Intra-Golgi formation of IgM-glycosaminoglycan complexes promotes Ig deposition

Immune complexes arise from interactions between secreted Ab and Ags in the surrounding milieu. However, it is not known whether intracellular Ag-Ab interactions also contribute to the formation of extracellular immune complexes. In this study, we report that certain murine B cell hybridomas accumulate intracellular IgM and release large, spherical IgM complexes. The complexes (termed "spherons") reach 2 μm in diameter, detach from the cell surface, and settle out of solution. The spherons contain IgM multimers that incorporate the J chain and resist degradation by endoglycosidase H, arguing for IgM passage through the Golgi. Treatment of cells with inhibitors of proteoglycan synthesis, or incubation of spherons with chondroitinase ABC, degrades spherons, indicating that spheron formation and growth depend on interactions between IgM and glycosaminoglycans. This inference is supported by direct binding of IgM to heparin and hyaluronic acid. We conclude that, as a consequence of IgM binding to glycosaminoglycans, multivalent IgM-glycan complexes form in transit of IgM to the cell surface. Intra-Golgi formation of immune complexes could represent a new pathogenic mechanism for immune complex deposition disorders.     

Isolation and characterization of halophilic bacteria from Urmia Lake in Iran

Urmia Lake is one of the most permanent hypersaline lakes in the world which is threatened by hypersalinity and serious dryness. In spite of its importance no paper has been published regarding bacterial community of this lake. Accordingly, the present study aimed to investigate the halophilic bacteria in the aforementioned lake. In so doing, thirty seven strains were isolated on six different culture media. The isolated strains were characterized using phenotypic and genotypic methods. Growth of the strains occurred at 2535 degrees C, pH 6-9 and 7 to 20% (w/v) NaCl indicating that most of the isolates were moderately halophiles. Catalase, oxidase and urease activities were found to be positive for the majority of the isolates. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the isolated bacteria belonged to two major taxa: Gammaproteobacteria (92%, including Salicola [46%], Pseudomonas [13.5%], Marinobacter [ 11%], Idiomarina [11%], and Halomonas [8%]) and Firmicutes (8%, including Bacillus [5%] and Halobacillus [3%]). In addition, a novel bacterium whose 16S rRNA gene sequence showed almost 98% sequence identity with the taxonomically troubled DSM 3050T, Halovibrio denitrificans HGD 3T and Halospina denitrificans HGD 1-3T, each, was isolated. 16S rRNA gene similarity levels along with phenotypic characteristics suggest that some of the isolated strains could be regarded as potential type strain for novel species, on which further studies are recommended.     

Study of Regulatory T-Cells in Patients with Gastric Malt Lymphoma: Influence on Treatment Response and Outcome

Purpose

FOXP3+ regulatory T cells (Treg) play an essential role in modulating host responses to tumors and infections. The role of these cells in the pathogenesis of MALT lymphomas remains unknown. The aims of the study were to quantify the number of infiltrating FOXP3+ and CD3+ cells in patients with gastric MALT lymphoma at diagnosis and to study kinetics of these cells and CD20+ tumor cells after treatment and during long-term follow-up.

Methods

FOXP3+, CD3+ and CD20+ cells were analyzed by immunohistochemistry and the number of cells was quantified using a micrometric ocular. Samples of 35 patients with gastric MALT lymphoma at diagnosis and after treatment were included. Diagnostic samples were compared to 19 cases of chronic gastritis and diffuse large B-cell lymphoma (DLBCL) of the stomach.

Results

The median number of FOXP3+ infiltrating cells was higher (27 cells/cm²) in gastric MALT patients than in DLBCL (10 cells; p = 0.162) but similar to chronic gastritis (20 cells; p = 0.605). No characteristic or specific distribution pattern of infiltrating FOXP3+ cells was found. Gastric MALT lymphoma patients responding to bacterial eradication therapy had higher number of FOXP3+ cells at study entry. Kinetics of both infiltrating FOXP3+ cells and tumor CD20+ cells were strongly dependent on the treatment administered.

