Hyperglycemia induced cathepsin L maturation linked to diabetic comorbidities and COVID-19 mortality.

Diabetes, a prevalent chronic condition, significantly increases the risk of mortality from COVID-19, yet the underlying mechanisms remain elusive. Emerging evidence implicates Cathepsin L (CTSL) in diabetic complications, including nephropathy and retinopathy. Our previous research identified CTSL as a pivotal protease promoting SARS-CoV-2 infection. Here, we demonstrate elevated blood CTSL levels in individuals with diabetes, facilitating SARS-CoV-2 infection. Chronic hyperglycemia correlates positively with CTSL concentration and activity in diabetic patients, while acute hyperglycemia augments CTSL activity in healthy individuals. In vitro studies reveal high glucose, but not insulin, promotes SARS-CoV-2 infection in wild-type cells, with CTSL knockout cells displaying reduced susceptibility. Utilizing lung tissue samples from diabetic and non-diabetic patients, alongside Leprdb/dbmice and Leprdb/+mice, we illustrate increased CTSL activity in both humans and mice under diabetic conditions. Mechanistically, high glucose levels promote CTSL maturation and translocation from the endoplasmic reticulum (ER) to the lysosome via the ER-Golgi-lysosome axis. Our findings underscore the pivotal role of hyperglycemia-induced CTSL maturation in diabetic comorbidities and complications.

People with diabetes are at greater risk of developing severe COVID-19 and dying from the illness, which is caused by a virus known as SARS-CoV-2. The high blood sugar levels associated with diabetes appear to be a contributing factor to this heightened risk. However, diabetes is a complex condition encompassing a range of metabolic disorders, and it is therefore likely that other factors may contribute. Previous research identified a link between an enzyme called cathepsin L and more severe COVID-19 in people with diabetes. Elevated cathepsin L levels are known to contribute to diabetes complications, such as kidney damage and vision loss. It has also been shown that cathepsin L helps SARS-CoV-2 to enter and infect cells. This raised the question of whether elevated cathepsin L is responsible for the increased COVID-19 vulnerability in patients with diabetes. To investigate, He, Zhao et al. monitored disease severity and cathepsin L levels in patients with COVID-19. This confirmed that people with diabetes had more severe COVID-19 and that higher levels of cathepsin L are linked to more severe disease. Analysis also revealed that cathepsin L activity increases as blood glucose levels increase. In laboratory experiments, cells exposed to glucose or fluid from the blood of people with diabetes were more easily infected with SARS-CoV-2, with cells genetically modified to lack cathepsin L being more resistant to infection. Further experiments revealed this was due to glucose promoting maturation and migration of cathepsin L in the cells. The findings of He, Zhao et al. help to explain why people with diabetes are more likely to develop severe or fatal COVID-19. Therefore, controlling blood glucose levels in people with diabetes may help to prevent or reduce the severity of the disease. Additionally, therapies targeting cathepsin L could also potentially help to treat COVID-19, especially in patients with diabetes, although more research is needed to develop and test these treatments.

Diabetic Bone Marrow Cell Injection Accelerated Acute Pancreatitis Progression.

Acute pancreatitis (AP) is one of the leading causes of hospital admission, 20% of which could progress to the severe type with extensive acinar cell necrosis. Clinical studies have reported that diabetes is an independent risk factor of the incidence of AP and is associated with higher severity than nondiabetic subjects. However, how diabetes participates in AP progression is not well defined. To investigate this question, wild-type (wt) and diabetic db/db mice at the age of 16 weeks were used in the study. AP was induced in wt recipients by 10 injections of 50 µg/kg caerulein with a 1 h interval. One hour after the last caerulein injection, bone marrow cells (BMC) isolated from wt and db/db mice were injected intraperitoneally into the recipients (1 × 107cells/recipient). The recipients with no BMC injection served as controls. Thirteen hours after BMC injection, serum lipase activity was 1.8- and 1.3-folds higher in mice that received db/db BMC, compared with those with no injection and wt BMC injection, respectively (p ≤ 0.02 for both). By H&E staining, the overall severity score was 14.7 for no cell injection and 16.6 for wt BMC injection and increased to 22.6 for db/db BMC injection (p ≤ 0.002 for both). In particular, mice with db/db BMC injection developed more acinar cell necrosis and vacuolization than the other groups (p ≤ 0.03 for both). When sections were stained with an antibody against myeloperoxidase (MPO), the density of MPO+ cells in pancreatitis was 1.9- and 1.6-folds higher than wt BMC and no BMC injection groups, separately (p ≤ 0.02 for both). Quantified by ELISA, db/db BMC produced more IL-6, GM-CSF, and IL-10 compared with wt BMC (p ≤ 0.04 for all). In conclusion, BMC of db/db mice produced more inflammatory cytokines. In response to acinar cell injury, diabetic BMC aggravated the inflammation cascade and acinar cell injury, leading to the progression of acute pancreatitis.

