Cu(II) Binding Increases the Soluble Toxicity of Amyloidogenic Light Chains

Light chain amyloidosis (AL) is caused by the aberrant overproduction of immunoglobulin light chains (LCs). The resulting abnormally high LC concentrations in blood lead to deposit formation in the heart and other target organs. Organ damage is caused not only by the accumulation of bulky amyloid deposits, but extensive clinical data indicate that circulating soluble LCs also exert cardiotoxic effects. The nematode C. elegans has been validated to recapitulate LC soluble toxicity in vivo, and in such a model a role for copper ions in increasing LC soluble toxicity has been reported. Here, we applied microscale thermophoresis, isothermal calorimetry and thermal melting to demonstrate the specific binding of Cu2+ to the variable domain of amyloidogenic H7 with a sub-micromolar affinity. Histidine residues present in the LC sequence are not involved in the binding, and yet their mutation to Ala reduces the soluble toxicity of H7. Copper ions bind to and destabilize the variable domains and induce a limited stabilization in this domain. In summary, the data reported here, elucidate the biochemical bases of the Cu2+-induced toxicity; moreover, they also show that copper binding is just one of the several biochemical traits contributing to LC soluble in vivo toxicity.

Childhood Systemic Lupus Erythematosus: Presentation, management and long-term outcomes in an Australian cohort

Objectives Systemic Lupus Erythematosus (SLE) is a serious autoimmune disease often resulting in major end-organ damage and increased mortality. Currently, no data exists focussing on the presentation, long-term management and progression of SLE in the Australian paediatric population. We conducted the first Australian longitudinal review of childhood SLE, focussing on response to treatment and outcomes. Methods Detailed clinical and laboratory data of 42 children diagnosed with SLE before 16 years from 1998 to 2018 resident in Western Australia was collected. Data was collected at diagnosis and key clinical review time points and compared using the Systemic Lupus Collaborating Clinics (SLICC) and Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) criteria. End organ damage was assessed against Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SDI). Incidence rates of disease complications and end organ damage were determined. Results Of the 42 children, 88% were female with average age at diagnosis of 12.5 years. Indigenous Australians were over represented with an incidence rate 18-fold higher than non-Indigenous, although most children were Caucasian, reflecting the demographics of the Australian population. Median duration of follow-up was 4.25 years. On final review, 28.6% had developed cumulative organ damage as described by the Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (incidence rate: 0.08/PY (95% CI 0.04–0.14)), and one child died. Twenty-nine children had renal involvement (incidence rate: 0.38/PY (95% CI 0.26–0.56)). Of the 27 patients with biopsy proven lupus nephritis, 70% had Class III or IV disease. Average length of prednisolone use from diagnosis was 32.5 months. Hydroxychloroquine ( n = 36) and mycophenolate mofetil ( n =21) were the most widely used steroid sparing agents. 61.9% received rituximab and/or cyclophosphamide. Conclusion This is the first longitudinal retrospective review of Australian children with SLE, with a markedly higher incidence in Indigenous children. Although improving, rates of end organ complications remain high, similar to international cohort outcomes. Longitudinal multi-centre research is crucial to elucidate risk factors for poor outcomes, and identifying those warranting early more aggressive therapy.

Gut Microbiome and Organ Fibrosis

Fibrosis is a pathological process associated with most chronic inflammatory diseases. It is defined by an excessive deposition of extracellular matrix proteins and can affect nearly every tissue and organ system in the body. Fibroproliferative diseases, such as intestinal fibrosis, liver cirrhosis, progressive kidney disease and cardiovascular disease, often lead to severe organ damage and are a leading cause of morbidity and mortality worldwide, for which there are currently no effective therapies available. In the past decade, a growing body of evidence has highlighted the gut microbiome as a major player in the regulation of the innate and adaptive immune system, with severe implications in the pathogenesis of multiple immune-mediated disorders. Gut microbiota dysbiosis has been associated with the development and progression of fibrotic processes in various organs and is predicted to be a potential therapeutic target for fibrosis management. In this review we summarize the state of the art concerning the crosstalk between intestinal microbiota and organ fibrosis, address the relevance of diet in different fibrotic diseases and discuss gut microbiome-targeted therapeutic approaches that are current being explored.

