 62years. Of the 108 patients initially recruited, 100 completed the 42-day follow-up period. The combination therapy of CQ and PQ for uncomplicated clinicalP. vivaxmalaria demonstrated excellent therapeutic efficacy, with a 100% cure rate observed at both day 28 and day 42. Additionally, the recommended low dose of PQ (0.25mg/kg) was well-tolerated, with no signs of. Additionally, most common malaria symptoms were disappeared early in the follow-up period. The combination of CQ plus PQ has exhibited excellent efficacy against uncomplicatedP. vivaxmalaria mono-infections. To preserve this efficacy, it is critical to ensure patients adhere to the full course of PQ treatment, despite its extended duration. Therefore, health authorities should put emphasis on the boosting of the public on the importance of finishing the prescribed medication regimen.

High frequency of artemisinin partial resistance mutations in the Great Lakes region revealed through rapid pooled deep sequencing.

In Africa, the first Plasmodium falciparum artemisinin partial resistance mutation, was Kelch13 (K13) 561H - detected and validated at appreciable frequency in Rwanda in 2014. Surveillance to better define the extent of the emergence in Rwanda and neighboring countries is critical. We used novel liquid blood drop preservation combined with pooled sequencing to provide cost-effective rapid assessment of resistance mutation frequencies at multiple collection sites across Rwanda and neighboring regions in Uganda, Tanzania, and the Democratic Republic of the Congo (DRC). Malaria-positive samples (n=5,465) from 39 health facilities collected between May 2022 and March 2023 were sequenced in 199 pools. In Rwanda, K13 561H and 675V were detected in 90% and 65% of sites with an average frequency of 19.0% (0-54.5%) and 5.0% (0-35.5%), respectively. In Tanzania, 561H had high frequency in multiple sites. 561H appeared at 1.6% in Uganda. 561H was absent from the DRC, although 675V was seen at low frequency. Concerningly candidate mutations were observed: 441L, 449A, and 469F co-occurred with validated mutations suggesting they are arising under the same pressures. Other markers for decreased susceptibility to artemether-lumefantrine are common: P. falciparum multidrug resistance protein 1 N86 at 98.0% (63.3-100%) and 184F at 47.0% (0-94.3%) and P. falciparum chloroquine resistance transporter 76T at 14.7% (0-58.6%). Additionally, sulfadoxine-pyrimethamine-associated mutations show high frequencies. K13 mutations are rapidly expanding in the region further endangering control efforts with the potential of engendering partner drug resistance.

Preparation and Evaluation of Stability and Acute Oral Toxicity of a Drug Delivery System Combining MIL‐100(Fe) with Chloroquine Phosphate

AbstractMetal‐organic framework materials (MOFs) are highly porous and are the subject of growing interest among scientists globally for their utilization in drug delivery. In this work, iron‐based metal‐organic frameworks (MOFs) MIL‐100(Fe) were synthesized by ultrasonic method and studied for the loading of the chloroquine phosphate (CQP). The CQP‐release behavior of the material was investigated in water media with various pH solutions of 1.2, 2, 4.5, and phosphate‐buffered saline (PBS) at temperatures of 25 °C to 45 °C. MIL‐100(Fe) material had a high surface area of up to 1080 m2/g and could completely release the CQP at a pH of 1.2 after 25 hours. At other pH conditions, the drug exhibited an initial rapid release, followed by a gradual slowdown, ultimately achieving complete release after 96 hours. The maximal loading capacity for the CQP by the MIL‐100(Fe) was determined to be approximately 30 % at the pH solution of 2 (stomach environment). The findings from the activity assessment against the K1 malaria parasite strain (P. falciparum) indicated that the concentration at which the active ingredient, when carried by the material, exhibited inhibition was 193 nM/L. The evaluation outcomes for acute toxicity of the drug carrier material revealed an LD50 value exceeding 5000 mg/kg (equivalent to 1500 mg of CQP base). In contrast, when using the active substance alone, acute toxicity resulted in an LD50 value of 675 mg/kg.

Identification of the drug/metabolite transporter 1 as a marker of quinine resistance in a NF54×Cam3.II P. falciparum genetic cross.

