Genetic removal of the CH1 exon leads to the production of hypofunctional heavy chain-only IgG2a in rats

Despite great values in many applications, heavy chain-only antibodies (HcAbs) are naturally only produced in camelids and sharks, which are not easy to access and handle. Production of the type of antibodies in small laboratory animals would remarkably facilitate their applications. We previously reported a mouse line in which the CH1 exon of mouse γ1 was deleted that could express heavy chain-only IgG1 antibodies. However, these mice showed an extremely weak IgG1 response to specific antigens when immunized, and we could only achieve single VH domains with low affinity to antigens using these mice. One possibility is that the mouse germline VH repertoire was not sufficient to support the expression of functional heavy chain-only antibodies. In this study, we report the generation of a rat line in which the CH1 exon of the γ2a gene was removed and the γ1 and γ2b genes were silenced. Although the genetically modified rats expressed heavy chain-only IgG2a, they also exhibited a very weak IgG2a response to antigen immunization. Panning of a phage library constructed using IgG2a VH segments amplified from immunized rats identified antigen-specific single VH antibodies, which also exhibited much lower affinity than that of commercial mAbs. Together with our previous report, this study suggests that the simple genetic removal of the CH1 exon does not guarantee the successful expression of functional heavy chain-only antibodies.

Stable expression ratios of five pyroptosis-inducing cytokines in the spleen and thymus of mice showed potential immune regulation at the organ level

BACKGROUND

The immune system is one of the most complex regulatory systems in the body and is essential for the maintenance of homeostasis. Despite recent breakthroughs in immunology, the regulation of the immune system and the etiology of autoimmune diseases such as lupus remain unclear. Systemic lupus erythematosus is a systemic autoimmune disease with abnormally and inconsistently expressed pro-inflammatory cytokines. Pyroptosis is a pro-inflammatory form of programmed cell death that is associated with systemic lupus erythematosus. The thymus and spleen are important immune organs involved in systemic lupus erythematosus. Therefore, this study investigated the difference in expression of pyroptosis-inducing pro-inflammatory cytokines between the spleen and thymus in lupus model mice and in control mice, to describe immune regulation at the organ level.

OBJECTIVE

To investigate differences in the expression of pyroptosis-inducing cytokines in the spleen and thymus and to explore immune regulatory networks at the organ level.

METHODS

Two groups of lupus mice and two groups of control mice were utilized for this study. Using the thymus and spleen of experimental animals, mRNA expression levels of five pyroptosis-inducing cytokines (interleukin 1β, interleukin 18, NLRP3, caspase-1 and TNF-α) were determined via quantitative polymerase chain reaction. In addition, tissue distribution of these cytokines was investigated via immunohistochemistry.

RESULTS

All five pyroptosis-inducing inflammatory cytokines showed higher expression in the spleen than in the thymus (p < 0.05). Moreover, the spleen/thymus expression ratios of all five pyroptosis-inducing cytokines were not statistically different between the four experimental groups. Expression of all five cytokines exhibited a stable ratio (spleen/thymus ratios). This distinctive stable spleen/thymus ratio was consistent in all four experimental groups. The stable spleen/thymus ratios of the five inflammatory cytokines were as follows: interleukin 1β (2.02 ± 0.9), interleukin 18 (2.07 ± 1.06), caspase-1 (1.93 ± 0.66), NLRP3 (3.14 ± 1.61) and TNF-α (3.16 ± 1.36). Immunohistochemical analysis showed the cytokines were mainly expressed in the red pulp region of the spleen and the medullary region of the thymus, where immune-activated cells aggregated.

CONCLUSION

The stable spleen/thymus expression ratios of pyroptosis-inducing cytokines indicated that immune organs exhibit strictly regulated functions to maintain immune homeostasis and adapt to the environment.

MR Diffusional Kurtosis Imaging-Based Assessment of Brain Microstructural Changes in Patients with Moyamoya Disease before and after Revascularization

BACKGROUND AND PURPOSE

Conventional imaging examinations are insufficient to accurately assess brain damage in patients with Moyamoya disease. Our aim was to observe brain microstructural changes in patients with Moyamoya disease by diffusional kurtosis imaging and provide support data for application of this technique in individualized assessment of disease severity and surgical outcome among patients with Moyamoya disease.

