Possible transport routes of IgM to the gut of teleost fish.

Fish rely on mucosal surfaces as their first defence barrier against pathogens. Maintaining mucosal homeostasis is therefore crucial for their overall well-being, and it is likely that secreted immunoglobulins (sIg) play a pivotal role in sustaining this balance. In mammals, the poly-Ig receptor (pIgR) is an essential component responsible for transporting polymeric Igs across mucosal epithelia. In teleost fish, a counterpart of pIgR has been identified and characterized, exhibiting structural differences and broader mRNA expression patterns compared to mammals. Despite supporting evidence for the binding of Igs to recombinant pIgR proteins, the absence of a joining chain (J-chain) in teleosts challenges the conventional understanding of Ig transport mechanisms. The transport of IgM to the intestine via the hepatobiliary route is observed in vertebrates and has been proposed in a few teleosts. Investigations on the stomachless fish, ballan wrasse, revealed a significant role of the hepatobiliary route and interesting possibilities for alternative IgM transport routes that might include pancreatic tissue. These findings highlight the importance of gaining a thorough understanding of the mechanisms behind Ig transport to the gut in various teleosts. This review aims to gather existing information on pIgR-mediated transport across epithelial cells and immunoglobulin transport pathways to the gut lumen in teleost fish. It provides comparative insights into the hepatobiliary transport of Igs to the gut, emphasizing the current understanding in teleost fish while exploring potential alternative pathways for Ig transport to the gut lumen. Despite significant progress in understanding various aspects, there is still much to uncover, especially concerning the diversity of mechanisms across different teleost species.

Novel serum protein biomarker panel for early diagnosis of pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers. Late presentation of disease at the time of diagnosis is one of the major reasons for dismal prognostic outcomes for PDAC patients. Currently, there is a lack of clinical biomarkers, which can be used to diagnose PDAC patients at an early resectable stage. This study performed proteomic mass spectrometry to identify novel blood-based biomarkers for early diagnosis of PDAC. Serum specimens from 88 PDAC patients and 88 healthy controls (60 discovery cohort and 28 validation cohort) were analyzed using data independent acquisition high resolution mass spectrometry to identify candidate biomarker proteins. A total of 249 proteins were identified and quantified by the mass spectrometric analysis. Six proteins were markedly (>1.5 fold) and significantly (p < .05; q < 0.1) increased in PDAC patients compared to healthy controls in discovery cohort. Notably, four of these six proteins were significantly upregulated in an independent validation cohort. The top three upregulated proteins (i.e., Polymeric Immunoglobulin Receptor [PIGR], von Willebrand Factor [vWF], and Fibrinogen) were validated using enzyme linked immunosorbent assay, which led to selection of PIGR and vWF as a diagnostic biomarker panel for PDAC. The panel showed high ability to diagnose early stage (stage I and II) PDAC patients (area under the curve [AUC]: 0.8926), which was further improved after the addition of clinically used prognostic biomarker (Ca 19-9) to the panel (AUC: 0.9798). In conclusion, a novel serum protein biomarker panel for early diagnosis of PDAC was identified.

Functional studies with IgM and IgA immunoglobulins: binding to pIgR, FcαµR, FcµR, and CDC activities.

IgMs are the first antibodies produced by the immune system upon encounter of a possible pathogen and are one of five antibody subclasses in humans. For IgG, the most intensively studied antibody class, the N-linked glycosylation site located in the Fc-domain is directly involved in high affinity binding to the respective receptors and initiation of corresponding immune response. IgM molecules have five N-glycosylation sites and one N-glycosylation site in the J-chain, which can be incorporated in IgM or IgA molecules. There is only limited knowledge available concerning the function of these N-glycosylations in IgMs. To address this question, we produced IgM molecules lacking a particular N-glycosylation site and tested these variants as well as IgA molecules for binding to the known receptors: the polymeric immunoglobulin receptor (pIgR), the dual receptor for IgA and IgM, FcαµR, and the specific receptor for IgM, FcµR. The single glycosylation sites did not show an impact on expression and multimerization, except for variant N402Q, which could not be expressed. In SPR measurements, no major impact on the binding to the receptors by particular glycosylation sites could be detected. In cellular assays, deglycosylated variants showed some alterations in induction of CDC activity. Most strikingly, we observed also binding of IgA to the FcµR in the same affinity range as IgM, suggesting that this might have a physiological role. To further substantiate the binding of IgA to FcµR we used IgA from different origins and were able to confirm binding of IgA preparations to the FcµR.

