Light Chain Expression Research Articles

Diagnostic criteria of lymphoproliferative diseases from the peripheral blood samples using a cell biochip

Background: At present, the diagnosis of lymphoproliferative disorders is based on the combination of blood or bone marrow smear morphology and immunophenotyping by flow cytometry. Immunophenotypic testing by flow cytometry technique is available only in big medical centers, which is not always convenient for a patient. Therefore, development of an available method for preliminary diagnosis of lymphoproliferative diseases not requiring special equipment seems relevant.Materials and methods: Peripheral blood mononuclear cells from 17 patients admitted to the hospital with suspicion of a lymphoproliferative disorder, and 17 healthy donors were studied on a cell biochip for determination of proportions of cells positive for various surface CD antigens. The diagnosis was verified by flow cytometry.Results: Compared to healthy controls and patients with T-cell lymphoproliferative disorders (TCLPD), the patients with B-cell lymphoproliferative disorders (BCLPD) had significantly lower proportion of CD7+ cells (medians, 7% and 73% respectively, p=2×10-6 for comparison with healthy controls; median 7% and 93% for comparison with TCLPD, p=0.032). In addition, the patients with BCLPD had higher proportion of peripheral СD19+ mononuclear cells, compared to that in the patients with TCLPD and healthy donors (medians 84% and 13% for comparison between BCLPD and healthy control, p=2×10-5; 84% and 3% for comparison of BCLPD and TCLPD, p=0.033). The patients with B-cell chronic lymphocytic leukemia had significantly higher CD5+ cells in the cell biochip compared to the patients with other BCLPD (medians 72% and 9%, p=0.024). The patients with TCLPD had significantly lower proportion of CD19+ cells than the healthy controls (medians, 3% and 13%, respectively, р=0.042).Conclusion: The study has demonstrated the potential to use the previously developed cell biochip for diagnosis of lymphoproliferative diseases. The biochip makes it possible to sort out white blood cells according to their surface differentiation antigen for their further morphological analysis. The cell biochip allows for the differential diagnosis between BCLPD and TCLPD and determination the lymphocyte clones based on the expression of immunoglobulin light chains.

Nitric oxide could promote development of Barrett's esophagus by S-nitrosylation-induced inhibition of Rho-ROCK signaling in esophageal fibroblasts.

Barrett's esophagus arises in the process of wound healing in distal esophageal epithelium damaged by gastroesophageal reflux disease. Differentiation of fibroblast into myofibroblasts, a smooth muscle cell-like phenotype and tissue contraction are crucial processes in wound healing. No study has evaluated mechanism by which luminal esophageal nitric oxide (NO) affect Rho-associated coiled coil-forming protein kinase (Rho-ROCK) signaling pathway, a key factor of tissue contraction, in stromal fibroblasts to develop Barrett's esophagus. Using esophageal fibroblasts, we performed collagen-based cell contraction assays and evaluated influence of Rho-ROCK signaling in the exposure to acidic bile salts and NOC-9, which is an NO donor. We found that enhanced cell contraction induced by acidic bile salts was inhibited by NO, accompanied by decrease in phosphorylated myosin light chain expression and stress fiber formation. NO directly S-nitrosylated GTP-RhoA and consequently blocked Rho-ROCK signaling. Moreover, exposure to NO and Y27632, a Rho-ROCK signaling inhibitor, decreased α-SMA expression and increased bone morphogenetic protein-4 (BMP4) expression and secretion. These findings could account for the increased expression of BMP4 in the columnar epithelial cells and stromal fibroblasts in human Barrett's esophagus. NO could impair wound contraction by blocking the Rho-ROCK signaling pathway and promote the development of Barrett's esophagus.NEW & NOTEWORTHY Barrett's esophagus is the condition where esophageal epithelium damaged by gastroesophageal reflux disease (GERD) is abnormally healed via replacing of metaplastic columnar epithelium, but very few studies have conducted focusing wound healing in the development of Barrett's esophagus. Esophageal luminal nitric oxide inhibits Rho-ROCK signaling pathway in esophageal fibroblasts, which leads to delay tissue contraction, a pivotal step in proper wound healing. Moreover, this inhibition increases tissue BMP4 expression. Impaired wound healing could be related to Barrett's esophagus.

Mantle cell lymphoma with chronic lymphocytic leukemia-like features: a diagnostic mimic and pitfall

Mantle cell lymphoma (MCL) is a mature B-cell neoplasm characterized by t(11;14) (q13;q32) and cyclin D1 overexpression in >95% of cases. Classic MCL cases are composed of a monotonous population of small- to medium-sized lymphocytes with irregular nuclear contours that are positive for cyclin D1 and SOX11and negative for CD23 and CD200. By contrast, occasional MCL cases express CD23 and CD200 but lack SOX11and morphologically and immunophenotypically resemble chronic lymphocytic leukemia (CLL), termed as CLL-like MCL in this study. These neoplasms pose a diagnostic challenge and are easy to be diagnosed as CLL in daily practice. We studied 14 cases of CLL-like MCL to define their clinicopathologic features and compared them with 33 traditional CLL cases. There were 8 men and 6 women with a median age of 62 years (range, 44-80). Compared with CLL, patients with CLL-like MCL have lower levels of peripheral blood and bone marrow involvementand more frequently had mutated IGHV. Immunophenotypically, CLL-like MCL often showed moderate to bright expression of B-cell antigens and surface immunoglobulin light chain, dim and partial expression of CD23 and CD200, infrequent CD43 positivity, and lack of LEF1. The overall survival of patients with CLL-like MCL was similar to that of CLL patients. In conclusion, CD23+, CD200+, and SOX11-negative MCL closely resemble CLL, both clinically and pathologically, including a similar indolent clinical course. They may pose a diagnostic challenge. However, patients with CLL-like MCL also have distinctive immunophenotypic features that are useful to distinguish these neoplasms from CLL.

