Effect of heterosexual intercourse on mucosal alloimmunisation and resistance to HIV-1 infection

Peptides Derived From Mismatched Paternal Human Leukocyte Antigen Predicted to Be Presented by HLA-DRB1, -DRB3/4/5, -DQ, and -DP Induce Child-Specific Antibodies in Pregnant Women

Predicted Indirectly ReCognizable Human Leukocyte Antigen (HLA) Epitopes (PIRCHE) are known to be a significant risk factor for the development of donor HLA-specific antibodies after organ transplantation. Most previous studies on PIRCHE limited their analyses on the presentation of the HLA-DRB1 locus, although HLA-DRB3/4/5, -DQ, and -DP are also known for presenting allopeptides to CD4+ T cells. In this study, we analyzed the impact of predicted allopeptides presented by these additional loci on the incidence of HLA-specific antibodies after an immunization event. We considered pregnancy as a model system of an HLA immunization and observed child-specific HLA antibody (CSA) development of 231 mothers during pregnancy by samples being taken at delivery. Our data confirm that PIRCHE presented by HLA-DRB1 along with HLA-DRB3/4/5, -DQ, and -DP are significant predictors for the development of CSA. Although there was limited peptidome overlap observed within the mothers’ presenting HLA proteins, combining multiple presenting loci in a single predictor improved the model only marginally. Prediction performance of PIRCHE further improved when normalizing scores by the respective presenters’ binding promiscuity. Immunogenicity analysis of specific allopeptides could not identify significant drivers of an immune response in this small cohort, suggesting confirmatory studies.

On the efficiency of HIV transmission: Insights through discrete time HIV models

There are different views on which of the two forms of viral spread is more efficient in vivo between cell-free and cell-associated virus. In this study, discrete time human immunodeficiency virus models are formulated and analysed with the goal of determining the form of viral spread that is more efficient in vivo. It is shown that on its own, cell-free viral spread cannot sustain an infection owing to the low infectivity of cell-free virus and cell-associated virus can sustain an infection because of the high infectivity of cell-associated virus. When acting concurrently, cell-associated virus is more efficient in spreading the infection upon exposure to the virus. However, in the long term, the two forms of viral spread contribute almost equally. Both forms of viral spread are shown to be able to initiate an infection.

The Incorporation of Host Proteins into the External HIV-1 Envelope

The incorporation of biologically active host proteins into HIV-1 is a well-established phenomenon, particularly due to the budding mechanism of viral egress in which viruses acquire their external lipid membrane directly from the host cell. While this mechanism might seemingly imply that host protein incorporation is a passive uptake of all cellular antigens associated with the plasma membrane at the site of budding, this is not the case. Herein, we review the evidence indicating that host protein incorporation can be a selective and conserved process. We discuss how HIV-1 virions displaying host proteins on their surface can exhibit a myriad of altered phenotypes, with notable impacts on infectivity, homing, neutralization, and pathogenesis. This review describes the canonical and emerging methods to detect host protein incorporation, highlights the well-established host proteins that have been identified on HIV-1 virions, and reflects on the role of these incorporated proteins in viral pathogenesis and therapeutic targeting. Despite many advances in HIV treatment and prevention, there remains a global effort to develop increasingly effective anti-HIV therapies. Given the broad range of biologically active host proteins acquired on the surface of HIV-1, additional studies on the mechanisms and impacts of these incorporated host proteins may inform the development of novel treatments and vaccine designs.

Dynamical properties and thresholds of an HIV model with super-infection

Super-infection by multiple HIV-1 subtypes, previously thought restricted to high risk groups, has now been reported in the general heterosexual populations at relatively the same incidence rate as in high risk groups. We present a simple deterministic HIV model with super-infection by two HIV-1 subtypes. Mathematical characteristics including the basic reproductive number $(\mathcal{R}_0)$, invasion threshold $(\mathcal{R}_{21},\mathcal{R}_{12})$ and conditions for asymptotic stability are derived. In the absence of super-infection the model exhibits competitive exclusion, and all equilibria are globally attracting if they exist except for the disease free which is a saddle for $\mathcal{R}_0>1.$ The results show that the subtype with the dominant reproductive number exceeding unity dominates the weaker subtype forcing it to extinction regardless of the size of the reproductive number. On the other end, super-infection may promote subtype co-existence whenever the minimum of the subtype specific reproductive numbers $(\mathcal{R}_1,\mathcal{R}_2)$ and the invasion reproductive numbers $(\mathcal{R}_{12},\mathcal{R}_{21})$ exceed unity. Our results demonstrate that if the partial reproductive numbers $(\mathcal{R}_1~\mbox{and}~\mathcal{R}_2 )$ and the invasion reproductive number for the weaker subtype $(\mathcal{R}_{21})$ satisfy $\mathcal{R}_2<1,~\mathcal{R}_1>1~\mbox{and}~\mathcal{R}_{21}>1,$ then primary infection by subtype $1$ may stay the extinction of subtype $2$ despite its relatively low reproductive fitness. For certain parameter ranges, hysteresis (including backward bifurcation) occurs with possible differences in the asymptotic level of disease prevalence. Super-infection may thus facilitate the continued re-generation of reproductively noncompetent subtypes whose subtype specific reproductive numbers will be less than unity while at the same time allowing for the mutual coexistence and persistence of multiple strains. Persistence and co-existence of multiple strains has detrimental effect on vaccine design and development and administration of ART where one or more of the strains are drug resistant.