Polymeric immunoglobulin receptor (pIgR) in cancer.

BACKGROUND: The polymeric immunoglobulin receptor (pIgR) is a transmembrane transporter of polymeric IgA through the intestinal epithelium. Its overexpression has been reported in several cancers, but its role as a diagnostic and prognostic biomarker of oncogenesis is currently unclear. METHOD: A literature search was conducted to summarize the functions of pIgR, its expression levels, and its clinical implications. RESULTS: pIgR expression has previously been investigated by proteomic analysis, RNA sequencing, and tissue microarray at the level of both RNA and protein in various cancers including pancreatic, esophageal, gastric, lung, and liver. However, studies have reported inconsistent results on how pIgR levels affect clinical outcomes such as survival rate and chemotherapy resistance. Possible explanations include pIgR mRNA levels being minimally correlated with the rate of downstream pIgR protein synthesis, and the diversity of antibodies used in immunohistochemistry studies further magnifying this ambiguity. In ovarian cancer cells, the transcytosis of IgA accompanied a series of transcriptional changes in intracellular inflammatory pathways that inhibit the progression of cancer, including the upregulation of IFN-gamma and downregulation of tumor-promoting ephrins. These findings suggest that both the levels of pIgR and secreted IgA from tumor-infiltrating B cells affect clinical outcomes. CONCLUSION: Overall, no direct correlation was observed between the levels of pIgR inside tumor tissue and the clinical features in cancer patients. Measuring pIgR protein levels with a more specific and possibly chemically defined antibody, along with tumoral IgA, is a potential solution to better understand the pathways and consequences of pIgR overexpression in cancer cells.

Expression of polymeric immunoglobulin receptor (PIGR) and the effect of PIGR overexpression on breast cancer cells.

Polymeric immunoglobulin receptor (PIGR) has a major role in mucosal immunity as a transporter of polymeric immunoglobulin across the epithelial cells. The aim of this study was to determine the effect of PIGR on cellular behaviours and chemo-sensitivity of MCF7 and MDA-MB468 breast cancer cell lines. Basal levels of PIGR mRNA and protein expression in MCF7 and MDA-MB468 cells were evaluated by real time quantitative polymerase chain reaction and Western blotting, respectively. MCF7/PIGR and MDA-MB468/PIGR stable cell lines, overexpressing the PIGR gene, were generated using a lentiviral vector with tetracycline dependent induction of expression. Cell viability, cell proliferation and chemo-sensitivity of PIGR transfected cells were evaluated and compared with un-transfected cells to determine the effect of PIGR overexpression on cell phenotype. The levels of PIGR mRNA and protein expression were significantly higher in MDA-MB468 cells than in MCF7 cells (380-fold, p < 0.0001). However, the differential expression of PIGR in these two cell lines did not lead to significant differences in chemosensitivity. Viral overexpression of PIGR was also not found to change any of the parameters measured in either cell line. PIGR per se did not affect cellular behaviours and chemosensitivity of these breast cancer cell lines.

Polymeric immunoglobulin receptor and galectin-3-binding protein are raised in biliary atresia: Reveals a proteomic-based study.

To identify and evaluate differentially expressed plasma proteins in biliary atresia (BA), we performed plasma proteome profiling using liquid chromatography with tandem mass spectrometry (LC-MS/MS) in 20 patients with BA and 10 control children. Serological assays validated the most significant and highly upregulated proteins in a cohort of 45 patients and 15 controls. Bioinformatics tools were used for functional classification and protein-protein interactions of differentially expressed proteins (DEPs). Of 405 proteins detected in patients and 360 in controls, 242 proteins, each with ≥2 unique peptides (total of 3230 peptides), were common in both groups. Compared to controls, 90 proteins in patients were differentially expressed and were dysregulated. Twenty-five were significantly upregulated with polymeric immunoglobulin receptor (PIgR), galectin-3-binding protein (Gal-3BP), complement C2, the most prominent, and 15 had low expression. The bioinformatic analysis revealed functional interaction between DEPs and their role in an inflammatory immune response. Enzyme immunoassay for PIgR and Gal-3BP in patients' plasma showed their levels raised significantly (p = 0.0021 and p = 0.0369, respectively). The PIgR and Gal-3BP are novel proteins upregulated in BA and may be tested further for their utility as potential circulating disease biomarker(s). SIGNIFICANCE: The study shows that plasma PIgR and GAL-3BP levels are significantly raised in infants with BA within the first 3 months of life. If tested in a larger cohort, these proteins may be found to have their diagnostic potential and utility as disease biomarkers. The study also provides valuable information on the involvement of several DEPs in innate immune response, chronic inflammation, and fibrosis. This strengthens the hypothesis that the immune-mediated inflammatory processes are responsible for the progressive nature of BA.