Inhibition of Pre-BCR Signaling Mediates a Metabolic Switch in B-Cell Progenitor Acute Lymphoblastic Leukemia

Despite improvements in overall survival for children with B-cell progenitor acute lymphoblastic leukemia (BCP-ALL), it remains the second-leading cause of cancer related death in children with approximately 200 deaths per year in the U.S. Thus, there remains a critical need for a definitive cure to prevent relapse for patients with BCP ALL. The accumulation of BCP ALL blasts results from the disruption of normal developmental checkpoints. One of these checkpoints, as pro-B cells transition to become pre-B cells, involves surface expression of the precursor-B-cell receptor (pre-BCR). Prior work has categorized BCP ALL into pre-BCR positive and pre-BCR negative subtypes based on the protein expression of Ig light chain and active signaling of SRC family kinases, SYK, BTK. Combining single cell analysis and machine learning, we previously identified pre-B cells with activation of pre-BCR signaling, namely CREB, 4EBP1, rpS6 and SYK, that are present at diagnosis and highly predictive of relapse. We call these relapse predictive cells. Relapse predictive cells were enriched in relapse samples, demonstrating their persistence from diagnosis to relapse and making them an actionable target to prevent relapse altogether.To better understand relapse predictive cells, we enriched pre-B cells from patients with known relapse status and performed whole transcriptome sequencing. Relapse predictive cells demonstrated significant upregulation of genes in the oxidative phosphorylation (OXPHOS), glycolysis, and reactive oxygen species (ROS) pathways compared to pre-B-like leukemia cells from patients who will not go on to relapse. Analysis of public genome-wide CRISPR screen datasets in 2 pre-BCR+ and 4 pre-BCR- cell lines found 69 essential genes uniquely present in pre-BCR+ cell lines, related to mitochondria translation, OXPHOS and TCA cycle pathway.We performed CRISPR knock down of proximal pre-BCR related tyrosine kinase SYK in pre-BCR+ (Nalm6, Kasumi-2) and pre-BCR- (697, REH, SUPB15) cell lines to understand how activated pre-BCR impacts cellular metabolism in pre-BCR+ and pre-BCR- cells. CyTOF analysis of pre-BCR signaling demonstrated effective inhibition of downstream pre-BCR pathway members in the KD cells (pSYK, pBLNK, pBTK). RNA sequencing demonstrated upregulation of mitochondrial translation and OXPHOS pathways with downregulation of hypoxia pathways in pre-BCR+ but not pre-BCR- SYK KD cells. Functional extracellular flux experiments by Seahorse confirmed pre-BCR+ SYK KD cells to have higher basal oxygen consumption rate (OCR) and lower extracellular acidification rate (ECAR) compared to wild-type pre-BCR+ cells, indicating a switch from highly glycolytic to aerobic metabolism.To determine the interplay between pre-BCR signaling and cellular metabolism at the single cell level, we performed CYTOF with a panel examining pre-BCR pathway members, developmental phenotype and metabolism in these cell lines as well as matched diagnosis-relapse patient-derived xenografts. These results indicate, in line with the RNA sequencing and Seahorse data, that inhibiting pre-BCR signaling is accompanied by inhibition of glycolysis with lower protein expression of glycolytic related enzymes HIF1A, GLUT1, PFKFB4, GAPDH, ENO1 and LDHA. Further, we observed in cells completely deficient in the ability to initiate pre-BCR signal (SYK knock out), activated p4EBP1 indicating signaling feedback from the PI3K-AKT pathway and a metabolic adaption indicating utilization of energy sources other than glucose in cells surviving SYK loss. Finally, to determine the impact of loss of pre-BCR signaling on proliferation, in vitro competition assays demonstrated SYK KD cells to be less proliferative in all the cell lines except pre-BCR- cell line 697. In vivo, SYK KO demonstrated significantly slower engraftment (median %hCD45: 84% vs 54%, P=0.009) in NSG mice and significantly longer survival time than the mice xenografted with wild-type cells (median survival 28 vs 39 days, P=0.0004).Together, our data indicate that individual BCP ALL cells with active pre-BCR signaling are associated with relapse and that these cells have a unique metabolic state that relies on active glycolysis and metabolic flexibility supporting proliferation in vitro as well as engraftment and aggressivity in vivo. Further metabolomics experiments and characterization of primary patient samples are underway. DisclosuresMullighan: Pfizer: Research Funding; Illumina: Membership on an entity's Board of Directors or advisory committees; AbbVie: Research Funding; Amgen: Current equity holder in publicly-traded company. Davis: Novartis Pharmaceuticals: Honoraria; Jazz Pharmaceuticals: Research Funding.

In Situ Vaccination Induces Changes in Follicular Lymphoma Tumor Cells That Correlate with Abscopal Clinical Regressions

In Situ Vaccination Induces Changes in Follicular Lymphoma Tumor Cells That Correlate with Abscopal Clinical Regressions

COMMD10 is critical for Kupffer cell survival and controls Ly6Chi monocyte differentiation and inflammation in the injured liver.

