Multiple Na,K-ATPase Subunits Colocalize in the Brush Border of Mouse Choroid Plexus Epithelial Cells

(1) Background: The unusual accumulation of Na,K-ATPase complexes in the brush border membrane of choroid plexus epithelial cells have intrigued researchers for decades. However, the full range of the expressed Na,K-ATPase subunits and their relation to the microvillus cytoskeleton remains unknown. (2) Methods: RT-PCR analysis, co-immunoprecipitation, native PAGE, mass spectrometry, and differential centrifugation were combined with high-resolution immunofluorescence histochemistry, proximity ligase assays, and stimulated emission depletion (STED) microscopy on mouse choroid plexus cells or tissues in order to resolve these issues. (3) Results: The choroid plexus epithelium expresses Na,K-ATPase subunits α1, α2, β1, β2, β3, and phospholemman. The α1, α2, β1, and β2, subunits are all localized to the brush border membrane, where they appear to form a complex. The ATPase complexes may stabilize in the brush border membrane via anchoring to microvillar actin indirectly through ankyrin-3 or directly via other co-precipitated proteins. Aquaporin 1 (AQP1) may form part of the proposed multi-protein complexes in contrast to another membrane protein, the Na-K-2Cl cotransporter 1 (NKCC1). NKCC1 expression seems necessary for full brush border membrane accumulation of the Na,K-ATPase in the choroid plexus. (4) Conclusion: A multitude of Na,K-ATPase subunits form molecular complexes in the choroid plexus brush border, which may bind to the cytoskeleton by various alternative actin binding proteins.     

Human Milk Antibodies against S1 and S2 Subunits from SARS-CoV-2, HCoV-OC43, and HCoV-229E in Mothers with a Confirmed COVID-19 PCR,Viral SYMPTOMS,and Unexposed Mothers

Background: Preexisting immunity to SARS-CoV-2 could be related to cross-reactive antibodies to common human-coronaviruses (HCoVs). This study aimed to evaluate whether human milk antibodies against to S1 and S2 subunits SARS-CoV-2 are cross-reactive to S1 and S2 subunits HCoV-OC43 and HCoV-229E in mothers with a confirmed COVID-19 PCR test, in mothers with previous viral symptoms during COVID-19 pandemic, and in unexposed mothers; Methods: The levels of secretory IgA (SIgA)/IgA, secretory IgM (SIgM)/IgM, and IgG specific to S1 and S2 SARS-CoV-2, and reactive to S1 + S2 HCoV-OC43, and HCoV-229E were measured in milk from 7 mothers with a confirmed COVID-19 PCR test, 20 mothers with viral symptoms, and unexposed mothers (6 Ctl1-2018 and 16 Ctl2-2018) using ELISA; Results: The S2 SARS-CoV-2 IgG levels were higher in the COVID-19 PCR (p = 0.014) and viral symptom (p = 0.040) groups than in the Ctl1-2018 group. We detected a higher number of positive correlations between the antigens and secretory antibodies in the COVID-19 PCR group than in the viral symptom and Ctl-2018 groups. S1 + S2 HCoV-OC43-reactive IgG was higher in the COVID-19 group than in the control group (p = 0.002) but did not differ for the other antibodies; Conclusions: Mothers with a confirmed COVID-19 PCR and mothers with previous viral symptoms had preexisting human milk antibodies against S2 subunit SARS-CoV-2. Human milk IgG were more specific to S2 subunit SARS-CoV-2 than other antibodies, whereas SIgA and SIgM were polyreactive and cross-reactive to S1 or S2 subunit SARS-CoV-2.     

The Effect of Cadmium on GFR Is Clarified by Normalization of Excretion Rates to Creatinine Clearance

Erroneous conclusions may result from normalization of urine cadmium and N-acetyl-β-D-glucosaminidase concentrations ([Cd]_u and [NAG]_u) to the urine creatinine concentration ([cr]_u). In theory, the sources of these errors are nullified by normalization of excretion rates (E_Cd and E_NAG) to creatinine clearance (C_cr). We hypothesized that this alternate approach would clarify the contribution of Cd-induced tubular injury to nephron loss. We studied 931 Thai subjects with a wide range of environmental Cd exposure. For x = Cd or NAG, E_x/E_cr and E_x/C_cr were calculated as [x]_u/[cr]_u and [x]_u[cr]_p/[cr]_u, respectively. Glomerular filtration rate (GFR) was estimated according to the Chronic Kidney Disease (CKD) Epidemiology Collaboration (eGFR), and CKD was defined as eGFR < 60 mL/min/1.73m². In multivariable logistic regression analyses, prevalence odds ratios (PORs) for CKD were higher for log(E_Cd/C_cr) and log(E_NAG/C_cr) than for log(E_Cd/E_cr) and log(E_NAG/E_cr). Doubling of E_Cd/C_cr and E_NAG/C_cr increased POR by 132% and 168%; doubling of E_Cd/E_cr and E_NAG/E_cr increased POR by 64% and 54%. As log(E_Cd/C_cr) rose, associations of eGFR with log(E_Cd/C_cr) and log(E_NAG/C_cr) became stronger, while associations of eGFR with log(E_Cd/E_cr) and log(E_NAG/E_cr) became insignificant. In univariate regressions of eGFR on each of these logarithmic variables, R² was consistently higher with normalization to C_cr. Our tabular and graphic analyses uniformly indicate that normalization to C_cr clarified relationships of E_Cd and E_NAG to eGFR.     