Development of a human leukocyte antigen-based HIV vaccine

Human immunodeficiency virus (HIV) carries abundant human cell proteins, particularly human leukocyte antigen (HLA) molecules when the virus leaves host cells. Immunization in macaques with HLAs protects the animals from simian immunodeficiency virus infection. This finding offers an alternative approach to the development of HLA molecule-based HIV vaccines. Decades of studies have enhanced a great deal of our understanding of the mechanisms of allo-immune response-mediated anti-HIV immunity. These include cell-mediated immunity, innate immunity, and antibody response. These studies provided a rationale for the future design of effective HIV vaccines.

Stimulation of HIV-specific T cell clonotypes using allogeneic HLA

We hypothesized that HIV-specific CD8 T cell clonotypes can be stimulated by allogeneic HLA molecules. Multiple HIV-specific CD8 T cell clones were derived from 12 individuals with chronic HIV infection, specific for 13 different HIV Gag antigens and restricted to 7 different HLA molecules. The generated T cell clones were assayed for alloreactivity against a panel of single HLA class I expressing cell lines (SALs). HIV-specific T cells recognising at least one allogeneic HLA molecule could be identified from 7 of 12 patients tested. Allorecognition was associated with IFNγ cytokine production, CD137 upregulation and cytotoxicity, suggesting high avidity allo-stimulation. Allo-HLA recognition by HIV-specific T cells was specific to the HIV target peptide/HLA restriction and TCR TRBV usage of the T cells. HIV-specific T cells do crossreact against allogeneic HLA molecules in an epitope and TRBV specific manner. Therefore allo-HLA stimulation could be exploited to induce or augment HIV-specific T cell responses.

Innate and Adaptive Mucosal Immunity in Protection against HIV Infection

The appalling toll on the populations of developing countries as a result of the HIV epidemic shows no signs of abatement. While costly drug therapies are effective in developed nations, the sheer scale of the epidemic elsewhere makes the need for a vaccine an ever more urgent goal. The prevalent DNA prime-viral boost strategy aims to elicit cytotoxic lymphocytes (CTL) against HIV, but this approach is undermined by the rapid mutation of HIV, which thereby escapes CTL control. Alloimmunity has been found to be protective in vertical transmission from infected mothers to their babies, in alloimmunization of women with their partners’ mononuclear cells, and in monkeys immunized with SIV grown in human T-cells. Vaginal mucosal immunization, as a result of unprotected sex with a regular partner, induced in vitro protection against HIV infection, and this was confirmed in macaques. The second type of natural protection is found in persons with the homozygous Δ32 CCR5 mutation, a 32-base-pair deletion of the CCR5 gene, which results in a lack of cell-surface expression of CCR5, which is associated with an increase in CC chemokines and the development of CCR5 antibodies. These two ‘experiments of nature’ have been used to develop vaccine strategies—first, in vaginal immunization of macaques with CCR5 peptides, in addition to HIV envelope (env) and SIV core (gag) antigens, all of which were linked to the 70-kD heat-shock protein (HSP70); and second, in mucosal allo-immunization of macaques, which also gave rise to in vitro protection from infection. Immunization with this vaccine elicited serum and vaginal IgG and IgA antibodies, IFNγ- and IL-12-producing cells, and increased concentrations of CCL-3 and CCL-4. Vaginal challenge with a simian immunodeficiency virus engineered to carry a human envelope protein (SHIV 89.6) showed significant clearance of SHIV in the immunized macaques. This platform strategy will now be developed to activate the co-stimulatory pathways with the aim of enhancing the primary allogeneic and CCR5-directed responses which are involved in natural protection against HIV infection. Abbreviations: IFN-γ, gamma interferon; IL-12, interleukin 12; MIP-1 α,β, Macrophage inflammatory protein-1; RANTES, Regulated on activation normal T-cell expressed and secreted; SDF-1, stromal-derived factor 1; SIV, simian immunodeficiency virus; and SHIV, engineered SIV carrying a human envelope protein.