The genetic basis of Plasmodium falciparum resistance to quinine (QN), a drug used to treat severe malaria, has long been enigmatic. To gain further insight, we used FRG-NOD human liver-chimeric mice to conduct a P. falciparum genetic cross between QN-sensitive and QN-resistant parasites, which also differ in their susceptibility to chloroquine (CQ). By applying different selective conditions to progeny pools prior to cloning, we recovered 120 unique recombinant progeny. These progeny were subjected to drug profiling and QTL analyses with QN, CQ, and monodesethyl-CQ (md-CQ, the active metabolite of CQ), which revealed predominant peaks on chromosomes 7 and 12, consistent with a multifactorial mechanism of resistance. A shared chromosome 12 region mapped to resistance to all three antimalarials and was preferentially co-inherited with pfcrt. We identified an ATP-dependent zinc metalloprotease (FtsH1) as one of the top candidates and observed using CRISPR/Cas9 SNP-edited lines that ftsh1 is a potential mediator of QN resistance and a modulator of md-CQ resistance. As expected, CQ and md-CQ resistance mapped to a chromosome 7 region harboring pfcrt. However, for QN, high-grade resistance mapped to a chromosome 7 peak centered 295kb downstream of pfcrt. We identified the drug/metabolite transporter 1 (DMT1) as the top candidate due to its structural similarity to PfCRT and proximity to the peak. Deleting DMT1 in QN-resistant Cam3.II parasites significantly sensitized the parasite to QN but not to the other drugs tested, suggesting that DMT1 mediates QN response specifically. We localized DMT1 to structures associated with vesicular trafficking, as well as the parasitophorous vacuolar membrane, lipid bodies, and the digestive vacuole. We also observed that mutant DMT1 transports more QN than the wild-type isoform in vitro. Our study demonstrates that DMT1 is a novel marker of QN resistance and a new chromosome 12 locus associates with CQ and QN response, with ftsh1 is a potential candidate, suggesting these genes should be genotyped in surveillance and clinical settings.

Potential role of host autophagy in Clonorchis sinensis infection.

An in vivo mouse model of Clonorchis sinensis (C. sinensis) infection with or without the administration of autophagy inhibitor chloroquine (CQ) stimulation was established to assess the possible involvement of autophagic response during C. sinensis infection. Abnormal liver function was observed at 4, 6, and 8weeks post-infection, as indicated by elevated levels of ALT/GPT, AST/GOT, TBIL, and α-SMA in the infected groups. These findings indicated that C. sinensis infection activated autophagy, as shown by a decreased LC3II/I ratio and accumulated P62 expression in infected mice. Interestingly, CQ administration exhibited dual and opposing effects during the infection. In the early stage of infection, the engagement of CQ appeared to mitigate symptoms by reducing inflammation and fibrotic responses. However, in the later stage of infection, CQ might contribute to parasite survival by evading autophagic targeting, thereby exacerbating hepatic impairment and worsening liver fibrosis. Autophagy in liver was suppressed throughout the infection. These observations attested that C. sinensis infection triggered autophagy, and highlighted a complex role for CQ, with both protective and detrimental effects, in the in vivo process of C. sinensis infection.

Frequency of chloroquine-resistant haplotype of Plasmodium falciparum (CVIET) in Ibadan, Southwest Nigeria 17 years post-chloroquine withdrawal

The replacement of chloroquine with artemisinin-based combination therapies (ACTs) for over a decade has had varying impacts on the ability of the malaria parasite to sustain its chloroquine resistance prowess in different malaria-endemic regions. We evaluated the frequency of Plasmodium falciparum chloroquine resistance transporter (PfCRT) mutations in Ibadan, Nigeria 17 years after the replacement of chloroquine with ACTs for malaria treatment. Fragments of PfCRT gene from genomic DNA of microscopically confirmed P. falciparum-infected patients were amplified and sequenced. There were 19% CVIET mutant and 81% CVMNK wild-type haplotypes on residues 72–76. A220S change were found in 16.7% of samples occurring concurrently with the CVIET haplotype, while a Q271E mutation occurred in a PfCRT wild-type isolate. The reduced prevalence of the PfCRT mutant alleles in this study compared to previous reports suggests a gradual disappearance of chloroquine-resistant malaria parasites following reduced drug pressure. It may also be a result of fitness demand on the parasites in attempts to evolve resistance against the current first-line regimen. However, evaluating the prevalence of other chloroquine resistance markers such as Plasmodium falciparum multidrug resistance 1 gene mutations in this population, and a more robust sample size will help to consolidate these findings.

