The expression of TLR2 and TLR4 in the kidneys and heart of mice infected with Acanthamoeba spp

Unveiling the role of sTLR2: A novel biomarker for predicting septic-associated AKI

BACKGROUND

Acute kidney injury (AKI) is common in septic patients and strongly associated with adverse outcomes. The pathophysiology of AKI in septic patients remains elusive, and detection of patients at risk of AKI or at risk of progression to severe and persistent AKI is critical for timely and adequate support measures, including mitigating further renal damage. Therefore, identification of biomarkers associated with septic-associated AKI that contribute to improve septic AKI is an area of intensive research.

METHODS

A total of 116 consecutive patients with sepsis were categorized into two groups (AKI and non-AKI) based on the occurrence of AKI within 24 h of admission to the intensive care unit (ICU). Serum levels of soluble TLR2 (sTLR2), as well as biomarkers such as interleukin(IL)-6, IL-22, IL-10, creatinine, urea, procalcitonin, hypersensitive C-reactive protein (hs-CRP), and D-Dimer (D2), were measured within 24 h after ICU admission. Demographic and clinical characteristics including sequential organ failure assessment (SOFA) scores and acute physiology and chronic health evaluation II (APACHE II) scores were recorded. Logistic regression analysis was conducted to identify potential predictive biomarkers. Receiver operating characteristic (ROC) curve analysis was employed to determine the optimal model for predicting septic-associated AKI.

RESULTS

Patients in the AKI group exhibited significantly higher serum concentrations of IL-6, IL-10, sTLR2, creatinine, urea, hs-CRP, procalcitonin, D2 and lower serum albumin concentrations as well as higher APACHE II scores compared to those in the non-AKI group. Logistic regression analysis revealed that APACHE II scores, log10-transformed sTLR2 concentration, creatinine and D2 concentration were valuable predictors of AKI among septic patients. ROC curves demonstrated that log10-transformed sTLR2 concentration exhibited comparable predictive value to creatinine in determining the incidence of sepsis-associated AKI. The model with variables of APACHE II score, Log10-transformed serum TLR2 concentration, creatinine and D2 concentration yielded the greatest area under the curve of 0.863.

CONCLUSION

Elevated levels of sTLR2 in early-stage of septic patients may serve as a promising novel biomarker for predicting sepsis-associated AKI.

Utilizing metagenomic next-generation sequencing and phylogenetic analysis to identify a rare pediatric case of Naegleria fowleri infection presenting with fulminant myocarditis

Background

Naegleria fowleri (N. fowleri), a rare and typically lethal amoeba, most commonly causes primary amoebic meningoencephalitis (PAM). This case report describes an exceptionally rare presentation of fulminant myocarditis as the primary manifestation in a 6-year-old child, diverging from the typical neurological pathogenesis associated with N. fowleri infection. Beyond neurological afflictions, the child developed arrhythmias and cardiac failure, necessitating treatment with extracorporeal membrane oxygenation (ECMO).

Methods

Diagnosis was confirmed via metagenomic next-generation sequencing (mNGS) of both blood and cerebrospinal fluid (CSF). This analysis not only substantiated the infection but also revealed a potential new genotype of N. fowleri, designated k39_3, suggesting broader genetic diversity than previously recognized.

Results

Immediate treatment with Amphotericin B (Am B) and rifampin was initiated upon diagnosis. Despite aggressive management and supportive care, the patient failed to maintain hemodynamic stability, continued to show a decrease in cardiac output, and exhibited relentless progression of central nervous system failure, culminating in death within 72 h.

Conclusion

Our report documents a rare pediatric case of N. fowleri infection presenting with fulminant myocarditis, revealing an unexpected clinical manifestation and broadening the known spectrum of its effects. This emphasizes the need for enhanced surveillance and targeted research to understand the pathogenic mechanisms and improve treatment strategies.

