Critical effect of Pol escape mutations associated with detrimental allele HLA-C*15: 05 on clinical outcome in HIV-1 subtype A/E infection

OBJECTIVE

The mechanism explaining the role of detrimental HLA alleles in HIV-1 infections has been investigated in very few studies. HLA-A*29:01-B*07:05-C*15:05 is a detrimental haplotype in HIV-1 subtype A/E-infected Vietnamese individuals. The accumulation of mutations at Pol 653/657 is associated with a poor clinical outcome in these individuals. However, the detrimental HLA allele and the mechanism responsible for its detrimental effect remains unknown. Therefore, in this current study we identified the detrimental HLA allele and investigated the mechanism responsible for the detrimental effect.

DESIGN AND METHODS

A T-cell epitope including Pol 653/657 and its HLA restriction were identified by using overlapping HIV-1 peptides and cell lines expressing a single HLA. The effect of the mutations on the T-cell recognition of HIV-1-infected cells was investigated by using target cells infected with the mutant viruses. The effect of these mutations on the clinical outcome was analyzed in 74 HLA-C*15:05 Vietnamese infected with the subtype A/E virus.

RESULTS

We identified HLA-C*15:05-restricted SL9 epitope including Pol 653/657. PolS653A/T/L mutations within this epitope critically impaired the T-cell recognition of HIV-1-infected cells, indicating that these mutations had escaped from the T cells. T-cell responders infected with these mutants showed significantly lower CD4 T-cell counts than those with the wild-type virus or Pol S653K/Q mutants, which are not associated with HLA-C*15:05.

CONCLUSION

The accumulation of Pol S653A/T/L escape mutants critically affected the control of HIV-1 by SL9-specific T cells and led to a poor clinical outcome in the subtype A/E-infected individuals having the detrimental HLA-C*15:05 allele.

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.

Specificity of CD8+ T-Cell Responses Following Vaccination with Conserved Regions of HIV-1 in Nairobi, Kenya

Sub-Saharan Africa carries the biggest burden of the human immunodeficiency virus type 1 (HIV-1)/AIDS epidemic and is in an urgent need of an effective vaccine. CD8+ T cells are an important component of the host immune response to HIV-1 and may need to be harnessed if a vaccine is to be effective. CD8+ T cells recognize human leukocyte antigen (HLA)-associated viral epitopes and the HLA alleles vary significantly among different ethnic groups. It follows that definition of HIV-1-derived peptides recognized by CD8+ T cells in the geographically relevant regions will critically guide vaccine development. Here, we study fine details of CD8+ T-cell responses elicited in HIV-1/2-uninfected individuals in Nairobi, Kenya, who received a candidate vaccine delivering conserved regions of HIV-1 proteins called HIVconsv. Using 10-day cell lines established by in vitro peptide restimulation of cryopreserved PBMC and stably HLA-transfected 721.221/C1R cell lines, we confirm experimentally many already defined epitopes, for a number of epitopes we define the restricting HLA molecule(s) and describe four novel HLA-epitope pairs. We also identify specific dominance patterns, a promiscuous T-cell epitope and a rescue of suboptimal T-cell epitope induction in vivo by its functional variant, which all together inform vaccine design.

Contribution of proteasome-catalyzed peptide cis-splicing to viral targeting by CD8+ T cells in HIV-1 infection

Peptides generated by proteasome-catalyzed splicing of noncontiguous amino acid sequences have been shown to constitute a source of nontemplated human leukocyte antigen class I (HLA-I) epitopes, but their role in pathogen-specific immunity remains unknown. CD8+ T cells are key mediators of HIV type 1 (HIV-1) control, and identification of novel epitopes to enhance targeting of infected cells is a priority for prophylactic and therapeutic strategies. To explore the contribution of proteasome-catalyzed peptide splicing (PCPS) to HIV-1 epitope generation, we developed a broadly applicable mass spectrometry-based discovery workflow that we employed to identify spliced HLA-I-bound peptides on HIV-infected cells. We demonstrate that HIV-1-derived spliced peptides comprise a relatively minor component of the HLA-I-bound viral immunopeptidome. Although spliced HIV-1 peptides may elicit CD8+ T cell responses relatively infrequently during infection, CD8+ T cells primed by partially overlapping contiguous epitopes in HIV-infected individuals were able to cross-recognize spliced viral peptides, suggesting a potential role for PCPS in restricting HIV-1 escape pathways. Vaccine-mediated priming of responses to spliced HIV-1 epitopes could thus provide a novel means of exploiting epitope targets typically underutilized during natural infection.

