Pronociceptive Roles of Schwann Cell-Derived Galectin-3 in Taxane-Induced Peripheral Neuropathy

Chemotherapy-induced peripheral neuropathy (CIPN) is a severe dose-limiting side effect of taxanes such as paclitaxel and docetaxel. Despite the high medical needs, insufficient understanding of the complex mechanism underlying CIPN pathogenesis precludes any endorsed causal therapy to prevent or relieve CIPN. In this study, we report that elevation of plasma galectin-3 level is a pathologic change common to both patients with taxane-treated breast cancer with CIPN and a mouse model of taxane-related CIPN. Following multiple intraperitoneal injections of paclitaxel in mice, galectin-3 levels were elevated in Schwann cells within the sciatic nerve but not in other peripheral organs or cells expressing galectin-3. Consistent with this, paclitaxel treatment of primary cultures of rat Schwann cells induced upregulation and secretion of galectin-3. In vitro migration assays revealed that recombinant galectin-3 induced a chemotactic response of the murine macrophage cell line RAW 264.7. In addition, perineural administration of galectin-3 to the sciatic nerve of naive mice mimicked paclitaxel-induced macrophage infiltration and mechanical hypersensitivity. By contrast, chemical depletion of macrophages by clodronate liposomes suppressed paclitaxel-induced mechanical hypersensitivity despite the higher level of plasma galectin-3. Deficiency (Galectin-3 ^-/- mice) or pharmacologic inhibition of galectin-3 inhibited paclitaxel-induced macrophage infiltration and mechanical hypersensitivity. In conclusion, we propose that Schwann cell-derived galectin-3 plays a pronociceptive role via macrophage infiltration in the pathogenesis of taxane-induced peripheral neuropathy. Therapies targeting this phenomenon, which is common to patients with CIPN and mouse models, represent a novel approach to suppress taxane-related CIPN. SIGNIFICANCE: These findings demonstrate that the elevation of plasma galectin-3 is a CIPN-related pathologic change common to humans and mice, and that targeting galectin-3 is a therapeutic option to delay CIPN progression.

T-cell responses to sequentially emerging viral escape mutants shape long-term HIV-1 population dynamics

HIV-1 strains harboring immune escape mutations can persist in circulation, but the impact of selection by multiple HLA alleles on population HIV-1 dynamics remains unclear. In Japan, HIV-1 Reverse Transcriptase codon 135 (RT135) is under strong immune pressure by HLA-B*51:01-restricted and HLA-B*52:01-restricted T cells that target a key epitope in this region (TI8; spanning RT codons 128-135). Major population-level shifts have occurred at HIV-1 RT135 during the Japanese epidemic, which first affected hemophiliacs (via imported contaminated blood products) and subsequently non-hemophiliacs (via domestic transmission). Specifically, threonine accumulated at RT135 (RT135T) in hemophiliac and non-hemophiliac HLA-B*51:01+ individuals diagnosed before 1997, but since then RT135T has markedly declined while RT135L has increased among non-hemophiliac individuals. We demonstrated that RT135V selection by HLA-B*52:01-restricted TI8-specific T-cells led to the creation of a new HLA-C*12:02-restricted epitope TN9-8V. We further showed that TN9-8V-specific HLA-C*12:02-restricted T cells selected RT135L while TN9-8T-specific HLA-C*12:02-restricted T cells suppressed replication of the RT135T variant. Thus, population-level accumulation of the RT135L mutation over time in Japan can be explained by initial targeting of the TI8 epitope by HLA-B*52:01-restricted T-cells, followed by targeting of the resulting escape mutant by HLA-C*12:02-restricted T-cells. We further demonstrate that this phenomenon is particular to Japan, where the HLA-B*52:01-C*12:02 haplotype is common: RT135L did not accumulate over a 15-year longitudinal analysis of HIV sequences in British Columbia, Canada, where this haplotype is rare. Together, our observations reveal that T-cell responses to sequentially emerging viral escape mutants can shape long-term HIV-1 population dynamics in a host population-specific manner.

Schwann cell-derived CXCL1 contributes to human immunodeficiency virus type 1 gp120-induced neuropathic pain by modulating macrophage infiltration in mice

The neuroinflammatory responses to human immunodeficiency virus type 1 (HIV-1) coat proteins, such as glycoprotein 120 (gp120), are considered to be responsible for the HIV-associated distal sensory neuropathy. Accumulating evidences suggest that T-cell line tropic X4 gp120 increases macrophage infiltration into the peripheral nerves, and thereby induces neuroinflammation leading to pain. However, the mechanisms underlying X4 gp120-induced macrophage recruitment to the peripheral nervous systems remain unclear. Here, we demonstrated that perineural application of X4 gp120 from HIV-1 strains IIIB and MN elicited mechanical hypersensitivity and spontaneous pain-like behaviors in mice. Furthermore, flow cytometry and immunohistochemical studies revealed increased infiltration of bone marrow-derived macrophages into the parenchyma of sciatic nerves and dorsal root ganglia (DRG) 7 days after gp120 IIIB or MN application. Chemical deletion of circulating macrophages using clodronate liposomes markedly suppressed gp120 IIIB-induced pain-like behaviors. In in vitro cell infiltration analysis, RAW 264.7 cell (a murine macrophage cell line) was chemoattracted to conditioned medium from gp120 IIIB- or MN-treated cultured Schwann cells, but not to conditioned medium from these gp120-treated DRG neurons, suggesting possible involvement of Schwann cell-derived soluble factors in macrophage infiltration. We identified using a gene expression array that CXCL1, a chemoattractant of macrophages and neutrophils, was increased in gp120 IIIB-treated cultured Schwann cells. Similar to gp120 IIIB or MN, perineural application of recombinant CXCL1 elicited pain-like behaviors accompanied by macrophage infiltration to the peripheral nerves. Furthermore, the repeated injection of CXCR2 (receptor for CXCL1) antagonist or CXCL1 neutralizing antibody prevented both pain-like behaviors and macrophage infiltration in gp120 IIIB-treated mice. Thus, the present study newly defines that Schwann cell-derived CXCL1, secreted in response to X4 gp120 exposure, is responsible for macrophage infiltration into peripheral nerves, and is thereby associated with pain-like behaviors in mice. We propose herein that communication between Schwann cells and macrophages may play a prominent role in the induction of X4 HIV-1-associated pain.

