Understanding the molecular mosaic of cardiotoxicity of light chains in plasma cell dyscrasias and cardiac light chain amyloidosis with the use of patient derived full-length light chains

Background

Cardiac light chain amyloidosis (AL-CA) is a life-threatening disease and the major determinant of prognosis in AL amyloidosis. The management of heart failure (HF) in AL is challenging and gold standard therapies for HF are poorly tolerated or ineffective. Cardiac toxicity of LCs in AL-CA is poorly understood and the comparison of cardiotoxicity of LCs derived from plasma cell dyscrasias (PCDs) such as multiple myeloma (MM) and monoclonal gammopathy of undetermined significance (MGUS), will improve our understanding of the mechanisms of cardiac damage.

Purpose

We aimed to 1) genetically identify and biotechnologically produce full-length LCs from patients with AL-CA, MM, MGUS or non-clonal LCs from healthy volunteers (HV), 2) identify LCs' cardiotoxicity and 3) investigate the underlying mechanisms of cardiotoxicity in vitro.

Methods

Bone marrow derived CD138+ cells from n=7 patients with AL-CA, n=2 patients with MM and n=2 patients with MGUS and peripheral blood mononuclear cells (PBMCs) from n=2 HV were isolated for RNA extraction and characterization of the LC gene family repertoire. At the protein level, LC expression was confirmed by immunoprecipitation in patients' serum followed by top-down proteomics. The overexpressed LC genes in each patient, encoding the full-length clonal LCs were cloned and produced in Shuffle E. coli cells. Two LCs were produced from HV based on the primary protein structure similarity with the patients' LCs. Primary adult ventricular murine cardiomyocytes (pAVMCs) were isolated and exposed at various LC concentrations for evaluation of cell death and investigation of the cardiotoxicity mechanisms via gene and protein expression. LCs folding, oligomerization and amyloidogenic potential were assessed via circular dichroism (CD), SDS page and electron microscopy respectively.

Results

We successfully identified the LCs responsible for the disease and isolated the respective proteins in all cases (7 AL-CA, 2 MM, 2 MGUS and 3 HV). Despite the similarity of the LCs in conformation as beta-sheet and oligomerization mainly as dimers, 5 out of 7 AL-CA derived LCs led to a different extent of cardiotoxicity in pAVMCs compared to the HV, MM and MGUS derived LCs which did not alter cell viability. Interestingly, these 5 LCs bared the highest amyloidogenic potency. LCs induced different molecular responses leading to cardiomyocyte death. AL-CA proteins κ-type induced apoptosis and overexpression of endoplasmic reticulum stress (ERS) markers while LCs λ-type increased unfolded protein response (UPR) markers and autophagy without inducing apoptosis. All LCs of κ-type including from MM and MGUS patients led to inteleukin-6 mediated inflammation indicating that this mechanism is independent of the observed toxicity.

Conclusions

AL-CA derived LCs induce cardiotoxicity, which correlates to their amyloidogenic potential via ERS, UPR, autophagy and apoptosis which can be considered targets for cardioprotection.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): Hellenic Foundation for Research and Innovation

Apoptosis in cells of bronchoalveolar lavage: a cellular reaction in patients who die with sepsis and respiratory failure

OBJECTIVE

Apoptosis represents a physiologic clearance mechanism in human tissues. The role of apoptosis has not been examined in lung cell populations, such as alveolar macrophages of septic patients, an organ frequently insulted in these patients. This study was designed to examine the effect of sepsis on the apoptosis of alveolar macrophages.

DESIGN

Prospective study.

SETTING

Intensive care unit and surgical intensive care and trauma unit of a large university hospital in Athens, Greece.

PATIENTS

Bronchoalveolar lavage was obtained from 20 consecutive patients who met the criteria for sepsis, admitted to two intensive care units. Bronchoalveolar lavage was obtained from nine volunteers without lung disease who served as controls.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The specimens were analyzed by using annexin V binding, terminal deoxynucleotidyl transfer-mediated deoxyuridine 5-triphosphate nick end labeling (TUNEL), DNA laddering, light microscopy, and immunohistochemistry. Spontaneous apoptosis of bronchoalveolar lavage cells and particularly of alveolar macrophages was significantly decreased in septic patients compared with nonseptic controls. This finding was confirmed by using morphologic criteria and the TUNEL method. Furthermore, gel electrophoresis of DNA obtained from bronchoalveolar cells revealed that DNA fragmentation was not necessarily associated with apoptotic cell death. The bcl-2 gene was minimally expressed in the control group. An inverse correlation was found between the percentage of apoptotic alveolar macrophages and the severity of sepsis.

CONCLUSIONS

The prolonged survival of lung cells in septic patients and especially of alveolar macrophages may be attributable to the inhibition of apoptosis. This seems to represent an initial attempt of the host to increase the defense capacity to kill the invading microorganism, resulting in an unbalanced tissue load of cells and an uncontrolled release of toxic metabolites. Furthermore, the inhibition of apoptosis in septic patients may explain why lung function is impaired, leading to sepsis-induced acute respiratory distress syndrome and death.

Induction of anti-tumour lymphocytes in cancer patients after brief exposure to supernatants from cultures of anti-CD3-stimulated allogeneic lymphocytes

The present study investigated the ability of supernatants collected from cultures of healthy donor-derived peripheral blood mononuclear cells (HD-PBMCs) stimulated with anti-CD3 monoclonal antibody (MAb) (allogeneic CD3 supernatants; ACD3S) to induce, upon brief exposure, tumour-reactive cytotoxic lymphocytes in cancer patients' PBMCs. ACD3S enhanced natural killer (NK) and lymphokine-activated killer (LAK) cell-mediated cytotoxicity. ACD3S contained increased levels of interleukins (IL) 1, 2, 6, 7 and 12, as well as of granulocyte-macrophage colony-stimulating factor (GM-CSF), gamma-interferon (IFN-gamma) and tumour necrosis factor-alpha (TNF-alpha). MAbs against these cytokines significantly reduced the ACD3S-induced cytotoxicity. ACD3S-induced cytotoxicity was not inhibited by anti-CD4, CD8 and MHC class I MAbs, but was markedly reduced in the presence of MAb against CD18. In contrast to HD-PBMC, ACD3S derived from cancer patients' lymphocytes exhibited lower levels of the above-mentioned cytokines and exerted reduced biological activity. In conclusion, ACD3S are able to activate, upon short-term incubation, tumour-reactive lymphocytes from cancer patients' PBMCs that lyse a variety of tumour targets, including autologous tumours. ACD3S contain high levels of certain cytokines that positively influence the induction of autologous tumour-reactive lymphocytes. Such supernatants can be collected easily from healthy donors and stored until use in clinical trials for adoptive cellular therapy of cancer. They may also be indicated in the construction of cytokine cocktails that have the ability to induce anti-tumour cytotoxicity.