Identification of novel HIV-1-derived HLA-E-binding peptides

Non-classical class Ib MHC-E molecule is becoming an increasingly interesting component of the immune response. It is involved in both the adaptive and innate immune responses to several chronic infections including HIV-1 and, under very specific circumstances, likely mediated a unique vaccine protection of rhesus macaques against pathogenic SIV challenge. Despite being recently in the spotlight for HIV-1 vaccine development, to date there is only one reported human leukocyte antigen (HLA)-E-binding peptide derived from HIV-1. In an effort to help start understanding the possible functions of HLA-E in HIV-1 infection, we determined novel HLA-E binding peptides derived from HIV-1 Gag, Pol and Vif proteins. These peptides were identified in three independent assays, all quantifying cell-surface stabilization of HLA-E*01:01 or HLA-E*01:03 molecules upon peptide binding, which was detected by HLA-E-specific monoclonal antibody and flow cytometry. Thus, following initial screen of over 400 HIV-1-derived 15-mer peptides, 4 novel 9-mer peptides PM9, RL9, RV9 and TP9 derived from 15-mer binders specifically stabilized surface expression of HLA-E*01:03 on the cell surface in two separate assays and 5 other binding candidates EI9, MD9, NR9, QF9 and YG9 gave a binding signal in only one of the two assays, but not both. Overall, we have expanded the current knowledge of HIV-1-derived target peptides stabilizing HLA-E cell-surface expression from 1 to 5, thus broadening inroads for future studies. This is a small, but significant contribution towards studying the fine mechanisms behind HLA-E actions and their possible use in development of a new kind of vaccines.

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.

CD8+ T cells specific for conserved, cross-reactive Gag epitopes with strong ability to suppress HIV-1 replication

BACKGROUND

Development of AIDS vaccines for effective prevention of circulating HIV-1 is required, but no trial has demonstrated definitive effects on the prevention. Several recent T-cell vaccine trials showed no protection against HIV-1 acquisition although the vaccines induced HIV-1-specific T-cell responses, suggesting that the vaccine-induced T cells have insufficient capacities to suppress HIV-1 replication and/or cross-recognize circulating HIV-1. Therefore, it is necessary to develop T-cell vaccines that elicit T cells recognizing shared protective epitopes with strong ability to suppress HIV-1. We recently designed T-cell mosaic vaccine immunogens tHIVconsvX composed of 6 conserved Gag and Pol regions and demonstrated that the T-cell responses to peptides derived from the vaccine immunogens were significantly associated with lower plasma viral load (pVL) and higher CD4⁺ T-cell count (CD4 count) in HIV-1-infected, treatment-naive Japanese individuals. However, it remains unknown T cells of which specificities have the ability to suppress HIV-1 replication. In the present study, we sought to identify more T cells specific for protective Gag epitopes in the vaccine immunogens, and analyze their abilities to suppress HIV-1 replication and recognize epitope variants in circulating HIV-1.

RESULTS

We determined 17 optimal Gag epitopes and their HLA restriction, and found that T-cell responses to 9 were associated significantly with lower pVL and/or higher CD4 count. T-cells recognizing 5 of these Gag peptides remained associated with good clinical outcome in 221 HIV-1-infected individuals even when comparing responders and non-responders with the same restricting HLA alleles. Although it was known previously that T cells specific for 3 of these protective epitopes had strong abilities to suppress HIV-1 replication in vivo, here we demonstrated equivalent abilities for the 2 novel epitopes. Furthermore, T cells against all 5 Gag epitopes cross-recognized variants in majority of circulating HIV-1.

CONCLUSIONS

We demonstrated that T cells specific for 5 Gag conserved epitopes in the tHIVconsvX have ability to suppress replication of circulating HIV-1 in HIV-1-infected individuals. Therefore, the tHIVconsvX vaccines have the right specificity to contribute to prevention of HIV-1 infection and eradication of latently infected cells following HIV-1 reactivation.