Exosomes in human semen carry a distinctive repertoire of small non-coding RNAs with potential regulatory functions

Semen contains relatively ill-defined regulatory components that likely aid fertilization, but which could also interfere with defense against infection. Each ejaculate contains trillions of exosomes, membrane-enclosed subcellular microvesicles, which have immunosuppressive effects on cells important in the genital mucosa. Exosomes in general are believed to mediate inter-cellular communication, possibly by transferring small RNA molecules. We found that seminal exosome (SE) preparations contain a substantial amount of RNA from 20 to 100 nucleotides (nts) in length. We sequenced 20-40 and 40-100 nt fractions of SE RNA separately from six semen donors. We found various classes of small non-coding RNA, including microRNA (21.7% of the RNA in the 20-40 nt fraction) as well as abundant Y RNAs and tRNAs present in both fractions. Specific RNAs were consistently present in all donors. For example, 10 (of ∼2600 known) microRNAs constituted over 40% of mature microRNA in SE. Additionally, tRNA fragments were strongly enriched for 5'-ends of 18-19 or 30-34 nts in length; such tRNA fragments repress translation. Thus, SE could potentially deliver regulatory signals to the recipient mucosa via transfer of small RNA molecules.

The incidence of preeclampsia in ICSI pregnancies

Objective: We aimed to evaluate the association between infertility etiology in ICSI pregnancies and preeclampsia; besides, we aimed to discuss the effect of the paternal factor in the pathogenesis of preeclampsia.

Hypothesis:We hypothesized that preeclampsia is more common in ICSI pregnancies with male factor. It is known that maternal exposure to paternal sperm cells over a time period has a protective effect against preeclampsia. Male partners with azospermia have no sperm cells in their seminal fluid, whose female partners will not be able to develop some protective immunity against preeclampsia. We hypothesized that the infertile couples with male factor (partner with azoospermia and also oligospermia) would be an ideal model to test the partner-specific protective immunity against preeclampsia, as the women had no chance to develop adequate protective immunity via the partner’s sperm exposure.

Methods: This Single-center, retrospective study included 508 infertile couples admitted to our IVF center between January 2001 and March 2008. The data regarding the maternal age, etiology of the infertility, the pregnancy rates, abortus ratio and viable pregnancy rates was collected from the case files. Antenatal complications such as preeclampsia, placenta previa, abruptio placenta, premature rupture of membranes, premature labor, oligohydramnios, gestational diabetes, postmaturity, postpartum complications and neonatal outcomes were evaluated via the file records and phone interviewing. The study population was divided into two main groups according to the etiology of infertility. 301 of the study population (group 1) was infertile due to male factor and 207 of the study population (group 2) was female factor and unexplained infertility cases.Group 1 patients were divided further into two subgroups: group 1a included 56 cases in which TESE (testicular sperm extraction) was used to obtain the sperm cells as the male factor was severe and as there was no sperm cells in seminal fluid. Group 1 b consists of 245oligospermic cases who obtained sperm cells via conventional methods.

Results: The mean ages of women in Group one and two were 30.22±5.06 and 31.58±4.36 years respectively (p=0.001). 129 cases (42,8%) from group one and 106 cases (51,2%) from Group two ended in first trimester and early second trimester (<24 gestational weeks) pregnancy loss. In group one, only 172 cases of 301 pregnancies passed over 24 weeks of gestational age, whereas in group two, 101 cases of 207 patients passed over 24 gestational weeks. There was no significant difference between two groups regarding chemical pregnancies and early pregnancy loss (p=0.314). There was no significant difference between the groups regarding placenta previa, gestational diabetes, oligo hydramnios and intrauterine growth retardation. One one pregnancy was 1.5 times more vulnerable for preeclampsia.

Conclusion: Pregnancies with azoospermic and oligospermic partners had an increased risk for developing preeclampsia.

The rise and fall of HIV in high-prevalence countries: a challenge for mathematical modeling

Several countries with generalized, high-prevalence HIV epidemics, mostly in sub-Saharan Africa, have experienced rapid declines in transmission. These HIV epidemics, often with rapid onsets, have generally been attributed to a combination of factors related to high-risk sexual behavior. The subsequent declines in these countries began prior to widespread therapy or implementation of any other major biomedical prevention. This change has been construed as evidence of behavior change, often on the basis of mathematical models, but direct evidence for behavior changes that would explain these declines is limited. Here, we look at the structure of current models and argue that the common “fixed risk per sexual contact" assumption favors the conclusion of substantial behavior changes. We argue that this assumption ignores reported non-linearities between exposure and risk. Taking this into account, we propose that some of the decline in HIV transmission may be part of the natural dynamics of the epidemic, and that several factors that have traditionally been ignored by modelers for lack of precise quantitative estimates may well hold the key to understanding epidemiologic trends.