Comparative Expression Analysis of Stress-Inducible Genes in Murine Immune Cells

Background: Psychological stress affects the immune system. Upon stress occurrence, glucocorticoid is released that binds to the glucocorticoid receptor and regulates gene expression. Thus, we aimed to examine the stress-induced immunomodulatory mechanisms by investigating the expression patterns of stress-inducible genes in murine immune cells. Methods: BALB/c, C57BL/6, glucocorticoid-receptor congenic mice, and corticotropin-releasing hormone (CRH)-deficient mice were exposed to synthetic glucocorticoid, dexamethasone, or placed under a restraint condition. The expression level of stress-related genes, such as Rtp801, Gilz, Mkp-1, Bnip3, and Trp53inp1 was measured in the immune cells in these mice. Results: Short restraint stress induced Rtp801 and Gilz expressions that were higher in the spleen of BALB/c mice than those in C57BL/6 mice. Mkp-1 expression increased equally in these two strains, despite the difference in the glucocorticoid level. These three genes induced by short restraint stress were not induced in the CRH-deficient mice. In contrast, Bnip3 and Trp53inp1 were only upregulated upon longer restraint events. In the thymus, Trp53inp1 expression was induced upon short restraint stress, whereas Gilz expression constantly increased upon short and repetitive restraint stresses. Conclusion: These results suggest that singular and repetitive bouts of stress lead to differential gene expression in mice and stress-induced gene expression in thymocytes is distinct from that observed in splenocytes. Gilz, Rtp801, and Mkp-1 genes induced by short restraint stress are dependent on CRH in the spleen.

[Identification of biomarkers and new therapies for taxane-induced peripheral neuropathy]

Chemotherapy-induced peripheral neuropathy (CIPN) is a side effect frequently caused by taxanes. Because the mechanisms underlying CIPN pathogenesis remain to be fully elucidated, there is no indicator for objective diagnosis like a biomarker. In addition, treatment options for CIPN is still unsatisfactory. We have previously demonstrated that paclitaxel preferentially impair myelin-forming Schwann cells, and consequently induce dedifferentiation and demyelination of Schwann cells. Recently, in a paclitaxel CIPN model mouse, we found that an inflammatory factor is released from dedifferentiated Schwann cells in the mouse sciatic nerve into the blood, highly correlated with the on-set of mechanical hypersensitivity. On the other hand, considering our previous findings, it seems that some drugs, which supply newly formed mature Schwann cells at the sites of demyelinated lesions, may be a new beneficial therapy for taxane-induced peripheral neuropathy. In this review, we will introduce our findings about new therapeutic drug candidate for taxane-related CIPN based on this concept, and plasma biomarker to detect CIPN on-set and progression.

Comparative Analysis of Bone Marrow-derived Mast Cell Differentiation in C57BL/6 and BALB/c Mice

Allergic diseases have increased in the last three decades. Mast cells play a critical role in allergic diseases along with allergen-specific immunoglobulin E (IgE). Following mast cell degranulation elicited by ligation of the IgE-FcεRI receptor complex with allergen, allergic reactions are followed by various symptoms such as vascular hyperpermeability, mucous secretion, itching, sneezing, wheezing, rashes, fever, and anaphylactic shock. Susceptibility or inclination to allergy varies depending on individual genetic traits and living environment, and it has long been believed that such an inclination is determined by an immunologic balance of T helper cell types. Mouse strains also have different susceptibilities to allergy. Similar to T helper cells and macrophages, it is not known whether mast cells can also be divided into two different types between mouse strains. In this study, we prepared bone marrow-derived mast cells from BALB/c and C57BL/6 mice and examined their cellular properties. Cellular response to IL-3 and the process of mast cell differentiation from bone marrow cells were different on the basis of cell surface marker molecules. BALB/c-derived cells more efficiently exhibited degranulation than did C57BL/6-derived cells following both calcium ionophore and receptor crosslinking. These functional differences persisted even after a longer cell culture for 8 weeks, suggesting a difference in cell-autonomous characteristics. These results support the concept that mast cells also have different cell types dependent on their genetic background. Abbreviations: Ab: antibody; BMMC: bone marrow-derived mast cell; DNP: dinitrophenyl; FACS: fluorescence-activated cell sorter; FCS: fetal calf serum; FITC: fluorescein isothiocyanate; FSC: forward scatter; HRP: horseradish peroxidase; HSA: human serum albumin; Ig: immunoglobulin; IL: interleukin; MIP-2: macrophage inflammatory protein-2; MCP: mast cell protease; PE: phycoerythrin; PerCP: Peridinin chlorophyll protein complex; SNP: single nucleotide polymorphisms; SSC: side scatter; Th: T helper; TNF-α: tumor necrosis factor alpha.

Impact of a single HLA-A*24:02-associated escape mutation on the detrimental effect of HLA-B*35:01 in HIV-1 control

Background

HLA-B*35 is an HLA allele associated with rapid progression to AIDS. However, a mechanism underlying the detrimental effect of HLA-B*35 on disease outcome remains unknown. Recent studies demonstrated that most prevalent subtype HLA-B*35:01 is a detrimental allele in HIV-1 clade B-infected individuals. We here investigated the effect of mutations within the epitopes on HLA-B*35:01-restricted CD8⁺ T cells having abilities to suppress HIV-1 replication.