In vitro antiplasmodium and antitrypanosomal activities, β-haematin formation inhibition, molecular docking and DFT computational studies of quinoline-urea-benzothiazole hybrids

Quinoline-urea-benzothiazole hybrids exhibited low to sub-micromolar in vitro activities against the Plasmodium falciparum (P. falciparum) 3D7 chloroquine (CQ)-sensitive strain, with compounds 5a, 5b and 5f showing activities ranging from 0.33 to 0.97 μM. Against the formation of β-haematin, the majority of the tested compounds were comparable to the reference drug, chloroquine (CQ), with compounds 5c (IC50 = 9.55 ± 0.62 μM) and 5h (IC50 = 9.73 ± 1.38 μM), exhibiting slightly better in vitro efficacy than CQ. The hybrids also exhibited low micromolar to submicromolar activities against Trypanosoma brucei brucei, with 5j-5k being comparable to the reference drug, pentamidine. Compound 5b displayed higher in silico binding energy than CQ when docked against P. falciparum dihydroorotate dehydrogenase enzyme. Compounds 5j and 5k showed higher binding energies than pentamidine within the trypanothione reductase enzyme binding pocket. The root means square deviations of the hit compounds 5b, 5j and 5k were stable throughout the 100 ns simulation period. Post-molecular dynamics MMGBSA binding free energies showed that the selected hybrids bind spontaneously to the respective enzymes. The DFT investigation revealed that the compounds have regions that can bind to the electropositive and electronegative sites of the proteins.

Analysis of &lt;em&gt;Pfmdr1&lt;/em&gt; and &lt;em&gt;Pfcrt drug&lt;/em&gt; resistant markers in &lt;em&gt;Plasmodium falciparum&lt;/em&gt; following treatments of patients from Nyando and Mbita, Nyanza region with Artemisinin-based combination therapy

The multidrug resistance of Plasmodium falciparum to antimalarial drugs is a major public health concern in the global management of malaria, especially in developing countries. As of today, malaria treatment is primarily dependent on the sustained efficacy of artemisinin-based combination therapy (ACT). Recent reports indicating decline in efficacy of ACT and artesunate monotherapy in Southeast Asia are a major threat to global malaria control achievements. Initially, mutations in Pfmdr1 were associated with chloroquine and amodiaquine resistance only, but there are now emerging field study reports of Pfmdr1 mutation conferring tolerance to ACT. The current study used Restriction Fragment Length Polymorphism to evaluate the prevalence of genetic polymorphisms of Plasmodium falciparum multidrug resistance (Pfmdr1) and Plasmodium falciparum chloroquine-resistant transporter (Pfcrt) gene mutations in Mbita and Nyando field isolates. The findings report that the prevalence of Pfcrt K76T mutation in Plasmodium falciparum field isolates in Mbita declined significantly from 76.3% (95% CI 21.0-31.0) in 2008 to 51.9% (95% CI 19.0-25.0) in 2014, a reduction of 24.4% (χ2df =1 = 4.709, P = 0.0000). In Nyando, prevalence stood at 66.8% (95% CI 12.0-14.0) in 2014 down from 73.7% (95% CI 27.0-48.0), insignificant reduction of 6.9% (χ2df =1 = 17.699, P = 0.0913). Prevalence for Pfmdr1 in Mbita stood at 14.7% (95% CI 44.0-51.0) in 2014 down from 21.9% (95% CI 31.0-49.0) in 2008, a significant reduction of 4.3% (χ2df =1 = 9.011, P = 0.001). While in Nyando, field isolate samples recorded 16.2% (95% CI 22.0-31.0) in 2014, down from 30.6% (95% CI 12.0-27.0), insignificant reduction of 1.9% (χ2df =1 = 11.777, P = 0.0591). Our findings confirm a common trend reported by previous studies: that there has been a small decline in the prevalence of the Pfcrt mutation over a decade since the withdrawal of Chloroquine as the first line of treatment for uncomplicated cases of malaria in Kenya.