The role of apoptosis and oxidative stress in the pathophysiology of Acanthamoeba spp. infection in the kidneys of hosts with different immunological status

BACKGROUND

Acanthamoeba spp. are opportunistic pathogens that cause inflammation, mostly in the brain, lungs and cornea. Recent reports indicate kidney dysfunction in hosts with systemic acanthamoebiasis. The aim of the study was to analyze the gene expression and protein concentration of NADPH oxidase 2 and 4 (NOX2 and NOX4, respectively) and nuclear erythroid 2-related factor (Nrf2) in the kidneys of hosts with systemic acanthamoebiasis. We also aimed to determine the protein and gene expressions of Bcl2, Bax, caspases 3 and 9.

METHODS

 Mice were divided into four groups based on their immunological status and Acanthamoeba sp. infection: A, immunocompetent Acanthamoeba sp.-infected mice; AS, immunosuppressed Acanthamoeba sp.- infected mice; C, immunocompetent uninfected mice; CS, immunosuppressed uninfected mice. NOX2, NOX4 and Nrf2 were analyzed by quantitative reverse transcription PCR (qRT-PCR) and ELISA methods, while pro-apoptotic and anti-apoptotic proteins (Bax and Bcl-2, respectively), Cas9, Cas3 were analyzed by qRT-PCR and western blot methods.  RESULTS: Increased gene expression and/or protein concentration of NOX2 and NOX4 were found in both immunocompetent and immunosuppressed mice infected with Acanthamoeba sp. (groups A and AS, respectively). Gene expression and/or protein concentration of Nrf2 were higher in group A than in control animals. Compared to control mice, in the AS group the expression of the Nrf2 gene was upregulated while the concentration of Nrf2 protein was decreased. Additionally in A group, higher gene and protein expression of Bcl-2, and lower gene as well as protein expression of Bax, caspases 3 and 9 were noted. In contrast, the AS group showed lower gene and protein expression of Bcl-2, and higher gene as well as protein expression of Bax, caspases 3 and 9.

CONCLUSIONS

This study is the first to address the mechanisms occurring in the kidneys of hosts infected with Acanthamoeba sp. The contact of Acanthamoeba sp. with the host cell surface and/or the oxidative burst caused by elevated levels of NOXs lead to an antioxidant response enhanced by the Nrf2 pathway. Acanthamoeba sp. have various strategies concerning apoptosis. In immunocompetent hosts, amoebae inhibit the apoptosis of kidney cells, and in immunosuppressed hosts, they lead to increased apoptosis by the intrinsic pathway and thus to a more severe course of the disease.

The Immunological Changes in the Skin of BALC/c Mice with Disseminated Acanthamoebiasis

Toll-like receptors (TLR) are involved in the recognition of numerous pathogens, including Acanthamoeba spp. Thanks to this, it is possible for immune cells to recognize microorganisms and trigger the body's innate immune response. The stimulation of TLRs also leads to the activation of specific immunity. The aim of the study was to determine the TLR2 and TLR4 gene expression in the skin of BALC/c mice infected with Acanthamoeba with AM22 strain isolated from a patient. Receptor expression was assessed by real-time polymerase chain reaction (qPCR) in the amoeba-infected host with normal (A) and reduced immunity (AS) as well as in the control host with normal immunity (C) and reduced immunity (CS). Statistical analysis of TLR2 gene expression in A and AS groups compared to C and CS groups, respectively, were statistically insignificant. In the A group, we found statistical upregulation of TLR4 gene expression at 8 dpi compared to the C group. While in AS group, TLR4 gene expression was at a similar level, such as in the CS group. Taking into account the host's immune status, the TLR4 gene expression was statistically higher in the skin of host from A group than in host from AS group at the beginning of the infection. Increased TLR4 gene expression in hosts with normal immunity infected with Acanthamoeba suggests the involvement of the studied receptor in the course of acanthamoebiasis. The above research results provide new data on the involvement of the studied receptor in the skin in the host's immune defense triggered during the Acanthamoeba infection.

