Attention for sex in COVID-19 trials: a review of regulatory dossiers.

An under-representation of women and a lack of sex-specific analyses in COVID-19 trials has been suggested. However, the higher number of men than women who are severely affected by COVID-19 and the restricted information in scientific publications may have biased these suggestions. Therefore, we evaluated sex proportionality and sex-specific efficacy and safety data in trials of COVID-19 treatments and vaccines using both publicly available regulatory documents and confidential documents used by regulators in their review of medicinal products. Included were two treatments (ie, remdesivir and dexamethasone) and four vaccines (ie, BNT162b2 mRNA (BioNTech/Pfizer), mRNA-1273 (Moderna), ChAdOx1-S (AstraZeneca) and Ad26.COV2-S (Janssen)) that received marketing authorisation by the European Commission at the time of the study conduct. An under-representation of women was shown in three of the nine data sets for one treatment (ie, remdesivir), but the proportion of women included was representative in each of the data sets for the other five products. This indicates that there is no structural under-representation of women in the COVID-19 trials. Currently, sex-specific efficacy data are available for five of the six assessed products and sex-specific safety data are available for half of the products only. It is important that this information will also be made available for the other products. There are only small differences in efficacy and safety between men and women which are likely to be of limited clinical relevance. Sex-specific efficacy information can generally be found in the publicly available regulatory documents other than the Summary of Product Characteristics, for which more awareness might be required.

Protective HLA Alleles Recruit Biased and Largely Similar Antigen-Specific T Cell Repertoires across Different Outcomes in HIV Infection.

CD8+ T cells play an important role in the control of untreated HIV infection. Several studies have suggested a decisive role of TCRs involved in anti-HIV immunity. HLA-B*27 and B*57 are often associated with a delayed HIV disease progression, but the exact correlates that provide superior immunity against HIV are not known. To investigate if the T cell repertoire underlies the protective effect in disease outcome in HLA-B*27 and B*57+ individuals, we analyzed Ag-specific TCR profiles from progressors (n = 13) and slow progressors (n = 11) expressing either B*27 or B*57. Our data showed no differences in TCR diversity between progressors and slow progressors. Both alleles recruit biased T cell repertoires (i.e., TCR populations skewed toward specific TRBV families or CDR3 regions). This bias was unrelated to disease progression and was remarkably profound for HLA-B*57, in which TRBV family usage and CDR3 sequences were shared to some extent even between epitopes. Conclusively, these data suggest that the T cell repertoires recruited by protective HLA alleles are highly similar between progressors and slow progressors in terms of TCR diversity, TCR usage, and cross-reactivity.

Immune activation correlates with and predicts CXCR4 co-receptor tropism switch in HIV-1 infection.

HIV-1 cell entry is mediated by binding to the CD4-receptor and chemokine co-receptors CCR5 (R5) or CXCR4 (X4). R5-tropic viruses are predominantly detected during early infection. A switch to X4-tropism often occurs during the course of infection. X4-tropism switching is strongly associated with accelerated disease progression and jeopardizes CCR5-based HIV-1 cure strategies. It is unclear whether host immunological factors play a causative role in tropism switching. We investigated the relationship between immunological factors and X4-tropism in a cross-sectional study in HIV-1 subtype C (HIV-1C)-infected patients and in a longitudinal HIV-1 subtype B (HIV-1B) seroconverter cohort. Principal component analysis identified a cluster of immunological markers (%HLA-DR+ CD4+ T-cells, %CD38+HLA-DR+ CD4+ T-cells, %CD38+HLA-DR+ CD8+ T-cells, %CD70+ CD4+ T-cells, %CD169+ monocytes, and absolute CD4+ T-cell count) in HIV-1C patients that was independently associated with X4-tropism (aOR 1.044, 95% CI 1.003-1.087, p = 0.0392). Analysis of individual cluster contributors revealed strong correlations of two markers of T-cell activation (%HLA-DR+ CD4+ T-cells, %HLA-DR+CD38+ CD4+ T-cells) with X4-tropism, both in HIV-1C patients (p = 0.01;p = 0.03) and HIV-1B patients (p = 0.0003;p = 0.0001). Follow-up data from HIV-1B patients subsequently revealed that T-cell activation precedes and independently predicts X4-tropism switching (aHR 1.186, 95% CI 1.065-1.321, p = 0.002), providing novel insights into HIV-1 pathogenesis and CCR5-based curative strategies.

