Metabolic plasticity, essentiality and therapeutic potential of ribose-5-phosphate synthesis in Toxoplasma gondii.

Ribose-5-phosphate (R5P) is a precursor for nucleic acid biogenesis; however, the importance and homeostasis of R5P in the intracellular parasite Toxoplasma gondii remain enigmatic. Here, we show that the cytoplasmic sedoheptulose-1,7-bisphosphatase (SBPase) is dispensable. Still, its co-deletion with transaldolase (TAL) impairs the double mutant's growth and increases 13C-glucose-derived flux into pentose sugars via the transketolase (TKT) enzyme. Deletion of the latter protein affects the parasite's fitness but is not lethal and is correlated with an increased carbon flux via the oxidative pentose phosphate pathway. Further, loss of TKT leads to a decline in 13C incorporation into glycolysis and the TCA cycle, resulting in a decrease in ATP levels and the inability of phosphoribosyl-pyrophosphate synthetase (PRPS) to convert R5P into 5'-phosphoribosyl-pyrophosphate and thereby contribute to the production of AMP and IMP. Likewise, PRPS is essential for the lytic cycle. Not least, we show that RuPE-mediated metabolic compensation is imperative for the survival of the ΔsbpaseΔtal strain. In conclusion, we demonstrate that multiple routes can flexibly supply R5P to enable parasite growth and identify catalysis by TKT and PRPS as critical enzymatic steps. Our work provides novel biological and therapeutic insights into the network design principles of intracellular parasitism in a clinically-relevant pathogen.

Is radiofrequency ablation effective in treating patients with chronic knee osteoarthritis? A meta-analysis of randomized controlled trials.

Background and aims: This meta-analysis aimed to evaluate the short-term and long-term efficacy of radiofrequency ablation (RFA) and explore the role of diagnostic genicular nerve blocks in predicting treatment outcomes. Methods: A comprehensive literature search was conducted, and nine randomized controlled trials involving 714 participants were included in the analysis. Data extraction, risk of bias assessment, and subgroup analyses were performed. The primary outcome measures were pain scores at 6 and 12 months, assessed using visual analogue scale and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). The quality of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology. Results: The meta-analysis revealed that RFA demonstrated a significant short-term efficacy in reducing pain compared to the control group at 6 months, as indicated by the pain scores [weighted mean difference (WMD): -2.69, 95% CI: -3.99, -1.40]. Similarly, WOMAC scores at 6 months favored the RFA group (WMD: -4.40, 95% CI: -7.12, -1.68). However, the long-term efficacy of RFA at 12 months remained uncertain for both pain scores (WMD: -0.88, 95% CI: -2.36, 0.61) and WOMAC (WMD: 0.03, 95% CI: -0.25, 0.32). Subgroup analysis suggested that a positive result from the diagnostic genicular nerve blocks test was associated with a more favourable short-term outcome. Conclusion: This meta-analysis provides moderate-quality evidence supporting the short-term efficacy of RFA in reducing pain in patients with knee osteoarthritis. The inclusion of a diagnostic genicular nerve blocks test prior to RFA may help identify patients likely to benefit from the procedure. But it still needs more large sample studies to verify the results. However, further research is needed to determine the long-term efficacy of RFA in managing knee osteoarthritis pain.

Impact of Prevention Strategies on Quality of Life in Patients with Osteoarthritis: A Meta-Analysis of Randomized Controlled Trials.