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.

Novel Conserved-region T-cell Mosaic Vaccine With High Global HIV-1 Coverage Is Recognized by Protective Responses in Untreated Infection

An effective human immunodeficiency virus type 1 (HIV-1) vaccine is the best solution for halting the acquired immune deficiency syndrome epidemic. Here, we describe the design and preclinical immunogenicity of T-cell vaccine expressing novel immunogens tHIVconsvX, vectored by DNA, simian (chimpanzee) adenovirus, and poxvirus modified vaccinia virus Ankara (MVA), a combination highly immunogenic in humans. The tHIVconsvX immunogens combine the three leading strategies for elicitation of effective CD8(+) T cells: use of regions of HIV-1 proteins functionally conserved across all M group viruses (to make HIV-1 escape costly on viral fitness), inclusion of bivalent complementary mosaic immunogens (to maximize global epitope matching and breadth of responses, and block common escape paths), and inclusion of epitopes known to be associated with low viral load in infected untreated people (to induce field-proven protective responses). tHIVconsvX was highly immunogenic in two strains of mice. Furthermore, the magnitude and breadth of CD8(+) T-cell responses to tHIVconsvX-derived peptides in treatment-naive HIV-1(+) patients significantly correlated with high CD4(+) T-cell count and low viral load. Overall, the tHIVconsvX design, combining the mosaic and conserved-region approaches, provides an indisputably better coverage of global HIV-1 variants than previous T-cell vaccines. These immunogens delivered in a highly immunogenic framework of adenovirus prime and MVA boost are ready for clinical development.

Raltegravir and elvitegravir-resistance mutation E92Q affects HLA-B*40:02-restricted HIV-1-specific CTL recognition

Interplay between drug-resistance mutations in CTL epitopes and HIV-1-specific CTLs may influence the control of HIV-1 viremia. However, the effect of integrase inhibitor (INI)-resistance mutations on the CTL recognition has not been reported. We here investigated the effect of a raltegravir and elvitegravir-resistance mutation (E92Q) on HLA-B*40:02-restricted Int92-102 (EL11: ETGQETAYFLL)-specific CTLs. EL11-specific CTLs recognized E92Q peptide-pulsed and E92Q mutant virus-infected cells less effectively than EL11 peptide-pulsed and wild-type virus-infected cells, respectively. Ex vivo ELISpot analysis showed no induction of E92Q-specific T cells in chronically HIV-1-infected individuals. Thus, we demonstrated that EL11-specific CTL recognition was affected by the INI-resistance mutation.

Recurrent peritoneal inclusion cysts successfully treated with oral contraceptives: a report of two cases

OBJECTIVE

To examine whether conservative treatment with oral contraceptives is effective in the shrinkage of a peritoneal inclusion cyst (PIC). This is a case report of two patients with a PIC that developed after gynecological surgery.

CASES

Both cases were suspected of a PIC based on the medical history, laboratory data, and image findings. It was difficult in differentiate a PIC from an ovarian tumor. Surgery was chosen at first. However, PICs in both cases recurred after surgery and were treated with oral contraceptives as a conservative treatment. PICs shrank after the treatment of oral contraceptives in both cases.

CONCLUSION

Due to the high rate of recurrence following surgery, conservative treatment is recommended to treat PICs. Hormone therapy using oral contraceptives seems to have some therapeutic benefit for the PICs.

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.

Heterotopic pregnancy diagnosed before the onset of severe symptoms: case report

BACKGROUND

A heterotopic pregnancy (HP) is an extremely rare disease that represents the simultaneous occurrence of two or more implantation sites in the uterus and extrauterus. Early diagnosis of HP is difficult because of the presence of an intrauterine pregnancy (IUP). In most cases, a precise diagnosis was made after symptoms develop through the rupture or bleeding of the ectopic pregnancy (EP). The authors present a case that was successfully diagnosed as an undemonstrative HP.

CASE

A 24-year-old multiparous woman became pregnant after taking clomiphene citrate. At ten weeks of pregnancy, an ultrasonography revealed gestational sacs containing fetuses in the uterus and the right adnexal region, respectively. The patient was diagnosed as having a HP and an emergency right tubal resectomy was performed. The IUP progressed normally and the fetus was delivered at 37 weeks of pregnancy.