Conventional and Unconventional Mechanisms by which Exocytosis Proteins Oversee β-cell Function and Protection

Type 2 diabetes (T2D) is one of the prominent causes of morbidity and mortality in the United States and beyond, reaching global pandemic proportions. One hallmark of T2D is dysfunctional glucose-stimulated insulin secretion from the pancreatic β-cell. Insulin is secreted via the recruitment of insulin secretory granules to the plasma membrane, where the soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) and SNARE regulators work together to dock the secretory granules and release insulin into the circulation. SNARE proteins and their regulators include the Syntaxins, SNAPs, Sec1/Munc18, VAMPs, and double C2-domain proteins. Recent studies using genomics, proteomics, and biochemical approaches have linked deficiencies of exocytosis proteins with the onset and progression of T2D. Promising results are also emerging wherein restoration or enhancement of certain exocytosis proteins to β-cells improves whole-body glucose homeostasis, enhances β-cell function, and surprisingly, protection of β-cell mass. Intriguingly, overexpression and knockout studies have revealed novel functions of certain exocytosis proteins, like Syntaxin 4, suggesting that exocytosis proteins can impact a variety of pathways, including inflammatory signaling and aging. In this review, we present the conventional and unconventional functions of β-cell exocytosis proteins in normal physiology and T2D and describe how these insights might improve clinical care for T2D.     

Na+ and/or Cl− Toxicities Determine Salt Sensitivity in Soybean (Glycine max (L.) Merr.), Mungbean (Vigna radiata (L.) R. Wilczek), Cowpea (Vigna unguiculata (L.) Walp.), and Common Bean (Phaseolus vulgaris L.)

Grain legumes are important crops, but they are salt sensitive. This research dissected the responses of four (sub)tropical grain legumes to ionic components (Na⁺ and/or Cl⁻) of salt stress. Soybean, mungbean, cowpea, and common bean were subjected to NaCl, Na⁺ salts (without Cl⁻), Cl⁻ salts (without Na⁺), and a “high cation” negative control for 57 days. Growth, leaf gas exchange, and tissue ion concentrations were assessed at different growing stages. For soybean, NaCl and Na⁺ salts impaired seed dry mass (30% of control), more so than Cl⁻ salts (60% of control). All treatments impaired mungbean growth, with NaCl and Cl⁻ salt treatments affecting seed dry mass the most (2% of control). For cowpea, NaCl had the greatest adverse impact on seed dry mass (20% of control), while Na⁺ salts and Cl⁻ salts had similar intermediate effects (~45% of control). For common bean, NaCl had the greatest adverse effect on seed dry mass (4% of control), while Na⁺ salts and Cl⁻ salts impaired seed dry mass to a lesser extent (~45% of control). NaCl and Na⁺ salts (without Cl⁻) affected the photosynthesis (P_n) of soybean more than Cl⁻ salts (without Na⁺) (50% of control), while the reverse was true for mungbean. Na⁺ salts (without Cl⁻), Cl⁻ salts (without Na⁺), and NaCl had similar adverse effects on P_n of cowpea and common bean (~70% of control). In conclusion, salt sensitivity is predominantly determined by Na⁺ toxicity in soybean, Cl⁻ toxicity in mungbean, and both Na⁺ and Cl⁻ toxicity in cowpea and common bean.     

The Neurovascular Unit Dysfunction in Alzheimer’s Disease

Alzheimer’s disease (AD) is the most common neurodegenerative disease worldwide. Histopathologically, AD presents with two hallmarks: neurofibrillary tangles (NFTs), and aggregates of amyloid β peptide (Aβ) both in the brain parenchyma as neuritic plaques, and around blood vessels as cerebral amyloid angiopathy (CAA). According to the vascular hypothesis of AD, vascular risk factors can result in dysregulation of the neurovascular unit (NVU) and hypoxia. Hypoxia may reduce Aβ clearance from the brain and increase its production, leading to both parenchymal and vascular accumulation of Aβ. An increase in Aβ amplifies neuronal dysfunction, NFT formation, and accelerates neurodegeneration, resulting in dementia. In recent decades, therapeutic approaches have attempted to decrease the levels of abnormal Aβ or tau levels in the AD brain. However, several of these approaches have either been associated with an inappropriate immune response triggering inflammation, or have failed to improve cognition. Here, we review the pathogenesis and potential therapeutic targets associated with dysfunction of the NVU in AD.     