MATERIALS AND METHODS

A total of 64 patients with Moyamoya disease and 15 healthy volunteers underwent diffusional kurtosis imaging, and a second scanning was offered to surgical patients 3-4 months after revascularization. The diffusional kurtosis imaging parameter maps were obtained for mean kurtosis, axial kurtosis, radial kurtosis, fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity. The parameter values were measured in sensory pathway-related regions for all subjects. Differences in diffusional kurtosis imaging parameters of these brain regions were examined for healthy volunteers, patients without acroparesthesia, and asymptomatic and symptomatic sides of patients with acroparesthesia. Changes in diffusional kurtosis imaging parameters of patients with Moyamoya disease before and after revascularization were compared.

RESULTS

Compared with healthy volunteers, patients with Moyamoya disease showed decreased mean kurtosis, axial kurtosis, radial kurtosis, and fractional anisotropy in the corona radiata. Similarly, mean kurtosis, radial kurtosis, and fractional anisotropy decreased in the posterior limb of the internal capsule, whereas axial kurtosis decreased and radial kurtosis increased in the thalami of patients with Moyamoya disease compared with healthy volunteers. Compared with the asymptomatic contralateral hemisphere, the symptomatic group showed increased mean kurtosis in the contralateral primary somatosensory cortex, increased fractional anisotropy in the contralateral corona radiata and posterior limb of the internal capsule, and decreased axial kurtosis in the contralateral thalamus. Among patients with Moyamoya disease with acroparesthesia, mean kurtosis decreased in the primary somatosensory cortex on the operated side following revascularization.

CONCLUSIONS

The diffusional kurtosis imaging technique is applicable to patients with Moyamoya disease for detecting brain microstructural changes in white and gray matter before and after revascularization; this feature is useful in the assessment of disease severity and surgical outcome.

Circular RNA_LARP4 inhibits the progression of non-small-cell lung cancer by regulating the expression of SMAD7

OBJECTIVE

Researchers have uncovered the importance of circular RNAs (circ) in malignant tumors. Circ LARP4 has been found to serve as a tumor suppressor gene in gastric cancer. However, the exact function of circ LARP4 in non-small-cell lung cancer (NSCLC) has not been fully elucidated. The aim of this study was to uncover the role of circ LARP4 in the tumorigenesis of NSCLC.

PATIENTS AND METHODS

Expression level of circ LARP4 in NSCLC tissues was detected through Real Time-quantitative Polymerase Chain Reaction (RT-qPCR). Subsequently, the association between expression and patients' prognosis was analyzed. Circ LARP4 lentivirus was constructed and transfected into NSCLC cells. The effect of circ LARP4 on NSCLC cell migration and invasion was detected by function assays. Furthermore, Western blot was performed to analyze the expression of predicted protein of circ LARP4.

RESULTS

Compared with adjacent tissues, circ LARP4 was lowly expressed in NSCLC tissues. Meanwhile, expression of circ LARP4 was associated with the prognosis of NSCLC patients. Downregulated circ LARP4 was found in NSCLC cell lines as well. The migration and invasion abilities of NSCLC cells were significantly inhibited via overexpression of circ LARP4. SMAD7, the predicted protein of circ LARP4, increased remarkably via overexpression of circ LARP4.

CONCLUSIONS

Circ LARP4 could suppress the metastasis of NSCLC by up-regulating SMAD7.

Intrinsic Nucleotide Preference of Diversifying Base Editors Guides Antibody Ex Vivo Affinity Maturation

Base editors (BEs) are emerging tools used for precision correction or diversifying mutation. It provides a potential way to recreate somatic hypermutations (SHM) for generating high-affinity antibody, which is usually screened from antigen-challenged animal models or synthetic combinatorial libraries. By comparing somatic mutations in the same genomic context, we screened engineered deaminases and CRISPR-deaminase coupling approaches and updated diversifying base editors (DBEs) to generate SHM. The deaminase used in DBEs retains its intrinsic nucleotide preference and mutates cytidines at its preferred motifs. DBE with AID targets the same hotspots as physiological AID does in vivo, while DBE with other deaminases generates distinct mutation profiles from the same DNA substrate. Downstream DNA repair pathways further diversified the sequence, while Cas9-nickase restricted mutation spreading. Finally, application of DBE in an antibody display system achieved antibody affinity maturation ex vivo. Our findings provide insight of DBE working mechanism and an alternative antibody engineering approach.