Therapeutic CFTR Correction Normalizes Systemic and Lung-Specific S1P Level Alterations Associated with Heart Failure

Heart failure (HF) is among the main causes of death worldwide. Alterations of sphingosine-1-phosphate (S1P) signaling have been linked to HF as well as to target organ damage that is often associated with HF. S1P’s availability is controlled by the cystic fibrosis transmembrane regulator (CFTR), which acts as a critical bottleneck for intracellular S1P degradation. HF induces CFTR downregulation in cells, tissues and organs, including the lung. Whether CFTR alterations during HF also affect systemic and tissue-specific S1P concentrations has not been investigated. Here, we set out to study the relationship between S1P and CFTR expression in the HF lung. Mice with HF, induced by myocardial infarction, were treated with the CFTR corrector compound C18 starting ten weeks post-myocardial infarction for two consecutive weeks. CFTR expression, S1P concentrations, and immune cell frequencies were determined in vehicle- and C18-treated HF mice and sham controls using Western blotting, flow cytometry, mass spectrometry, and qPCR. HF led to decreased pulmonary CFTR expression, which was accompanied by elevated S1P concentrations and a pro-inflammatory state in the lungs. Systemically, HF associated with higher S1P plasma levels compared to sham-operated controls and presented with higher S1P receptor 1-positive immune cells in the spleen. CFTR correction with C18 attenuated the HF-associated alterations in pulmonary CFTR expression and, hence, led to lower pulmonary S1P levels, which was accompanied by reduced lung inflammation. Collectively, these data suggest an important role for the CFTR-S1P axis in HF-mediated systemic and pulmonary inflammation.

Oxidative Stress in Intestinal Ischemia-Reperfusion

Ischemia-reperfusion (I/R) injury is a manifestation of tissue or organ damage that is followed by ischemia and exacerbated by the return of blood flow to a previously damaged tissue or organ. The intestines are one of the most sensitive tissues and organs to I/R injury. Moreover, the adverse consequences of intestinal I/R (II/R) injury are not limited to the intestine itself and can also lead to damage of the distant tissues and organs. The mechanism of II/R is extremely complex and oxidative stress is the key link in the pathogenesis of II/R injury. This study summarizes the roles of oxidative stress and its signaling pathways involved in II/R. The signaling pathways that mitigate II/R injury include the nuclear factor erythroid-related factor 2 (Nrf2)-mediated signaling pathway, Wnt/β-catenin pathway, and phosphatidylinositol kinase 3 (PI3K)/Akt pathway; those that aggravate II/R injury include the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway, Toll-like receptor (TLR) receptor-mediated signaling pathway, protein kinase CβII (PKCβII)/p66shc pathway, and microRNA (miRNA)/p66shc pathway; the effect of miRNA on related pathways and mitochondrial DNA translocation. The aforementioned pathways provide new ideas for further exploring the occurrence and development of II/R and more effective treatments for II/R injury.

Assessing and improving the validity of COVID-19 autopsy studies - a multi center approach to establish essential standards for immunohistochemical and ultrastructural analyses

Background Autopsy studies have provided valuable insights into the pathophysiology of COVID-19. Controversies remain whether the clinical presentation is due to direct organ damage by SARS-CoV-2 or secondary effects, e.g. by an overshooting immune response. SARS-CoV-2 detection in tissues by RT-qPCR and immunohistochemistry (IHC) or electron microscopy (EM) can help answer these questions, but a comprehensive evaluation of these applications is missing. Methods We assessed publications using IHC and EM for SARS-CoV-2 detection in autopsy tissues. We systematically evaluated commercially available antibodies against the SARS-CoV-2 spike protein and nucleocapsid, dsRNA, and non-structural protein Nsp3 in cultured cell lines and COVID-19 autopsy tissues. In a multicenter study, we evaluated specificity, reproducibility, and inter-observer variability of SARS-CoV-2 nucleocapsid staining. We correlated RT-qPCR viral tissue loads with semiquantitative IHC scoring. We used qualitative and quantitative EM analyses to refine criteria for ultrastructural identification of SARS-CoV-2. Findings Publications show high variability in the detection and interpretation of SARS-CoV-2 abundance in autopsy tissues by IHC or EM. In our study, we show that IHC using antibodies against SARS-CoV-2 nucleocapsid yields the highest sensitivity and specificity. We found a positive correlation between presence of viral proteins by IHC and RT-qPCR-determined SARS-CoV-2 viral RNA load (r=-0.83, p-value <0.0001). For EM, we refined criteria for virus identification and also provide recommendations for optimized sampling and analysis. 116 of 122 publications misinterpret cellular structures as virus using EM or show only insufficient data. We provide publicly accessible digitized EM and IHC sections as a reference and for training purposes. Interpretation Since detection of SARS-CoV-2 in human autopsy tissues by IHC and EM is difficult and frequently incorrect, we propose criteria for a re-evaluation of available data and guidance for further investigations of direct organ effects by SARS-CoV-2.