DISCUSSION

Even if a gestational sac can be confirmed in the uterus, a careful ultrasonographic examination should always be considered to determine the presence of a concurrent extrauterine pregnancy.

CTL recognition of HIV-1-infected cells via cross-recognition of multiple overlapping peptides from a single 11-mer Pol sequence

It is known that overlapping HIV-1 peptides of different lengths can be presented by a given HLA class I molecule. However, the role of those peptides in CD8(+) T cells recognition of HIV-1-infected cells remains unclear. Here we investigated the recognition of overlapping 8-mer to 11-mer peptides of Pol 155-165 by HLA-B*54:01-restricted CD8(+) T cells. The analysis of ex vivo T cells using ELISPOT and tetramer binding assays showed that there were different patterns of CD8(+) T-cell responses to these peptides among chronically HIV-1-infected HLA-B*54:01(+) individuals, though the response to the 9-mer peptide was the strongest among them. CD8(+) T-cell clones with TCRs specific for the 9-mer, 10-mer, and/or 11-mer peptides effectively killed HIV-1-infected cells. Together, these results suggest that the 9-mer and 10-mer peptides could be predominantly presented by HLA-B*54:01, though it remains possible that the 11-mer peptide was also presented by this HLA allele. The present study demonstrates effective CD8(+) T-cell recognition of HIV-1-infected cells via presentation of multiple overlapping HIV-1 peptides and cross-recognition by the CD8(+) T cells.

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.

Molecular phylogeny and diversity of Myanmar and Bhutan mithun based on mtDNA sequences

The mithun (Bos frontalis), synonymous with mithan and gayal, is considered to be a domesticated form of gaur (B. gaurus). However, there has been a controversy concerning its origin. In an effort to address this issue, the mitochondrial cytochrome b (cytb) genes of 20 mithun from Myanmar and 13 from Bhutan were sequenced to trace its maternal origin. Seven cytb haplotypes were found in the 33 mithun, and the phylogenetic tree for these haplotypes clearly showed three embranchments involving five gaur types, a B. indicus type, and a B. taurus type. Sixteen Myanmar and 12 Bhutan mithun had gaur haplotypes, while a B. indicus haplotype was found in three Myanmar and one Bhutan mithun. The B. taurus haplotype was detected in a single Myanmar animal. These results demonstrated that the principal maternal origin of mithun was gaur and suggested that it was directly domesticated from gaur. However, some introgression of domestic cattle existed in current mithun populations. The presence of cattle mtDNA raised the question of how many cattle nuclear genes might have been integrated into the gene pool of mithun.

Identification and characterization of 2 HIV-1 Gag immunodominant epitopes restricted by Asian HLA allele HLA-B*4801

HLA-B*4801 is frequently found in Asian populations but rarely in Caucasian or African populations. Although HLA-B*4801-restricted human immunodeficiency virus-1 (HIV-1) epitopes would be useful for acquired immune deficiency syndrome (AIDS) vaccine development in Asia, they have not been reported so far. In the present study, we sought to identify HLA-B*4801-restricted HIV-1 epitopes by using 17-mer overlapping peptides derived from HIV-1 Gag, Pol, and Nef as well as 8- to 11-mer truncated peptides, and thereby identified two HLA-B*4801-restricted Gag epitopes. These epitope-specific CD8(+) T cells strongly responded to HIV-1-infected cells expressing HLA-B*4801, confirming that these Gag epitopes were endogenously presented by HLA-B*4801. These epitope-specific CD8(+) T cells were elicited in five of the seven tested chronically HIV-1-infected individuals with HLA-B*4801, suggesting them to be immunodominant epitopes. These epitopes will be useful for the studies of AIDS immunopathogenesis and the development of an HIV-1 vaccine in Asia.