OBJECTIVE: To evaluate the impact of prevention strategies on the quality of life in patients with osteoarthritis (OA) through a comprehensive analysis of randomized controlled trials (RCTs). METHODS: A systematic search was conducted in multiple electronic databases, including Cochrane Library, PubMed, Embase, and ClinicalTrials.gov, up to June 10th, 2023. Eligible studies were RCTs assessing the effectiveness of prevention strategies in adult patients diagnosed with OA, with validated instruments used to measure quality of life outcomes. A total of 10 RCTs met the inclusion criteria and were included in the meta-analysis. The analyzed prevention strategies encompassed enhanced exercise, education, or a combination of both. The quality of evidence was evaluated using the Grading of Recommendations Assessment, Development and Evaluation approach. RESULTS: The pooled results revealed a significant improvement in the quality of life of OA patients who underwent enhanced exercise or education compared to control groups (standardized mean difference = 0.44, 95% confidence interval 0.08-0.8). However, the overall quality of evidence was graded as low according to the Grading of Recommendations Assessment, Development and Evaluation assessment. CONCLUSIONS: This meta-analysis provides evidence that prevention strategies, particularly enhanced exercise or education, have a positive impact on the quality of life in patients with OA. Despite the observed benefits, the overall quality of evidence is limited, highlighting the need for larger, well-designed trials to strengthen the evidence base. These findings underscore the importance of implementing effective prevention strategies in the management of OA to improve patient outcomes and enhance their quality of life. Further research is warranted to optimize the selection and implementation of prevention strategies for OA patients.

Effectiveness of COVID-19 vaccines among children and adolescents against SARS-CoV-2 variants: a meta-analysis.

This systematic review and meta-analysis aimed to evaluate the effectiveness of COVID-19 vaccines among children and adolescents against SARS-CoV-2 variants. We searched PubMed, Embase, Web of Science, the Cochrane Library, and ClinicalTrials.gov for studies published on or before June 20, 2023. Studies evaluating the effectiveness of COVID-19 vaccines in children and adolescents (≤ 18 years of age) were included. Data extraction, quality assessment, and analysis were conducted following PRISMA guidelines. Ten studies were included, comprising five cohort studies (527,778 participants) and four case-control studies (1,477,422 participants). The overall vaccine effectiveness (VE) against SARS-CoV-2 variants was 68% (95% CI = 60-74%). In terms of age, the VE was higher in adolescents aged 12-18 years [69%(95% CI = 61-75%)] than in children aged 5-11 years [44%(95% CI = 1-68%)]. "Fully vaccinated" may offer greater protection than "partially vaccinated," with a VE of 71% (95%CI = 59-79%) and 66% (95%CI = 51-76%), respectively.    Conclusion: This meta-analysis presents moderate-quality evidence that the COVID-19 vaccine is effective in safeguarding children and adolescents from the SARS-CoV-2 variant. Being fully vaccinated may offer greater protection than being partially vaccinated. Nevertheless, additional high-quality controlled trials are required to verify this finding. What is Known: • The COVID-19 pandemic has led to the rapid development and deployment of vaccines worldwide. Children and adolescents are a unique population for vaccination, and the effectiveness of vaccines against SARS-CoV-2 variants in this age group is of concern. What is New: • The COVID-19 vaccine is effective in protecting children and adolescents against the SARS-CoV-2 variant. Being fully vaccinated may offer greater protection than being partially vaccinated.

Role of 6-phosphogluconate dehydrogenase enzyme 1 in growth and virulence of Toxoplasma gondii and development of attenuated live vaccine.

Toxoplasma gondii is a ubiquitous pathogen that infects all warm-blooded animals, including humans, causing substantial socioeconomic and healthcare burdens. However, there is no ideal vaccine for toxoplasmosis. As metabolism is important in the growth and virulence of Toxoplasma, some key pathways are promising antiparasitic targets. Here, we identified 6-phosphogluconate dehydrogenase 1 (Tg6PGDH1) in the oxidative pentose phosphate pathway as a cytoplasmic protein that is dispensable for tachyzoite growth of T. gondii in vitro but critical for virulence and cyst formation in vivo. The depletion of Tg6PGDH1 causes decreased gene transcription involved in signal transduction, transcriptional regulation and virulence. Furthermore, we analysed the protective effect of the ME49Δ6pgdh1 mutant as an attenuated vaccine and found that ME49Δ6pgdh1 immunization stimulated strong protective immunity against lethal challenges and blocked cyst formation caused by reinfection. Furthermore, we showed that ME49Δ6pgdh1 immunization stimulated increased levels of interferon-gamma, tumour necrosis factor-alpha and Toxoplasma-specific IgG antibodies. These data highlight the role of Tg6PGDH1 in the growth and virulence of T. gondii and its potential as a target for the development of a live-attenuated vaccine.