Liver-resident macrophages Kupffer cells (KCs) and infiltrating Ly6Chi monocytes both contribute to liver tissue regeneration in various pathologies but also to disease progression upon disruption of orderly consecutive regeneration cascades. Little is known about molecular pathways that regulate their differentiation, maintenance, or inflammatory behavior during injury. Here, we show that copper metabolism MURR1 domain (COMMD)10-deficient KCs adopt liver-specific identity. Strikingly, COMMD10 deficiency in KCs and in other tissue-resident macrophages impedes their homeostatic survival, leading to their continuous replacement by Ly6Chi monocytes. While COMMD10 deficiency in KCs mildly worsens acetaminophen-induced liver injury (AILI), its deficiency in Ly6Chi monocytes results in exacerbated and sustained hepatic damage. Monocytes display unleashed inflammasome activation and a reduced type I interferon response and acquire "neutrophil-like" and lipid-associated macrophage differentiation fates. Collectively, COMMD10 appears indispensable for KC and other tissue-resident macrophage survival and is an important regulator of Ly6Chi monocyte fate decisions and reparative behavior in the diseased liver.

Skeletal Muscle Phenotype in Patients Undergoing Long-Term Hemodialysis Awaiting Kidney Transplantation.

Age and comorbidity-related sarcopenia represent a main cause of muscle dysfunction in patients on long-term hemodialysis. However, recent findings suggest muscle abnormalities that are not associated with sarcopenia. The aim of this study was to isolate functional and cellular muscle abnormalities independently of other major confounding factors, including malnutrition, age, comorbidity, or sedentary lifestyle, which are common in patients on maintenance hemodialysis. To overcome these confounding factors, alterations in skeletal muscle were analyzed in highly selected patients on long-term hemodialysis undergoing kidney transplantation. In total, 22 patients on long-term hemodialysis scheduled for kidney transplantation with few comorbidities, but with a long-term uremic milieu exposure, and 22 age, sex, and physical activity level frequency-matched control participants were recruited. We compared biochemical, functional, and molecular characteristics of the skeletal muscle using maximal voluntary force and endurance of the quadriceps, 6-minute walking test, and muscle biopsy of vastus lateralis. For statistical analysis, mean comparison and multiple regression tests were used. In patients on long-term hemodialysis, muscle endurance was lower, whereas maximal voluntary force was not significantly different. We observed a transition from type I (oxidative) to type II (glycolytic) muscle fibers, and an alteration of mitochondrial structure (swelling) without changes in DNA content, genome replication (peroxisome proliferator activator receptor γ coactivator-1α and mitochondrial transcription factor A), regulation of fusion (mitofusin and optic atrophy 1), or fission (dynamin-related protein 1). Notably, there were autophagosome structures containing glycogen along with mitochondrial debris, with a higher expression of light chain 3 (LC3) protein, indicating phagophore formation. This was associated with a greater conversion of LC3-I to LC3-II and the expression of Gabaralp1 and Bnip3l genes involved in mitophagy. In this highly selected long-term hemodialysis population, a low oxidative phenotype could be defined by a poor endurance, a fiber-type switch, and an alteration of mitochondria structure, without evidence of sarcopenia. This phenotype could be related to uremia through the activation of autophagy/mitophagy. NCT02794142 and NCT02040363.

VpreB surrogate light chain expression in B-lineage ALL: a report from the Children's Oncology Group

AbstractImmunotherapies directed against B-cell surface markers have been a common developmental strategy to treat B-cell malignancies. The immunoglobulin heavy chain surrogate light chain (SLC), comprising the VpreB1 (CD179a) and Lamda5 (CD179b) subunits, is expressed on pro- and pre-B cells, where it governs pre–B-cell receptor (BCR)-mediated autonomous survival signaling. We hypothesized that the pre-BCR might merit the development of targeted immunotherapies to decouple “autonomous” signaling in B-lineage acute lymphoblastic leukemia (B-ALL). We used the Children's Oncology Group (COG) minimal residual disease (MRD) flow panel to assess pre-BCR expression in 36 primary patient samples accrued to COG standard- and high-risk B-ALL studies through AALL03B1. We also assessed CD179a expression in 16 cases with day 29 end-induction samples, preselected to have ≥1% MRD. All analyses were performed on a 6-color Becton-Dickinson flow cytometer in a Clinical Laboratory Improvement Amendment/College of American Pathologist–certified laboratory. Among 36 cases tested, 32 cases were at the pre-B and 4 cases were at the pro-B stages of developmental arrest. One or both monoclonal antibodies (mAbs) showed that CD179a was present in ≥20% of the B-lymphoblast population. All cases expressed CD179a in the end-induction B-lymphoblast population. The CD179a component of the SLC is commonly expressed in B-ALL, regardless of genotype, stage of developmental arrest, or National Cancer Institute risk status.

Ferrum phosphoricum D12 Treatment Affects J774A.1 Cell Proliferation, Transcription Levels of Iron Metabolism, Antioxidant Defense, and Inflammation-related Genes.