Effect of shape of sodium salicylate particles on physical property and in vitro aerosol performance of granules prepared by pressure swing granulation method

The purpose of this research was to investigate the effect of the shape of sodium salicylate (SS) particles on the physical properties as well as the in vitro aerosol performance of the granules granulated by the pressure swing granulation method. SS was pulverized with a jet mill (JM) to prepare the distorted particles, and SS aqueous solution was spray dried (SD) to prepare the nearly spherical particles. The particle size distribution, crushing strength, and pore size distribution of the granules were measured. The adhesive force of the primary particles in the granules was calculated according to Rumpf's equation. The in vitro aerosol performance of the granules was evaluated using a cascade impactor. Both JM and SD particles can be spherically granulated by the pressure swing granulation method without the use of a binder. The size of SD granules was smaller than that of JM granules. Although the crushing strength of the JM and SD granules is almost the same, the internal structures of JM granules and SD granules were found to differ, and the SD particles appear to have been condensed uniformly, resulting in a nearly spherical shape. In the inhalation investigation, the percentage of SS particles of appropriate size delivered to the region for treatment was noticeably higher for SD granules than for JM granules. This finding might be because the adhesive force of the SD primary particles was smaller than that of the JM primary particles in the granules and because the SD granules could be easily separated by air current to obtain the primary particles.

Effects of the levonorgestrel-releasing intrauterine system on proliferation and apoptosis in the endometrium

BACKGROUND

The levonorgestrel-releasing intrauterine system (LNg-IUS) has been shown to be effective in the management of menorrhagia. In order to evaluate the effects of LNg-IUS on endometrial proliferation and apoptosis, proliferating cell nuclear antigen (PCNA) expression, apoptosis, Fas and Bcl-2 protein expression in the endometrium were determined at the early proliferative phase of the menstrual cycle before and 3 months after LNg-IUS insertion.

METHODS

PCNA, Fas and Bcl-2 protein expression were analysed using an avidin-biotin immunoperoxidase method. Apoptosis was assessed by the terminal deoxynucleotidyl transferase-mediated deoxy-UTP nick-end labelling (TUNEL) method.

RESULTS

PCNA, immunolocalized both in the nuclei of endometrial glands and stroma was less abundant 3 months after insertion (P < 0.05). Bcl-2 protein, immunolocalized in the cytoplasm of endometrial glands but not in the stroma, became scanty 3 months after insertion. Fas antigen, immunolocalized only in endometrial glands before insertion, became prominent in both endometrial glands and stroma 3 months after insertion. The apoptosis-positive rate of the nuclei in both endometrial glands and stroma was significantly higher 3 months after insertion relative to that before insertion (P < 0.05).

CONCLUSIONS

LNg-IUS resulted in a decrease in endometrial proliferation and an increase in apoptosis in endometrial glands and stroma. The increase in apoptosis associated with increased Fas antigen expression and decreased Bcl-2 protein expression in the endometrium may be one of the underlying molecular mechanisms by which LNg-IUS insertion causes the atrophic change of the endometrium.

Regulation of human trophoblast proliferation and apoptosis during pregnancy

In order to elucidate the regulation of human placental growth during pregnancy, we have assessed PCNA expression, apoptosis and Bcl-2 protein expression in placental trophoblasts over the course of pregnancy. PCNA, Bcl-2 protein and Fas antigen expression were examined by the avidin/biotin immunoperoxidase method, while apoptosis was assessed by in situ DNA 3'-end labeling method. Both PCNA expression and apoptotic DNA fragmentation were noted in cytotrophoblasts (C-cells), being most abundant in very early placenta, less abundant in midterm placenta and least abundant in term placenta. In contrast, Bcl-2 protein expression was noted in syncytiotrophoblasts (S-cells), being least abundant in very early placenta, less abundant in midterm placenta and most abundant in term placenta. These results indicate that very early placenta is characterized by highly proliferative activity of C-cells associated with increased occurrence of apoptosis. Since Bcl-2 protein is an apoptosis-inhibiting gene product, the minimal occurrence of apoptosis in term placenta seems likely to be attributable to the increased expression of Bcl-2 protein in S-cell in term placenta. On the other hand, in extravillous trophoblasts on cell columns, both PCNA and Bcl-2 protein expression were pronounced only in the shallower part, while Fas/Fas ligand expression and apoptosis were prominent in the deeper part. Thus, it seems likely that Bcl-2 protein expression also participates in the regulation of extravillous trophoblast apoptosis.