Interferon-γ mediating overexpression of polymeric immunoglobulin receptor in grass carp (Ctenopharyngodon idellus) liver cells.

The polymeric immunoglobulin receptor (pIgR) have a vital function in transcytosis of polymeric immunoglobulins in order to defense against invading microorganisms, however, the regulation pathway of pIgR expression in teleosts remains unclear. In this investigation, to examine if the cytokine IFN-γ affected the expression of pIgR, the recombinant proteins of IFN-γ of grass carp was first prepared, after validating that natural pIgR expressed on grass carp (Ctenopharyngodon idellus) hepatocytes (L8824), the L8824 cells were supplemented by different recombinant IFN-γ concentrations at various times, the outcomes revealed a significant dose- and time-dependent increase in pIgR expressions at the gene and secretion component (SC) proteins levels. The levels of pIgR mRNA was measured increasing at 9 h, and increasing most significant during the 9-12 h period, the growth of SC was delayed until 24 h after IFN-γ stimulation. Moreover, protein synthesis inhibitors cycloheximide (CHX) was used to study on whether IFN-γ regulated pIgR expressions through a protein synthesis dependent pathway. Upon inhibitors CHX treatment, the expression of pIgR mRNA were inhibited significantly, and CHX treatment at any time during the first 9 h period demolished the growth in pIgR mRNA that was promoted by IFN-γ, suggesting that IFN-γ is required for the stimulation of pIgR mRNA, which needs de novo protein synthesis. All these outcomes revealed that IFN-γ could upregulate pIgR gene expression, and production of SC, and this IFN-γ stimulated pIgR expression through a protein synthesis dependent pathway, which provided evidences for IFN-γ serves as a regulator for the expression of pIgR, as well as our current knowledge of the expression of pIgR in teleost fish has been improved as a result.

Effects of Diabetes and Voluntary Exercise on IgA Concentration and Polymeric Immunoglobulin Receptor Expression in the Submandibular Gland of Rats.

Background and Objectives: Patients with diabetes are more susceptible to upper respiratory tract infections (URTIs) because they are easily infected. Salivary IgA (sali-IgA) levels play a major role in transmitting URTIs. Sali-IgA levels are determined by salivary gland IgA production and polymeric immunoglobulin receptor (poly-IgR) expression. However, it is unknown whether salivary gland IgA production and poly-IgR expression are decreased in patients with diabetes. While exercise is reported to increase or decrease the sali-IgA levels, it is unclear how exercise affects the salivary glands of patients with diabetes. This study aimed to determine the effects of diabetes and voluntary exercise on IgA production and poly-IgR expression in the salivary glands of diabetic rats. Materials and Methods: Ten spontaneously diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) rats (eight-week-old) were divided into two groups of five rats each: a non-exercise group (OLETF-C) and a voluntary wheel-running group (OLETF-E). Five Long-Evans Tokushima Otsuka (LETO) rats without diabetes were bred under the same conditions as the OLETF-C. Sixteen weeks after the study began, the submandibular glands (SGs) were collected and analyzed for IgA and poly-IgR expression levels. Results: IgA concentrations and poly-IgR expression levels in SGs were lower in OLETF-C and OLETF-E than in LETO (p < 0.05). These values did not differ between the OLETF-C and OLETF-E. Conclusions: Diabetes decreases IgA production and poly-IgR expression in the salivary glands of rats. Moreover, voluntary exercise increases sali-IgA levels but does not increase IgA production and poly-IgR expression in the salivary glands of diabetic rats. Increasing IgA production and poly-IgR expression in the salivary glands, which is reduced in diabetes, might require slightly higher-intensity exercise than voluntary exercise under the supervision of a doctor.