Discussion

Gastric MALT lymphomas have a number of Treg cells more similar to chronic gastritis than to DLBCL. Patients with higher number of tumor infiltrating FOXP3+ cells at study entry seem to have better response to antibiotics. Kinetics of Treg and tumor cells are influenced by type of treatment.     

Palmitate and inflammatory state additively induce the expression of PTP1B in muscle cells

The factors responsible for up-regulation of PTP1B, a negative regulator of insulin signaling, in insulin resistance state are not well understood. We performed a series of experiments in C2C12 muscle cells to determine the role of palmitate and an inflammatory state in regulation of PTP1B. Palmitate (0.75 mM) induced PTP1B mRNA and protein level only at 16 h. The combination of palmitate and macrophages, accompanied by a great increase of TNF-α and IL-6 in the culture media, additively caused a higher level of PTP1B protein levels in the muscle. Higher concentrations of palmitate reduced insulin stimulated glucose uptake in myotubes. A specific inhibitor of PTP1B partly increased insulin stimulated glucose uptake in palmitate treated cells. In conclusion, our results showing the additive influence of palmitate and the inflammatory state in the expression of PTP1B imply the involvement of these factors in the overexpression of PTP1B in insulin resistance state. We further provided the evidence suggesting the mediatory role for PTP1B in palmitate induced insulin resistance in myotubes.     

Histone deimination as a response to inflammatory stimuli in neutrophils

Posttranslational modifications, such as the deimination of arginine to citrulline by peptidyl arginine deiminase (PAD4), change protein structure and function. For autoantigens, covalent modifications represent a mechanism to sidestep tolerance and stimulate autoimmunity. To examine conditions leading to histone deimination in neutrophils, we used Abs that detect citrullines in the N terminus of histone H3. Deimination was investigated in human neutrophils and HL-60 cells differentiated into granulocytes. We observed rapid and robust H3 deimination in HL-60 cells exposed to LPS, TNF, lipoteichoic acid, f-MLP, or hydrogen peroxide, which are stimuli that activate neutrophils. Importantly, we also observed H3 deimination in human neutrophils exposed to these stimuli. Citrullinated histones were identified as components of extracellular chromatin traps (NETs) produced by degranulating neutrophils. In contrast, apoptosis proceeded without detectable H3 deimination in HL-60 cells exposed to staurosporine or camptothecin. We conclude that histone deimination in neutrophils is induced in response to inflammatory stimuli and not by treatments that induce apoptosis. Our results further suggest that deiminated histone H3, a covalently modified form of a prominent nuclear autoantigen, is released to the extracellular space as part of the neutrophil response to infections. The possible association of a modified autoantigen with microbial components could, in predisposed individuals, increase the risk of autoimmunity.     

SMER28 Attenuates Dopaminergic Toxicity Mediated by 6-Hydroxydopamine in the Rats via Modulating Oxidative Burdens and Autophagy-Related Parameters