Glomerular function in relation to fine airborne particulate matter in a representative population sample.

From 1990 until 2017, global air-pollution related mortality increased by 40%. Few studies addressed the renal responses to ultrafine particulate [≤ 2.5 µm (PM2.5)], including black carbon (BC), which penetrate into the blood stream. In a Flemish population study, glomerular filtration estimated from serum creatinine (eGFR) and the urinary albumin-to-creatinine ratio were measured in 2005-2009 in 820 participants (women, 50.7%; age, 51.1 years) with follow-up of 523 after 4.7 years (median). Serum creatinine, eGFR, chronic kidney disease (eGFR < 60 mL/min/1.73 m2) and microalbuminuria (> 3.5/> 2.5 mg per mmol creatinine in women/men) were correlated in individual participants via their residential address with PM2.5 [median 13.1 (range 0.3-2.9) µg/m3] and BC [1.1 (0.3-18) µg/m3], using mixed models accounting for address clusters. Cross-sectional and longitudinally, no renal outcome was associated with PM2.5 or BC in models adjusted for sex and baseline or time varying covariables, including age, blood pressure, heart rate, body mass index, plasma glucose, the total-to-HDL serum cholesterol ratio, alcohol intake, smoking, physical activity, socioeconomic class, and antihypertensive treatment. The subject-level geocorrelations of eGFR change with to BC and PM2.5 were 0.13 and 0.02, respectively (P ≥ 0.68). In conclusion, in a population with moderate exposure, renal function was unrelated to ultrafine particulate.

Cathepsin L plays a key role in SARS-CoV-2 infection in humans and humanized mice and is a promising target for new drug development.

To discover new drugs to combat COVID-19, an understanding of the molecular basis of SARS-CoV-2 infection is urgently needed. Here, for the first time, we report the crucial role of cathepsin L (CTSL) in patients with COVID-19. The circulating level of CTSL was elevated after SARS-CoV-2 infection and was positively correlated with disease course and severity. Correspondingly, SARS-CoV-2 pseudovirus infection increased CTSL expression in human cells in vitro and human ACE2 transgenic mice in vivo, while CTSL overexpression, in turn, enhanced pseudovirus infection in human cells. CTSL functionally cleaved the SARS-CoV-2 spike protein and enhanced virus entry, as evidenced by CTSL overexpression and knockdown in vitro and application of CTSL inhibitor drugs in vivo. Furthermore, amantadine, a licensed anti-influenza drug, significantly inhibited CTSL activity after SARS-CoV-2 pseudovirus infection and prevented infection both in vitro and in vivo. Therefore, CTSL is a promising target for new anti-COVID-19 drug development.

Roles of Hematopoietic Stem and Progenitor Cells in Ischemic Cardiovascular Disease.

Macrophage proliferation and skewed myelopoiesis-induced monocytosis, as well as neutrophils, enhance the generation of atherogenic inflammatory cells in a lesion area, leading to plaque formation and Cardiovascular Disease (CVD). Among all risk factors, accumulated data have shown that hyperlipidemia activates Hematopoietic Stem/Progenitor Cells (HSPCs) in the Bone Marrow (BM) niche. Recently, proliferation of Granulocyte-Monocyte Progenitors (GMPs) has been demonstrated to drive skewed myelopoiesis, while HSPCs remain quiescent. In this review, we discuss how HSPCs and GMPs participate in atherosclerosis of mice in terms of proliferation and cell mobilization from BM to peripheral blood and the lesion area. We also describe how the spleen, an extramedullary organ, is involved in skewed myelopoiesis and inflammation in atherosclerosis. We further summarize the clinical evidence of the relationship of HSPCs with coronary stenoses in patients with CVD. Ultimately, this review facilitates understanding the pathological roles of HSPCs and GMPs in atherosclerosis for future treatments.

Central hemodynamics in relation to blood lead in young men prior to chronic occupational exposure.