Tumor necrosis factor-α upregulates polymeric immunoglobulin receptor expression by NF-κB signaling pathways in grass carp (Ctenopharyngodon idellus) liver cells.

The polymeric immunoglobulin receptor (pIgR) is essential for controlling polymeric immunoglobulin to defend species from invading pathogens. However, the modulation pathway of pIgR expression in teleosts remains unclear. In this paper, to define that the cytokine TNF-α impacted the expression of pIgR, the recombinant proteins of TNF-α of grass carp were first prepared after approving that natural pIgR was expressed in liver cells of grass carp (Ctenopharyngodon idellus) (L8824). L8824 cells were incubated with variable amounts of recombinant TNF-α at various times, the results revealed that pIgR expressions showed a significant dose-dependent elevation at the gene and proteins, and a similar alteration trend was detected for the pIgR protein (secretory component: SC) secreted by L8824 cells into the culture supernatant. Moreover, nuclear factor kappa-B (NF-κB) inhibitors PDTC was used to study whether TNF-α regulated pIgR expressions through the NF-κB signaling pathways. L8824 cells were treated with TNF-α, inhibitor PDTC, and TNF-α + PDTC mixtures, respectively, and the levels of pIgR genes and pIgR protein in cells and SC in the culture supernatant decreased in cells treated with PDTC contrasted to the control, and subjected to reduced expression of PDTC + TNF-α reduced expression contrasted to that treated just with TNF-α, demonstrating that suppression of NF-κB obstructed the ability of TNF-α to elevate pIgR gene and pIgR protein in cells and SC in the culture supernatant. These outcomes indicated that TNF-α raised pIgR gene expression, pIgR protein, and SC creation, and this pIgR expression induced by TNF-α was modulated by complicated pathways that included NF-κB signaling mechanism, confirming TNF-α as a pIgR expression modulator and enhancing a deeper insight of the regulatory pathway for pIgR expression in teleosts.

Molecular cloning and functional analysis of polymeric immunoglobulin receptor, pIgR, gene in mandarin fish Siniperca chuatsi.

Polymeric immunoglobulin receptor (pIgR) can bind and transport immunoglobulins (Igs), thus playing a role in mucosal immunity. In this study, pIgR gene was cloned in mandarin fish, Siniperca chuatsi, with the open reading frame (ORF) of 1011 bp, encoding 336 amino acids. The pIgR protein consists of a signal peptide, an extracellular domain, a transmembrane domain and an intracellular region, with the presence of two Ig-like domains (ILDs) in the extracellular domain, as reported in other species of fish. The pIgR gene was expressed in all organs/tissues of healthy mandarin fish, with higher level observed in liver and spleen. Following the immersion infection of Flavobacterium columnare, pIgR transcripts were detected in immune related, especially mucosal tissues, with significantly increased transcription during the first two days of infection. Through transfection of plasmids expressing pIgR, IgT and IgM, pIgR was found to be interacted with IgT and IgM as revealed by co-immunoprecipitation and immunofluorescence.

Microbiota-dependent and -independent postnatal development of salivary immunity.

While saliva regulates the interplay between the microbiota and the oral immune system, the mechanisms establishing postnatal salivary immunity are ill-defined. Here, we show that high levels of neutrophils and neonatal Fc receptor (FcRn)-transferred maternal IgG are temporarily present in the neonatal murine salivary glands in a microbiota-independent manner. During weaning, neutrophils, FcRn, and IgG decrease in the salivary glands, while the polymeric immunoglobulin receptor (pIgR) is upregulated in a growth arrest-specific 6 (GAS6)-dependent manner independent of the microbiota. Production of salivary IgA begins following weaning and relies on CD4-help, IL-17, and the microbiota. The weaning phase is characterized by a transient accumulation of dendritic cells capable of migrating from the oral mucosa to the salivary glands upon exposure to microbial challenges and activating T cells. This study reveals the postnatal mechanisms developed in the salivary glands to induce immunity and proposes the salivary glands as an immune inductive site.

Hepatic pIgR-mediated secretion of IgA limits bacterial translocation and prevents ethanol-induced liver disease in mice.