Postmortem Study of Organ-Specific Toxicity in Glioblastoma Patients Treated with a Combination of Temozolomide, Irinotecan and Bevacizumab

Purpose Systemic monotherapy with temozolomide (TMZ) or bevacizumab (BEV); two-drug combinations, such as Irinotecan (IRI) and BEV, TMZ and BEV and a three-drug combination with TMZ, IRI and BEV (TIB) have been used in treating patients with progressive high-grade gliomas including glioblastoma. Most patients tolerated these regimens well with well-established sides effects of hypertension, proteinuria, and reversible clinical myelosuppression (CM). However, organ-specific toxicities have never been examined by postmortem studies. Methods Postmortem tissues (from all major organs) were prospectively collected and examined by standard institution autopsy and brain cutting procedures from 76 decedents, including gliomas (N=68, 44/M, and 24/F) and brain metastases (N=8, 5/M, and 3/F) between 2009 and 2019. Standard hematoxylin and eosin (H&E) were performed on all major organs and brain samples harvested. Electronic microscopic (EM) study was carried on selected subjects kidney samples per standard EM protocol. Results Twenty-four glioma subjects were treated with TIB [median: 5.5 (range: 1-25) cycles] at glioma recurrence. Exposure to IRI significantly increased the frequency of CM (p=0.05). No unexpected adverse events were detected clinically or permenant end-organ damage by postmortem examination among subjects who received TIB compared to subjects who received standard of care (SOC) therapies. Among glioma decedents, the most common causes of death (COD) were tumor progression (63.2%, N=43), followed by aspiration pneumonia (48.5%, N=33). No COD was attributed to acute toxicity from TIB. The study also demonstrated that postmortem kidney specimen is unsuitable for studying renal ultrastructural pathological changes due to autolysis. Conclusion IRI, but not the extended use of TMZ, significantly increased CM in recurrent glioma patients. There is no permanent organ-specific toxicity among glioma decedents who received prolonged BEV, TMZ or TIB regimen based chemotherapies except expected occasional myelosuppresson. COD are most commonly resulted from glioma tumor progression and aspiration pneumonia.

Simulation of COVID-19 Symptoms in a Genetically Engineered Mouse Model

The ongoing infectious viral disease pandemic (also known as the coronavirus disease-19; COVID-19) by a constantly emerging viral agent commonly referred as the severe acute respiratory syndrome corona virus 2 or SARS-CoV-2 has revealed unique pathological findings from infected human beings, and the postmortem observations. The list of disease symptoms, and post-mortem observations is too long to mention; however, a few notable ones are worth mentioning to put into a perspective in understanding the malignity of this pandemic starting with respiratory distress or dyspnea, chest congestion, muscle or body aches, malaise, fever, chills, etc. We opine that further improvement for delivering highly effective treatment, and preventive strategies would be benefited from validated animal disease models. In this context, we designed a study and show that a genetically engineered mouse expressing the human angiotensin converting enzyme 2; hACE2 (the receptor used by SARS-CoV-2 agent to enter host cells) represents an excellent investigative resource in simulating important clinical features of the COVID-19 infection. The hACE2 mouse model (which is susceptible to SARS-CoV-2) when administered with a recombinant SARS-CoV-2 spike (S) protein intranasally exhibited a profound cytokine storm capable of altering the physiological parameters including significant changes in in vivo cardiac function along with multi-organ damage that was further confirmed via histological findings. More importantly, visceral organs from SARS-CoV-2 spike (S) treated mice revealed thrombotic blood clots as seen during postmortem examination of the mice. Thus, the hACE2 engineered mouse appears to be a suitable model for studying intimate viral pathogenesis paving the way for further identification, and characterization of appropriate prophylactics as well as therapeutics for COVID-19 management.

Vitamin D Deficiency Is Associated with Glycometabolic Changes in Nondiabetic Patients with Arterial Hypertension

Recent evidence indicates that mildly increased fasting and post-oral load blood glucose concentrations contribute to development of organ damage in nondiabetic patients with hypertension. In previous studies, vitamin D deficiency was associated with decreased glucose tolerance. The aim of this study was to examine the relationships between serum 25(OH)D levels and glucose tolerance and insulin sensitivity in hypertension. In 187 nondiabetic essential hypertensive patients free of cardiovascular or renal complications, we measured serum 25-hydroxyvitamin D (25(OH)D) and parathyroid hormone (PTH) and performed a standard oral glucose tolerance test (OGTT). Patients with 25(OH)D deficiency/insufficiency were older and had significantly higher blood pressure, fasting and post-OGTT (G-AUC) glucose levels, post-OGTT insulin (I-AUC), PTH levels, and prevalence of metabolic syndrome than patients with normal serum 25(OH)D. 25(OH)D levels were inversely correlated with age, blood pressure, fasting glucose, G-AUC, triglycerides, and serum calcium and PTH, while no significant relationships were found with body mass index (BMI), fasting insulin, I-AUC, HOMA index, and renal function. In a multivariate regression model, greater G-AUC was associated with lower 25(OH)D levels independently of BMI and seasonal vitamin D variations. Thus, in nondiabetic hypertensive patients, 25(OH)D deficiency/insufficiency could contribute to impaired glucose tolerance without directly affecting insulin sensitivity.