A Study of the Synergistic Interaction of Konjac Glucomannan/Curdlan Blend Systems under Alkaline Conditions

To improve the gelation performance of konjac glucomannan (KGM) thermo-irreversible gel in the condition of alkaline, this study investigated the interactions between KGM and curdlan (CUD) in terms of the sol state and gelation process. The apparent viscosity, rheological properties during heating and cooling, thermodynamic properties, gelation properties and water holding capacity of KGM/CUD blend systems in an alkaline environment were studied using physical property testing instruments and methods. The results showed that the viscosity of the KGM/CUD blended solution was greater than the value calculated from the ideal mixing rules in the condition of alkaline (pH = 10.58). As the proportion of CUD in the system increased, the intersection of storage modulus (G') and loss modulus (G") shifted to low frequencies, the relaxation time gradually increased, and the degree of entanglement of molecular chains between these two components gradually increased. The addition of CUD helped decrease the gelation temperature of KGM, increased the gelation rate and inhibited the thinning phenomenon of KGM gels at low temperatures (2-20 °C). The addition of CUD increased the hardness and gel strength of KGM but did not significantly improve the water holding capacity of the KGM/CUD blend gel. The process of mixing KGM and CUD improved the thermal stability of the gel. In summary, KGM/CUD exhibited excellent compatibility under alkaline conditions, and the blend systems produced a "viscosifying effect". KC8 and KC5 show better thermal stability, low temperature resistance and gel strength compared to KGM. This blended gel can be used as a structural support material to provide reference for the development of konjac bionic vegetarian products.

Road network intersection density and childhood obesity risk in the US: a national longitudinal study

OBJECTIVES

Road intersection density is an important indicator of walkability. The objectives of this study were to examine the trends in intersection density in the US from 2007 to 2011 and assess the associations between intersection density and childhood obesity risk at the state level.

STUDY DESIGN

Longitudinal analyses were conducted to assess the spatial-temporal changes of population-weighted intersection density in relation to the risk of childhood obesity in the US.

METHODS

Road network data from the Topologically Integrated Geographic Encoding and Referencing (TIGER) (2007-2011), the prevalence of overweight and obesity data from the National Survey of Children's Health (NSCH) (2007-2011), and the American Community Survey (ACS) (2011) were used. Geographic information system (GIS) visualization and spatial and regression analyses were conducted. Mixed-effect models were fit to assess the longitudinal relationship between intersection density and childhood obesity.

RESULTS

Between 2007 and 2011, population-weighted intersection density remained relatively stable in most states. Low-intersection-density states were clustered in the Southeastern region in both 2007 and 2011. The high-intersection-density states were clustered in the Middle Atlantic Division. California and Nevada also were identified as high-intersection-density clusters in 2011. States with lower road intersection density corresponded with states with higher childhood obesity prevalence. Our mixed-effect model estimates suggested that increased intersection density was associated with decreased obesity prevalence.

CONCLUSIONS

This study provided empirical evidence for longitudinal associations between neighborhood intersection density and childhood obesity prevalence based on national data and offered a new perspective of the role that road network plays in childhood obesity prevention.

The LEPR K109R and Q223R Might Contribute to the Risk of NAFLD: A Meta-Analysis

BACKGROUND

Leptin and insulin resistance have been pointed out to play a role in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). Increasing genes were shown to be associated with the risk of NAFLD.

OBJECTIVE

The study aimed to investigate the genetic association between two leptin receptor (LEPR) polymorphisms (Q223R and K109R) and the NAFLD risk.

METHODS

Studies were retrieved and included by using PubMed, Web of Science, the Cochrane Library databases, Chinese National Knowledge Infrastructure (CNKI) and EMBASE database. Genetic associations were assessed with pooled odds ratios (ORs) with 95% confidence intervals (CIs).

RESULTS

Five case-control studies with 1711 NAFLD patients and 1732 healthy controls were included in this meta-analysis. The K109R was significantly associated with NAFLD in allelic model in Southeast Asian subgroup (p=0.01, OR=0.59, 95% CI [0.39- 0.90]), but not in Chinese subgroup (p=0.24, OR=1.10, 95% CI [0.94-1.29]). The Q223R was significantly associated with NAFLD in both allelic and recessive models (allelic model: p<0.001, OR=0.57, 95% CI [0.50-0.65]; recessive model: p=0.001, OR=0.67, 95% CI [0.52-0.85]). However, subgroup analysis showed that the significant association between Q223R and NAFLD in allelic model cannot be found in Southeast Asians subgroup (p=0.07, OR=0.67, 95% CI [0.52-0.85]).