Changes in proliferative potential, apoptosis and Bcl-2 protein expression in cytotrophoblasts and syncytiotrophoblast in human placenta over the course of pregnancy

In order to evaluate placental trophoblast proliferation and apoptosis during pregnancy, we investigated proliferating cell nuclear antigen (PCNA) expression, apoptosis and Bcl-2 protein expression in the human placenta using avidin/biotin immunoperoxidase method to examine PCNA and Bcl-2 protein expression, and TUNEL method to assess apoptosis. The appearance of apoptotic cells in very early term placental trophoblasts was also examined by transmission electron microscopy. PCNA was immunolocalized in the nuclei of cytotrophoblasts (C-cells). Determination of the mean percentage of PCNA-positive nuclei of C-cells revealed that PCNA expression in C-cells was highest in very early term (4th to 5th wk) placentas and significantly decreased with the advance of pregnancy. Bcl-2 protein was immunolocalized in the cytoplasm of syncytiotrophoblast (S-cell), being least abundant in very early term placentas, less abundant in early term and midterm placentas, and most abundant in term placentas. On the basis of TUNEL method, apoptosis was apparent in the nuclei of both C-cells and S-cell. The apoptosis positive rate of C-cell nuclei was highest in very early term 4th to 5th wk placentas, and significantly decreased in early term 7th to 9th wk and midterm placentas, but somewhat increased in term placentas compared to that in midterm placentas. On the other hand, apoptosis positive rate of S-cell nuclei was remarkably higher only in very early term 4th to 5th wk placentas compared to that in early term, midterm and term placentas. Transmission electron microscopy revealed the appearance of apoptotic nucleus in very early term placental trophoblasts. These results demonstrate for the first time that apoptosis in the human normal placenta predominates in both C-cells and S-cell in very early term 4th to 5th wk pregnancy and drastically diminished after 7th wk of pregnancy. An apparent increase in apoptosis in C-cells in term placentas compared to that in midterm placentas may reflect aging of the placenta or parturition-associated biological change. The abundant expression of Bcl-2 protein in S-cell in term placentas may be responsible for the diminished occurrence of apoptosis in S-cell in term placentas.

Identification of the Kv2.1 K+ channel as a major component of the delayed rectifier K+ current in rat hippocampal neurons

Molecular cloning studies have revealed the existence of a large family of voltage-gated K+ channel genes expressed in mammalian brain. This molecular diversity underlies the vast repertoire of neuronal K+ channels that regulate action potential conduction and neurotransmitter release and that are essential to the control of neuronal excitability. However, the specific contribution of individual K+ channel gene products to these neuronal K+ currents is poorly understood. We have shown previously, using an antibody, "KC, " specific for the Kv2.1 K+ channel alpha-subunit, the high-level expression of Kv2.1 protein in hippocampal neurons in situ and in culture. Here we show that KC is a potent blocker of K+ currents expressed in cells transfected with the Kv2.1 cDNA, but not of currents expressed in cells transfected with other highly related K+ channel alpha-subunit cDNAs. KC also blocks the majority of the slowly inactivating outward current in cultured hippocampal neurons, although antibodies to two other K+ channel alpha-subunits known to be expressed in these cells did not exhibit blocking effects. In all cases the blocking effects of KC were eliminated by previous incubation with a recombinant fusion protein containing the KC antigenic sequence. Together these studies show that Kv2.1, which is expressed at high levels in most mammalian central neurons, is a major contributor to the delayed rectifier K+ current in hippocampal neurons and that the KC antibody is a powerful tool for the elucidation of the role of the Kv2.1 K+ channel in regulating neuronal excitability.

Morphological variations in transplanted tumors developed by inoculation of spontaneous mesothelioma cell lines derived from F344 rats

Morphological and immunohistochemical features of the abdominal mesotheliomas that were developed by inoculation of 3 cell lines (MeET-4, -5 and -6) established from spontaneous abdominal mesotheliomas in male F344 rats. Although the original tumors of three cell lines showed signs of epithelioid growth with a predominantly simple papillary pattern, transplanted tumors revealed a variety of morphologic features including epithelioid with glandular structures, sarcomatous, and a mixture of these components. All tumor cells of transplanted tumors were positive for alpha-smooth muscle actin (ASMA) but almost negative for desmin as were epithelioid cells of the original tumors, and the cell lines were positive for desmin but not for ASMA. These results suggested that mesothelioma in the F344 rat had the potential for wide spectrum differentiation under in vitro conditions. The microenvironmental factors obtained in vivo can modify their potential ability and their morphological aspects. These factors may be related to tumor cell reexpression of ASMA of tumor cells that were masked under in vitro culture conditions.