Rapid reconstitution of CD4 T cells and NK cells protects against CMV-reactivation after allogeneic stem cell transplantation.

BACKGROUND: Epstein-Barr virus and Cytomegalovirus reactivations frequently occur after allogeneic stem cell transplantation (SCT). METHODS: Here we investigated the role of immune cell reconstitution in the onset and subsequent severity of EBV- and CMV-reactivation. To this end, 116 patients were prospectively sampled for absolute T cell (CD4 and CD8), B-cell (CD19) and NK-cell (CD16 and CD56) numbers weekly post-SCT during the first 3 months and thereafter monthly until 6 months post-SCT. Viral load was monitored in parallel. RESULTS: In contrast to the general belief, we found that early T-cell reconstitution does not play a role in the onset of viral reactivation. CMV reactivation in the first 7 weeks after SCT however resulted in higher absolute CD8(+) T-cell numbers 6 months post-SCT in patients with high-level reactivation, many of which were CMV-specific. Interestingly, rapid reconstitution of CD4(+) T-cells, as well as NK cells and the presence of donor KIR3DL1, are associated with the absence of CMV-reactivation after SCT, suggestive of a protective role of these cells. In contrast, EBV-reactivations were not affected in any way by the level of immune reconstitution after SCT. CONCLUSION: In conclusion, these data suggest that CD4(+) T-cells and NK cells, rather than CD8(+) T-cells, are associated with protection against CMV-reactivation.

The presence of protective cytotoxic T lymphocytes does not correlate with shorter lifespans of productively infected cells in HIV-1 infection.

OBJECTIVES AND DESIGN: CD8+ cytotoxic T lymphocytes (CTL) are important in the control of HIV infection. Although CTL are thought to reduce the lifespan of productively infected cells, CD8+ T-cell depletion in simian immunodeficiency virus-infected rhesus-macaques showed no effect on the lifespan of productively infected cells. As CD8+ T-cell responses that successfully delay HIV disease progression occur only in a minority of HIV-infected individuals, we studied the hypothesis that the ability of CTL to reduce the lifespan of productively infected cells is limited to protective CTL responses only. METHODS: We correlated features of CD8+ T cells that are associated with control of HIV infection, namely restriction by protective human leukocyte antigen (HLA) alleles, and/or a broad, high or poly-functional Gag-specific CD8+ T-cell response, to the lifespan of productively infected cells in 36 HIV-infected individuals, by measuring their plasma viral load declines immediately after start of combined antiretroviral therapy. RESULTS: The average lifespan of productively HIV-infected cells varied greatly between individuals, from 1.01 to 3.68 days (median 1.82 days) but was not different between individuals with or without the protective HLA molecules B27 or B57 (P=0.76, median 1.94 and 1.79 days, respectively). Although the CD8+ T-cell response against HIV Gag was the dominant HIV-specific T-cell response, its magnitude (r=0.02, P = 0.5), breadth (r = 0.03, P = 0.4), and poly-functionality (r = 0.01, P = 0.8), did not correlate with the lifespan of productively HIV-infected cells. CONCLUSION: The features of CD8+ T-cell responses that have clearly been associated with control of HIV infection do not correlate with a reduced lifespan of productively infected cells in vivo. This suggests that protective CD8+ T cells exert their effect on target-cells before onset of productive infection, or via noncytolytic mechanisms.

Measles Virus Epitope Presentation by HLA: Novel Insights into Epitope Selection, Dominance, and Microvariation.