Background: Aortic pulse wave velocity (aPWV) predicts cardiovascular complications, but the association of central arterial properties with blood lead level (BL) is poorly documented. We therefore assessed their association with BL in 150 young men prior to occupational lead exposure, using baseline data of the Study for Promotion of Health in Recycling Lead (NCT02243904). Methods: Study nurses administered validated questionnaires and performed clinical measurements. Venous blood samples were obtained after 8-12 h of fasting. The radial, carotid and femoral pulse waves were tonometrically recorded. We accounted for ethnicity, age, anthropometric characteristics, mean arterial pressure, heart rate, smoking and drinking, and total and high-density lipoprotein serum cholesterol, as appropriate. Results: Mean values were 4.14 µg/dL for BL, 27 years for age, 108/79/28 mm Hg for central systolic/diastolic/pulse pressure, 100/10% for the augmentation ratio/index, 1.63 for pressure amplification, 5.94 m/s for aPWV, 27/11 mm Hg for the forward/backward pulse pressure height, and 43% for the reflection index. Per 10-fold BL increase, central diastolic pressure and the augmentation ratio were respectively 5.37 mm Hg (95% confidence interval [CI], 1.00-9.75) and 1.57 (CI, 0.20-2.94) greater, whereas central pulse pressure and the forward pulse pressure height were 3.74 mm Hg (CI, 0.60-6.88) and 3.37 mm Hg (CI, 0.22-6.53) smaller (p ≤ .036 for all). The other hemodynamic measurements were unrelated to BL. The reflected pulse peak time was inversely correlated with diastolic pressure (r = -0.20; p ≤ .017). Conclusion: At the exposure levels observed in our current study, aPWV, the gold standard to assess arterial stiffness, was not associated with BL. Increased peripheral arterial resistance, as reflected by higher diastolic pressure, might bring reflection points closer to the heart, thereby moving the backward wave into systole and increasing the augmentation ratio in relation to BL.

Circulating Hematopoietic Stem/Progenitor Cells are Associated with Coronary Stenoses in Patients with Coronary Heart Disease.

Inflammatory cells in atherosclerotic plaque exclusively originate from hematopoietic stem/progenitor cells (HSPCs). In this study, we investigated whether circulating HSPCs frequency related to coronary stenosis in patients with coronary heart disease (CHD). Coronary angiography was performed in 468 participants who were recruited at Cardiology Centre in LuHe Hospital from March 2016 to May 2017. Among these subjects, 344 underwent echocardiography. Mononuclear cells isolated from peripheral blood were stained with an antibody cocktail containing anti-human CD34, anti-human lineage, anti-human CD38, and anti-human CD45RA. Lineage-CD38-CD45RAdimCD34+HSPCs were quantified by flow cytometry. CHD was defined as coronary stenosis ≥50% and the extent of CHD was further categorised by coronary stenosis ≥70%. A p < 0.0031 was regarded statistically significant by the Bonferroni correction. Circulating HSPCs frequency was 1.8-fold higher in CHD patients than non-CHD participants (p = 0.047). Multivariate-adjusted logistic analysis demonstrated that HSPCs was the only marker that was associated with the odds ratio of having mild vs. severe coronary stenosis (2.08 (95% CI, 1.35-3.21), p = 0.0009). Left ventricular ejection fraction was inversely correlated with HSPCs frequency and CRP in CHD patients (p < 0.05 for both). In conclusion, HSPCs frequency in circulation is intimately related to coronary stenoses in CHD patients.

Neurocognitive function in relation to blood lead among young men prior to chronic occupational exposure.

Objectives Higher than contemporary exposure levels and advanced age of study participants have limited the interpretation of previous studies relating neurocognitive function to lead exposure. We reassessed this association in young American men prior to chronic occupational exposure at lead recycling plants, using baseline measurements of the Study for Promotion of Health in Recycling Lead (NCT02243904). Methods We administered the Stroop test (ST) and the digit-symbol test (DST) to 339 men (mean age, 28.6 years; participation rate 82.7%). Whole blood lead (BL) was determined by inductively coupled plasma mass spectrometry and related ST and DST test results using multivariable-adjusted regression. Results Average values were 4.26 µg/dL for BL, 1624 ms and 1474 ms for mean reaction time in incongruent and congruent ST trials, and 109 sec for mean total latency in DST. The number of participants with fully correct answers amounted to 281 (82.9%) and 334 (98.5%) in incongruent and congruent ST trials, respectively, and to 198 (58.4%) in the DST. In multivariable-adjusted analyses, there was no association between cognitive performance and BL except for a weak but opposite association in DST; for a 10-fold BL increment, mean total latency was 5.4% (95% confidence interval, -0.4‒11.5%; P=0.066) higher, whereas the error score was 42% (-10‒69%; P=0.096) lower. To exclude an effect of the cumulative lead dose, sensitivity analyses restricted to workers <40, 35 and 30 years were confirmatory. Conclusions At the exposure levels in our current study, we failed to demonstrate a consistent inverse association of BL with neurocognitive performance in young American men.