Synergistic Interaction of Chloroquine with Artemisia kopetdaghensis Semipolar Extract Against Plasmodium berghei: Histopathological and Immunological Studies in a Mouse Model

Background: Malaria parasites have gradually developed resistance to commonly used antimalarial drugs. For decades, chloroquine was the most widely used drug to eradicate malaria. However, with the spread of chloroquine resistance, many countries have adopted combination therapies that utilize two drugs acting synergistically instead of monotherapy. In this study, the synergistic effect of chloroquine and the semipolar extract of Artemisia kopetdaghensis. Semipolar extract (SPE) was investigated in vivo through pathological and parasitological studies on murine mice. Methods: Sixty female Balb/c mice infected with the Plasmodium berghei parasite were treated with different concentrations of the semipolar extract of Artemisia kopetdaghensis (SPE) according to the protocol. The mean percentage of parasitemia, the mean survival time of the mice, the serum levels of IFN-γ, IL-4, IL-17, and TGF-β, and the effects of the whole plant extract on the kidney, spleen, and liver tissues were investigated and compared across different treatment groups. The data were analyzed using Bonferroni, ANOVA, and Tukey tests. Results: The semipolar extract of Artemisia kopetdaghensis (SPE) demonstrated better therapeutic effects in both synergistic and monotherapy conditions compared to chloroquine alone. The combination of chloroquine and SPE resulted in the lowest parasitemia rate, the highest percentage of parasite inhibition, and the longest average survival time. Pathological studies showed no signs of acute toxicity in the organs. Conclusions: This study demonstrated that using chloroquine in combination with Artemisia kopetdaghensis semipolar extract has synergistic effects in reducing parasitemia, enhancing the inhibitory effect on parasite growth and reproduction, and balancing the host immune system.

Autophagic inhibitor ROC-325 ameliorates glomerulosclerosis and podocyte injury via inhibiting autophagic flux in experimental FSGS mice

BackgroundAutophagy plays an important role in the pathogenesis of focal segmental glomerulosclerosis (FSGS). Podocyte-specific Yes-associated protein (YAP) deletion mice, referred to as YAP-KO mice, is considered a new animal model to study the underlying mechanism of FSGS. ROC-325 is a novel small-molecule lysosomal autophagy inhibitor that is more effective than chloroquine (CQ) and hydroxychloroquine (HCQ) in suppressing autophagy. In this study, we sought to determine the therapeutic benefit and mechanism of action of ROC-325 in YAP-KO mice, an experimental FSGS model. Methods and resultsYAP-KO mice were treated with ROC-325 (50 mg/kg, p.o.) daily for one month. Our results revealed that albuminuria, mesangial matrix expension, and focal segmental glomerulosclerosis in YAP-KO mice were significantly attenuated by ROC-325 administration. Transmission electron microscopy and immunofluorescence staining showed that ROC-325 treatment significantly inhibited YAP-KO-induced autophagy activation by decreasing autophagosome-lysosome fusion and increasing LC3A/B and p62/SQSTM. Meanwhile, Immunofluorescence staining revealed that preapplication of ROC-325 in podocyte with YAP-targeted siRNA and mRFP-GFP-LC3 adenovirus markedly suppressed autophagic flux in vitro, suggesting that autophagy intervention may serve as a target for FSGS. ConclusionsThese results showed that the role of autophagic activity in FSGS mice model and ROC-325 could be a novel and promising agent for the treatment of FSGS.

Combined Autophagy Inhibition and Dendritic Cell Recruitment Induces Antitumor Immunity and Enhances Immune Checkpoint Blockade Sensitivity in Pancreatic Cancer.

The effect of immune checkpoint inhibitors is extremely limited in patients with pancreatic ductal adenocarcinoma (PDAC) due to the suppressive tumor immune microenvironment (TIME). Autophagy, which has been shown to play a role in anti-tumor immunity, has been proposed as a therapeutic target for PDAC. Here, single-cell RNA-sequencing of autophagy-deficient murine PDAC tumors revealed that autophagy inhibition in cancer cells induced dendritic cell (DC) activation. Analysis of human PDAC tumors substantiated a negative correlation between autophagy and DC activation signatures. Mechanistically, autophagy inhibition increased intracellular accumulation of tumor antigens, which could activate DCs. Administration of chloroquine (CQ), an autophagy inhibitor, in combination with Flt3 ligand (Flt3L)-induced DC infiltration inhibited tumor growth and increased tumor-infiltrating T lymphocytes. However, autophagy inhibition in cancer cells also induced CD8+ T cell exhaustion with high expression of immune checkpoint LAG3. A triple therapy comprising CQ, Flt3L, and an anti-LAG3 antibody markedly reduced tumor growth in orthotopic syngeneic PDAC mouse models. Thus, targeting autophagy in cancer cells and activating DCs sensitizes PDAC tumors to immune checkpoint inhibitor therapy, warranting further development of this treatment approach to overcome immunosuppression in pancreatic cancer.