Immunity to infections with measles virus (MV) can involve vigorous human leukocyte antigen (HLA) class I-restricted CD8(+) cytotoxic T cell (CTL) responses. MV, albeit regarded monotypic, is known to undergo molecular evolution across its RNA genome. To address which regions of the MV proteome are eligible for recognition by CD8(+) CTLs and how different HLA class I loci contribute to the epitope display, we interrogated the naturally processed and presented MV peptidome extracted from cell lines expressing in total a broad panel of 16 different common HLA-A, -B, and -C molecules. The repertoire and abundance of MV peptides were bona fide identified by nanoHPLC-MS/MS. -Eighty-nine MV peptides were discovered and assignment to an HLA-A, -B, or -C allele, based on HLA-peptide affinity prediction, was in most cases successful. Length variation and presentation by multiple HLA class I molecules was common in the MV peptidome. More than twice as many unique MV epitopes were found to be restricted by HLA-B than by HLA-A, while MV peptides with supra-abundant expression rates (>5,000 cc) were rather associated with HLA-A and HLA-C. In total, 59 regions across the whole MV proteome were identified as targeted by HLA class I. Sequence coverage by epitopes was highest for internal proteins transcribed from the MV-P/V/C and -M genes and for hemagglutinin. At the genome level, the majority of the HLA class I-selected MV epitopes represented codons having a higher non-synonymous mutation rate than silent mutation rate, as established by comparison of a set of 58 unique full length MV genomes. Interestingly, more molecular variation was seen for the epitopes expressed at rates ≥1,000 cc. These data for the first time indicate that HLA class I broadly samples the MV proteome and that CTL pressure may contribute to the genomic evolution of MV.

Comprehensive Analysis of the Naturally Processed Peptide Repertoire: Differences between HLA-A and B in the Immunopeptidome.

The cytotoxic T cell (CTL) response is determined by the peptide repertoire presented by the HLA class I molecules of an individual. We performed an in-depth analysis of the peptide repertoire presented by a broad panel of common HLA class I molecules on four B lymphoblastoid cell-lines (BLCL). Peptide elution and mass spectrometry analysis were utilised to investigate the number and abundance of self-peptides. Altogether, 7897 unique self-peptides, derived of 4344 proteins, were eluted. After viral infection, the number of unique self-peptides eluted significantly decreased compared to uninfected cells, paralleled by a decrease in the number of source proteins. In the overall dataset, the total number of unique self-peptides eluted from HLA-B molecules was larger than from HLA-A molecules, and they were derived from a larger number of source proteins. These results in B cells suggest that HLA-B molecules possibly present a more diverse repertoire compared to their HLA-A counterparts, which may contribute to their immunodominance. This study provides a unique data set giving new insights into the complex system of antigen presentation for a broad panel of HLA molecules, many of which were never studied this extensively before.

A lower viral set point but little immunological impact after early treatment during primary HIV infection.

The Primo-SHM trial, a multicenter randomized trial comparing no treatment with 24 or 60 weeks of combination antiretroviral therapy (cART) during primary human immunodeficiency virus (HIV) infection (PHI), recently demonstrated that temporary early cART lowered the viral set point and deferred the need for re-initiation of cART during chronic HIV infection. This study examined whether the beneficial effect of early treatment was caused by preservation of immunological responses. Twenty-seven treated and 20 untreated PHI individuals participating in the Primo-SHM trial were compared at viral set point, that is, 36 weeks after baseline or after treatment interruption, respectively, for a diverse set of immunological parameters. The results show no differences between treated and untreated individuals at the level of effector T-cell formation or replication capacity of the T-cells; regulation of various T, B, natural killer, or dendritic cells; polyfunctionality of the CD8 T-cells; preservation of CD4 T-cells in the gut associated lymphoid tissue; or immune activation. There were subtle differences in the quality of the cytolytic CD4 T-cell response: 11% (median) of CD4 T-cells of the early treated individuals produced the cytolytic molecule perforin compared to 5% in untreated individuals (p=0.046), and treatment caused a modest increase in CD4 T-cells expressing both perforin and granzyme B (median 9% vs. 4% of CD4 T-cells; p=0.045). Early treatment had a modest positive effect on the quality of the CD4 T-cell response. It remains unclear, however, whether these subtle immunological differences were the cause or a result of the lower viral set point in patients who received early treatment.

Complex T-cell receptor repertoire dynamics underlie the CD8+ T-cell response to HIV-1.