Association of sex work with reduced activation of the mucosal immune system

BACKGROUND

Unprotected intercourse and seminal discharge are powerful activators of the mucosal immune system and are important risk factors for transmission of human immunodeficiency virus (HIV). This study was designed to determine if female sex work is associated with changes in the mucosal immunity.

METHODS

Cervicovaginal lavage and plasma from 122 HIV-uninfected female sex workers (FSW) and 44 HIV-uninfected low-risk non-FSW from the same socioeconomic district of Nairobi were analyzed for evidence of immune activation (IA). The cervico-mononuclear cells (CMC) were analyzed for cellular activation by flow cytometry.

RESULTS

Lower IA was observed in FSW compared to the low-risk women as demonstrated by the lower level of MIP-3α (P < .001), ITAC (P < .001), MIG (p.0001), IL-1α (P < .001), IL-1β (P < .001), IL-1Rα (P = .0002), IL-6 (P < .001), IL-8 (P < .001), IL-10 (P = .01), IP-10 (P = .0001), MDC (P < .001), MIP-1α, (P < .001), MIP-1β (P = .005), MCP-1 (P = .03), and TNF-α (P = .006). Significant differences were noted as early as 1 year following initiation of sex work and increased with duration of sex work.

CONCLUSION

This study showed that sex work is associated with important changes in the mucosal immune system. By analyzing chemokine/cytokine levels and CMC activation, we observed a lower mucosal IA in HIV-uninfected FSW compared to low-risk women.

Chimerism in transfusion medicine: the grandmother effect revisited

Transfusion therapy is complicated by the production of alloantibodies to antigens present in the donor and lacking in the recipient through the poorly-understood but likely multi-factorial process of alloimmunization. The low prevalence of alloimmunization in transfused patients (6.1%) (1) suggests that processes central to immunologic tolerance may be operating in the vast majority of transfused patients who do not produce alloantibodies. Using RhD as a prototype, evidence is reviewed that the ability to make antibodies to red blood cell (RBC) antigens may result in part from immunologic tolerance acquired in utero. These ideas are extended to other examples of maternal microchimerism (MMc) of other non-inherited maternal antigens (NIMA). An evolutionary argument is offered that multi-generational immunity supports the hypothesis that MMc may partly explain the "non-responder" phenotype in RBC alloimmunization.

Greater ethnic diversity correlates with lower HIV prevalence in Africa: justification for an alloimmunity vaccine

Purpose

After decades of research, AIDS continues to be a major pandemic and to date, adaptive immunity vaccine designs have had little to no success. Data indicate the alloimmune response is a potent mitigator of human immunodeficiency virus (HIV) infection, for which experiments of nature should be demonstrable to justify pursuit of an alloimmune vaccine strategy. We sought to determine if large-scale alloimmune diversity correlates with lower HIV infection rates.

Methods

Using published data of African linguistic groups to determine sub-Saharan country ethnicity profiles as a proxy for human leukocyte antigen (HLA) diversity, a correlation analysis was performed against respective sub-Saharan country HIV infection rates. Ethnicity data from 37 sub-Saharan nations in 2003 and from 38 nations in 2005 were used to calculate the Meyers-Macintosh ethnic diversity score for each nation as the independent variable. World Health Organization data on HIV infection rates for the same countries were used as the dependent variable. The main outcome measure was the correlation coefficient of ethnic diversity versus HIV infection rate.

Results

A significant negative correlation was shown between ethnic diversity and HIV infection: for 2003 data, −0.4586 (two-tailed P-value of 0.0043); and, for 2005 data, −0.3866 (two-tailed P-value of 0.0165).

Conclusion

In conjunction with substantial evidence that alloimmunity confers protection against HIV transmission and recent work identifying specific anti-HIV mechanisms, this analysis strongly justifies an HLA-based alloimmune vaccine strategy against HIV.

Professor Thomas Lehner: archetypal translational scientist

Professor Thomas Lehner is one of the most distinguished oral and dental researchers to have come out of the UK. Over the past 40 years, he has made an astonishing number of discoveries which have had an impact on our understanding of the pathogenesis of a variety of mucosal diseases. He has consistently practiced both basic and clinical research and built an integrated group of clinical and non-clinical researchers, which allowed him easy transition from the laboratory to the clinic. Tom Lehner was among the early scientists studying mucosal immunology, initially exploring oral diseases, with special emphasis on the immunobiology of Streptococcus mutans, leading to active and passive vaccination against dental caries. He was the first to demonstrate cellular immunity as the immunopathological basis of periodontal diseases, recurrent aphthous stomatitis, and candidiasis. Over the past 20 years, his expertise in mucosal immunobiology has been applied to the immunology of HIV/SIV infections. His seminal contributions include regional innate mucosal immunity, prevention of SIV infection in macaques by secretory IgA antibodies, up-regulation of CC chemokines, and the first demonstration of protective CCR5 antibodies. Arguably, his leadership, his students, and the establishment of immunology applied to oral mucosal diseases will be his greatest legacy. His contributions continue unabated.