Methods

We analyzed 16 HLA-B*35:01-restricted epitope-specific T cells in 63 HIV-1 clade B-infected Japanese B*35:01⁺ individuals and identified HLA-B*35:01-restricted CD8⁺ T cells having abilities to suppress HIV-1 replication. We further analyzed the effect of HLA-associated mutations on the ability of these T cells.

Findings

The breadth of T cell responses to 4 epitopes was inversely associated with plasma viral load (pVL). However, the accumulation of an Y135F mutation in NefYF9 out of the 4 epitopes, which is selected by HLA-A*24:02-restricted T cells, affected the ability of YF9-specific T cells to suppress HIV-1 replication. HLA-B*35:01⁺ individuals harboring this mutation had much higher pVL than those without it. YF9-specific T cells failed to suppress replication of the Y135F mutant in vitro. These results indicate that this mutation impairs suppression of HIV-1 replication by YF9-specific T cells.

Interpretation

These findings indicate that the Y135F mutation is a key factor underlying the detrimental effect of HLA-B*35:01 on disease outcomes in HIV-1 clade B-infected individuals.

Fund

Grants-in-aid for AIDS Research from AMED and for scientific research from the Ministry of Education, Science, Sports, and Culture, Japan.

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T cells specific for 4 HLA-B*35:01-restricted epitopes have abilities to suppress HIV-1 replication in vivo.

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An Y135F mutation selected by HLA-A*24:02-restricted T cells affected HIV-1 control by NefYF9-specific T cells in vivo.

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The NefY135F mutation impaired suppression of HIV-1 replication by NefYF9-specific T cells in vitro.

A SNP uncoupling Mina expression from the TGFβ signaling pathway

INTRODUCTION

Mina is a JmjC family 2-oxoglutarate oxygenase with pleiotropic roles in cell proliferation, cancer, T cell differentiation, pulmonary inflammation, and intestinal parasite expulsion. Although Mina expression varies according to cell-type, developmental stage and activation state, its transcriptional regulation is poorly understood. Across inbred mouse strains, Mina protein level exhibits a bimodal distribution, correlating with inheritance of a biallelic haplotype block comprising 21 promoter/intron 1-region SNPs. We previously showed that heritable differences in Mina protein level are transcriptionally regulated.

METHODS

Accordingly, we decided to test the hypothesis that at least one of the promoter/intron 1-region SNPs perturbs a Mina cis-regulatory element (CRE). Here, we have comprehensively scanned for CREs across a Mina locus-spanning 26-kilobase genomic interval.

RESULTS

We discovered 8 potential CREs and functionally validated 4 of these, the strongest of which (E2), residing in intron 1, contained a SNP whose BALB/c-but not C57Bl/6 allele-abolished both Smad3 binding and transforming growth factor beta (TGFβ) responsiveness.

CONCLUSIONS

Our results demonstrate the TGFβ signaling pathway plays a critical role in regulating Mina expression and SNP rs4191790 controls heritable variation in Mina expression level, raising important questions regarding the evolution of an allele that uncouples Mina expression from the TGFβ signaling pathway.

Control of HIV-1 by an HLA-B*52:01-C*12:02 Protective Haplotype

HLA-B*52:01-C*12:02, which is found in approximately 20% of all Japanese persons, is well known to be associated with ulcerative colitis and Takayasu arteritis. This haplotype is also known to be protective in individuals infected with human immunodeficiency virus (HIV) type 1. Recent studies showed that HLA-B*52:01-restricted HIV-1-specific T cells suppress HIV-1 and that HLA-C*12:02 together with KIR2DL2 play an important role in natural killer cell-mediated control of HIV-1. However, the role of HLA-C*12:02-restricted cytotoxic T lymphocytes (CTLs) in suppressing HIV-1 replication remains unknown. In the present study, we demonstrated that HLA-C*12:02-restricted CTLs specific for 2 immunodominant epitopes, Pol IY11 and Nef MY9, contributed to the suppression of HIV-1 replication in HIV-1-infected individuals. Further analysis demonstrated that these 2 HLA-C*12:02-restricted CTLs together with 4 HLA-B*52:01-restricted ones effectively suppressed HIV-1 in individuals with the HLA-B*52:01-C*12:02 haplotype. Thus, both HLA-C*12:02 and HLA-B*52:01 alleles contribute to HIV-1 suppression via both HIV-1-specific CTLs and natural killer cells in individuals with this haplotype.

HIV-1 Control by NK Cells via Reduced Interaction between KIR2DL2 and HLA-C∗12:02/C∗14:03

Natural killer (NK) cells control viral infection in part through the interaction between killer cell immunoglobulin-like receptors (KIRs) and their human leukocyte antigen (HLA) ligands. We investigated 504 anti-retroviral (ART)-free Japanese patients chronically infected with HIV-1 and identified two KIR/HLA combinations, KIR2DL2/HLA-C^∗12:02 and KIR2DL2/HLA-C^∗14:03, that impact suppression of HIV-1 replication. KIR2DL2⁺ NK cells suppressed viral replication in HLA-C^∗14:03⁺ or HLA-C^∗12:02⁺ cells to a significantly greater extent than did KIR2DL2^- NK cells in vitro. Functional analysis showed that the binding between HIV-1-derived peptide and HLA-C^∗14:03 or HLA-C^∗12:02 influenced KIR2DL2⁺ NK cell activity through reduced expression of the peptide-HLA (pHLA) complex on the cell surface (i.e., reduced KIR2DL2 ligand expression), rather than through reduced binding affinity of KIR2DL2 to the respective pHLA complexes. Thus, KIR2DL2/HLA-C^∗12:02 and KIR2DL2/HLA-C^∗14:03 compound genotypes have protective effects on control of HIV-1 through a mechanism involving KIR2DL2-mediated NK cell recognition of virus-infected cells, providing additional understanding of NK cells in HIV-1 infection.