Seroprevalence and risk factors of Toxoplasma gondii in urban cats from China.

BACKGROUND: Toxoplasma gondii infects almost all warm-blooded animals, and cats play a crucial role in the epidemiology of T. gondii as the definitive host. Despite sporadic reports on the seroprevalence of T. gondii in domestic cats, systematic surveys are lacking and some regions remain in China uninvestigated. METHODS: A total of 1,521 serum samples were collected from 10 regions of China and analyzed by antibodies against T. gondii by ELISA with the purpose of identifying risk factors of T. gondii infection in cats across China and obtaining seroprevalence data from some previously uninvestigated areas. RESULTS: Antibodies to T. gondii were detected in 62 of 1,478 (4.2%) urban pet cats and in 9 of 43 (20.9%) stray cats. Among the regions examined, the prevalence was 13% in Sichuan, 12.8% in Chongqing, 6.4% in Hunan, 2.5% in Hubei and 0.9% in Guangdong. Additionally, this is the first report on the seroprevalence of T. gondii in urban pet cats from Qinghai (6.2%), Anhui (3.1%), Jiangxi (2.5%), Shaanxi (2.4%) and Ningxia (1.6%). The age and lifestyle (stray or pet) of cats were identified as the risk factors for seropositivity by multivariate analysis of the data. CONCLUSIONS: Our findings improve our understanding of seroprevalence and risk factors of T. gondii infection in cats across China, and provide useful information for the formulating of preventive and control measures against this widespread zoonotic parasite.

Metabolic flexibilities and vulnerabilities in the pentose phosphate pathway of the zoonotic pathogen Toxoplasma gondii.

Metabolic pathways underpin the growth and virulence of intracellular parasites and are therefore promising antiparasitic targets. The pentose phosphate pathway (PPP) is vital in most organisms, providing a reduced form of nicotinamide adenine dinucleotide phosphate (NADPH) and ribose sugar for nucleotide synthesis; however, it has not yet been studied in Toxoplasma gondii, a widespread intracellular pathogen and a model protozoan organism. Herein, we show that T. gondii has a functional PPP distributed in the cytoplasm and nucleus of its acutely-infectious tachyzoite stage. We produced eight parasite mutants disrupting seven enzymes of the PPP in T. gondii. Our data show that of the seven PPP proteins, the two glucose-6-phosphate dehydrogenases (TgG6PDH1, TgG6PDH2), one of the two 6-phosphogluconate dehydrogenases (Tg6PGDH1), ribulose-5-phosphate epimerase (TgRuPE) and transaldolase (TgTAL) are dispensable in vitro as well as in vivo, disclosing substantial metabolic plasticity in T. gondii. Among these, TgG6PDH2 plays a vital role in defense against oxidative stress by the pathogen. Further, we show that Tg6PGDH2 and ribulose-5-phosphate isomerase (TgRPI) are critical for tachyzoite growth. The depletion of TgRPI impairs the flux of glucose in central carbon pathways, and causes decreased expression of ribosomal, microneme and rhoptry proteins. In summary, our results demonstrate the physiological need of the PPP in T. gondii while unraveling metabolic flexibility and antiparasitic targets.

Effectiveness of omega-3 polyunsaturated fatty acids against microbial pathogens.

Microorganisms provide both beneficial and harmful effects to human beings. Beneficial effects come from the symbiotic relationship that exists between humans and microbiota, but then several human illnesses have turned some friendly microbes into opportunistic pathogens, causing several microbial-related diseases. Various efforts have been made to create and utilize antimicrobial agents in the treatment and prevention of these infections, but such efforts have been hampered by the emergence of antimicrobial resistance. Despite extensive studies on drug discovery to alleviate this problem, issues with the toxicity and tolerance of certain compounds and continuous microbial evolution have forced researchers to focus on screening various phytochemical dietary compounds for antimicrobial activity. Linolenic acid and its derivatives (eicosapentaenoic acid and docosahexaenoic acid) are omega-3 fatty acids that have been studied due to their role in human health, being important for the brain, the eye, the cardiovascular system, and general human growth. However, their utilization as antimicrobial agents has not been widely appreciated, perhaps due to a lack of understanding of antimicrobial mechanisms, toxicity, and route of administration. Therefore, this review focuses on the efficacy, mechanism, and toxicity of omega-3 fatty acids as alternative therapeutic agents for treating and preventing diseases associated with pathogenic microorganisms.