As good as it gets? The problem of HIV persistence despite antiretroviral drugs

Human immunodeficienty virus (HIV) infection is suppressed but not eliminated by antiretroviral drugs. Viral persistence in the face of therapy has been explained by viral latency, lowered effectiveness of drugs in some anatomical sites and cell types, and cell-to-cell spread. These mechanisms allow for drug-sensitive virus to persist despite treatment. Understanding the persistence mechanism at work at different times after infection, including the time of initial infection immediately following transmission when reservoirs are first formed, will reveal if we are at the limit of what can be achieved with the current therapy paradigm of suppressing ongoing virus replication with drugs. We discuss some of the possible reasons why HIV persists at different points on the infection timeline, focusing on the role ongoing replication may have in maintaining the infection despite drugs at early times postexposure.

Salivary basic proline-rich proteins are elevated in HIV-exposed seronegative men who have sex with men

OBJECTIVE

Innate mucosal factors are associated with protection in HIV-exposed seronegative (HESN) individuals, but studies of MSM have been very limited. We performed proteomic analysis of saliva from a cohort of HESN MSM who have regular unprotected oral receptive intercourse with their HIV-infected partner.

METHODS

Saliva samples from HESN (n = 25) and non-exposed male controls (n = 22) were analyzed by 2D-LC mass spectrometry. An overexpressed innate protein factor was further characterized by immunoblot, and compared with CC-chemokine expression, HIV-neutralizing activity, clinical factors, and sexual behavior.

RESULTS

Of 337 total proteins, seven were identified as differentially abundant in the HESN group. The five overabundant proteins (Basic salivary proline-rich proteins (bPRP) 2 and 3, Histatin-3, Lysozyme C, and SLPI) have known antimicrobial activity. bPRP2 showed the highest overabundance (>six-fold) in HESN individuals compared with controls (P = 0.009), including multiple isoforms. Salivary bPRP2 correlated with CC-chemokine levels in HESN individuals including RANTES (P = 0.02), MIP-1-alpha (P = 0.01), MIP-1-beta (P = 0.0002), MCP-1 (P = 0.005) and Eotaxin (P = 0.003) but not with frequency of HIV neutralizing activity, oral sexual practices, or viral load of the sexual partner.

CONCLUSION

This study identifies salivary bPRP2 as a novel soluble factor elevated in the oral compartment of HIV-exposed MSM.

Biological basis for the protective effect conferred by male circumcision against HIV infection

Here we provide an up-to-date review of research that explains why uncircumcised men are at higher risk of HIV infection. The inner foreskin is a mucosal epithelium deficient in protective keratin, yet rich in HIV target cells. Soon after sexual exposure to infected mucosal secretions of a HIV-positive partner, infected T-cells from the latter form viral synapses with keratinocytes and transfer HIV to Langerhans cells via dendrites that extend to just under the surface of the inner foreskin. The Langerhans cells with internalized HIV migrate to the basal epidermis and then pass HIV on to T-cells, thus leading to the systemic infection that ensues. Infection is exacerbated in inflammatory states associated with balanoposthitis, the presence of smegma and ulceration - including that caused by infection with herpes simplex virus type 2 and some other sexually transmitted infections (STIs). A high foreskin surface area and tearing of the foreskin or associated frenulum during sexual intercourse also facilitate HIV entry. Thus, by various means, the foreskin is the primary biological weak point that permits HIV infection during heterosexual intercourse. The biological findings could explain why male circumcision protects against HIV infection.

Knowledge of specific HIV transmission modes in relation to HIV infection in Mozambique

Background: In prior research, Africans who knew about blood-borne risks were modestly less likely to be HIV-infected than those who were not aware of such risks.

Objectives/Methods: I examined the association between knowledge of specific HIV transmission modes and prevalent HIV infection with data from the 2009 Mozambique AIDS Indicator Survey.

Results: Respondents displayed high awareness of blood exposures and vaginal sex as modes of HIV transmission. However, only about half of respondents were aware of anal sex as a way HIV can be transmitted. After adjustments for demographics and sexual behaviors, respondents who knew that HIV could spread by contact with infected blood or by sharing injection needles or razor blades were less likely to be infected than those who did not know about these risks. Respondents who knew about sexual risks were as, or more, likely to be HIV infected as those who did not know about sexual risks. Also, children of HIV-uninfected mothers were less likely to be infected if their mothers were aware of blood-borne HIV risks than if their mothers were unaware.

Conclusion: HIV education campaigns in Mozambique and elsewhere in sub-Saharan Africa should include a focus on risks from blood exposures and anal sex.