Lanthanum chloride exerts therapeutic potential for chronic kidney disease by suppressing nanohydroxyapatite-induced mitophagy and mitochondria-mediated apoptosis

ObjectiveTo investigate the protective effect of lanthanum chloride on kidney injury in chronic kidney disease and its mechanism. Methods1. Patients with CKD stage 2–5 were selected to analyze the effect of lanthanum-containing preparations on CKD. 2. Sixty healthy male Wistar rats were randomly divided into control group, model group, lanthanum chloride groups (0.03 ng/kg, 0.1 ng/kg, 0.3 ng/kg, q.3d., i.v.), and lanthanum carbonate group (0.3 g/kg, q.d., p.o.). The model group was given 2 % adenine suspension (200 mg/kg, q.d., p.o.) for the first two weeks, followed by adenine (200 mg/kg, b.i.d., p.o.) for 2 weeks, and all animals were sacrificed after eight weeks of administration. 3. The serum and kidneys of rats in each group were collected to detect the oxidative stress indicators and the expressions of LC3B-Ⅱ/Ⅰ, p62, Bcl-2, Bax, Caspase-3 and Cleaved Caspase-3. 4. Human renal tubular epithelial cells (HK-2 cells) were divided into control group, model group, lanthanum chloride group, pyrophosphate (PPI) group, chloroquine (CQ) group, rapamycin group, doxorubicin (DOX) group and N-acetyl-L-cysteine (NAC) group. The mitochondrial status, mitophagy and apoptosis levels were detected. Results1.Lanthanum-containing preparations can significantly reduce the biochemical indexes of kidney injury in patients with CKD. 2. In the model group, the glomerular and renal tubular edema, the mitochondria were short and round, and the expression of LC3B-Ⅱ/Ⅰ and Bax increased, while the expression of P62, Bcl-2 and Caspase-3 decreased, and there was a significant improvement in the administration group, especially the 0.1 ng/kg group and lanthanum carbonate group. 3. In the HK-2 cell model group, mitochondrial membrane potential decreased, morphology changed and the results were reversed by lanthanum chloride. ConclusionLanthanum chloride may alter the morphology of nano-hydroxyapatite, thereby inhibiting its induced mitophagy and mitochondria-mediated apoptosis, and ultimately improve CKD renal injury effectively.

Abstract C026: Concurrent inhibition of the RAS ERK-MAPK pathway and PIKfyve as a therapeutic strategy for pancreatic cancer

Abstract Pancreatic ductal adenocarcinoma (PDAC) is characterized clinically by poor survival and mechanistically by KRAS- and autophagy-dependent growth. We and others previously demonstrated that inhibition of KRAS signaling via downstream inhibition of the RAF-MEK-ERK pathway enhanced autophagic flux and dependency of PDAC on autophagy. Furthermore, we demonstrated that concurrent treatment with the nonspecific autophagy inhibitor chloroquine (CQ) and ERK MAPK inhibitors synergistically blocked PDAC growth. These findings provided rationale for our initiation of Phase I/II clinical trials evaluating the combination of MEKi (binimetinib; NCT4132505) or ERKi (LY3214996; NCT04386057) with HCQ in PDAC. However, a limitation of this approach is that CQ/HCQ is limited in terms of specificity and potency. Thus, we aimed to identify alternative anti-autophagy strategies. We performed a CRISPR-Cas9 loss- of-function screen in PDAC cell lines that identified the lipid kinase PIKfyve as a growth- promoting gene. PIKfyve is a lipid kinase that is essential for the generation of PI(3,5)P2 and critical for the dynamic regulation of lysosomal recycling. Because PIKfyve has been implicated in regulation of autophagy in other cellular contexts, we evaluated the effects of PIKfyve inhibition on growth and autophagic flux in PDAC cell lines and tumors. We demonstrated that PIKfyve inhibition by the small molecule apilimod resulted in durable growth suppression, with much greater potency than CQ treatment. PIKfyve inhibition potently reduced autophagy as indicated by decreased autophagic flux and the robust accumulation of autophagy-related proteins. Additionally, PIKfyve inhibition resulted in the accumulation of LAMP1 positive vacuoles that exhibited impaired cargo degradation, likely due to a lack of required acidity. Next, we hypothesized that PIKfye inhibition would sensitize PDAC cells to RAS pathway inhibition. We demonstrated that PIKfyve inhibition blocked the compensatory increases in autophagic flux associated both with MEK inhibition and with direct RAS inhibition. Accordingly, combined inhibition of PIKfyve and either the RAS ERK-MAPK pathway or RAS itself showed robust growth suppression across a panel of KRAS-mutant PDAC models. Growth suppression was due, in part, to potentiated cell cycle arrest and induction of apoptosis following loss of IAP proteins. These findings implicate PIKfyve as an effective anti-autophagy target when paired with RAS or ERK-MAPK pathway inhibition in pre-clinical models of PDAC. Citation Format: Jonathan M DeLiberty, Mallory K Roach, Clint A Stalnecker, Ryan Robb, Elyse G Schechter, Noah L Pieper, Runying Yang, Scott Bang, Khalilah E Taylor, Kristina Drizyte-Miller, John P Morris IV, Channing J Der, Adrienne D Cox, Kirsten L Bryant. Concurrent inhibition of the RAS ERK-MAPK pathway and PIKfyve as a therapeutic strategy for pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr C026.