Comparative study to develop a single method for retrieving wide class of recombinant proteins from classical inclusion bodies.

The formation of inclusion bodies (IBs) is considered as an Achilles heel of heterologous protein expression in bacterial hosts. Wide array of techniques has been developed to recover biochemically challenging proteins from IBs. However, acquiring the active state even from the same protein family was found to be an independent of single established method. Here, we present a new strategy for the recovery of wide sub-classes of recombinant protein from harsh IBs. We found that numerous methods and their combinations for reducing IB formation and producing soluble proteins were not effective, if the inclusion bodies were harsh in nature. On the other hand, different practices with mild solubilization buffers were able to solubilize IBs completely, yet the recovery of active protein requires large screening of refolding buffers. With the integration of previously reported mild solubilization techniques, we proposed an improved method, which comprised low sarkosyl concentration, ranging from 0.05 to 0.1% coupled with slow freezing (- 1 °C/min) and fast thaw (room temperature), resulting in greater solubility and the integrity of solubilized protein. Dilution method was employed with single buffer to restore activity for every sub-class of recombinant protein. Results showed that the recovered protein's activity was significantly higher compared with traditional solubilization/refolding approach. Solubilization of IBs by the described method was proved milder in nature, which restored native-like conformation of proteins within IBs.

Expression and Antitumor Function of Latcripin-4 RCC1 and ANK Domain Protein on HepG2 from the Shiitake Medicinal Mushroom, Lentinus edodes C91-3 (Agaricomycetes), Transcriptome.

The recombinant protein of Latcripin-4 regulator of chromosome condensation 1 (RCC1) and ankyrin (ANK) domains were expressed and the antitumor activity of Latcripin-4 on HepG2 cells was studied. First, the Latcripin-4 transcript was selected from the medicinal mushroom Lentinus edodes C91-3 transcriptome by bioinformatics. Then the full-length gene of Latcripin-4 was isolated with 3'-full rapid amplification of cDNA ends (RACE) and 5'-full RACE methods according to the transcriptome. The RCC1 and ANK domains from the full-length gene were selected and inserted into the expression vector pET-32a (+) and expressed in Escherichia coli Rosetta-gami (DE3). Western blotting indicated that the protein was expressed successfully. The biological function of Latcripin-4 RCC1 and ANK domain protein on HepG2 cells was studied with the CCK-8 assay. All results demonstrated that Latcripin-4 RCC1 and ANK domain protein can inhibit the growth of human HepG2 liver cancer cells, which brings new insights to identifying antitumor proteins from medicinal food for cancer therapy.

Combined effect of linolenic acid and tobramycin on Pseudomonas aeruginosa biofilm formation and quorum sensing.

Pseudomonas aeruginosa is a ubiquitous Gram negative opportunistic pathogen capable of causing severe nosocomial infections in humans, and tobramycin is currently used to treat P. aeruginosa associated lung infections. Quorum sensing regulates biofilm formation which allows the bacterium to result in fatal infections forcing clinicians to extensively use antibiotics to manage its infections leading to emerging multiple drug resistant strains. As a result, tobramycin is also becoming resistant. Despite extensive studies on drug discovery to alleviate microbial drug resistance, the continued microbial evolution has forced researchers to focus on screening various phytochemicals and dietary compounds for antimicrobial potential. Linolenic acid (LNA) is an essential fatty acid that possesses antimicrobial actions on various microorganisms. It was hypothesized that LNA may affect the formation of biofilm on P. aeruginosa and improve the potency of tobramycin. The present study demonstrated that LNA interfered with cell-to-cell communication and reduced virulence factor production. It further enhanced the potency of tobramycin and synergistically inhibited biofilm formation through P. aeruginosa quorum sensing systems. Therefore, LNA may be considered as a potential agent for adjunctive therapy and its utilization may decrease tobramycin concentration in combined treatment thereby reducing aminoglycoside adverse effects.