Immunization with recombinant macaque major histocompatibility complex class I and II and human immunodeficiency virus gp140 inhibits simian–human immunodeficiency virus infection in macaques

Genetic, epidemiological and experimental evidence suggest that the major histocompatibility complex (MHC) is critical in controlling human immunodeficiency virus (HIV) infection. The objectives of this study were to determine whether novel recombinant Mamu MHC constructs would elicit protection against rectal challenge with heterologous simian–human immunodeficiency virus (SHIV) strain SF162.P4 in rhesus macaques. Mamu class I and II gene products were linked together with HIV gp140, simian immunodeficiency virus (SIV) p27 and heat-shock protein 70 to dextran. The vaccine was administered to two groups, each consisting of nine macaques, either subcutaneously (SC), or rectally and boosted by SC immunization. The controls were untreated or adjuvant-treated animals. Repetitive rectal challenges with up to ten doses of SHIV SF162.P4 showed a significant decrease in the peak and sequential viral RNA concentrations, and three macaques remained uninfected, in the nine SC-immunized animals, compared with infection in all nine controls. Macaques immunized rectally followed by SC boosters showed a less significant decrease in both sequential and peak viral loads compared with the SC-immunized animals, and all were infected following rectal challenge with SHIV SF162.P4. Plasma and mucosal IgG and IgA antibodies to Mamu class I alleles and HIV gp120, as well as to RANTES (regulated upon activation, normal T-cell expressed, and secreted; CCR5) were increased, and showed significant inverse correlations with the peak viral load. These results suggested that allo-immunization with recombinant MHC constructs linked to HIV–SIV antigens merits further investigation in preventing HIV-1 infection.

Transmaternal cell flow leads to antigen-experienced cord blood

Umbilical cord blood (UCB) is used for HSCT. It is known that UCB can comprise Ag-specific T cells. Here we question whether solely transmaternal cell flow may immunize UCB. Twenty-three female UCB samples were collected from healthy mothers and analyzed for minor histocompatibility Ag HY-specific responses. Forty-two of 104 tetramer(pos) T-cell clones, isolated from 16 of 17 UCB samples, showed male-specific lysis in vitro. Male microchimerism was present in 6 of 12 UCB samples analyzed. In conclusion, female UCB comprises HY-specific cytotoxic T cells. The immunization is presumably caused by transmaternal cell flow of male microchimerism present in the mother. The presence of immune cells in UCB that are not directed against maternal foreign Ags is remarkable and may explain the reported clinical observation of improved HSCT outcome with younger sibling donors.

Seminal fluid induces leukocyte recruitment and cytokine and chemokine mRNA expression in the human cervix after coitus

In mice, seminal fluid elicits an inflammation-like response in the female genital tract that activates immune adaptations to advance the likelihood of conception and pregnancy. In this study, we examined whether similar changes in leukocyte and cytokine parameters occur in the human cervix in response to the male partner's seminal fluid. After a period of abstinence in proven-fertile women, duplicate sets of biopsies were taken from the ectocervix in the periovulatory period and again 48 h later, 12 h after unprotected vaginal coitus, vaginal coitus with use of a condom, or no coitus. A substantial influx of CD45(+) cells mainly comprising CD14(+) macrophages and CD1a(+) dendritic cells expressing CD11a and MHC class II was evident in both the stratified epithelium and deeper stromal tissue after coitus. CD3(+)CD8(+)CD45RO(+) T cells were also abundant and increased after coitus. Leukocyte recruitment did not occur without coitus or with condom-protected coitus. An accompanying increase in CSF2, IL6, IL8, and IL1A expression was detected by quantitative RT-PCR, and microarray analysis showed genes linked with inflammation, immune response, and related pathways are induced by seminal fluid in cervical tissues. We conclude that seminal fluid introduced at intercourse elicits expression of proinflammatory cytokines and chemokines, and a robust recruitment of macrophages, dendritic cells, and memory T cells. The leukocyte and cytokine environment induced in the cervix by seminal fluid appears competent to initiate adaptations in the female immune response that promote fertility. This response is also relevant to transmission of sexually transmitted pathogens and potentially, susceptibility to cervical metaplasia.