Ferrum phosphoricum (FP) is prescribed as a homeopathic remedy to treat the early stages of fever and inflammation in cases of colds or flu, muscle fatigue and anemia. We aimed to analyze the molecular mechanisms of action of FP D12 on cell proliferation and mRNA expression of iron metabolism, antioxidant defense and inflammation-related genes in mouse J774A.1 macrophages. Cell proliferation was examined using the MTT test. RT-qPCR analyses were performed to estimate gene expression changes. Relative gene expression levels were calculated using the 2-ΔΔCt method. The effect of treatment using FP D12 tablets was compared with that using placebo tablets (PT). FP D12 in low concentrations (0.0125 mg/mL to 0.025 mg/mL) significantly stimulated proliferation of J774A.1 cells by up to 11% (p < 0.01) versus control untreated cells and by up to 40% (p < 0.01) versus PT-treated cells in the respective concentration. FP D12 versus PT induced a significant increase in mRNA expression of ferritin light chain (Ftl1) (by 8-fold, p < 0.01), β-2-microglobulin (B2m) (by 2.5-fold, p < 0.05) and iron-responsive element binding protein 2 (Ireb2) (by 4-fold, p < 0.05), and induced a slight decrease in myosin IE (Myo1e) mRNA expression levels (by 0.4-fold, p < 0.01) in macrophages. A highly significant (r2 = 0.99, p < 0.05) correlation was observed between Ireb2 and B2m transcription levels. Significant stimulation of antioxidant enzyme Gpx-1 (by 1.27-fold, p < 0.01) in cells by 0.025 mg/mL FP D12, but a slight decrease (by 0.12-fold, p < 0.05) in 0.0125 mg/mL-treated cells, was observed. A significant increase in the gene expression of IL-1β (by 3.5-fold, р < 0.05) in macrophages was also detected. Ferrum phosphoricum in D12 dilution potentially exhibits iron retention, antioxidant and immunomodulation activities, possibly by modulating transcription levels of related genes in non-stimulated mouse macrophages.

Novel Corneal Protein Biomarker Candidates Reveal Iron Metabolic Disturbance in High Myopia Eyes.

Myopia is a major public health concern with increasing global prevalence and is the leading cause of vision loss and complications. The potential role of the cornea, a substantial component of refractive power and the protective fortress of the eye, has been underestimated in the development of myopia. Our study acquired corneal stroma tissues from myopic patients undergoing femtosecond laser-assisted small incision lenticule extraction (SMILE) surgery and investigated the differential expression of circulating proteins between subjects with low and high myopia by means of high-throughput proteomic approaches—the quantitative tandem mass tag (TMT) labeling method and parallel reaction monitoring (PRM) validation. Across all corneal stroma tissue samples, a total of 2,455 proteins were identified qualitatively and quantitatively, 103 of which were differentially expressed between those with low and high myopia. The differentially abundant proteins (DAPs) between the groups of stroma samples mostly demonstrated catalytic activity and molecular function regulator and transporter activity and participated in metabolic processes, biological regulation, response to stimulus, and so forth. Pathway enrichment showed that mineral absorption, ferroptosis, and HIF-1 signaling pathways were activated in the human myopic cornea. Furthermore, TMT analysis and PRM validation revealed that the expression of ferritin light chain (FTL, P02792) and ferritin heavy chain (FTH1, P02794) was negatively associated with myopia development, while the expression of serotransferrin (TF, P02787) was positively related to myopia status. Overall, our results indicated that subjects with low and high myopia could have different proteomic profiles or signatures in the cornea. These findings revealed disturbances in iron metabolism and corneal oxidative stress in the more myopic eyes. Iron metabolic proteins could serve as an essential modulator in the pathogenesis of myopia.

Expression of atrial‑fetal light chains in cultured human cardiomyocytes after chemical ischemia‑reperfusion injury.

Atrial light chains (ALC1) are naturally present in adult heart atria, while ventricular light chains (VLC1) are predominant in ventricles. Degradation of VLC1 and re-expression of ALC1 in heart ventricles are associated with heart disorders in response to pressure overload. The aim of the current study was to investigate changes in myosin light chain expression after simulated ischemia and simulated reperfusion (sI/sR). Human cardiomyocytes (HCM) isolated from adult heart ventricles were subjected to chemical ischemia. The control group was maintained under aerobic conditions. Myocyte injury was determined by testing lactate dehydrogenase (LDH) activity. The gene expression of ALC1, VLC1 and MMP-2 were assessed by reverse transcription-quatitive PCR. Additionally, protein synthesis was measured using ELISA kits and MMP-2 activity was measured by zymography. The results revealed that LDH activity was increased in sI/sR cell-conditioned medium (P=0.02), confirming the ischemic damage of HCM. ALC1 gene expression and content in HCM were also increased in the sI/sR group (P=0.03 and P<0.001, respectively), while VLC1 gene expression after sI/sR was decreased (P=0.008). Furthermore, MMP-2 gene expression and synthesis were lower in the sI/sR group when compared with the aerobic control group (P<0.001 and P=0.03, respectively). MMP-2 activity was also increased in sI/sR cell-conditioned medium (P=0.006). In conclusion, sI/sR treatment led to increased ALC1 and decreased VLC1 expression in ventricular cardiomyocytes, which may constitute an adaptive mechanism to altered conditions and contribute to the improvement of heart function.

Abstract MP17: Neuropilin-1 Is A Novel Regulator Of Vascular Tone And Blood Pressure