Abstract IA-06: Elucidation of metabolic resistance mechanisms to RAS inhibition

Abstract Pancreatic ductal adenocarcinoma (PDAC) is characterized by KRAS- and autophagy-dependent growth. We previously determined that concurrent inhibition of autophagy, using the lysosomal inhibitor chloroquine (CQ), and of ERK, using a small molecule ERK inhibitor (ERKi), synergistically suppressed the growth of pancreatic ductal adenocarcinoma (PDAC) cell lines and patient xenograft-derived (PDX) organoids in vitro and PDX tumors in vivo. Our findings provided the rationale for our initiation of Phase I and Phase I/II clinical trials evaluating the combination of MEKi (binimetinib; NCT04132505) or ERKi (LY3214996; NCT04386057) with hydroxychloroquine (HCQ) in PDAC. We have extended these findings and determined that the combined inhibition of KRASG12C or KRASG12D and autophagy was effective in KRAS-mutant cancers. Our ongoing studies are centered on developing additional combinations for targeting metabolic resistance mechanisms to KRAS or ERK MAPK targeted therapies. First, we performed a CRISPR/Cas-9 mediated genetic loss-of-function screen in the presence of CQ to determine additional sensitizers to autophagy inhibition. Top sensitizers included multiple facilitators of the DNA damage response, mTOR pathway components, and genes involved in the upstream regulation of the autophagy pathway. Additionally, we identified PIKfyve, a lipid kinase critical for the recycling dynamics of lysosomes, as an essential autophagy-related gene in PDAC cells. PIKfyve inhibition with apilimod resulted in a potent reduction of autophagic flux and growth. Importantly, PIKfyve inhibition blocked the compensatory increases in autophagic flux associated both with MEK inhibition and with direct RAS inhibition. Accordingly, combined inhibition of PIKfyve and either the RAS ERK-MAPK pathway or RAS itself showed robust growth suppression across a panel of KRAS-mutant PDAC models. Growth suppression was due, in part, to potentiated cell cycle arrest and induction of apoptosis following loss of IAP proteins. We conclude that concurrent inhibition of RAS and PIKfyve is a synergistic, cytotoxic combination that may represent a novel therapeutic strategy for PDAC. In a parallel line of investigation, we determined that autophagic signaling is temporally regulated following RAS pathway inhibition, peaking at 48-72 hours, and returning to basal levels by 7 days. Interestingly, we found that as autophagic upregulation subsides, another nutrient scavenging pathway, macropinocytosis, increases. We hypothesize that further dissection of the dynamic regulation of autophagy and macropinocytosis will improve current anti-nutrient scavenging treatment strategies. We conclude that concurrent suppression of multiple metabolic processes, to block compensatory rebound activities, will be needed for effective PDAC treatment. Citation Format: Jonathan M. DeLiberty, Ryan Robb, Mallory K. Roach, Sarah E. Ackermann, Runying Yang, Noah L. Pieper, Khalilah E. Taylor, Scott Bang, Elisa Baldelli, Emanuel F. Petricoin III, John P. Morris IV, Clint A. Stalnecker, Kirsten L. Bryant. Elucidation of metabolic resistance mechanisms to RAS inhibition [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr IA-06.