A comparative study of colorimetric cell proliferation assays in immune cells

Cell proliferation assays are basic and essential techniques for assessing cellular function. Various colorimetric assays, such as MTT-, WST-1-, and resazurin-based assays, are available; however, studies directly comparing the suitability of each method for immune cell proliferation are scarce. Thus, we aimed to determine the best reagent and its optimal conditions based on variables such as cell number range, stimulation dose, kinetics, and compatibility with the cell division assay using CFSE fluorescence dye which is able to directly monitor divided cells by flow cytometry. In the absence of stimulation, MTT solubilized with SDS (MTT-SDS) and resazurin appeared to accurately reflect the cell numbers in a linear fashion. On the other hand, WST-1 exhibited a higher stimulation index following strong stimulation, whereas MTT-SDS and resazurin exhibited a better sensitivity to weak stimulation. A longer duration for stimulation did not necessarily increase sensitivity. CFSE staining revealed incremental cell division in response to anti-CD3 antibody stimulation in a dose-dependent manner. The cell numbers indirectly estimated from cell division profiles were consistent with the dose-response curve in the absorbance of MTT-SDS and resazurin. The absorbance does not increase before cell division, irrespective of T cell activation status, suggesting that these reagents reflect the cell number but not the cellular volume. Collectively, resazurin and MTT-SDS seem to be more reliable than others, and thus appear applicable in various conditions for the immune cell experiments.

HIV subtype influences HLA-B*07:02-associated HIV disease outcome

Genetic polymorphisms within the MHC encoding region have the strongest impact on HIV disease progression of any in the human genome and provide important clues to the mechanisms of HIV immune control. Few analyses have been undertaken of HLA alleles associated with rapid disease progression. HLA-B*07:02 is an HLA class I molecule that is prevalent in most populations worldwide and that has previously been consistently linked to accelerated disease progression in B-clade infection. This study investigates the observation that HLA-B*07:02 is not associated with a high viral setpoint in C-clade infection. We examine the hypothesis that this clade-specific difference in association with disease outcome may be related to distinct targeting of CD8(+) T cell epitopes. We observed that C-clade-infected individuals with HLA-B*07:02 target a broader range of Gag epitopes, and to higher magnitudes, than do individuals infected with B-clade infection. In particular, a novel p17-Gag (Gag22-30, RPGGKKHYM) epitope is targeted in >50% of HLA-B*07:02-positive C-clade-infected individuals but clade-specific differences in this epitope result in nonimmunogenicity in B-clade infection. Only the C-clade p24-Gag "GL9" (Gag355-363, GPSHKARVL) epitope-specific CD8(+) T cell response out of 16 studied was associated with a low viral setpoint. Although this epitope was also targeted in B-clade infection, the escape mutant S357S is present at higher frequency in B-clade infection than in C-clade infection (70% versus 43% in HLA-B*07:02-negative subjects). These data support earlier studies suggesting that increased breadth of the Gag-specific CD8(+) T cell response may contribute to improved HIV immune control irrespective of the particular HLA molecules expressed.

Transcriptional activation of Mina by Sp1/3 factors

Mina is an epigenetic gene regulatory protein known to function in multiple physiological and pathological contexts, including pulmonary inflammation, cell proliferation, cancer and immunity. We showed previously that the level of Mina gene expression is subject to natural genetic variation linked to 21 SNPs occurring in the Mina 5′ region [1]. In order to explore the mechanisms regulating Mina gene expression, we set out to molecularly characterize the Mina promoter in the region encompassing these SNPs. We used three kinds of assays – reporter, gel shift and chromatin immunoprecipitation – to analyze a 2 kb genomic fragment spanning the upstream and intron 1 regions flanking exon 1. Here we discovered a pair of Mina promoters (P1 and P2) and a P1-specific enhancer element (E1). Pharmacologic inhibition and siRNA knockdown experiments suggested that Sp1/3 transcription factors trigger Mina expression through additive activity targeted to a cluster of four Sp1/3 binding sites forming the P1 promoter. These results set the stage for comprehensive analysis of Mina gene regulation from the context of tissue specificity, the impact of inherited genetic variation and the nature of upstream signaling pathways.

Identification of cross-clade CTL epitopes in HIV-1 clade A/E-infected individuals by using the clade B overlapping peptides

Identification of cross-clade T cell epitopes is one of key factors for the development of a widely applicable AIDS vaccine. We here investigated cross-clade CD8(+) T cell responses between clade B and A/E viruses in chronically HIV-1 clade A/E-infected Japanese individuals. CD8(+) T cell responses to 11-mer overlapping peptides derived from Nef, Gag, and Pol clade B consensus sequences were at a similar level to those to the same peptides found in clade B-infected individuals. Fifteen cross-clade CTL epitopes were identified from 13 regions where the frequency of responders was high in the clade A/E-infected individuals. The sequences of 6 epitopes were conserved between the clade B and clade A/E viruses whereas 9 epitopes had different amino acid sequences between the 2 viruses. CD8(+) T cells specific for the 6 conserved epitopes recognized cells infected with the clade A/E virus, whereas those for 8 diverse epitopes recognized both the clade A/E virus-infected and clade B-infected cells. All of the cross-clade CD8(+) T cells specific for conserved and diverse epitopes were detected in chronically HIV-1 clade A/E-infected individuals. These results show that in addition to conserved regions polymorphic ones across the clades can be targets for cross-clade CTLs.

