A new kid in the folding funnel: Molecular chaperone activities of the BRICHOS domain.

The BRICHOS protein superfamily is a diverse group of proteins associated with a wide variety of human diseases, including respiratory distress, COVID-19, dementia, and cancer. A key characteristic of these proteins-besides their BRICHOS domain present in the ER lumen/extracellular part-is that they harbor an aggregation-prone region, which the BRICHOS domain is proposed to chaperone during biosynthesis. All so far studied BRICHOS domains modulate the aggregation pathway of various amyloid-forming substrates, but not all of them can keep denaturing proteins in a folding-competent state, in a similar manner as small heat shock proteins. Current evidence suggests that the ability to interfere with the aggregation pathways of substrates with entirely different end-point structures is dictated by BRICHOS quaternary structure as well as specific surface motifs. This review aims to provide an overview of the BRICHOS protein family and a perspective of the diverse molecular chaperone-like functions of various BRICHOS domains in relation to their structure and conformational plasticity. Furthermore, we speculate about the physiological implication of the diverse molecular chaperone functions and discuss the possibility to use the BRICHOS domain as a blood-brain barrier permeable molecular chaperone treatment of protein aggregation disorders.

A Pilot Study on Blood Components in COVID-19 Affected Subjects: A Correlation to UPR Signalling and ER-Stress.

Abstract: The endoplasmic reticulum (ER) is the site for protein synthesis, its folding and secretion. An intricate set of signalling pathways, called UPR pathways, have been evolved by ER in mammalian cells, to allow the cell to respond the presence of misfolded proteins within the ER. Breaching of these signalling systems by disease oriented accumulation of unfolded proteins may develop cellular stress. The aim of this study is to explore whether COVID-19 infection is responsible for developing this kind of endoplasmic reticulum related stress (ER-stress). ER-stress was evaluated by checking the expression of ER-stress markers e.g. PERK (adapting) and TRAF2 (alarming). ER-stress was correlated to several blood parameters viz. IgG, pro- and anti-inflammatory cytokines, leukocytes, lymphocytes, RBC, haemoglobin and PaO2/FiO2 ratio (ratio of arterial oxygen partial pressure to fractional inspired oxygen) in COVID-19 affected subjects. COVID-19 infection was found to be a state of protein homeostasis (proteostasis) collapse. Changes in IgG levels showed very poor immune response by the infected subjects. At the initial phase of the disease, pro-inflammatory cytokine levels were high and anti-inflammatory cytokines levels were low; though they were partly compromised at later phase of the disease. Total leukocyte concentration increased over the period of time; while percentage of lymphocytes were dropped. No significant changes were observed in cases of RBC counts and haemoglobin (Hb) levels. Both RBC and Hb were maintained at their normal range. In mildly stressed group, PaO2/FiO2 ratio (oxygenation status) was in the higher side of normal range; whereas in other two groups the ratio was in respiratory distress syndrome mode. Virus could induce mild to severe ER-stress, which could be the cause of cellular death and systemic dysfunction introducing fatal consequences. Graphical Abstract: Schematic representation of SARS-CoV-2 infection and related consequences.

A CASE OF TRACHEOBRONCHIAL AMYLOIDOSIS PRESENTING AS SYNCOPE

SESSION TITLE: Systemic Diseases with Deceptive Pulmonary Manifestations SESSION TYPE: Rapid Fire Case Reports PRESENTED ON: 10/18/2022 12:25 pm - 01:25 pm INTRODUCTION: Amyloidosis of the respiratory tract is rare. We present a case of tracheobronchial amyloid presenting as multifactorial cough with syncope. CASE PRESENTATION: The patient is a 65-year-old man with history of hypertension, hyperlipidemia, and allergic rhinitis who presented to the ED after a syncopal event. Two weeks prior, he had a new-onset myalgias and severe persistent cough, not resolving with over-the-counter medications. During a coughing paroxysm, he experienced a brief loss of consciousness. On arrival, his vital signs and physical exam were within normal limits except for Mallampati II, BM of 38.8 kg/m2. Basic laboratory testing was also unremarkable except for troponin T of 251 nl/dL and NT-ProBNP of 1181 pg/mL. NP swab for Sars-CoV-19 (PCR), Influenza A and B were not detected. CT of the chest revealed an area of circumferential mural soft tissue thickening in the left lower lobe bronchi. Cardiac MRI showed an area of subepicardial delayed enhancement, suggestive of myocardial inflammation or edema. Flexible bronchoscopy confirmed that the left lower lobe bronchus and proximal subsegmental bronchi had an infiltrative process with a friable, erythematous irregular mucosal surface. Forceps biopsy sampling and staining with Congo red, sulfate Alcian blue and Trichome stain were positive for amyloid deposits. Immunostain revealed predominantly CD3 positive T-Cells. Mass spectometry showed AL (lamda)-type amyloid deposition. GMS and AFB stains were negative. Telemetry showed 2-3 second pauses, correlated with episodes of cough. DISCUSSION: Amyloidosis is a disorder caused by misfolding of proteins and fibril accumulation in the extracellular space. It can present as a diffuse or localized process to one organ system. Several patterns of lung involvement have been described: nodular pulmonary, diffuse alveolar-septal, cystic, pleural, and tracheobronchial amyloidosis. Tracheobronchial amyloidosis is usually limited and not associated with systemic disease or hematologic malignancy. It can be asymptomatic, or can present with cough, dyspnea or signs of obstruction, including postobstructive pneumonia. Congo Red stained samples reveal green birefringence under polarized light microscopy. Further analysis of proteins usually reveals localized immunoglobulin light chains (AL). Cough syncope is due to increased intrathoracic pressure, decreased venous return and cardiac output, stimulation of baroreceptors, decreased chronotropic response, arterial hypotension and decreased cerebral perfusion. Our patient presented with multifactorial cough (possible viral infection, upper airway cough syndrome, amyloidosis) causing sinus pauses and syncope, on underlying myocarditis. CONCLUSIONS: Amyloid infiltration of the respiratory system is rare, but it should be considered in the differential diagnosis of airway disorders, nodular or cystic lung diseases, and pleural processes. Reference #1: Milani P, Basset M, Russo F, et al. The lung in amyloidosis. Eur Respir Rev 2017;26: 170046 [https://doi.org/10.1183/16000617.0046-2017]. Reference #2: Utz JP, Swensen SJ, Gertz MA. Pulmonary amyloidosis. The Mayo Clinic experience from 1980 to 1993. Ann Intern Med. 1996 Feb 15;124(4):407-13. doi: 10.7326/0003-4819-124-4-199602150-00004 Reference #3: Dicpinigaitis PV, Lim L, Farmakidis C. Cough syncope. Respir Med. 2014 Feb;108(2):244-51. doi: 10.1016/j.rmed.2013.10.020. Epub 2013 Nov 5. PMID: 24238768. DISCLOSURES: No relevant relationships by Amarilys Alarcon-Calderon No relevant relationships by Ashokakumar Patel