UNLABELLED: Although CD8(+) T cells are important for the control of HIV-1 in vivo, the precise correlates of immune efficacy remain unclear. In this study, we conducted a comprehensive analysis of viral sequence variation and T-cell receptor (TCR) repertoire composition across multiple epitope specificities in a group of antiretroviral treatment-naive individuals chronically infected with HIV-1. A negative correlation was detected between changes in antigen-specific TCR repertoire diversity and CD8(+) T-cell response magnitude, reflecting clonotypic expansions and contractions related to alterations in cognate viral epitope sequences. These patterns were independent of the individual, as evidenced by discordant clonotype-specific transitions directed against different epitopes in single subjects. Moreover, long-term asymptomatic HIV-1 infection was characterized by evolution of the TCR repertoire in parallel with viral replication. Collectively, these data suggest a continuous bidirectional process of adaptation between HIV-1 and virus-specific CD8(+) T-cell clonotypes orchestrated at the TCR-antigen interface. IMPORTANCE: We describe a relation between viral epitope mutation, antigen-specific T-cell expansion, and the repertoire of responding clonotypes in chronic HIV-1 infection. This work provides insights into the process of coadaptation between the human immune system and a rapidly evolving lentivirus.

Differential characteristics of cytotoxic T lymphocytes restricted by the protective HLA alleles B*27 and B*57 in HIV-1 infection.

OBJECTIVE: HLA-B*27 and B*57 are associated with relatively slow progression to AIDS. Mechanisms held responsible for this protective effect include the immunodominance and high magnitude, breadth, and affinity of the cytotoxic T lymphocytes (CTL) response restricted by these HLA molecules, as well as superior maintenance of CTL responses during HIV-1 disease progression. DESIGN: We examined CTL responses from HIV-1-infected individuals restricted through protective and nonprotective HLA alleles within the same host, thereby excluding any effects of slow or rapid progression on the CTL response. RESULTS: We found that neither immunodominance, nor high magnitude and breadth, nor affinity of the CTL response are general mechanisms of protection against disease progression. HLA-B*57-restricted CTL responses were of exceptionally high affinity and dominated the HLA-A*02-restricted CTL response in individuals coexpressing these HLA alleles. In contrast, HLA-B*27-restricted CTL responses were not of particularly high affinity and did not dominate the response in individuals coexpressing HLA-B*27 and HLA-A*02. Instead, in individuals expressing HLA-B*27, the CTL response restricted by nonprotective HLA alleles was significantly higher and broader, and of higher affinity than in individuals expressing these alleles without HLA-B*27. Although HLA-B*27 and B*57 are thought to target the most conserved parts of HIV, during disease progression, CTL responses restricted by HLA-B*27 and B*57 were lost at least as fast as CTL responses restricted by HLA-A*02. CONCLUSIONS: Our data show that many of the mechanisms of CTL that are generally held responsible for slowing down HIV-1 disease progression hold for HLA-B*57 but do not hold for HLA-B*27.

Elevated granzyme M-expressing lymphocytes during cytomegalovirus latency and reactivation after allogeneic stem cell transplantation.

Human cytomegalovirus (HCMV) reactivation can cause serious complications in allogeneic stem cell transplantation (SCT) patients. HCMV is controlled by cytotoxic lymphocytes that release antiviral granzymes. Recently, we have demonstrated that granzyme M (GrM) inhibits HCMV replication in vitro, however the physiological role of GrM and its cellular distribution during HCMV infection remains unknown. Here, we examined GrM expression in lymphocyte populations during HCMV infection. The percentage of GrM-expressing effector-memory CD4(+) T-cells was higher in HCMV latently-infected healthy individuals compared to that of uninfected individuals. SCT recipients had higher percentages of GrM-expressing CD4(+) T, CD8(+) T, γδT, and NKT cells. Despite lower total T-cell numbers, HCMV reactivation in SCT patients specifically associated with higher percentages of GrM-expressing CD4(+) (total and central-memory) T-cells. GrM was elevated in plasma during HCMV reactivation, pointing to extracellular perforin-independent functions of GrM. We conclude that GrM may be important in regulating HCMV latency and reactivation in SCT patients.

CD8+ TCR repertoire formation is guided primarily by the peptide component of the antigenic complex.