Effective recognition of HIV-1-infected cells by HIV-1 integrase-specific HLA-B∗4002-restricted T cells

HLA-B∗4002 is one of the common HLA-B alleles in the world. All 7 reported HLA-B∗4002-restricted HIV epitopes are derived from Gag, Nef, and Vpr. In the present study we sought to identify novel HLA-B∗4002-restricted HIV epitopes by using overlapping 11-mer peptides of HIV-1 Nef, Gag, and Pol, and found that 6 of these 11-mer Pol peptides included HLA-B∗4002-restricted epitopes. Analysis using truncated peptides of these 6 peptides defined 4 optimal Pol (integrase) epitopes. All epitopes previously reported had Glu at position 2 (P2), suggesting that Glu at P2 is the anchor residue for HLA-B∗4002; whereas only 2 of the integrase epitopes that we here identified had Glu at P2. CTL clones specific for the 2 epitopes effectively recognized HIV-1-infected cells whereas those for other 2 epitopes only weakly recognized them. The antigen sensitivity of the former clones for the epitope peptide was much higher than that of the latter clones, suggesting 2 possibilities: 1) the former T cells have high-affinity TCRs and/or 2) the epitope peptides recognized by the former T cells are highly presented by HLA-B∗4002 in HIV-1-infected cells. These integrase-specific T cells with high antigen sensitivity may contribute to the suppression of HIV-1 replication in HIV-1-infected HLA-B∗4002+ individuals.

Diversifying selection and functional analysis of interleukin-4 suggests antagonism-driven evolution at receptor-binding interfaces

Background

Interleukin-4 (IL4) is a secreted immunoregulatory cytokine critically involved in host protection from parasitic helminths [1]. Reasoning that helminths may have evolved mechanisms to antagonize IL4 to maximize their dispersal, we explored mammalian IL4 evolution.

Results

This analysis revealed evidence of diversifying selection at 15 residues, clustered in epitopes responsible for IL4 binding to its Type I and Type II receptors. Such a striking signature of selective pressure suggested either recurrent episodes of pathogen antagonism or ligand/receptor co-evolution. To test the latter possibility, we performed detailed functional analysis of IL4 allotypes expressed by Mus musculus musculus and Mus musculus castaneus, which happen to differ at 5 residues (including three at positively selected sites) in and adjacent to the site 1 epitope that binds the IL4Rα subunit shared by the Type I and Type II IL4 receptors. We show that this intra-species variation affects the ability of IL4 neither to bind IL4 receptor alpha (IL4Rα) nor to signal biological responses through its Type I receptor.

Conclusions

Our results -- reminiscent of clustered positively selected sites revealing functionally important residues at host-virus interaction interfaces -- are consistent with IL4 having evolved to avoid recurrent pathogen antagonism, while maintaining the capacity to bind and signal through its cognate receptor. This work exposes what may be a general feature of evolutionary conflicts fought by pathogen antagonists at host protein-protein interaction interfaces involved in immune signaling: the emergence of receptor-binding ligand epitopes capable of buffering amino acid variation.

Reduced T cell expansion by a superantigen as a result of impaired B cell development in mice deficient for the p85alpha regulatory subunit of PI3K

PI3K plays crucial roles in the immune system. Mice deficient for p85alpha, a major regulatory subunit of class IA PI3K, show various defects and alterations in B cells, mast cells, macrophages, and DCs, and peripheral T cells are reportedly normal, at least in vitro. In normal mice, long-term exposure to a SAg, SEA, in vivo induced a high level of the protracted expansion of SEA-reactive Vbeta3(+)CD4(+) T cells, whereas the same treatment induced T cell expansion in p85alpha-deficient mice but to a much lesser extent than in normal mice. However, mixed bone marrow chimera mice, which have normal and p85alpha-deficient T and B cells, demonstrated equal responses of both T cells following stimulation with a SEA pump. In reciprocal cotransfer experiments of T and B cells from normal and p85alpha-deficient mice into Rag2-deficient mice, followed by SEA stimulation, p85alpha-deficient T cells revealed much higher proliferative capacity in the presence of normal B cells than did normal T cells with p85alpha-deficient B cells. Histologically, a marked B cell reduction was observed in the follicles and MZ of the spleen, and DCs accumulated in the MZ. In addition, p85alpha-deficient B cells had a low level of MHC class II expression. Collectively, these data suggested that the PI3K p85alpha subunit alters the SAg presentation capacity of B cells and indirectly modulates the magnitude of the T cell response, which may affect the protection against SEA-containing bacteria.

Cutting edge: Dab2 is a FOXP3 target gene required for regulatory T cell function

FOXP3-expressing regulatory T (Treg) cells are vital for maintaining peripheral T cell tolerance and homeostasis. The mechanisms by which FOXP3 target genes orchestrate context-dependent Treg cell function are largely unknown. In this study we show that in mouse peripheral lymphocytes the Drosophila Disabled-2 (Dab2) homolog, a gene that is involved in enhancing TGFbeta responses, is exclusively expressed in FOXP3+ regulatory T cells. Dab2 is a direct target of FOXP3, and regulatory T cells lacking DAB2 are functionally impaired in vitro and in vivo. However, not all aspects of Treg cell function are perturbed, and DAB2 appears to be dispensable for Treg cell function in maintaining naive T cell homeostasis.

Mina, an Il4 repressor, controls T helper type 2 bias

T helper type 2 (T(H)2) bias, which is the propensity of naive CD4(+) T cells to differentiate into interleukin 4 (IL-4)-secreting T(H)2 cells, is a genetic trait that affects susceptibility to infectious, autoimmune and allergic diseases. T(H)2 bias correlates with the amount of IL-4 initially secreted by newly activated helper T cells that feeds back positively through the pathway of the IL-4 receptor and the transcription factors STAT6 and GATA-3 to drive T(H)2 development. Here we identify Mina, a member of the jumonji C (JmjC) protein family, as a genetic determinant of T(H)2 bias. Mina specifically bound to and repressed the Il4 promoter. Mina overexpression in transgenic mice impaired Il4 expression, whereas its knockdown in primary CD4(+) T cells led to Il4 derepression. Our findings collectively provide mechanistic insight into an Il4-regulatory pathway that controls helper T cell differentiation and genetic variation in T(H)2 bias.