Identification and validation of hub genes in drug induced acute kidney injury basing on integrated transcriptomic analysis

Background

Drug-induced acute kidney damage (DI-AKI) is a clinical phenomenon of rapid loss of kidney function over a brief period of time as a consequence of the using of medicines. The lack of a specialized treatment and the instability of traditional kidney injury markers to detect DI-AKI frequently result in the development of chronic kidney disease. Thus, it is crucial to continue screening for DI-AKI hub genes and specific biomarkers.

Methods

Differentially expressed genes (DEGs) of group iohexol, cisplatin, and vancomycin’s were analyzed using Limma package, and the intersection was calculated. DEGs were then put into String database to create a network of protein-protein interactions (PPI). Ten algorithms are used in the Cytohubba plugin to find the common hub genes. Three DI-AKI models’ hub gene expression was verified in vivo and in vitro using PCR and western blot. To investigate the hub gene’s potential as a biomarker, protein levels of mouse serum and urine were measured by ELISA kits. The UUO, IRI and aristolochic acid I-induced nephrotoxicity (AAN) datasets in the GEO database were utilized for external data verification by WGCNA and Limma package. Finally, the Elisa kit was used to identify DI-AKI patient samples.

Results

95 up-regulated common DEGs and 32 down-regulated common DEGs were obtained using Limma package. A PPI network with 84 nodes and 24 edges was built with confidence >0.4. Four hub genes were obtained by Algorithms of Cytohubba plugin, including TLR4, AOC3, IRF4 and TNFAIP6. Then, we discovered that the protein and mRNA levels of four hub genes were significantly changed in the DI-AKI model in vivo and in vitro. External data validation revealed that only the AAN model, which also belonged to DI-AKI model, had significant difference in these hub genes, whereas IRI and UUO did not. Finally, we found that plasma TLR4 levels were higher in patients with DI-AKI, especially in vancomycin-induced AKI.

Conclusion

The immune system and inflammation are key factors in DI-AKI. We discovered the immunological and inflammatory-related genes TLR4, AOC3, IRF4, and TNFAIP6, which may be promising specific biomarkers and essential hub genes for the prevention and identification of DI-AKI.

Epigenetic regulation of Toll-like receptors 2 and 4 in kidney disease

Kidney disease affects more than 10% of the worldwide population and causes significant morbidity and mortality. Epigenetic mechanisms such as DNA methylation, histone modifications, and non-coding RNAs (ncRNAs) play a pivotal role in the progression of kidney disease. These epigenetic mechanisms are reversible and majorly involved in regulating gene expression of inflammatory, fibrotic, and apoptotic proteins. Emerging data suggest that the Toll-like receptor 2 and Toll-like receptor 4 (TLR2 and TLR4) are expressed by almost all types of kidney cells and known for promoting inflammation by recognizing damage-associated molecular proteins (DAMPs). Epigenetic mechanisms regulate TLR2 and TLR4 signaling in various forms of kidney disease where different histone modifications promote the transcription of the TLR2 and TLR4 gene and its ligand high mobility group box protein 1 (HMGB1). Moreover, numerous long non-coding RNAs (LncRNAs) and microRNAs (miRNAs) modulate TLR2 and TLR4 signaling in kidney disease. However, the precise mechanisms behind this regulation are still enigmatic. Studying the epigenetic mechanisms involved in the regulation of TLR2 and TLR4 signaling in the development of kidney disease may help in understanding and finding novel therapeutic strategies. This review discusses the intricate relationship of epigenetic mechanisms with TLR2 and TLR4 in different forms of kidney diseases. In addition, we discuss the different lncRNAs and miRNAs that regulate TLR2 and TLR4 as potential therapeutic targets in kidney disease.