CD8(+) T cells recognize infected or dysregulated cells via the clonotypically expressed αß TCR, which engages Ag in the form of peptide bound to MHC class I (MHC I) on the target cell surface. Previous studies have indicated that a diverse Ag-specific TCR repertoire can be beneficial to the host, yet the determinants of clonotypic diversity are poorly defined. To better understand the factors that govern TCR repertoire formation, we conducted a comprehensive clonotypic analysis of CD8(+) T cell populations directed against epitopes derived from EBV and CMV. Neither pathogen source nor the restricting MHC I molecule were linked with TCR diversity; indeed, both HLA-A and HLA-B molecules were observed to interact with an overlapping repertoire of expressed TRBV genes. Peptide specificity, however, markedly impacted TCR diversity. In addition, distinct peptides sharing HLA restriction and viral origin mobilized TCR repertoires with distinct patterns of TRBV gene usage. Notably, no relationship was observed between immunodominance and TCR diversity. These findings provide new insights into the forces that shape the Ag-specific TCR repertoire in vivo and highlight a determinative role for the peptide component of the peptide-MHC I complex on the molecular frontline of CD8(+) T cell-mediated immune surveillance.

Pegylated interferon-α monotherapy leads to low response rates in HIV-infected patients with acute hepatitis C.

BACKGROUND: Despite a rising incidence of acute HCV in patients infected with HIV, the optimal therapeutic strategy (pegylated interferon-α [PEG-IFN-α] monotherapy or in combination with ribavirin) is still under debate. METHODS: A total of 23 HIV-infected patients were prospectively diagnosed with acute HCV and treated with PEG-IFN-α2a monotherapy (180 µg/week) for 24 or 48 weeks. Add-on ribavirin was allowed from week 4 of therapy onwards. There were three patients who were not included for different reasons. Blood samples were routinely drawn for viral load measurement and IL28B polymorphism analysis. RESULTS: Spontaneous viral clearance occurred in 1 (4%) patient. Nineteen patients (13 genotype 1 and 6 genotype 4) received treatment with PEG-IFN-α monotherapy (3 with add-on ribavirin) resulting in a rapid virological response (HCV RNA<50 IU/ml at week 4) in 7 (37%) patients. A sustained virological response (SVR) was reached in 7 (37%) patients, whereas 9 (47%) patients were null-responders to treatment (that is, <2 log10 drop in HCV RNA at week 12 of therapy). The unfavourable G allele of the IL28B polymorphism rs8099917 was detected in 66% of the non-responders. In case of re-emergence of HCV viraemia after treatment discontinuation, sequence analysis of quasispecies confirmed an HCV relapse in 3 patients while 2 patients were re-infected by their previously non-responding partner. CONCLUSIONS: PEG-IFN-α monotherapy resulted in a low SVR rate and a high percentage of null-response, whereas non-SVR was associated with a polymorphism in the IL28B gene (rs8099917).

Influence of HIV infection on cytomegalovirus-specific immunity: T-cell responses to pp65 and IE1 before and after HAART may reflect altered cytomegalovirus biology.

BACKGROUND: Data are inconclusive whether treatment with HAART induces functional recovery of HIV-specific T-cells. Since the introduction of HAART, a marked decrease of cytomegalovirus (CMV) disease - for which untreated HIV-infected individuals are at increased risk - is observed, suggesting that this treatment influences CMV-specific T-cell immunity. METHODS: To study potential functional recovery of HIV- and CMV-specific T-cells, CD4(+) and CD8(+) T-cell responses were measured longitudinally after in vitro expansion using gag, pp65 and IE1 peptide pools, during HIV infection and after long-term HAART. RESULTS: HIV-specific T-cell function, measured by interferon (IFN)-γ production, was low after initiation of HAART. Interestingly, the cytotoxic function - measured by CD107a expression - of these T-cells temporarily increased after start of treatment, suggesting some functional recovery. The pp65-specific CD8(+) T-cell responses tended to decrease during HIV infection, whereas pp65-specific CD4(+) T-cell responses decreased upon treatment with HAART. Both pp65-specific CD4(+) and CD8(+) T-cell responses were low after initiation of HAART compared to healthy controls. By contrast, IE1-specific CD4(+) T-cell responses increased during the course of HIV infection. After initiation of HAART, IE1-specific T-cell responses decreased, but IE1-specific CD8(+) T-cells seemed increased compared to healthy controls. CONCLUSIONS: This study suggests that HIV-infection leads to an altered CMV biology, affecting pp65- and IE1-specific T-cell responses in a different way, which is not restored by treatment with long-term HAART.