CONCLUSION

LEPR K109R might be a susceptible factor for NAFLD in Southeast Asian population. And LEPR Q223R might be a susceptible factor for NAFLD in Chinese population.

Notch3 signaling activation in smooth muscle cells promotes extrauterine growth restriction-induced pulmonary hypertension

BACKGROUND AND AIMS

Early postnatal life is a critical developmental period that affects health of the whole life. Extrauterine growth restriction (EUGR) causes cardiovascular development problems and diseases, including pulmonary arterial hypertension (PAH). PAH is characterized by proliferation, migration, and anti-apoptosis of pulmonary artery smooth muscle cells (PASMCs). However, the role of PASMCs in EUGR has not been studied. Thus, we hypothesized that PASMCs dysfunction played a role in EUGR-induced pulmonary hypertension.

METHODS AND RESULTS

Here we identified that postnatal nutritional restriction-induced EUGR rats exhibited an elevated mean pulmonary arterial pressure and vascular remodeling at 12 weeks old. PASMCs of EUGR rats showed increased cell proliferation and migration features. In EUGR-induced PAH rats, Notch3 signaling was activated. Relative mRNA and protein expression levels of Notch3 intracellular domain (Notch3 ICD), and Notch target gene Hey1 in PASMCs were upregulated. We further demonstrated that pharmacological inhibition of Notch3 activity by using a γ-secretase inhibitor DAPT, which blocked the cleavage of Notch proteins to ICD peptides, could effectively inhibit PASMC proliferation. Specifically knocked down of Notch3 in rat PASMCs by shRNA restored the abnormal PASMC phenotype in vitro. We found that administration of Notch signaling inhibitor DAPT could successfully reduce mean pulmonary arterial pressure in EUGR rats.

CONCLUSIONS

The present study demonstrated that upregulation of Notch3 signaling in PASMCs was crucial for the development of EUGR-induced PAH. Blocking Notch3-Hey1 signaling pathway in PASMCs provides a potential therapeutic target for PAH.

Differential tissue expression of erythroblast macrophage protein in a MRL/lpr mouse model of lupus

OBJECTIVE

The objective of this study was to observe the expression features of erythroblast macrophage protein (EMP) between the tissues of MRL/lpr mice, a mouse model of systemic lupus erythematosus (SLE), and control mice.

METHODS

We examined the serum ANA in both mice groups through indirect immunofluorescence (IIF). Expression features of EMP in bone marrow, liver, renal, spleen, brain, and lung tissues of the MRL/lpr mice and control mice groups were followed using quantitative real-time polymerase chain reaction (Q-PCR). Meanwhile, the expression of EMP was located through immunohistochemical (IHC) studies and the expressive cell identified through double immunofluorescent labeling.

RESULTS

IIF showed that lupus mice have strong positive fluorescence, but no significant fluorescence was observed in control mice. Q-PCR detection revealed that EMP was expressed in the marrow, liver, renal, spleen, lung, and brain tissues of lupus mice. The highest levels were observed in the bone marrow, but there was no statistical difference between these tissues. EMP mRNA expression in the liver (t = 2.747, p = 0.01) and bone marrow (t = 3.853, p = 0.008) of lupus mice was significantly higher than in the control mice. However, no differences in EMP mRNA expression were observed in the renal, spleen, lung, and brain tissues between the lupus and control mice (p > 0.05). In addition, the IHC results showed that EMP protein is ubiquitously expressed in all of the tissues of the lupus and control mice. The positive expression rate in the bone marrow and liver tissues of the lupus mice was higher than in the control mice, but without an obvious difference in the other tissues. The double IF staining method shows that EMP protein was expressed in macrophages in the tissues of the lupus mice and the control mice.

CONCLUSIONS

Our data showed that EMP is ubiquitously expressed in macrophages at all of the tissues of the lupus and control mice. However, the expression of EMP in bone marrow and liver tissues of lupus mice was higher than in the control mice, which indicates that EMP may be important in the development of SLE.

Abstract PD9-12: Integrative molecular profiling of breast cancer brain metastasis and patient-derived xenograft organoids from resected breast cancer brain metastases to interrogate and prioritize therapeutic personalized strategies

Background: Breast cancer brain metastasis (BM) is an area of unmet need in metastatic breast cancer patients. Novel therapeutic interventions to help prevent and treat BM are warranted. We conducted integrative molecular profiling of BM and matched primary tumors (PT) using next-generation DNA and RNA sequencing to examine the molecular landscape. In addition, we established patient-derived xenograft/organoid (PDX/PDO) to examine drug sensitivity according to the molecular and clinical features of the BM.