Introduction: Neuropilin-1 (NRP1) is a transmembrane receptor present in vascular smooth muscle cells (VSMC) that mediates the inhibition of Rho signaling by binding the Class 3 Semaphorin (SEMA) ligand SEMA3A. Hypothesis: We hypothesize that loss of NRP1 in VSMC mitigates SEMA3A-induced Rho inhibition, thereby increasing vascular tone and blood pressure in vivo . Methods: Male and female adult mice (8-12 weeks) with inducible, smooth muscle cell-specific deletion of NRP1 (SM22a-Cre ERT2 X Nrp1 flox/flox ) were examined. Following recombination using 4-hydroxy tamoxifen (SM- NRP1 KO), systolic blood pressure (SBP) was measured using a tail cuff and compared to age- and sex-matched mice that did not receive tamoxifen (control). Aortic vascular reactivity and expression of key proteins in the Rho signaling cascade were measured using ex vivo tension myography and western blotting, respectively. Results: SBP was significantly increased in SM- NRP1 KO mice following recombination compared to control mice (SBP: 136.5 ± 10.9 vs 112.9 ± 5.6 mmHg; p=0.0006). Contractile responses in aortas of SM- NRP1 KO mice to phenylephrine (p=0.025), KCl (p=0.012), and the thromboxane agonist U44619 (p=0.019) were significantly enhanced compared to controls. Expression of total myosin light chain and LIMK-2 proteins were increased in SM- NRP1 KO compared to control aortas. In vitro , treatment of murine primary VSMC expressing NRP1 with SEMA3A decreased angiotensin II-induced Rho-GTP activation. Additionally, control and SM- NRP1 KO mice (starting at 2 weeks post-recombination) were administered angiotensin II (490 ng/kg/day) for 4 weeks. While there was no significant difference in SBP at weeks 1 and 2, SM- NRP1 KO mice had significantly lower SBP at weeks 3 and 4 following angiotensin II infusion compared to controls (Week 4 SBP: 150 ± 1.4 vs 130.5 ± 2.5 mmHg; p=0.02), suggesting a low ejection fraction and cardiac dysfunction in these mice. In support of this observation, mRNA expression of atrial natriuretic peptide was increased in hearts of angiotensin II-infused SM- NRP1 KO mice. Conclusion: Our data suggest that VSMC NRP1 regulates basal tone and blood pressure, and that loss of NRP1 causes hypertension and exacerbates cardiac dysfunction.

MM-359: Pattern-Based Identification of Normal and Aberrant Plasma Cell Compartment across a Spectrum of Plasma Cell Proliferative Disorders Using Multiparametric Flow Cytometry

Context The discriminative power of various antigens for delineating normal plasma cells (NPC) from aberrant plasma cells (APC) is variable; thus, understanding of the multiparametric flow cytometry (MFC)-based PC compartment is crucial for reliable PC characterization across various PC proliferative disorders (PCPD). Objective The expression profile and patterns of currently used immunophenotypic (IPT) markers were assessed for their ability to differentiate NPC from APC across the spectrum of PCPDs. Design This is a prospective analysis of patients diagnosed with PCPD (per standard IMWG criteria). Setting Tertiary care cancer center. Patients A total of 900 patients with diagnosis of PCPD were evaluated (MM: 724, PCL: 15, SMM: 12, MGUS: 42, Plasmacytoma: 54, Amyloidosis: 31, POEMS: 22). Interventions Bone marrow aspirate from cases (n=900) and controls (n=30) were processed per consensus guidelines from the Euro-flow protocol. An aberrant PC cluster was defined by >30 plasma cells with light chain expression beyond the range of control samples (0.26 to 3.08) and/or aberrant immunophenotypes (≥3). Main Outcomes Measures 1. Utility of cytoplasmic light chain restriction and 2. Most useful combination of markers to discriminate NPC from APC. Results All cases were segregated into three groups: cases with 1. only APC (n=181); 2. with both NPC and APC (n=574); or 3. only NPC (n=145). The PC compartment was solely characterized by light chain expression and IPT aberrancy in 36.22% (n=326) and 21.88% cases (n=197), respectively (p Conclusions Assessment of cytoplasmic light chain expression by MFC is essential for demonstrating clonality in cases with all normal or all aberrant PC. Pattern-based recognition is a useful parameter that identifies aberrant PC reliably in the majority of cases with co-existing NPC and APC, especially in setting of smaller clones of APC, which are likely to be missed by light chain assessment alone.

MM-329: Evaluation of Immunophenotype of the Non-Neoplastic Plasma Cell Compartment and Post-Therapy Immunomodulation to Understand Nuances in MRD Assessment of Multiple Myeloma Using Next-Generation Flow Cytometry

Context A deeper understanding of the normal plasma cell (PC) compartment and changes in the immunophenotypic profile post-treatment is required to assess low levels of residual disease in multiple myeloma (MM) using multiparametric flow cytometry. Objective The expression profile of selective antigens on normal and aberrant plasma cells prior to and following anti-myeloma therapy was assessed to ascertain its relevance in MRD assessment. Design This is a prospective analysis of 702 patients with the diagnosis of MM (January 2015 to June 2020). Setting The study was conducted at a tertiary care cancer center. Patients A total of 702 cases (321 treatment naive; 321 post-therapy; 60 control samples) were evaluated. Sixty samples from non-MM staging marrow were assessed to study antigenic profiles of normal PC. Interventions Bone marrow samples were collected in EDTA and processed within 6 hours of collection per the consensus recommendation from the Euro-flow protocol using two tube 8-color/single tube 10-color panel. An aberrant PC cluster was defined by presence of >30 plasma cells with light chain restriction and/or aberrant immunophenotypes. Main Outcomes Measures 1. Expression profile of antigens on the polyclonal PC compartment; 2. Post-therapy immunomodulation in MM. Results Polyclonal PC were observed in 65.42% of treatment naive samples compared to 88.16% post-treatment samples (p=0.001). Frequency of aberrant expression of markers in polyclonal PC was higher at follow-up time point: CD45 (33% vs 38%; p=0.6), CD19 (19% vs 41%; p=0.001), CD56 (14% vs 41%; p Conclusions Flow cytometry-based MRD assessment in MM is challenged by wide immunophenotypic variation in non-neoplastic PCs and changes in immunophenotype after chemotherapy; thus, simultaneous analysis of multiple immunophenotypic markers, including light chain expression, is required for reliable MRD assessment.