Parkinson’s disease is the second most common neurodegenerative disease that occurs due to cellular autophagy deficiency and the accumulation of alpha-synuclein in the dopaminergic neurons of the substantia nigra pars compacta (SNc) of the brainstem. The SMER28 (also known as 6-Bromo-N-prop-2-enylquinazolin-4-amine) is an autophagy inducer. In this study, the neuroprotective effects of SMER28 were evaluated on autophagy induction, antioxidant system activation, and microgliosis attenuation. The Parkinson’s disease model was developed in the male Wistar rats by injection of 6-OHDA into the left striatum. Apomorphine-induced behavior assessment test and SNc cell counting were performed to investigate the neuroprotective effects of SMER28. This study examined the pharmacological roles of SMER28, especially by focusing on the autophagy (p62/ SQSTM1 and LC3II/LC3I ratio where LC3 is microtubule-associated protein 1A/1B-light chain 3), inhibiting free radicals, and activating the antioxidant system. The levels of malondialdehyde (MDA), reactive oxygen species (ROS), glutathione (GSH), GSH/glutathione peroxidase (GP_X), superoxide dismutase (SOD) activity and nuclear factor-erythroid 2-related factor-2 (Nrf2) were measured to evaluate the antioxidant activity of SMER28. Moreover, Iba-1 (ionized calcium binding adaptor molecule, indicating microgliosis) and tyrosine hydroxylase immunoreactivities were evaluated in the SNc. In the behavioral assessment, SMER28 (50 µg/kg) attenuated damages to the SNc dopaminergic neurons, characterized by improved motor function. The tissue observations revealed that SMER28 prevented the destruction of SNc neurons and attenuated microgliosis as well. It also reduced MDA and ROS production and increased GSH, GP_X, SOD, and Nrf2 activities by inducing autophagy (decreasing p62 and increasing LC3II/LC3I ratio). Consequently, possibly with further studies, it can be considered as a drug for neurodegenerative diseases with proteinopathy etiology.     

PsbN Is Required for Assembly of the Photosystem II Reaction Center in Nicotiana tabacum

The chloroplast-encoded low molecular weight protein PsbN is annotated as a photosystem II (PSII) subunit. To elucidate the localization and function of PsbN, encoded on the opposite strand to the psbB gene cluster, we raised antibodies and inserted a resistance cassette into PsbN in both directions. Both homoplastomic tobacco (Nicotiana tabacum) mutants ∆psbN-F and ∆psbN-R show essentially the same PSII deficiencies. The mutants are extremely light sensitive and failed to recover from photoinhibition. Although synthesis of PSII proteins was not altered significantly, both mutants accumulated only ∼25% of PSII proteins compared with the wild type. Assembly of PSII precomplexes occurred at normal rates, but heterodimeric PSII reaction centers (RCs) and higher order PSII assemblies were not formed efficiently in the mutants. The ∆psbN-R mutant was complemented by allotopic expression of the PsbN gene fused to the sequence of a chloroplast transit peptide in the nuclear genome. PsbN represents a bitopic trans-membrane peptide localized in stroma lamellae with its highly conserved C terminus exposed to the stroma. Significant amounts of PsbN were already present in dark-grown seedling. Our data prove that PsbN is not a constituent subunit of PSII but is required for repair from photoinhibition and efficient assembly of the PSII RC.     

Remote controlling of CAR-T cells and toxicity management: Molecular switches and next generation CARs

Cell-based immunotherapies have been selected for the front-line cancer treatment approaches. Among them, CAR-T cells have shown extraordinary effects in hematologic diseases including chemotherapy-resistant acute lymphoblastic leukemia (ALL), chronic lymphocytic leukemia (CLL), and non-Hodgkin lymphoma (NHL). In this approach, autologous T cells isolated from the patient''s body genetically engineered to express a tumor specific synthetic receptor against a tumor antigen, then these cells expanded ex vivo and re-infusion back to the patient body. Recently, significant clinical response and high rates of complete remission of CAR T cell therapy in B-cell malignancies led to the approval of Kymriah and Yescarta (CD19-directed CAR-T cells) were by FDA for treatment of acute lymphoblastic leukemia and diffuse large B-cell lymphoma. Despite promising therapeutic outcomes, CAR T cells also can elicit the immune-pathologic effects, such as Cytokine Release Syndrome (CRS), Tumor Lysis Syndrome (TLS), and on-target off-tumor toxicity, that hampered its application. Ineffective control of these highly potent synthetic cells causes discussed potentially life-threatening toxicities, so researchers have developed several mechanisms to remote control CAR T cells. In this paper, we briefly review the introduced toxicities of CAR-T cells, then describe currently existing control approaches and review their procedure, pros, and cons.