OBJECTIVE: Alcohol-associated liver disease is accompanied by microbial dysbiosis, increased intestinal permeability and hepatic exposure to translocated microbial products that contribute to disease progression. A key strategy to generate immune protection against invading pathogens is the secretion of IgA in the gut. Intestinal IgA levels depend on the polymeric immunoglobulin receptor (pIgR), which transports IgA across the epithelial barrier into the intestinal lumen and hepatic canaliculi. Here, we aimed to address the function of pIgR during ethanol-induced liver disease. DESIGN: pIgR and IgA were assessed in livers from patients with alcohol-associated hepatitis and controls. Wild-type and pIgR-deficient (pIgR-/- ) littermates were subjected to the chronic-binge (NIAAA model) and Lieber-DeCarli feeding model for 8 weeks. Hepatic pIgR re-expression was established in pIgR-/- mice using adeno-associated virus serotype 8 (AAV8)-mediated pIgR expression in hepatocytes. RESULTS: Livers of patients with alcohol-associated hepatitis demonstrated an increased colocalisation of pIgR and IgA within canaliculi and apical poles of hepatocytes. pIgR-deficient mice developed increased liver injury, steatosis and inflammation after ethanol feeding compared with wild-type littermates. Furthermore, mice lacking pIgR demonstrated increased plasma lipopolysaccharide levels and more hepatic bacteria, indicating elevated bacterial translocation. Treatment with non-absorbable antibiotics prevented ethanol-induced liver disease in pIgR-/- mice. Injection of AAV8 expressing pIgR into pIgR-/- mice prior to ethanol feeding increased intestinal IgA levels and ameliorated ethanol-induced steatohepatitis compared with pIgR-/- mice injected with control-AAV8 by reducing bacterial translocation. CONCLUSION: Our results highlight that dysfunctional hepatic pIgR enhances alcohol-associated liver disease due to impaired antimicrobial defence by IgA in the gut.

Intracellular immunoglobulin A (icIgA) in protective immunity and vaccines.

Virus neutralization at respiratory mucosal surfaces is important in the prevention of infection. Mucosal immunity is mediated mainly by extracellular secretory immunoglobulin A (sIgA) and its role has been well studied. However, the protective role of intracellular specific IgA (icIgA) is less well defined. Initially, in vitro studies using epithelial cell lines with surface expressed polymeric immunoglobulin receptor (pIgR) in transwell culture chambers have shown that icIgA can neutralize influenza, parainfluenza, HIV, rotavirus and measles viruses. This effect appears to involve an interaction between polymeric immunoglobulin A (pIgA) and viral particles within an intracellular compartment, since IgA is transported across the polarized cell. Co-localization of specific icIgA with influenza virus in patients' (virus culture positive) respiratory epithelial cells using well-characterized antisera was initially reported in 2018. This review provides a summary of in vitro studies with icIgA on colocalization and neutralization of the above five viruses. Two other highly significant respiratory infectious agents with severe global impacts viz. SARS-2 virus (CoViD pandemic) and the intracellular bacterium-Mycobacterium tuberculosis-are discussed. Further studies will provide more detailed understanding of the mechanisms and kinetics of icIgA neutralization in relation to viral entry and early replication steps with a specific focus on mucosal infections. This will inform the design of more effective vaccines against infectious agents transmitted via the mucosal route.

Polymeric immunoglobulin receptor deficiency exacerbates autoimmune hepatitis by inducing intestinal dysbiosis and barrier dysfunction.

Autoimmune hepatitis (AIH) is an immune-mediated inflammatory liver disease with unclear pathogenesis. The gut microbiota and intestinal barrier play an essential role in AIH. Polymeric immunoglobulin receptor (pIgR) is a central component of mucosal immunity. Herein, we aimed to test the hypothesis that pIgR plays a pivotal role in maintaining gut microbiota homeostasis and gut barrier integrity in an AIH mouse model. The expression of intestinal pIgR shows the variation tendency of falling after rising with the aggravation of experimental AIH (EAH). The deletion of Pigr exacerbates liver damage in EAH. Furthermore, we identified a distinct microbiota profile of Pigr-deficient EAH mice, with a significant increased aboundance in the Oscillospiraceae family, particularly the Anaeromassilibacillus genus. Such a situation occurs because the loss of Pigr inhibits MEK/ERK, a key signal pathway whereby pIgR transports immunoglobulin A (IgA), resulting in reduced IgA secretion, which leads to the destruction of intestinal epithelial tight junction proteins and intestinal flora disturbance. Increased intestinal leakage causes increased translocation of bacteria to the liver, thus aggravating liver inflammation in EAH. Treatment with the Lactobacillus rhamnosus GG supernatant reverses liver damage in EAH mice but loses its protective effect without pIgR. Our study identifies that intestinal pIgR is a critical regulator of the adaptive response to S100-induced alterations in gut flora and the gut barrier function, which closely correlates with liver injury. Intestinal upregulation of pIgR could be a novel approach for treating AIH.