Exposure to apoptotic activated CD4+ T cells induces maturation and APOBEC3G-mediated inhibition of HIV-1 infection in dendritic cells

Dendritic cells (DCs) are activated by signaling via pathogen-specific receptors or exposure to inflammatory mediators. Here we show that co-culturing DCs with apoptotic HIV-infected activated CD4(+) T cells (ApoInf) or apoptotic uninfected activated CD4(+) T cells (ApoAct) induced expression of co-stimulatory molecules and cytokine release. In addition, we measured a reduced HIV infection rate in DCs after co-culture with ApoAct. A prerequisite for reduced HIV infection in DCs was activation of CD4(+) T cells before apoptosis induction. DCs exposed to ApoAct or ApoInf secreted MIP-1α, MIP-1β, MCP-1, and TNF-α; this effect was retained in the presence of exogenous HIV. The ApoAct-mediated induction of co-stimulatory CD86 molecules and reduction of HIV infection in DCs were partially abrogated after blocking TNF-α using monoclonal antibodies. APOBEC3G expression in DCs was increased in co-cultures of DCs and ApoAct but not by apoptotic resting CD4(+) T cells (ApoRest). Silencing of APOBEC3G in DC abrogated the HIV inhibitory effect mediated by ApoAct. Sequence analyses of an env region revealed significant induction of G-to-A hypermutations in the context of GG or GA dinucleotides in DNA isolated from DCs exposed to HIV and ApoAct. Thus, ApoAct-mediated DC maturation resulted in induction of APOBEC3G that was important for inhibition of HIV-infection in DCs. These findings underscore the complexity of differential DC responses evoked upon interaction with resting as compared with activated dying cells during HIV infection.

The etiology of preeclampsia: the role of the father

Preeclampsia is often considered as simply a maternal disease with variable degrees of fetal involvement. More and more the unique immunogenetic maternal-paternal relationship is appreciated, and also the specific 'genetic conflict' that is characteristic of haemochorial placentation. From that perspective, pre-eclampsia can be seen as a disease of an individual couple with primarily maternal and fetal manifestations. The maternal and fetal genomes perform different roles during development. Heritable paternal, rather than maternal, imprinting of the genome is necessary for normal trophoblast development. Large population studies have estimated that 35% of the variance in susceptibility to preeclampsia is attributable to maternal genetic effects; 20% to fetal genetic effects (with similar contributions of both parents), 13% to the couple effect, less than 1% to the shared sibling environment and 32% to unmeasured factors. Not one of these large population studies focussed on the paternal contribution to preeclampsia, which is demonstrated by (1) the effect of the length of the sexual relationship; (2) the concept of primipaternity versus primigravidity; and (3) the existence of the so-called 'dangerous' father, as demonstrated in various large population studies. It is currently unknown how the father exerts this effect. Possible mechanisms include seminal cytokine levels and their effect on maternal immune deviation, specific paternal HLA characteristics and specific paternal single nucleotide polymorphisms (SNPs), in particular in the paternally expressed genes affecting placentation. Several large cohort studies, including the large international SCOPE consortium, have identified paternal SNPs with strong associations with preeclampsia.

Natural anti-CCR5 antibodies in HIV-infection and -exposure

Natural antibodies constitute a first-line of defence against pathogens; they may also play other roles in immune regulation and homeostasis, through their ability to bind host antigens, surface molecules and receptors. Natural anti-CCR5 antibodies can be decisive in preventing HIV infection in mucosal tissues and offer prompt and effective protection just at major sites of virus entry. Among natural anti-CCR5 antibodies, IgG and IgA to the ECL1 domain have been shown to block HIV effectively and durably without causing harm to the host. Their biological properties and their uncommon generation in subsets of HIV-infected and HIV-exposed individuals (so called ESN) will be introduced and discussed, with the aim at exploiting their potential in therapy and prevention.

HIV-1 exposed uninfected men who have sex with men have increased levels of salivary CC-chemokines associated with sexual behavior

OBJECTIVES

To determine whether soluble molecules with known anti-HIV-1 activity are increased in saliva of HIV-1 exposed uninfected individuals of discordant couples of men who have sex with men (MSM), and whether the levels of these molecules are associated with genetic polymorphisms, sexual behavior and/or HIV-1 neutralizing capacity.

METHODS

Saliva and PBMC were collected from exposed uninfected individuals (n=25), and low-risk controls (n=22). Levels of CCL2, CCL3, CCL4, CCL5 and CCL11 were detected by Luminex, and SLPI, LL-37, alpha-defensins and IgA2 were detected by ELISA. Single nucleotide polymorphisms (SNPs) were investigated using mass spectrometry or PCR-sequencing. HIV-1 neutralizing activity was assessed using PBMCbased neutralization assays. Self-reported questionnaires described sexual behavior.

RESULTS

Exposed uninfected individuals had significantly higher levels of salivary CCL2, CCL4, CCL5 and CCL11 as compared with controls although genetic polymorphisms within the corresponding regions were equally distributed. IgA2 was also increased in exposed uninfected individuals, whereas neither CCL3, SLPI, LL-37 nor alpha-defensins differed between exposed uninfected individuals and controls. The HIV-1 neutralizing capacity of saliva was associated with higher levels of CC-chemokines (but not SLPI, LL-37, alpha-defensins or IgA2) in both exposed uninfected individuals and controls. The increased levels of CC-chemokines were associated with a higher frequency of unprotected oral sex and/or additional casual sex partners.