Phosphorylation of the Kv2.1 K+ channel alters voltage-dependent activation

The voltage-gated delayed-rectifier-type K+ channel Kv2.1 is expressed in high-density clusters on the soma and proximal dendrites of mammalian central neurons; thus, dynamic regulation of Kv2.1 would be predicted to have an impact on dendritic excitability. Rat brain Kv2.1 polypeptides are phosphorylated extensively, leading to a dramatically increased molecular mass on sodium dodecyl sulfate gels. Phosphoamino acid analysis of Kv2.1 expressed in transfected cells and labeled in vivo with 32P shows that phosphorylation was restricted to serine residues and that a truncation mutant, DeltaC318, which lacks the last 318 amino acids in the cytoplasmic carboxyl terminus, was phosphorylated to a much lesser degree than was wild-type Kv2.1. Whole-cell patch-clamp studies showed that the voltage-dependence of activation of DeltaC318 was shifted to more negative membrane potentials than Kv2.1 without differences in macroscopic kinetics; however, the differences in the voltage-dependence of activation between Kv2.1 and DeltaC318 were eliminated by in vivo intracellular application of alkaline phosphatase, suggesting that these differences were due to differential phosphorylation. Similar analyses of other truncation and point mutants indicated that the phosphorylation sites responsible for the observed differences in voltage-dependent activation lie between amino acids 667 and 853 near the distal end of the Kv2.1 carboxyl terminus. Together, these parallel biochemical and electrophysiological results provide direct evidence that the voltage-dependent activation of the delayed-rectifier K+ channel Kv2. 1 can be modulated by direct phosphorylation of the channel protein; such modulation of Kv2.1 could dynamically regulate dendritic excitability.

Identification of a cytoplasmic domain important in the polarized expression and clustering of the Kv2.1 K+ channel

The voltage-sensitive K+ channel Kv2.1 has a polarized and clustered distribution in neurons. To investigate the basis for this localization, we expressed wild-type Kv2.1 and two COOH-terminal truncation mutants, delta C318 and delta C187, in polarized epithelial MDCK cells. These functional channel proteins had differing subcellular localization, in that while both wild-type Kv2.1 and delta C187 localized to the lateral membrane in high density clusters, delta C318 was expressed uniformly on both apical and lateral membranes. A chimeric protein containing the hemagglutinin protein from influenza virus and the region of Kv2.1 that differentiates the two truncation mutants (amino acids 536-666) was also expressed in MDCK cells, where it was found in high density clusters similar to those observed for Kv2.1. Polarized expression and clustering of Kv2.1 correlates with detergent solubility, suggesting that interaction with the detergent insoluble cytoskeleton may be necessary for proper localization of this channel.

Determination of KA values by controlled receptor expression in Xenopus oocytes

1. In the present study we estimated the KA value of endothelin-1 (ET-1) for ETA-receptors by a new method in which the level of expression of ETA-receptors in Xenopus oocytes was altered in a controlled way. 2. Kvl.2 (a delayed rectifier type K channel) c RNA at the fixed concentration of 0.2 micro g micro l(-1) was mixed with ETA-receptor cRNA at various concentration ratios (10(-3)-3). Oocytes were examined 2-4 days after the injection of the cRNA mixtures. 3. In these oocytes, ET-1 suppressed the amplitude of Kvl.2 current in a dose-dependent manner in the range of 0.1-100 nM; the maximum inhibition produced by ET-1 was larger and the EC50 value for the inhibition by ET-1 was smaller as the mixture ratio was increased. Double-reciprocal plots of equiactive concentrations of ET-1 in 1/1- and 1/30-injected oocytes yielded a KA for ET-1 of 7.4 nM. The number of ETA-receptors in 1/30-injected oocytes was 13% of that in 1/1-injected oocytes, whereas the inhibition of the current in 1/30-injected oocytes was about 60% of that in 1/1-injected oocytes. This suggests the presence of spare receptors of ETA in the latter. 4. A saturation binding experiment estimated a KD value of 0.1 nM for ET-1 at ETA-receptors and the number of ETA-receptors in 1/30-injected oocytes was 23% of that in 1/1-injected ones. This value was not significantly different from that estimated by the above new method. However, there was a discrepancy between KA and KD, which could be due to factors unique to the expression system employed in the present study.