Histological Changes in the Kidneys and Heart in Experimental Acanthamoebiasis in Immunocompetent and Immunosuppressed Hosts

The course of Acanthamoeba spp. infection depends on the age and immune status of the host, and the virulence of the Acanthamoeba spp. strain. Some strains of free-living amoebae exhibit organ specificity, during the course of infection, while others may cause changes in many organs or completely lose pathogenicity. The aim of the current study was to investigate the pathological properties of Acanthamoeba spp. isolated from a patient with acute myeloid leukemia and atypical pneumonia (AM22). Moreover, the objective was to investigate the histopathological changes in the kidneys and heart of immunocompetent and immunosuppressed mice infected with Acanthamoeba spp. Amoebae were re-isolated from both the kidneys and hearts of the inoculated mice, although no cysts or trophozoites of the amoebae were detected in microscopic slides of the fragments of these organs. Acanthamoeba spp. induced changes in the kidney and heart weight of infected mice. In immunocompetent and immunosuppressed Acanthamoeba spp. infected mice, we found some histopathological changes, including areas with less acidic cytoplasm and a relaxation of muscle fibers. In further studies, it is important to analyze changes in gene and protein expressions in the heart and kidneys of hosts with disseminated acanthamoebiasis to better understand the course of infection in these organs, because the results of histological analysis varied depending on the immune status and duration of infection.

Potential Biomarkers in Diagnosis of Renal Acanthamoebiasis

Recent studies indicate that Acanthamoeba spp. may play a significant role in kidney dysfunction. The aim of the study was to examine the levels of kidney injury molecule 1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), and monocyte chemotactic protein 1 (MCP-1), as well as an activity of matrix metalloproteinases 2 and 9 (MMP-2 and MMP-9, respectively) in the kidneys of immunocompetent and immunosuppressed mice infected with Acanthamoeba spp. The levels of KIM-1, NGAL, and MCP-1 were analyzed by enzyme-linked immunosorbent assay (ELISA), and the activity of MMPs was determined by gelatin zymography. The elevated KIM-1 level was found in the kidneys of immunocompetent mice at the beginning of Acanthamoeba spp. infection. In the immunosuppressed mice, the KIM-1 level was statistically different. The statistically decreased NGAL level was found in the kidneys of immunocompetent mice compared to the uninfected mice. In the immunocompromised mice, we found statistically significant differences in MCP-1 levels between the uninfected and infected groups. There was an increase in the expression of both MMP-2 and MMP-9 in the kidneys of immunocompetent and immunosuppressed mice infected with Acanthamoeba spp. compared to the uninfected mice. The results indicate that KIM-1, NGAL, MCP-1, MMP-2, MMP-9, and MMP-9/NGAL might be promising biomarkers of renal acanthamoebiasis.

Pathomechanisms in the Kidneys in Selected Protozoan Parasitic Infections

Leishmaniasis, malaria, toxoplasmosis, and acanthamoebiasis are protozoan parasitic infections. They remain important contributors to the development of kidney disease, which is associated with increased patients' morbidity and mortality. Kidney injury mechanisms are not fully understood in protozoan parasitic diseases, bringing major difficulties to specific therapeutic interventions. The aim of this review is to present the biochemical and molecular mechanisms in kidneys infected with Leishmania spp., Plasmodium spp., Toxoplasma gondii, and Acanthamoeba spp. We present available mechanisms of an immune response, oxidative stress, apoptosis process, hypoxia, biomarkers of renal injury in the serum or urine, and the histopathological changes of kidneys infected with the selected parasites. Pathomechanisms of Leishmania spp. and Plasmodium spp. infections have been deeply investigated, while Toxoplasma gondii and Acanthamoeba spp. infections in the kidneys are not well known yet. Deeper knowledge of kidney involvement in leishmaniasis and malaria by presenting their mechanisms provides insight into how to create novel and effective treatments. Additionally, the presented work shows gaps in the pathophysiology of renal toxoplasmosis and acanthamoebiasis, which need further research.