Mina53, an IL4 repressor controlling TH2-bias (136.42)

The naïve CD4 T helper (TH) cell can differentiate into several effector TH subsets, depending on the host-pathogen environment. TH1 cells, which express high levels of the cytokine IFNγ, are essential for clearance of intracellular pathogens, while TH2 cells, which express high levels of IL-4, are required for responses to extracellular pathogens. TH2-bias, which occurs when a naïve T cell preferentially differentiates to a TH2 cell, is a genetic trait impacting infectious, autoimmune, and allergic disease susceptibility. Previous studies in our laboratory have identified a quantitative trait locus that regulates TH2 bias in mice (Dice1.2). Here, we have identified Mina53, a JmjC family member, as the genetic determinant of Dice1.2. Mina53 specifically represses transcription from the Il4 promoter in transient reporter assays, while over-expression of Mina53 converts TH2 bias from high to low. Moreover, Mina53 binds to the proximal Il4 promoter, and this binding requires an interaction between Mina53 and nuclear factor of activated T cells (NFAT), a key regulator of cytokine expression. Taken together, these data provide mechanistic insight into the Il4 regulatory pathway controlling effector T cell differentiation and account, in part, for genetic variation in TH2 bias.

Long-term exposure to superantigen induces p27Kip1 and Bcl-2 expression in effector memory CD4+ T cells

The long-term exposure of mice to superantigen SEA using a mini-osmotic pump (SEA pump) induced a long-lasting expansion of Vbeta3+ CD4+ T cells with T helper (Th) 2 cell-type properties. Removal of the SEA pump 10 days after pump implantation did not significantly alter the level of Vbeta3+ CD4+ T cell expansion/maintenance. Furthermore, CFSE-labeled CD4+ T cells failed to divide when transferred to post-implantation day 15 mice. Thus, CD4+ T cells appeared to survive for at least 30 days in the absence of a sufficient amount of antigen to trigger cell division. STAT6 deficient mice, in which Th2 cell development is largely impaired, also exhibited a protracted cell expansion, similar to that observed in normal mice, suggesting that the Th2 cell property is dispensable for the maintenance of Vbeta3+ CD4+ T cell expansion. The expanded CD4+ T cells on post-implantation day 26 were arrested in the G0/G1 phase of the cell cycle and showed a lower level of cell division upon restimulation. The Cdk inhibitor p27(Kip1) was highly expressed, and Cdk2 was downregulated. Moreover, the CD4+ T cells were resistant to in vitro apoptosis induction in parallel with their level of Bcl-2 expression. Collectively, the Vbeta3+ CD4+ T cells appeared to develop into long-lived memory T cells with cell cycle arrest upon long-term exposure to SEA.

[Mediastinal emphysema after a punch on the back; report of a case]

A 19-year-old man was punched on the back, and anterior chest pain appeared about 3 hours after injury. The patient was consulted a physician complaining of anterior chest pain. On chest X-ray, mediastinal emphysema was suspected, and transferred to our hospital. Chest computed tomography (CT) revealed mediastinal emphysema. On esophageal radiography and bronchofiberscopy, no abnormal findings were detected. Conservative therapy was conducted, and symptoms had gradually improved. On the 8th hospital day, mediastinal emphysema was improved on chest CT. The patient was discharged on the 10th hospital day. The most frequent cause of mediastinal emphysema after trauma is traffic or downfall accident, and no report on this condition after the punch on the back was found.

CD28 is required for induction and maintenance of immunological memory in toxin-reactive CD4+ T cells in vivo

We previously reported that Vbeta3+ CD4+ T cells maintained a protracted expansion, with the phenotypes of memory Th2 cells, for 30 days in C57BL/6 (B6) mice implanted with SEA-containing mini-osmotic pumps. In the present study, we followed the fate of Vbeta3+ CD4+ T cells in CD28-/- mice. Vbeta3+ CD4+ T cells increased to a degree similar to that of B6 Vbeta3+ CD4+ T cells until day 10 after implantation, then declined rapidly reaching the control level by 28 days. Remaining Vbeta3+ CD4+ T cells at that time did not exhibit memory phenotypes nor Th2-deviated responses. The rapid drop in Vbeta3+ CD4+ T cells in CD28-/- mice was attributable to upregulated induction of apoptosis owing to marginal inductions of Bcl-2 and Bcl-xL. Collectively, these data indicate CD28 to play critical roles in the generation and maintenance of SEA-reactive CD4+ T cells in vivo.

EZH2 and histone 3 trimethyl lysine 27 associated with Il4 and Il13 gene silencing in Th1 cells

Differentiation of naïve CD4 T cells toward the T helper 1 (T(H)1) and T helper 2 (T(H)2) fates involves the transcriptional repression and enhancement, respectively, of Il4 and Il13, adjacent chromosome 11 genes encoding the canonical T(H)2 cytokines interleukin-4 and interleukin-13. Proper execution of this developmental fate choice during immune responses is critical to host defense and, when misregulated, leads to susceptibility to infectious microbes and to allergic and autoimmune diseases. Here, using chromatin immunoprecipitation and real time reverse transcription PCR we identify the Polycomb family histone methyltransferase EZH2 as the enzyme responsible for methylating lysine 27 of histone H3 at the Il4-Il13 locus of T(H)1 but not T(H)2 cells, implicating EZH2 in the mechanism of Il4 and Il13 transcriptional silencing.