Fighting Type-2 Diabetes: Present and Future Perspectives.

BACKGROUND: Type-2 diabetes mellitus accounts for 80-90% of diabetic patients. So far, the treatment of diabetes mainly aims at elevating insulin level and lowering glucose level in the peripheral blood and mitigating insulin resistance. Physiologically, insulin secretion from pancreatic ß cells is delicately regulated. Thus, how insulin-related therapies could titrate blood glucose appropriately and avoid the occurrence of hypoglycemia remains an important issue for decades. Similar question is addressed on how to attenuate vascular complication in diabetic subjects. METHODS: We overviewed the evolution of each class of anti-diabetic drugs that have been used in clinical practice, focusing on their mechanisms, clinical results and cautions. RESULTS: Glucagon-like peptide-1 receptor agonists stimulate ß cells for insulin secretion in response to diet but not in fasting stage, which make them superior than conventional insulinsecretion stimulators. DPP-4 inhibitors suppress glucagon-like peptide-1 degradation. Sodium/ glucose co-transporter 2 inhibitors enhance glucose clearance through urine excretion. The appearance of these new drugs provides new information about glycemic control. We update the clinical findings of Glucagon-like peptide-1 receptor agonists, DPP-4 inhibitors and Sodium/glucose cotransporter 2 inhibitors in glycemic control and the risk or progression of cardiovascular disease in diabetic patients. Stem cell therapy might be an alternative tool for diabetic patients to improve ß cell regeneration and peripheral ischemia. We summarize the clinical results of mesenchymal stem cells transplanted into patients with diabetic limb and foot. CONCLUSION: A stepwise intensification of dual and triple therapy for individual diabetic patient is required to achieve therapeutic target.

The Impact of Integrin ß2 on Granulocyte/Macrophage Progenitor Proliferation.

Previously, we reported that although the HSPC frequency in bone marrow cells (BMC) was comparable between ß2-/- and ß2+/+ mice, transplantation of ß2-/- BMC into lethally irradiated CD45.1 recipient resulted in more myeloid cell production than ß2+/+ BMC. The objective of this study is to address if integrin ß2 deficiency skews granulocyte/macrophage progenitor (GMP) proliferation. FACS analysis demonstrated that GMP frequency and cell number were higher and megakaryocyte/erythrocyte progenitor frequency and cell number were lower in ß2-/- mice than ß2+/+ mice. However, the common myeloid progenitors (CMP) frequency and cell number were similar between the two groups. The increased GMP number was due to GMP proliferation as evidenced by the percentage of BrdU-incorporating GMP. Whole genome transcriptome analysis identified increased FcεRIα expression in ß2-/- CMP compared to ß2+/+ CMP. FcεRIα expression on ß2-/- GMP was detected increased in ß2-/- mice by qRT-PCR and FACS. Although transplantation of FcεRIαhi GMP or FcεRIαlo GMP into lethally irradiated CD45.1 recipient resulted in comparable myeloid cell production, transplantation of ß2 deficient FcεRIαhi GMP generated more myeloid cells than ß2+/+ FcεRIαhi GMP. GATA2 expression was increased in ß2-/- GMP. Using a luciferase reporter assay, we demonstrated that mutation of the GATA2 binding site in the FcεRIα promoter region diminished FcεRIα transcription. In vitro, the addition of IgE, the ligand of FcεRIα, promoted GMP expansion, which was abrogated by inhibition of JNK phosphorylation. Integrin ß2 deficiency promoted GMP proliferation and myeloid cell production, which was mediated via FcεRIα/IgE-induced JNK phosphorylation in GMP. Stem Cells 2019;37:430-440.

Glomerular function in relation to circulating adhesion molecules and inflammation markers in a general population.