Loss of HIV-1-derived cytotoxic T lymphocyte epitopes restricted by protective HLA-B alleles during the HIV-1 epidemic.

OBJECTIVE AND DESIGN: HIV-1 is known to adapt to the human immune system, leading to accumulation of escape mutations during the course of infection within an individual. Cross-sectional studies have shown an inverse correlation between the prevalence of human leukocyte antigen (HLA) alleles in a population and the number of cytotoxic T lymphocyte (CTL) escape mutations in epitopes restricted by those HLA alleles. Recently, it was demonstrated that at a population level HIV-1 is adapting to the humoral immune response, which is reflected in an increase in resistance to neutralizing antibodies over time. Here we investigated whether adaptations to cellular immunity have also accumulated during the epidemic. METHODS: We compared the number of CTL epitopes in HIV-1 strains isolated from individuals who seroconverted at the beginning of the HIV-1 epidemic and from individuals who seroconverted in recent calendar time. RESULTS: The number of CTL epitopes in HIV-1 variants restricted by the most common HLA alleles in the population did not change significantly during the epidemic. In contrast, we found a significant loss of CTL epitopes restricted by HLA-B alleles associated with a low relative hazard of HIV-1 disease progression during the epidemic. Such a loss was not observed for CTL epitopes restricted by HLA-A alleles. CONCLUSION: Despite the large degree of HLA polymorphism, HIV-1 has accumulated adaptations to CTL responses within 20 years of the epidemic. The fact that such adaptations are driven by the HLA-B molecules that provide best protection against HIV-1 disease progression has important implications for our understanding of HIV evolution.

Immunological analysis of treatment interruption after early highly active antiretroviral therapy.

We longitudinally evaluated HIV-specific T-cell immunity after discontinuation of highly active antiretroviral therapy (HAART). After treatment interruption (TI), some individuals could maintain a low plasma viral load (<15,000 copies/mL), whereas others could not (>50,000 copies/mL). Before HAART was initiated, plasma viral load was similar. After TI, the numbers of CD8(+) T cells increased more in individuals without viral control, whereas individuals maintaining a low viral load showed a more pronounced increase in HIV-specific CD8(+) T-cell numbers. No differences were seen in the number or percentage of cytokine-producing HIV-1-specific CD4(+) T cells, or in proliferative capacity of T cells. Four weeks after TI, the magnitude of the total HIV-1-specific CD8(+) T-cell response (IFN-γ(+) and/or IL-2(+) and/or CD107a(+)) was significantly higher in individuals maintaining viral control. Degranulation contributed more to the overall CD8(+) T-cell response than cytokine production. Whether increased T-cell functionality is a cause or consequence of low viral load remains to be elucidated.

Abundance of early functional HIV-specific CD8+ T cells does not predict AIDS-free survival time.

BACKGROUND: T-cell immunity is thought to play an important role in controlling HIV infection, and is a main target for HIV vaccine development. HIV-specific central memory CD8(+) and CD4(+) T cells producing IFNgamma and IL-2 have been associated with control of viremia and are therefore hypothesized to be truly protective and determine subsequent clinical outcome. However, the cause-effect relationship between HIV-specific cellular immunity and disease progression is unknown. We investigated in a large prospective cohort study involving 96 individuals of the Amsterdam Cohort Studies with a known date of seroconversion whether the presence of cytokine-producing HIV-specific CD8(+) T cells early in infection was associated with AIDS-free survival time. METHODS AND FINDINGS: The number and percentage of IFNgamma and IL-2 producing CD8(+) T cells was measured after in vitro stimulation with an overlapping Gag-peptide pool in T cells sampled approximately one year after seroconversion. Kaplan-Meier survival analysis and Cox proportional hazard models showed that frequencies of cytokine-producing Gag-specific CD8(+) T cells (IFNgamma, IL-2 or both) shortly after seroconversion were neither associated with time to AIDS nor with the rate of CD4(+) T-cell decline. CONCLUSIONS: These data show that high numbers of functional HIV-specific CD8(+) T cells can be found early in HIV infection, irrespective of subsequent clinical outcome. The fact that both progressors and long-term non-progressors have abundant T cell immunity of the specificity associated with low viral load shortly after seroconversion suggests that the more rapid loss of T cell immunity observed in progressors may be a consequence rather than a cause of disease progression.