Reelin depletion alleviates multiple myeloma bone disease by promoting osteogenesis and inhibiting osteolysis

Extracellular matrix glycoprotein Reelin is associated with tumor metastasis and prognosis in various malignancies. However, its effects on multiple myeloma (MM) are not fully understood. Here, we investigated the regulatory effects of Reelin on MM and its underlying pathogenic mechanisms. Lentivirus plasmid containing short hairpin RNA targeting Reelin (LV3-Reln) was transfected into SP2/0 cells to knockdown Reelin expression. Flow cytometry assay analyzed cell cycle and apoptosis while Transwell assay evaluated invasiveness. BALB/c mice were inoculated with LV3-Reln-transfected SP2/0 cells to establish MM model. Primary myeloma cells and osteoblasts/osteoclast were isolated from tumor tissue and limb long bones respectively. ELISA examined serum biomarkers and immunohistochemistry detected immunoglobulin light chain expression. Morphological changes and osteoclast/osteoblast differentiation were observed by histological staining. mRNA and proteins expression were determined by qPCR and WB. In vitro studies showed that Reelin depletion regulated osteolysis and osteogenesis balance, cell cycle, invasiveness, and apoptosis in SP2/0 cells. In LV3-Reln mice, tumor growth and invasiveness were suppressed, meanwhile, reduced osteoclast activation and enhanced osteoblast activity were observed. Reelin knockdown alleviated extramedullary morbidity and inhibited spleen immune cell apoptosis by down-regulating CDK5, IL-10, and Cyto-C expression. Furthermore, reduced Reelin expression restrained osteoclast differentiation while promoted osteogenesis in the bone of LV3-Reln mice. This was further supported by down-regulation of osteolytic specific mRNAs and proteins (Trap, Mmp9, Ctsk, Clcn7) and up-regulation of osteogenic specific ones (COL-1, Runx2, β-Catenin). Reelin exerted important impacts on myeloma development through rebalancing osteolysis and osteogenesis, thus might be a potential therapeutic target for MM.

MicroRNA 223 Targeting ATG16L1 Affects Microglial Autophagy in the Kainic Acid Model of Temporal Lobe Epilepsy.

This study aimed to explore whether microRNA (miR) 223 affects microglial autophagy by targeting autophagy-related 16-like 1 (ATG16L1) in the kainic acid (KA) model of temporal lobe epilepsy (TLE). The miRNA and mRNA expression levels were quantified using quantitative real-time polymerase chain reaction (qRT-PCR), and the protein expression was investigated using western blotting. A dual-luciferase reporter assay was used to test the direct interaction between miR 223 and ATG16L1. In situ hybridization was performed to measure the hippocampal expression of miR 223. We used immunofluorescence staining to assess the expression of ATG16L1 and microtubule-associated protein light chain 3 (LC3) in the murine hippocampal microglia. Inhibitor of miR 223 was utilized to investigate the role of miR 223 in TLE, and the epileptic activity was assessed using electroencephalography (EEG). The autophagosomes were observed by transmission electron microscopy. In patients with TLE, the murine KA model of TLE, and the KA-stimulated BV2 cells, miR 223, and sequestosome 1 (SQSTM1/P62) expressions were remarkably increased, whereas ATG16L1 and LC3 levels were significantly decreased. Using a dual-luciferase reporter assay, ATG16L1 was determined as a direct target of miR 223. Treatment with antagomir 223 alleviated epilepsy, prevented abnormalities in EEG recordings and increased the ATG16L1 and LC3 levels in KA-treated mice. Inhibition of miR 223 induced increased autophagy in BV2 cells upon Rapamycin stimulation. These findings show that miR 223 affects microglial autophagy via ATG16L1 in the KA model of TLE. The miR 223/ATG16L1 pathway may offer a new treatment option for TLE.

Small-Molecule Integrated Stress Response Inhibitor Reduces Susceptibility to Postinfarct Atrial Fibrillation in Rats via the Inhibition of Integrated Stress Responses.

Phosphorylation of the eukaryotic translation initiation factor 2 α-subunit, which subsequently upregulates activating transcription factor 4 (ATF4), is the core event in the integrated stress response (ISR) pathway. Previous studies indicate phosphorylation of eukaryotic translation initiation factor 2 ɑ-subunit in atrial tissue in response to atrial fibrillation (AF). This study investigated the role of ISR pathway in experimental AF by using a small-molecule ISR inhibitor (ISRIB). Accordingly, rats were subjected to coronary artery occlusion to induce myocardial infarction (MI), or sham operation, and received either trans-ISRIB (2 mg/kg/d, i.p.) or vehicle for seven days. Thereafter, animals were subjected to the AF inducibility test by transesophageal rapid burst pacing followed by procurement of left atrium (LA) for assessment of atrial fibrosis, inflammatory indices, autophagy-related proteins, ISR activation, ion channel, and connexin 43 expression. Results showed a significant increase in the AF vulnerability and the activation of ISR in LA as evidenced by enhanced eukaryotic translation initiation factor 2 ɑ-subunit phosphorylation. ISRIB treatment suppressed upregulation of ATF4, fibrosis as indexed by determination of α-smooth muscle actin and collagen levels, inflammatory macrophage infiltration (i.e., CD68 and inducible nitric oxide synthase/CD68-positive macrophage), and autophagy as determined by expression of light chain 3. Further, ISRIB treatment reversed the expression of relevant ion channel (i.e., the voltage-gated sodium channel 1.5 , L-type voltage-dependent calcium channel 1.2, and voltage-activated A-type potassium ion channel 4.3) and connexin 43 remodeling. Collectively, the results suggest that the ISR is a key pathway in pathogenesis of AF, post-MI, and represents a novel target for treatment of AF. SIGNIFICANCE STATEMENT: The activation of integrated stress response (ISR) pathway as evidenced by enhanced eukaryotic translation initiation factor 2 ɑ-subunit phosphorylation in left atrium plays a key role in atrial fibrillation (AF). ISR inhibitor (ISRIB) reduces AF occurrence and atrial proarrhythmogenic substrate. The beneficial action of ISRIB may be mediated by suppressing ISR pathway-related cardiac fibrosis, inflammatory macrophage infiltration, autophagy, and restoring the expression of ion channel and connexin 43. This study suggests a key dysfunctional role for ISR in pathogenesis of AF with implications for novel treatment.