Characterization of four monosialo and a novel disialo Asn N-glycosides from the urine of a patient with aspartylglycosaminuria

We previously reported for the first time two Japanese patients with aspartylglycosaminuria (AGU). A novel disialo Asn N-glycoside (AG-5) has been isolated from the urine of one of the patients in addition to four known monosialo Asn N-glycosides (AG-1 to AG-4) by gel filtration and anion exchange chromatography in this study. Final purification of AG-5 was achieved by an electrochemical chromatographic method, high performance liquid chromatography with pulsed amperometric detector (HPLC-PAD). The yield of AG-5 was approximately 1 mg l-1 urine. The chemical structures of AG-1 to AG-5 were characterized by gas-liquid chromatography, a permethylation study, fast atom bombardment-mass spectrometry (FAB-MS), and nuclear magnetic resonance (NMR). Based on the structural analysis, AG-5 had the following novel structure: NeuAc alpha 2-->8NeuAc alpha 2-->3Gal beta 1-->4GlcNAc beta 1-->Asn.

Hybrid potassium channels by tandem linkage of inactivating and non-inactivating subunits

We constructed tandem cDNA by linking the 5' end of a delayed rectifier-type (Kv1.2) clone to the 3' end of a transient-type (Kv1.4) K+ channel clone. Fusion genes were also constructed, consisting of Kv1.4 and mutants of Kv1.2, which have a single amino acid substitution in the S4-S5 loop. From electrophysiological characterization, it is likely that two pairs of tandem heterodimer constructs can form hybrid channels. In addition, it has been revealed that the wild-type hybrid channel shows a time constant of inactivation very similar to that observed in the homotetrameric Kv1.4 channel. Difference of inactivation kinetics between wild-type and mutant hybrid K+ channels suggests that not only the S4-S5 loop of Kv1.4 but also that of Kv1.2 can serve as the acceptor sites for the inactivation gates, and that all of four sets of loops should be functional for rapid inactivation. From these results, in the hybrid channels the structure and composition of the acceptor sites could be important factors for determining the rate of inactivation.

Receptor-mediated modulation of rat KV1.2 in Xenopus oocytes

To investigate mechanisms for the receptor-mediated inhibition of a rat cardiac K+ channel clone (KV1.2), we coexpressed KV1.2 with a subtype of endothelin receptors (ETA) in Xenopus oocytes. Effects of endothelin ETA receptor stimulation were mimicked by application of PMA (4-beta-phorbol 12-myristate 13-acetate; 0.1 microM) or intracellular injection of CaCl2 (estimated concentration of 1 microM). These effects diminished in the presence of staurosporine (1 microM) or EGTA (estimated concentration of 5 mM). These results suggest that both activation of protein kinase C and an increase in intracellular Ca2+ contribute to the suppression.

Cloning and modulation by endothelin-1 of rat cardiac K channel

We have cloned a delayed rectifier type K channel from rat heart (RH1). RH1 was identical to the rat brain K channel BK2 and differed from recently cloned rat cardiac K channel RAK by one amino acid residue. Endothelin receptors(ETRs)-mediated modulation of RH1 current (IRH1) was studied using Xenopus oocyte expression system. Activation of two different subtypes of ETRs by endothelin-1 equally suppressed the amplitude of IRH1. Stimulation of phosphatidylinositol turnover will probably be responsible for the suppression.

[A personal computer system for observation and analysis of copulatory behavior in small rodents]

A personal computer system was developed for measuring values of copulatory behavior of small laboratory rodents. This system enabled us to get the analysis data of copulatory behavior of male rats as soon as possible after observation. This present system could be useful to measure other reproductive behavior of small rodents.