Impact of SARS-CoV-2 RBD Mutations on the Production of a Recombinant RBD Fusion Protein in Mammalian Cells.

SARS-CoV-2 receptor-binding domain (RBD) is a major target for the development of diagnostics, vaccines and therapeutics directed against COVID-19. Important efforts have been dedicated to the rapid and efficient production of recombinant RBD proteins for clinical and diagnostic applications. One of the main challenges is the ongoing emergence of SARS-CoV-2 variants that carry mutations within the RBD, resulting in the constant need to design and optimise the production of new recombinant protein variants. We describe here the impact of naturally occurring RBD mutations on the secretion of a recombinant Fc-tagged RBD protein expressed in HEK 293 cells. We show that mutation E484K of the B.1.351 variant interferes with the proper disulphide bond formation and folding of the recombinant protein, resulting in its retention into the endoplasmic reticulum (ER) and reduced protein secretion. Accumulation of the recombinant B.1.351 RBD-Fc fusion protein in the ER correlated with the upregulation of endogenous ER chaperones, suggestive of the unfolded protein response (UPR). Overexpression of the chaperone and protein disulphide isomerase PDIA2 further impaired protein secretion by altering disulphide bond formation and increasing ER retention. This work contributes to a better understanding of the challenges faced in producing mutant RBD proteins and can assist in the design of optimisation protocols.

Creutzfeldt-Jakob disease after COVID-19: infection-induced prion protein misfolding? A case report.

Creutzfeldt-Jakob disease (CJD) is a rare, fatal disease presenting with rapidly progressive neurological deficits caused by the accumulation of a misfolded form (PrPSc) of prion protein (PrPc). Coronavirus disease 2019 (COVID-19) is a primarily respiratory syndrome caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2); many diverse neurological complications have been observed after COVID-19. We describe a young patient developing CJD two months after mild COVID-19. Presenting symptoms were visuospatial deficits and ataxia, evolving into a bedridden state with preserved consciousness and diffuse myoclonus. Diagnostic work-up was suggestive of CJD. The early age of onset and the short interval between respiratory and neurological symptoms might suggest a causal relationship: a COVID-19-related neuroinflammatory state may have induced the misfolding and subsequent aggregation of PrPSc. The present case emphasizes the link between neuroinflammation and protein misfolding. Further studies are needed to establish the role of SARS-CoV-2 as an initiator of neurodegeneration.

Multidisciplinary Approaches for Transthyretin Amyloidosis.

Amyloidosis caused by systemic deposition of transthyretin (TTR) is called ATTR amyloidosis and mainly includes hereditary ATTR (ATTRv) amyloidosis and wild-type ATTR (ATTRwt) amyloidosis. Until recently, ATTRv amyloidosis had been considered a disease in the field of neurology because neuropathic symptoms predominated in patients described in early reports, whereas advances in diagnostic techniques and increased recognition of this disease revealed the presence of patients with cardiomyopathy as a predominant feature. In contrast, ATTRwt amyloidosis has been considered a disease in the field of cardiology. However, recent studies have suggested that some of the patients with ATTRwt amyloidosis present tenosynovial tissue complications, particularly carpal tunnel syndrome, as an initial manifestation of amyloidosis, necessitating an awareness of this disease among neurologists and orthopedists. Although histopathological confirmation of amyloid deposits has traditionally been considered mandatory for the diagnosis of ATTR amyloidosis, the development of noninvasive imaging techniques in the field of cardiology, such as echocardiography, magnetic resonance imaging, and nuclear imaging, enabled nonbiopsy diagnosis of this disease. The mechanisms underlying characteristic cardiac imaging findings have been deciphered by histopathological studies. Novel disease-modifying therapies for ATTR amyloidosis, such as TTR stabilizers, short interfering RNA, and antisense oligonucleotides, were initially approved for ATTRv amyloidosis patients with polyneuropathy. However, the indications for the use of these disease-modifying therapies gradually widened to include ATTRv and ATTRwt amyloidosis patients with cardiomyopathy. Since the coronavirus disease 2019 (COVID-19) pandemic, which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, occurred, the minimization of hospital visits and telemedicine have become increasingly important. As older age and cardiovascular disease are major factors associated with increased disease severity and mortality of COVID-19, many ATTR amyloidosis patients are at increased risk of disease aggravation when they are infected with SARS-CoV-2. From this viewpoint, close interspecialty communication to determine the optimal interval of evaluation is needed for the management of patients with ATTR amyloidosis.