Cell-Free DNA Fragments as Biomarkers of Islet β-Cell Death in Obesity and Type 2 Diabetes

Type 2 diabetes (T2D) typically occurs in the setting of obesity and insulin resistance, where hyperglycemia is associated with decreased pancreatic β-cell mass and function. Loss of β-cell mass has variably been attributed to β-cell dedifferentiation and/or death. In recent years, it has been proposed that circulating epigenetically modified DNA fragments arising from β cells might be able to report on the potential occurrence of β-cell death in diabetes. Here, we review published literature of DNA-based β-cell death biomarkers that have been evaluated in human cohorts of islet transplantation, type 1 diabetes, and obesity and type 2 diabetes. In addition, we provide new data on the applicability of one of these biomarkers (cell free unmethylated INS DNA) in adult cohorts across a spectrum from obesity to T2D, in which no significant differences were observed, and compare these findings to those previously published in youth cohorts where differences were observed. Our analysis of the literature and our own data suggest that β-cell death may occur in subsets of individuals with obesity and T2D, however a more sensitive method or refined study designs are needed to provide better alignment of sampling with disease progression events.     

The Association of Human Herpesviruses with Malignant Brain Tumor Pathology and Therapy: Two Sides of a Coin

The role of certain viruses in malignant brain tumor development remains controversial. Experimental data demonstrate that human herpesviruses (HHVs), particularly cytomegalovirus (CMV), Epstein–Barr virus (EBV) and human herpes virus 6 (HHV-6), are implicated in brain tumor pathology, although their direct role has not yet been proven. CMV is present in most gliomas and medulloblastomas and is known to facilitate oncomodulation and/or immunomodulation, thus promoting cancer cell proliferation, invasion, apoptosis, angiogenesis, and immunosuppression. EBV and HHV-6 have also been detected in brain tumors and high-grade gliomas, showing high rates of expression and an inflammatory potential. On the other hand, due to the neurotropic nature of HHVs, novel studies have highlighted the engagement of such viruses in the development of new immunotherapeutic approaches in the context of oncolytic viral treatment and vaccine-based strategies against brain tumors. This review provides a comprehensive evaluation of recent scientific data concerning the emerging dual role of HHVs in malignant brain pathology, either as potential causative agents or as immunotherapeutic tools in the fight against these devastating diseases.     

Sex-Related Differences in Regional Blood–Brain Barrier Integrity in Non-Demented Elderly Subjects

The role of the blood–brain barrier (BBB) breakdown has been recognized as being important in Alzheimer’s disease pathogenesis. We aimed to evaluate whether regional BBB integrity differed according to sex and whether differences in BBB integrity changed as a consequence of aging or cognitive decline, using dynamic contrast-enhanced (DCE)-magnetic resonance imaging (MRI). In total, 75 participants with normal cognition (NC) or mild cognitive impairment (MCI) underwent cognitive assessments and MRI examination including DCE-MRI. Regional K_trans was calculated in cortical regions and the Patlak permeability model was used to calculate BBB permeability (K_trans, min⁻¹). Females had a lower median K_trans in the cingulate and occipital cortices. In the “older old” group, sex differences in K_trans were only observed in the occipital cortex. In the MCI group, sex differences in K_trans were only observed in the occipital cortex. Age was the only predictor of cognitive assessment scores in the male MCI group; however, educational years and K_trans in the occipital cortex could predict cognitive scores in the female MCI group. Our study revealed that females may have better BBB integrity in cingulate and occipital cortices. We also found that sex-related differences in BBB integrity are attenuated with aging or cognitive decline.     

Gouda Cheese with Modified Content of β-Casein as a Source of Peptides with ACE- and DPP-IV-Inhibiting Bioactivity: A Study Based on In Silico and In Vitro Protocol

In silico and in vitro methods were used to analyze ACE- and DPP-IV-inhibiting potential of Gouda cheese with a modified content of β-casein. Firstly, the BIOPEP-UWM database was used to predict the presence of ACE and DPP-IV inhibitors in casein sequences. Then, the following Gouda cheeses were produced: with decreased, increased, and normative content of β-casein after 1 and 60 days of ripening each (six variants in total). Finally, determination of the ACE/DPP-IV-inhibitory activity and the identification of peptides in respective Gouda-derived water-soluble extracts were carried out. The identification analyses were supported with in silico calculations, i.e., heatmaps and quantitative parameters. All Gouda variants exhibited comparable ACE inhibition, whereas DPP-IV inhibition was more diversified among the samples. The samples derived from Gouda with the increased content of β-casein (both stages of ripening) had the highest DPP-IV-inhibiting potency compared to the same samples measured for ACE inhibition. Regardless of the results concerning ACE and DPP-IV inhibition among the cheese samples, the heatmap showed that the latter bioactivity was predominant in all Gouda variants, presumably because it was based on the qualitative approach (i.e., peptide presence in the sample). Our heatmap did not include the bioactivity of a single peptide as well as its quantity in the sample. In turn, the quantitative parameters showed that the best sources of ACE/DPP-IV inhibitors were all Gouda-derived extracts obtained after 60 days of the ripening. Although our protocol was efficient in showing some regularities among Gouda cheese variants, in vivo studies are recommended for more extensive investigations of this subject.