Methods: Archived, formalin fixed paraffin-embedded BM was collected retrospectively. BM were also collected prospectively at the time of clinically indicated surgical resection through the central nervous system tissue banking and the Michigan Oncology Sequencing Center (MI-ONCOSEQ) protocols. Matched archived PT tissues were collected when available. Integrative next-generation sequencing was conducted using the MI-ONCOSEQ platform. The prospectively collected BM were further used to establish PDXs/ PDOs. Successfully established PDXs/PDOs were used for ex vivo drug testing via MiDrugScreen, a novel drug sensitivity testing platform, where testing was performed in a dose-response format with drug selection prioritized by clinical scenario and molecular alterations if known a priori.

Results: 12 matched BM-PT pairs were analyzed: 6 triple negative, 5 HER2 positive, and 1 ER positive HER2 negative. All except one (11/12) had TP53 mutations. When present, TP53 mutations in BM were also found in PT (except for 1 unknwon case in PT due to low coverage). ER+HER2- was the only one without TP53 mutation but had hyper-mutation (APOBEC signature). Driver mutations and unique copy number alterations (CDKN2A loss in 1/12, mutations in PIK3CA in 1/12 and ESR1 in 1/12, CCNE1 amplification in 1/12) were noted in BMs. In 75% of cases, mutational burden was higher in BM vs. PT. 2 PDX/PDO were available for drug testing. PDO-BC9 was noted to have RB1 (splice acceptor) and LOH. As predicted by this alteration, PDO-BC9 was insensitive to CDK4/6 inhibitors (palbociclib, abemaciclib) tested on MiDrugScreen panel. PDX-BC4 was established from PIK3CA and ESR1 mutated BM from an ER+HER2- patient who had previously progressed on endocrine therapy with a CDK4/6 inhibitor. As predicted, the PDX-BC4 was resistant to CDK4/6 inhibitor but interestingly sensitive to PIK3CA, ERK, and MEK inhibitors.

Conclusions: TP53 mutation was highly prevalent and may be a biomarker for increased risk of BM. Further study is warranted to see if specific TP53 mutations are associated with a risk of BM development and can be used in risk stratification for BM specific intervention. Unique molecular alterations in BM compared to matched PT may have a therapeutic implication as a target or resistance biomarker. Conducting drug testing in addition to molecular profiling has the strong potential of being informative in tailoring or prioritizing therapeutic agents in the era of precision medicine. Additional BM PDXs/PDOs from breast and other solid tumors are being examined using this novel therapeutic tailoring approach with the combination of MIONCOSEQ and MiDrugScreen.

Citation Format: Morikawa A, Robinson DR, Soellner M, Wu Y-M, Lonigro R, Gilani R, Cheng X, Lachacz E, Thomas D, McMurray K, Smerage J, Henry NL, Heth J, Chinnaiyan A, Hayes DF, Merajver S. Integrative molecular profiling of breast cancer brain metastasis and patient-derived xenograft organoids from resected breast cancer brain metastases to interrogate and prioritize therapeutic personalized strategies [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD9-12.

Identification of Two Nonrearranging IgSF Genes in Chicken Reveals a Novel Family of Putative Remnants of an Antigen Receptor Precursor

In this study, we identified a pair of nonrearranging VJ-joined Ig superfamily genes, termed putative remnants of an Ag receptor precursor (PRARP) genes, in chicken. Both genes encode a single V-set Ig domain consisting of a canonical J-like segment and a potential immunoreceptor tyrosine-based inhibitory or switch motif in the cytoplasmic region. In vitro experiments showed that both genes were expressed at the cell surface as membrane proteins, and their recombinant products formed a monomer and a disulfide-linked homodimer or a heterodimer. These two genes were mainly expressed in B and T cells and were upregulated in response to stimulation with poly(I:C) in vitro and vaccination in vivo. Orthologs of PRARP have been identified in bony fish, amphibians, reptiles, and other birds, and a V-C1 structure similar to that of Ig or TCR chains was found in all these genes, with the exception of those in avian species, which appear to contain degenerated C1 domains or divergent Ig domains. Phylogenetic analyses suggested that the newly discovered genes do not belong to any known immune receptor family and appear to be a novel gene family. Further elucidation of the functions of PRARP and their origin might provide significant insights into the evolution of the immune system of jawed vertebrates.