Molecular cloning and characteristic analysis of polymeric immunoglobulin receptor-like (plgRL) in large yellow croaker (Larimichthys crocea).

In the present study, the polyimmunoglobulin receptor-like (pIgRL) of large yellow croaker (Larimichthys crocea) was first cloned and characterized. LcpIgRL's full-length cDNA was 1610 bp, encoding 377 amino acids, and the protein's predicted molecular weight was 41.9 kDa, containing two immunoglobulin-like structural domains. The transcript levels of LcpIgRL in different tissues of healthy large yellow croaker were examined by real-time fluorescence quantitative PCR, and the results showed that the gills and head kidney had the highest levels. Within 36 h of the large yellow croaker being infected with Vibrio harveyi, pIgRL mRNA first increased and then decreased in all determined tissues, with the highest expression in the skin and hindgut. Furthermore, a recombinant protein of the extracellular region of LcpIgRL was expressed in E. coli BL21, and a murine rLcpIgRL polyclonal antibody was prepared, which could react specifically with the natural LcpIgRL in skin mucus, but no natural LcpIgRL was detected in serum. Meanwhile, it was found that the rLcpIgRL could bind to the recombinant IgM and the natural IgM, indicating that LcpIgRL could mediate the transport of IgM in mucus. In addition, rLcpIgRL binds to Aeromonas hydrophila and V. harveyi, as well as lipopolysaccharide (LPS) and various saccharides, and reduced binding to bacteria was observed under LPS treatment, suggesting that LcpIgRL can bind to bacteria to prevent infection and that saccharide binding is an important mechanism of interaction between pIgRL and bacteria.

Evolutionary analyses of polymeric immunoglobulin receptor (pIgR) in the mammals reveals an outstanding mutation rate in the lagomorphs.

Background: The transcytosis of polymeric immunoglobulins, IgA and IgM, across the epithelial barrier to the luminal side of mucosal tissues is mediated by the polymeric immunoglobulin receptor (pIgR). At the luminal side the extracellular ligand binding region of pIgR, the secretory component (SC), is cleaved and released bound to dimeric IgA (dIgA), protecting it from proteolytic degradation, or in free form, protecting the mucosa form pathogens attacks. The pIgR was first cloned for rabbit in early 1980's and since then has been described for all vertebrates, from fish to mammals. The existence of more than one functional pIgR alternative-spliced variant in the European rabbit, the complete pIgR as other mammals and a shorter pIgR lacking two SC exons, raised the question whether other lagomorphs share the same characteristics and how has the PIGR gene evolved in these mammals. Results: To investigate these questions, we sequenced expressed pIgR genes for other leporid genus, Lepus spp., and obtained and aligned pIgR sequences from representative species of all mammalian orders. The obtained mammalian phylogeny, as well as the Bayesian inference of evolutionary rates and genetic distances, show that Lagomorpha pIgR is evolving at a higher substitution rate. Codon-based analyses of positive selection show that mammalian pIgR is evolving under strong positive selection, with strong incidence in the domains excised from the rabbit short pIgR isoform. We further confirmed that the hares also express the two rabbit pIgR isoforms. Conclusions: The Lagomorpha pIgR unique evolutionary pattern may reflect a group specific adaptation. The pIgR evolution may be linked to the unusual expansion of IgA genes observed in lagomorphs, or to neofunctionalization in this group. Further studies are necessary to clarify the driving forces behind the unique lagomorph pIgR evolution.

M1 macrophages evoke an increase in polymeric immunoglobulin receptor (PIGR) expression in MDA-MB468 breast cancer cells through secretion of interleukin-1ß.