CD5-Negative Mantle Cell Lymphoma Defines a Distinct Disease Entity Characterized By an Indolent Clinical Course Irrespective of Known Prognostic Markers

Introduction: Mantle Cell Lymphoma (MCL) is an aggressive CD5-positive B-cell malignancy with a median survival of 3 to 5 years. A small subset of patients present with an indolent disease and can be managed on a “watch and wait” approach. Indolent MCL remains ill-defined, but is classically associated with hypermutated IGHV, non-nodal presentation, and absence of SOX11 expression. Up to 10% of MCL lack CD5 expression, but there has been limited attention given to its clinical and biological implications. We performed an extensive review of all reported cases of CD5-negative MCL to further characterize this disease subset.Patients and Methods: A systematic literature search was performed and included studies published from June 1994 to July 2017 in Pubmed, Embase, and Web of Science. We used the key words CD5 negative, CD5-, mantle cell lymphoma, and MCL. Data was tabulated regarding 20 variables: t(11;14)(q13;32), cyclin-D1, CD5, CD10, CD19, CD20, CD23, BCL2, BCL6, and Ki-67 (higher or lower than 30%), IGHV mutation status (mutated defined as >3% discordance with germline), SOX11, morphology, initial site of diagnosis, gender, age, light chain expression, presence of leukemic phase, stage, and overall survival (OS). Data was reported as percent and total number of cases with available data of each variable, and compared to historic data on CD5-positive MCL (referred to as conventional MCL). We used the Kaplan-Meier method to study OS, and log-rank test to compare OS between disease subsets.Results and discussion: 140 of 818 screened articles included CD5-negative MCL cases. After exclusion of duplicates and non-English articles, 70 sources were included. Additionally, we included 2 cases identified at our institution. Data of 323 cases of CD5-negative MCL was collected (Figure 1A). Conventional and CD5-negative MCL shared certain similarities: both had a median age of diagnosis between 60 and 70 years, showed male predominance, and presented as stage IV disease. They shared overexpression of cyclin-D1 (100%, 241/241), possessed the t(11;14)(q13;32) (96%, 107/111: 107 of 111 cases with available data on translocation), were CD19-positive (86%, 32/37), CD20-positive (97%, 107/110), BCL2-positive (98%, 44/45), CD10-negative (91%, 77/85), CD23-negative (84%, 91/109), and BCL6-negative (71%, 29/41). Presence or absence of leukemic phase was reported in 31 cases, 14 of those were positive for circulating MCL cells (45%). Lymph node was frequently the initial site of MCL diagnosis (59%, 57/97). Majority of cases showed the classical MCL morphology with small to medium sized lymphoid cells (59%, 61/104). The proliferation marker Ki-67 was reported in 82 cases, 48 (59%) of which were <30%.There were considerable clinical and biological differences between CD5-negative and conventional MCL. Most notably, the median OS (mOS) of 79 CD5-negative MCL cases with available follow-up was >14 years (Figure 1B), which compares very favorably to the historic survival of conventional MCL. SOX11, an MCL-specific biomarker that is positive in 90% of conventional cases was expressed in only 44% (11/25) of CD5-negative MCL cases. Lack of SOX11 expression in MCL predicts an indolent MCL subset. Surprisingly, OS was not significantly different between SOX11-positive and SOX11-negative CD5-negative MCL (Figure 1C, P=0.88). SOX11 stains were performed by expert hematopathologists at Tulane (2 cases) or other reliable institutions. Akin to SOX11 expression, λ light chain restriction and unmutated IGHV, two variables known topredict worse outcomes in conventional MCL, did not significantly impact OS in CD5-negative MCL. Similarly, higher Ki-67 expression (>30%) did not affect OS of CD5-negative MCL. Variables more prevalent in CD5-negative MCL compared to conventional MCL included κ light chain restriction (70%, 26/37) and IGHV hypermutation (79%, 15/19). Though sample size is limited, our survival analysis highly suggests that lack of CD5-expression might in fact represent an independently good prognostic marker in MCL.Conclusion: Lack of CD5 appears to improve survival in MCL independently of other favorable prognostic markers such as IGHV hypermutation, absence of SOX11 expression, low Ki-67, and κ restriction. Reasons for this indolent behavior remain unknown. Our analysis indicates that CD5-negative MCL deserves deeper investigation to further understand its biological implications. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

IgD Myeloma: Clinical Features and Outcome from a Multicenter Retrospective Study in Chinese and Korean of 308 Patients from Asian Myeloma Network (AMN) Project