Statin synergizes with LPS to induce IL-1beta release by THP-1 cells through activation of caspase-1.

Mevalonate kinase deficiency (MKD) is a hereditary syndrome characterized by recurring episodes of fever and inflammation. Peripheral blood mononuclear cells from MKD patients secrete high levels of interleukin (IL)-1beta when stimulated with lipopolysaccharide (LPS), which is thought to be a primary cause of the inflammation. However, the link between a deficient mevalonate kinase and excessive IL-1beta release remains unclear. To investigate this we made use of a model in which monocytic cells (THP-1) were treated with simvastatin. Statins are compounds that inhibit 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) reductase and thereby artificially impair the isoprenoid biosynthesis pathway, mimicking mevalonate kinase deficiency. Our study revealed that LPS-stimulated THP-1 cells treated with simvastatin had an increased caspase-1 mediated processing of proIL-1beta. This increased processing was caused by enhanced autoprocessing of caspase-1, rather than enhanced transcription or translation of caspase-1 or proIL-1beta. Simvastatin-induced activation of caspase-1 was caused by an impairment of non-sterol isoprenoid biosynthesis, as the isoprenyl intermediate GGPP could block activation of caspase-1 and mIL-1beta release. In addition, inhibition of both farnesyl pyrophosphate synthase and geranylgeranyltransferase I also induce mIL-1beta release. Taken together, these results demonstrate that simvastatin augments LPS-induced IL-1beta release post-translationally, by inducing caspase-1 activity. These findings suggest that MKD patients may have overactive caspase-1, causing enhanced IL-1beta processing and subsequent inflammation in response to bacterial components.

A nonprogressive clinical course in HIV-infected individuals expressing human leukocyte antigen B57/5801 is associated with preserved CD8+ T lymphocyte responsiveness to the HW9 epitope in Nef.

The human leukocyte antigen (HLA) B57 allele and the closely related HLA-B5801 allele are overrepresented among human immunodeficiency virus type 1 (HIV-1)-infected individuals with a long-term nonprogressive clinical course of disease (known as "long-term nonprogressors" [LTNPs]). These alleles are, however, also present among individuals with normal disease progression (known as "progressors"). In a comparison of HLA-B57/5801-expressing progressors and LTNPs, we observed a similar prevalence of escape mutations in 4 Nef epitopes and a similar reactivity of CD8+ T cells against 3 of 4 of these epitopes and their autologous escape variants. However, LTNPs tended to have frequent and preserved CD8+ T cell interferon-gamma responses against the wild-type HW9 Nef epitope, whereas progressors did not maintain a specific CD8+ T cell response. This finding is in line with the findings of a more exhausted phenotype of CD8+ T cells in progressors, as is demonstrated by their enhanced level of expression of inhibitory receptor "programmed death 1" (PD-1). The results of the present study suggest that preservation of HW9-specific T cell responses is associated with a more benign clinical course of infection.

An unanticipated lack of consensus cytotoxic T lymphocyte epitopes in HIV-1 databases: the contribution of prediction programs.

BACKGROUND: Most consensus HIV-1-specific cytotoxic T lymphocytes epitopes presented via intensively studied HLA molecules are thought to be known OBJECTIVE: To identify possible novel HIV-1 epitopes for HLA-B27 and HLA-B57; two HLA types which are abundantly studied because of their correlation with slow HIV disease progression. METHODS: HIV-1 consensus subtype B sequences were analysed using peptide prediction programs based on major histocompatibility complex binding, proteasomal cleavage and TAP (transporter associated with antigen processing) transport. Recognition of the novel identified epitopes by cytotoxic T lymphocytes was tested using interferon-gamma ELISpot assay. RESULTS: In total, 22 novel epitopes predicted to be presented by either HLA-B27 or HLA-B57 were selected. Of these, 86% elicited significant immune responses in HIV-1-infected individuals. CONCLUSIONS: These data show that numerous HIV-1 epitopes remain to be identified, and that prediction programs are powerful tools for this purpose.