Cytocidal effect of Streptococcus pyogenes on mouse neutrophils in vivo and the critical role of streptolysin S

We analyzed the in vivo dynamics of peritoneal exudate cells (PECs) in mice injected with group A streptococcus (GAS). A live low-virulence strain, as well as heat-killed low- and high-virulence strains, significantly increased the number of PECs (primarily neutrophils), whereas a live high-virulence strain did not. When coinjected with thioglycollate, the live high-virulence strain, as well as most other GAS strains, suppressed the ability of thioglycollate to induce neutrophil exudation. This suppression was due to a cytocidal effect of GAS on exuded neutrophils rather than an inhibition of neutrophil migration. In addition, GAS enhanced the apoptosis of neutrophils. These cytocidal effects were significantly reduced by the deletion of functional streptolysin S from GAS. Our findings suggest that, in addition to the production of antiphagocytic factors and survival inside phagocytes, GAS uses a more aggressive method--the elimination of neutrophils--to evade the host's innate immune system.

Immunologic immaturity, but high IL-4 productivity, of murine neonatal thymic CD4 single-positive T cells in the last stage of maturation

To determine the levels of maturation and differentiation of murine CD4 single-positive (SP) T cells, we compared the secondary responses of staphylococcal enterotoxin A (SEA)-induced neonatal thymic, adult thymic and adult splenic CD4 SP T cell blasts prepared from whole or heat-stable antigen(low) CD4 SP T cells. Proliferative responses upon re-stimulation with SEA were strong in adult splenic CD4 SP T cell blasts, but quite weak in neonatal thymic and adult thymic CD4 SP T cell blasts. SEA-induced IL-2 production was weaker in neonatal thymic blasts than in the adult splenic CD4 SP T cell blasts. In contrast, SEA-induced IL-4 production was high in neonatal thymic CD4 SP T cell blasts, and low in adult splenic and thymic CD4 SP T cell blasts. Expression of GATA-3, that directs production of IL-4 in T cells, examined at protein and mRNA levels, was higher in neonatal thymic cells than in adult thymic and splenic cells. These results suggest that neonatal and adult thymic CD4 SP T cells in the final stage of maturation are relatively immature compared with adult splenic CD4 SP T cells. The cytokine production profile of neonatal thymic CD4 SP T cells suggests that they are inclined towards a T(h)2 response.

Genetic characterization and specific detection of beer-spoilage Lactobacillus sp. LA2 and related strains

AIMS

Lactobacillus sp. LA2 (DSM15502) and related strains (LA2 group) possess strong beer-spoilage ability. The 16S rDNA sequence of LA2 strain is virtually indistinguishable from that of L. collinoides, generally considered to be nonbeer-spoilage bacteria. The aim of this study was to identify the genetic marker to distinguish between Lactobacillus sp. LA2 group and L. collinoides and to provide a rapid means of identifying beer-spoilage strains belonging to Lactobacillus sp. LA2 group.

METHODS AND RESULTS

The 16-23S rDNA intergenic spacer (ITS) regions of Lactobacillus sp. LA2 and L. collinoides JCM1123T were sequenced to identify a genetic marker to distinguish between the two groups. As a result, 300 and 500 bp ITS regions of Lactobacillus sp. LA2 were found to be almost identical with those of L. collinoides JCM1123T. Sequence comparison analysis between Lactobacillus sp. LA2 and L. collinoides JCM1123T revealed that the two contiguously located nucleotides are absent in both ITS regions of Lactobacillus sp. LA2. Based on the sequence difference, we have designed specific PCR primers with a minor modification to the primer sequence that can differentiate between beer-spoilage Lactobacillus sp. LA2 group and nonbeer-spoilage L. collinoides.

CONCLUSIONS

The PCR-based method has been developed to identify Lactobacillus sp. LA2 group, providing a rapid and sensitive means of determining the beer-spoilage ability of detected bacterial strains.

SIGNIFICANCE AND IMPACT OF THE STUDY

The substitution of one nucleotide, located at the third position to the 3'-end in the primer sequence, enhanced the specificity of the PCR method while retaining sufficient sensitivity. The nucleotide gap identified in this study appeared to serve as a useful genetic marker that can differentiate 12 beer-spoilage Lactobacillus sp. LA2 group strains from its close relatives that exhibit no beer-spoilage ability.

Genetic characterization of non-spoilage variant isolated from beer-spoilage Lactobacillus brevis ABBC45C

AIMS

To characterize the non-spoilage variant obtained from beer-spoilage Lactobacillus brevis ABBC45C and to identify a potential genetic marker capable of discriminating beer-spoilage L. brevis strains from non-spoilers.

METHODS AND RESULTS

A non-spoilage variant was obtained from beer-spoilage L. brevis ABBC45C by repeatedly subculturing the strain at 37 degrees C. Genetic characterization of the variant revealed that 12,605 bp portion of one plasmid, designated pRH45II, was lost in the variant. The sequence analysis indicates the presence of 12 ORFs in the deleted region of pRH45II. The PCR and Southern hybridization study revealed that the homologues of ORF5 found in the deleted region were present in all of the beer-spoilage L. brevis strains examined in this study. In contrast, the homlogues appeared to be absent in non-spoilage L. brevis strains.

CONCLUSIONS

The presence or absence of ORF5 homologues was found to be highly correlated with the beer-spoilage ability of L. brevis strains, indicating this ORF is potentially a useful genetic marker capable of differentiating beer-spoilage strains among L. brevis.

SIGNIFICANCE AND IMPACT OF THE STUDY

A non-spoilage variant was successfully isolated from beer-spoilage L. brevis ABBC45C. This study could facilitate the understanding of mechanisms underlying beer-spoilage ability of L. brevis.