High expression of polymeric immunoglobulin receptor (PIGR) in breast cancer is associated with increased 5-year survival rate. However, the factors influencing PIGR expression in breast cancer have not been elucidated. The aim of this study was to determine the role of macrophages and cytokines affecting expression of PIGR in two breast cancer cell lines. M1, M2 macrophage conditioned media (CM) and recombinant human cytokines were used to determine factors which increased PIGR expression in MCF7 (HTB-22) and MDA-MB468 (HTB-132) breast cancer cell lines. The level of PIGR expression in the cells and PIGR secretory component were evaluated by real-time quantitative polymerase chain reaction and Western blotting. M1 macrophage CM induced a dose-dependent increase in PIGR mRNA expression in MDA-MB468 cells, up to 20-fold. The level of PIGR expression in MCF7 cells was very low and not affected by M1 and M2 CM. Interferon gamma (IFN-γ) and interleukin (IL)-1ß also increased PIGR expression in MDA-MB468 and MCF7 cells. However, IL-1ß was demonstrated to increase in M1 macrophages, while IFN-γ was not. The role of IL-1ß secreted from M1 macrophages in increasing expression of PIGR was confirmed by IL-1 receptor blockade, indicating that IL-1ß was the major M1 macrophage-derived cytokine that enhanced PIGR expression. Elevated PIGR expression in breast cancer in vivo may reflect the polarization state of tumor-associated immune cells.

White spot syndrome virus directly activates mTORC1 signaling to facilitate its replication via polymeric immunoglobulin receptor-mediated infection in shrimp.

Previous studies have shown that the mechanistic target of rapamycin complex 1 (mTORC1) signaling pathway has antiviral functions or is beneficial for viral replication, however, the detail mechanisms by which mTORC1 enhances viral infection remain unclear. Here, we found that proliferation of white spot syndrome virus (WSSV) was decreased after knockdown of mTor (mechanistic target of rapamycin) or injection inhibitor of mTORC1, rapamycin, in Marsupenaeus japonicus, which suggests that mTORC1 is utilized by WSSV for its replication in shrimp. Mechanistically, WSSV infects shrimp by binding to its receptor, polymeric immunoglobulin receptor (pIgR), and induces the interaction of its intracellular domain with Calmodulin. Calmodulin then promotes the activation of protein kinase B (AKT) by interaction with the pleckstrin homology (PH) domain of AKT. Activated AKT phosphorylates mTOR and results in the activation of the mTORC1 signaling pathway to promote its downstream effectors, ribosomal protein S6 kinase (S6Ks), for viral protein translation. Moreover, mTORC1 also phosphorylates eukaryotic translation initiation factor 4E-binding protein 1 (4EBP1), which will result in the separation of 4EBP1 from eukaryotic translation initiation factor 4E (eIF4E) for the translation of viral proteins in shrimp. Our data revealed a novel pathway for WSSV proliferation in shrimp and indicated that mTORC1 may represent a potential clinical target for WSSV control in shrimp aquaculture.

Profiling prediction of nuclear receptor modulators with multi-task deep learning methods: toward the virtual screening.

Nuclear receptors (NRs) are ligand-activated transcription factors, which constitute one of the most important targets for drug discovery. Current computational strategies mainly focus on a single target, and the transfer of learned knowledge among NRs was not considered yet. Herein we proposed a novel computational framework named NR-Profiler for prediction of potential NR modulators with high affinity and specificity. First, we built a comprehensive NR data set including 42 684 interactions to connect 42 NRs and 31 033 compounds. Then, we used multi-task deep neural network and multi-task graph convolutional neural network architectures to construct multi-task multi-classification models. To improve the predictive capability and robustness, we built a consensus model with an area under the receiver operating characteristic curve (AUC) = 0.883. Compared with conventional machine learning and structure-based approaches, the consensus model showed better performance in external validation. Using this consensus model, we demonstrated the practical value of NR-Profiler in virtual screening for NRs. In addition, we designed a selectivity score to quantitatively measure the specificity of NR modulators. Finally, we developed a freely available standalone software for users to make profiling predictions for their compounds of interest. In summary, our NR-Profiler provides a useful tool for NR-profiling prediction and is expected to facilitate NR-based drug discovery.