IgD myeloma is a rare hematologic malignancy for which clinical and biological features and patient outcomes have not been extensively studied. However, previous studies found 3.1% IgD myeloma prevalence in Asian myeloma patients, and with the high incidence of 6%, especially for younger than 50 years with 10.3% in Chinese myeloma patients (Kim K. et al. Am J Hematol. 2014, Lu J. et al. Drug Des Devel Ther. 2016). Therefore, to further assess the frequency and the specific characteristics and evaluate the outcome of patients with IgD myeloma, we carried out a multicenter retrospective study in Chinese and Korean patients from AMN project with diagnosis of IgD myeloma.A total of 308 patients from 22 centers were included in this analysis. The median age at diagnosis was 56 years with a male predominance (65.70%). Anemia and renal dysfunction were found in 86.7% and 46.2%, respectively. Renal failure is more common at presentation with an increase in serum creatinine (> 2 mg/dL) in more than 10% various series of IgD MM. The bias for λ light chain expression with a reversed light chain ratio is a characteristic feature of IgD MM, which showed 95.79% of patients with IgD λ light chain in Asian patients. DS stage 1, 2, and 3 were showed in 1.30%, 5.84%, and 92.86%, respectively. The chromosomal aberration accounted in 58.14% and t(11;14) was the most common cytogenetic finding (40.57%). Median overall survival (OS) was 39.2 months (95% CI 31.56-41.43). Higher International Staging System (ISS) stages III (62.62%) might be associated with worse survival (P = 0.02), while ISS stages I and II were seen in 16.39% and 20.98%. Patents received with stem cell transplantation showed better survival rates. New drugs including bortezomib, thalidomide, and lenalidomide were used in more than 60% of all patients and affected OS when used as a first-line treatment.In this multicenter retrospective study from Chinese and Korean IgD myeloma patients, we found that IgD MM more likely presented at advanced stage and showed a more aggressive clinical course. The underlying tumor biology responsible for these differences remains to be determined. DisclosuresNo relevant conflicts of interest to declare.

Lettuce Plants Expressing High Levels of Factor VIII Antigen in the Chloroplast for Oral Tolerance in Hemophilia a

Inhibitor formation is a serious complication in factor VIII (FVIII) replacement therapy for the X-linked bleeding disorder hemophilia A and occurs in 20-30% of patients. No prophylactic tolerance protocols exist. In previous proof-of-principle work, we demonstrated oral tolerance induction to FVIII in hemophilia A mice using frozen tobacco leaf cells expressing the heavy chain (HC) and C2 domain of human B domain-deleted (BDD) FVIII (Blood 124:1659-68, 2014). This approach is based on expression of heterologous proteins in the chloroplasts of green leaves and natural bioencapsulation provided by plant cell wall, so that the antigen is protected until its release in the small intestine. The antigens are expressed as fusions with the transmucosal carrier CTB proteins for effective targeting of the gut epithelium and translocation to the immune system. However, significant hurdles toward clinical feasibility remained that we now successfully addressed. Until now, methods to express large human proteins in chloroplasts of edible crop plants did not exist. Building on our recently established gene transfer technology for lettuce chloroplasts and identification of powerful posttranscriptional regulatory elements, we focused on the development of chloroplast genomics tools (e.g. bioinformatics tools for codon optimization and assays that identify sites of ribosome stalling), which ultimately allowed us to express high levels of FVIII antigen in edible crop plants that are suitable for clinical application. Remarkably, codon-optimization improved expression of FVIII heavy chain (HC) and light chain (LC) by15- to 42-fold. Hence, the entire BDD-FVIII sequence can be orally delivered, thereby covering the entire patient population regardless of individual CD4+ T cell epitope usage. A clinical grade manufacturing process is in place, and lyophilization of leaf cells generates material that is stable at ambient temperature for at least 2 years. Testing in hemophilia A mice showed effectiveness of low FVIII antigen doses upon delivery of lyophilized lettuce cells. Repeated oral gavage (twice/week for 2 months) of a mixture of CTB-HC and CTB-C2 suppressed subsequent inhibitor formation against intravenous FVIII (1IU, once/ week for 4 weeks) in hemophilia A mice as well as the original tobacco material, using very low doses of 0.15-0.5 ug/antigen/mouse. When using CTB-HC/CTB-LC combination, a dose of 1.5 ug was most optimal and suppressed inhibitor titers by ~1 log (avg. 4.7 BU/ml vs 44 BU/ml in controls; 50% of tolerized mice had 0-3 BU/ml, while 86% of controls developed 6-126 BU/ml, n=12-14, P <0.05). Translational oral tolerance studies in humans would benefit from cellular biomarkers. Our prior studies showed induction of two subsets of Treg that suppress antibody formation against FVIII, namely CD4+CD25+FoxP3+ Treg and LAP+CD4+CD25-FoxP3- Treg. The latter stain positive on the cell surface for LAP (latency-associated peptide) because of overexpression of TGF-b. Although we found increases in the frequencies of LAP+CD4+CD25-FoxP3- Treg in peripheral blood, a statistical significance was not always observed when compared to the blood of control mice that received intravenous FVIII but not oral tolerance. However, we found significant and consistent increases in the frequencies of circulating LAP-expressing CD4+CD25+FoxP3+ Treg in tolerized mice, suggesting that LAP may be a suitable cellular biomarker for plant-based oral tolerance induction. In conclusion, clinical candidates for oral tolerance to FVIII are now available in form of lettuce plants expressing immunogenic domains or the entire antigen. DisclosuresHerzog:Novo Nordisk: Research Funding; Applied Genetic Technologies Corporation: Consultancy; Spark Therapeutics: Patents & Royalties. Daniell:Novo Nordisk: Research Funding.