Continuous exposure of mice to superantigenic toxins induces a high-level protracted expansion and an immunological memory in the toxin-reactive CD4+ T cells

We analyzed the responses of several T cell fractions reactive with superantigenic toxins (SAGTs), staphylococcal enterotoxin A (SEA), or Yersinia pseudotuberculosis-derived mitogen (YPM) in mice implanted with mini-osmotic pumps filled with SEA or YPM. In mice implanted with the SEA pump, SEA-reactive Vbeta3(+)CD4(+) T cells exhibited a high-level protracted expansion for 30 days, and SEA-reactive Vbeta11(+)CD4(+) T cells exhibited a low-level protracted expansion. SEA-reactive CD8(+) counterparts exhibited only a transient expansion. A similar difference in T cell expansion was also observed in YPM-reactive T cell fractions in mice implanted with the YPM pump. Vbeta3(+)CD4(+) and Vbeta11(+)CD4(+) T cells from mice implanted with the SEA pump exhibited cell divisions upon in vitro restimulation with SEA and expressed surface phenotypes as memory T cells. CD4(+) T cells from mice implanted with the SEA pump exhibited high IL-4 production upon in vitro restimulation with SEA, which was due to the enhanced capacity of the SEA-reactive CD4(+) T cells to produce IL-4. The findings in the present study indicate that, in mice implanted with a specific SAGT, the level of expansion of the SAGT-reactive CD4(+) T cell fractions varies widely depending on the TCR Vbeta elements expressed and that the reactive CD4(+) T cells acquire a capacity to raise a memory response. CD8(+) T cells are low responders to SAGTs.

Antiinflammatory and antiarteriosclerotic actions of HMG-CoA reductase inhibitors in a rat model of chronic inhibition of nitric oxide synthesis

Recent studies suggest that some of the beneficial effects of 3-hydroxyl-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) may be due to their cholesterol-lowering independent effects on the blood vessels. Chronic inhibition of endothelial nitric oxide (NO) synthesis by oral administration of N(omega)-nitro-L-arginine methyl ester (L-NAME) to rats induces early vascular inflammation as well as subsequent arteriosclerosis. The aim of the study is to test whether treatment with statins attenuates such arteriosclerotic changes through their cholesterol-lowering independent effects. We investigated the effect of statins (pravastatin and cerivastatin) on the arteriosclerotic changes in the rat model. We found that treatment with statins did not affect serum lipid levels but markedly inhibited the L-NAME-induced vascular inflammation and arteriosclerosis. Treatment with statins augmented endothelial NO synthase activity in L-NAME-treated rats. We also found the L-NAME induced increase in Rho membrane translocation in hearts and its prevention by statins. Such vasculoprotective effects of statins were suppressed by the higher dose of L-NAME. In summary, in this study, we found that statins such as pravastatin and cerivastatin inhibited vascular inflammation and arteriosclerosis through their lipid-lowering independent actions in this model. Such antiarteriosclerotic effects may involve the increase in endothelial NO synthase activity and the inhibition of Rho activity.

Regression by ACE inhibition of arteriosclerotic changes induced by chronic blockade of NO synthesis in rats

We previously reported that chronic inhibition of nitric oxide (NO) synthesis with N(omega)-nitro-L-arginine methyl ester (L-NAME) induces vascular inflammation at week 1 and produces subsequent arteriosclerosis at week 4 and that cotreatment with an angiotensin-converting enzyme (ACE) inhibitor prevents such changes. In the present study, we tested the hypothesis that treatment with an ACE inhibitor after development of vascular inflammation could inhibit arteriosclerosis in rats. Wistar-Kyoto rats were randomized to four groups: the control group received no drugs, the 4wL-NAME group received L-NAME (100 mg x kg(-1) x day(-1)) for 4 wk, the 1wL + 3wNT group received L-NAME for 1 wk and no treatment for the subsequent 3 wk, and the 1wL + 3wACEI group received L-NAME for 1 wk and the ACE inhibitor imidapril (20 mg x kg(-1) x day(-1)) for the subsequent 3 wk. After 4 wk, we observed significant arteriosclerosis of the coronary artery (medial thickening and fibrosis) and increased cardiac ACE activity in the 1wL + 3wNT group as well as in the 4wL-NAME group, but not in the 1wL + 3wACEI group. In a separate study, we examined apoptosis formation and found that posttreatment with imidapril (20 mg x kg(-1) x day(-1)) or an ANG II AT1-receptor antagonist, CS-866 (5 mg x kg(-1) x day(-1)), induced apoptosis (TdT-mediated nick end-labeling) in monocytes and myofibroblasts appearing in the inflammatory lesions associated with a clear degradation in the heart (DNA electrophoresis). In conclusion, treatment with the ACE inhibitor after 1 wk of L-NAME administration inhibited arteriosclerosis by inducing apoptosis in the cells with inflammatory lesions in this study, suggesting that increased ANG II activity inhibited apoptosis of the cells with inflammatory lesions and thus contributed to the development of arteriosclerosis.

New anti-monocyte chemoattractant protein-1 gene therapy attenuates atherosclerosis in apolipoprotein E-knockout mice

BACKGROUND

Monocyte recruitment into the arterial wall and its activation may be the central event in atherogenesis. Monocyte chemoattractant protein-1 (MCP-1) is an important chemokine for monocyte recruitment, and its receptor (CCR2) may mediate such in vivo response. Although the importance of the MCP-1/CCR2 pathway in atherogenesis has been clarified, it remains unanswered whether postnatal blockade of the MCP-1 signals could be a unique site-specific gene therapy.

METHODS AND RESULTS

We devised a new strategy for anti-MCP-1 gene therapy to treat atherosclerosis by transfecting an N-terminal deletion mutant of the human MCP-1 gene into a remote organ (skeletal muscle) in apolipoprotein E-knockout mice. This strategy effectively blocked MCP-1 activity and inhibited the formation of atherosclerotic lesions but had no effect on serum lipid concentrations. Furthermore, this strategy increased the lesional extracellular matrix content.

CONCLUSIONS

We conclude that this anti-MCP-1 gene therapy may serve not only to reduce atherogenesis but also to stabilize vulnerable atheromatous plaques. This strategy may be a useful and feasible form of gene therapy against atherosclerosis in humans.