Autoimmune diseases - New insights into a troublesome field

Recent updates in the diagnosis and management of chronic inflammatory conditions can be brought together to better understand autoimmune diseases (ADs). With organ-specific or organ-limited and systemic ADs, physicians often are faced with a dilemma when making a diagnosis and may feel a kind of embarrassment when a more distinct nosological entity cannot be found. ADs often overlap with other diseases and good diagnostic procedures for ADs only become evidence-based when refined histopathologic, immunopathologic, and general laboratory analyses are available. Immunofluorescence analyses, Western blotting, CUT & RUN technology allow localization of the site of autoantibody-reactivity on the relevant DNA sequence. The Polymerase chain reaction technology and CRISPR-Cas9, the new gene editor using pools of synthetic non-coding RNAs in screening experiments, are expected to lead to advances in the diagnosis of ADs. The current use of mRNA as a vaccine against COVID-19 has increased confidence in the use of mRNA or long non-coding RNAs in the treatment strategy for ADs. The integration of new knowledge about innate immunity, the complement system, vaccinology, and senescence into the care of patients with ADs expands the therapeutic arsenal of disease-modifying drugs and allows for the repurposing of anti-cytokine monoclonal/biosimilar antibodies, originally designed for chronic inflammatory diseases, for ADs. This review article brings together some of the most relevant ideas; a case report included in this review highlights the difficulty of distinguishing between ADs, chronic inflammation, and/or granular disease.

Oral glucose tolerance test does not affect degree of hemoglobin glycation as measured by routine assay

BACKGROUND

Hemoglobin A1c (HbA1c) is an accurate index of fluctuation in glycemia over the 2-3 months prior to quantitative assessment. During this time, hemoglobin (Hb) slowly glycates until it shows the properties of advanced glycation end-products. Glycation kinetics is intensified by prolonged glucose exposure. In subjects undergoing oral glucose tolerance testing (OGTT), immediately after ingestion, glucose is ostensibly transported by the glucose transporter 1 (GLUT1) to erythrocyte corpuscular hemoglobin. The earliest significant measurable level of hemoglobin glycation associated with this transportation is still not clear.

SUBJECTS AND METHODS

We attempted to explore the early impact of short-term glucose load on HbA1c levels, because it is now known that transmembrane GLUT1-mediated glucose transport occurs immediately. A total of 88 participants (46 patients and 42 clinically healthy controls) underwent fasting plasma glucose quantitation during an OGTT. HbA1c, revealed by a monoclonal anti-glycation epitope antibody and adiponectin, was quantitated before (T0) and 2 hours (T120) after 80 g glucose ingestion.

RESULTS

Wilcoxon test revealed that the HbA1c values did not significantly vary (P=0.15) during the OGTT, whereas glucose concentration varied strongly between T0 and T120.

DISCUSSION

It is well known that quantitative estimation of HbA1c is informative for clinical care, independently of glucose level. The molecular mechanisms and dynamics by which glucose enters/exits red blood cells are incompletely known and may differ between individuals. We here show, for the first time, that HbA1c levels do not significantly increase during OGTT, supporting the view that non-enzymatic glycation of hemoglobin occurs slowly and that glycation during the 2 hours of an OGTT is insignificant.

Impact of the isoelectric point of model parvoviruses on viral retention in anion-exchange chromatography

Anion-exchange chromatography (AEX) is used in the downstream purification of monoclonal antibodies to remove impurities and potential viral contamination based on electrostatic interactions. Although the isoelectric point (pI) of viruses is considered a key factor predicting the virus adsorption to the resin, the precise molecular mechanisms involved remain unclear. To address this question, we compared structurally homologous parvoviruses that only differ in their surface charge distribution. A single charged amino acid substitution on the capsid surface of minute virus of mice (MVM) provoked an increased apparent pI (pI_app ) 6.2 compared to wild-type MVM (pI_app  = 4.5), as determined by chromatofocusing. Despite their radically different pI_app , both viruses displayed the same interaction profile in Mono Q AEX at different pH conditions. In contrast, the closely related canine parvovirus (pI_app  = 5.3) displayed a significantly different interaction at pH 5. The detailed structural analysis of the intricate three-dimensional structure of the capsids suggests that the charge distribution is critical, and more relevant than the pI, in controlling the interaction of a virus with the chromatographic resin. This study contributes to a better understanding of the molecular mechanisms governing virus clearance by AEX, which is crucial to enable robust process design and maximize safety.

From Langmuir-Blodgett to Grafted Films

A locally organized monolayer film strongly attached to a gold surface is obtained by transfer of a Langmuir-Blodgett (LB) film of octadecylamine (ODA) or alcohol (ODOH) onto a Au surface and simultaneous oxidative electrografting of this film still in contact with the aqueous subphase. As opposed to LB films, these films resist ultrasonication; and unlike electrografted films, they are organized monolayers by construction. They are characterized by AFM (atomic force microscopy), water contact angle, ellipsometry, XPS (X-ray photoelectron spectroscopy), IRRAS (infrared reflection absorption spectroscopy), and GIXD (grazing incidence X-ray diffraction).

A Tomato Tocopherol-Binding Protein Sheds Light on Intracellular α-Tocopherol Metabolism in Plants

Tocopherols are non-polar compounds synthesized in the plastids, which function as major antioxidants of the plant cells and are essential in the human diet. Both the intermediates and final products of the tocopherol biosynthetic pathway must cross plastid membranes to reach their sites of action. So far, no protein with tocopherol binding activity has been reported in plants. Here, we demonstrated that the tomato SlTBP protein is targeted to chloroplasts and able to bind α-tocopherol. SlTBP-knockdown tomato plants exhibited reduced levels of tocopherol in both leaves and fruits. Several tocopherol deficiency phenotypes were apparent in the transgenic lines, such as alterations in photosynthetic parameters, dramatic distortion of thylakoid membranes and significant variations in the lipid profile. These results, along with the altered expression of genes related to photosynthesis, and tetrapyrrole, lipid, isoprenoid, inositol/phosphoinositide and redox metabolism, suggest that SlTBP may act in conducting tocopherol (or its biosynthetic intermediates) between the plastid compartments and/or at the interface between chloroplast and endoplasmic reticulum membranes, affecting interorganellar lipid metabolism.

Rosuvastatin upregulates the antioxidant defense protein heme oxygenase-1

Cholesterol-independent, pleiotropic actions of HMG-CoA reductase inhibitors (statins) lead to anti-inflammatory and antioxidant actions by as yet unidentified mechanisms. This study explores the role of heme oxygenase-1 (HO-1) as target and potential mediator of rosuvastatin. In cultured human endothelial cells (ECV 304), rosuvastatin increased HO-1 mRNA and protein levels in a concentration-dependent fashion. HO-1 induction by rosuvastatin remained unaffected by mevalonate and N-nitro-L-arginine-methylester, showing that isoprenoid- and NO-dependent pathways were not involved. Pretreatment of endothelial cells with rosuvastatin reduced NADPH-dependent production of oxygen radicals. The HO-1 metabolite bilirubin, when added exogenously to the cells, virtually abolished NADPH-dependent oxidative stress. Rosuvastatin-induced inhibition of free radical formation was rescued in the presence of the HO inhibitor, tin protoporphyrin-IX. Our results demonstrate that HO-1 is a target site and antioxidant mediator of rosuvastatin in endothelial cells. This novel pathway may contribute to and partially explain the pleiotropic antiatherogenic actions of rosuvastatin.