Background: Inflammation is a hallmark of chronic kidney disease (CKD) and stimulates glomerular expression of vascular adhesion molecules (VCAMs). We investigated in a general population whether estimated glomerular filtration rate (eGFR) is associated with circulating adhesion molecules, inflammation markers or both. Methods: We measured serum levels of five adhesion molecules [VCAM-1, intracellular adhesion molecule-1 (ICAM-1), P-selectin, E-selectin and monocyte chemoattractant protein-1 (MCP-1)] and seven inflammation markers [C-reactive protein (CRP), neutrophil gelatinase-associated lipocalin (NGAL), tumour necrosis factor receptor 1 (TNF-R1), TNF-α, interleukin 6 (IL-6), IL-8 and vascular endothelial growth factor] in 1338 randomly recruited people (50.8% women, mean age 51.7 years, eGFR 79.9 mL/min/1.73 m2). Results: In multivariable-adjusted analyses, eGFR decreased (P ≤ 0.004) with higher VCAM-1 (association size expressed in mL/min/1.73 m2 for a doubling of the marker, -2.99), MCP-1 (-1.19), NGAL (-1.19), TNF receptor 1 (-2.78), TNF-α (-2.28) and IL-6 (-0.94). The odds ratios of having eGFR <60 versus ≥60 mL/min/1.73 m2 (n = 138 versus 1200) were significant (P ≤ 0.001) for VCAM-1 (1.77), MCP-1 (1.32), NGAL (1.26), TNF-R1 (1.49), TNF-α (1.45) and IL-6 (1.20). Compared with 24-h albuminuria, VCAM-1 increased (P <0.0001) the area under the curve from 0.57 to 0.65, MCP-1 to 0.67 and TNF-R1 to 0.79, but TNF-R1 outperformed both adhesion molecules (P < 0.0001). Conclusions: In a general population, eGFR is inversely associated with circulating adhesion molecules VCAM-1 and MCP-1 and several inflammation markers, but inflammation markers, in particular TNF-R1 and TNF-α, identify patients with eGFR <60 mL/min/1.73 m2 more accurately.

Brown adipogenic potential of brown adipocytes and peri-renal adipocytes from human embryo.

Both brown adipocytes (BAC) and beige cells hold therapeutic potential for the treatment of metabolic disorders. Unfortunately, the amount and activity of these cells are limited in adults. Although BAC marker expression has been shown in peri-renal adipose tissues in children and adults, functional assessment is lacking. Furthermore, it is entirely unknown whether adipose progenitors are present in human embryo and able to give rise to BAC in situ during evolution. Therefore, adipose tissues in the interscapular and peri-renal regions were dissected from human embryo and subcutaneous white adipose tissues (sWAT) were obtained from an adult. After subjected to differentiation in vitro, adipocyte progenitors were detected present in all these adipose tissues. When stimulated for adipogenesis, differentiated adipocytes in the intercapular and peri-renal regions showed similar features: (1) induced BAC and beige cell marker expression including UCP1 and PRDM16 and comparable mitochondrion copy number; (2) similar gene expression patterns by RNA-Seq analysis; and (3) similar maximal oxygen consumption rates examined by respirometry. Nevertheless, stimulation of adipocyte progenitors in sWAT induces neither BAC and beige cell marker expression nor any change of oxygen consumption. In conclusion, peri-renal adipocyte progenitors in human embryo hold browning potential for BAC production.

Cytokines downregulate the sarcoendoplasmic reticulum pump Ca2+ ATPase 2b and deplete endoplasmic reticulum Ca2+, leading to induction of endoplasmic reticulum stress in pancreatic beta-cells.

Cytokines and free radicals are mediators of beta-cell death in type 1 diabetes. Under in vitro conditions, interleukin-1beta (IL-1beta) + gamma-interferon (IFN-gamma) induce nitric oxide (NO) production and apoptosis in rodent and human pancreatic beta-cells. We have previously shown, by microarray analysis of primary beta-cells, that IL-1beta + IFN-gamma decrease expression of the mRNA encoding for the sarcoendoplasmic reticulum pump Ca(2+) ATPase 2b (SERCA2b) while inducing expression of the endoplasmic reticulum stress-related and proapoptotic gene CHOP (C/EBP [CCAAT/enhancer binding protein] homologous protein). In the present study we show that cytokine-induced apoptosis and necrosis in primary rat beta-cells and INS-1E cells largely depends on NO production. IL-1beta + IFN-gamma, via NO synthesis, markedly decreased SERCA2b protein expression and depleted ER Ca(2+) stores. Of note, beta-cells showed marked sensitivity to apoptosis induced by SERCA blockers, as compared with fibroblasts. Cytokine-induced ER Ca(2+) depletion was paralleled by an NO-dependent induction of CHOP protein and activation of diverse components of the ER stress response, including activation of inositol-requiring ER-to-nucleus signal kinase 1alpha (IRE1alpha) and PRK (RNA-dependent protein kinase)-like ER kinase (PERK)/activating transcription factor 4 (ATF4), but not ATF6. In contrast, the ER stress-inducing agent thapsigargin triggered these four pathways in parallel. In conclusion, our results suggest that the IL-1beta + IFN-gamma-induced decrease in SERCA2b expression, with subsequent depletion of ER Ca(2+) and activation of the ER stress pathway, is a potential contributory mechanism to beta-cell death.