CONCLUSION

HIV-1 exposed uninfected MSM had higher levels of salivary CC-chemokines compared with controls, this finding associated with sexual behavior rather than with genetic polymorphisms. The increased levels of CC-chemokines associated with HIV-1 neutralizing capacity in saliva.

Overestimation of heterosexually attributed AIDS deaths is associated with immature psychological defence mechanisms and clitoral masturbation during penile–vaginal intercourse

Research shows that (1) greater use of immature psychological defence mechanisms (associated with psychopathology) is associated with lesser orgasmic consistency from penile–vaginal intercourse (PVI), but greater frequency of other sexual behaviours and greater condom use for PVI, and (2) unlike the vectors of receptive anal intercourse and punctures, HIV acquisition during PVI is extremely unlikely in reasonably healthy persons. However, the relationship between overestimation of AIDS deaths due to ‘heterosexual transmission’ (often misunderstood as only PVI), sexual behaviour and mental health has been lacking. Two hundred and twenty-one Scottish women completed the Defense Style Questionnaire, reported past month frequencies of their various sexual activities, and estimated the total number of women who died from AIDS in Scotland nominally as a result of heterosexual transmission in the UK from a partner not known to be an injecting drug user, bisexual or infected through transfusion. The average respondent overestimated by 226,000%. Women providing lower estimates were less likely to use immature psychological defences, and had a lower frequency of orgasms from clitoral masturbation during PVI and from vibrator use. The results indicate that those who perceive ‘heterosexual transmission’ led to many AIDS deaths have poorer psychological functioning, and might be less able to appreciate PVI.

Heterosexual and homosexual partners practising unprotected sex may develop allogeneic immunity and to a lesser extent tolerance

BACKGROUND

Epidemiological studies suggest that allogeneic immunity may inhibit HIV-1 transmission from mother to baby and is less frequent in multiparous than uniparous women. Alloimmune responses may also be elicited during unprotected heterosexual intercourse, which is associated ex vivo with resistance to HIV infection.

METHODOLOGY/PRINCIPAL FINDINGS

The investigation was carried out in well-defined heterosexual and homosexual monogamous partners, practising unprotected sex and a heterosexual cohort practising protected sex. Allogeneic CD4(+) and CD8(+) T cell proliferative responses were elicited by stimulating PBMC with the partners' irradiated monocytes and compared with 3(rd) party unrelated monocytes, using the CFSE method. Significant increase in allogeneic proliferative responses was found in the CD4(+) and CD8(+) T cells to the partners' irradiated monocytes, as compared with 3(rd) party unrelated monocytes (p<or=0.001). However, a significant decrease in proliferative responses, especially of CD8(+) T cells to the partners' compared with 3(rd) party monocytes was consistent with tolerization, in both the heterosexual and homosexual partners (p<0.01). Examination of CD4(+)CD25(+)FoxP3(+) regulatory T cells by flow cytometry revealed a significantly greater proportion of these cells in the homosexual than heterosexual partners practising unprotected sex (p<0.05). Ex vivo studies of infectivity of PBMC with HIV-1 showed significantly greater inhibition of infectivity of PBMC from heterosexual subjects practising unprotected compared with those practising protected sex (p = 0.02).

CONCLUSIONS/SIGNIFICANCE

Both heterosexual and homosexual monogamous partners practising unprotected sex develop allogeneic CD4(+) and CD8(+) T cell proliferative responses to the partners' unmatched cells and a minority may be tolerized. However, a greater proportion of homosexual rather than heterosexual partners developed CD4(+)CD25FoxP3(+) regulatory T cells. These results, in addition to finding greater inhibition of HIV-1 infectivity in PBMC ex vivo in heterosexual partners practising unprotected, compared with those practising protected sex, suggest that allogeneic immunity may play a significant role in the immuno-pathogenesis of HIV-1 infection.

Duration of sexual relationship and its effect on preeclampsia and small for gestational age perinatal outcome

The aim of this study was to determine if women with preeclampsia or delivering small for gestational age (SGA) babies are more likely to have a short duration of sexual relationship compared with those who have uncomplicated pregnancies. In a prospective cohort study, 2507 nulliparous women with singleton pregnancies were interviewed at 15+/-1 weeks gestation about the duration of their sexual relationship with the biological father. Short duration of sexual relationship (< or =6 months, < or =3 months, or first intercourse) was compared between women with preeclampsia (N=131) or SGA babies (N=263) and those with uncomplicated pregnancies (N=1462). Short duration of sexual relationship was more common in women with preeclampsia compared with uncomplicated pregnancies (< or =6 months 14.5% versus 6.9%, adjusted odds ratio [adjOR] 1.88, 95% CI 1.05-3.36; < or =3 months 6.9% versus 2.5%, adjOR 2.32, 95% CI 1.03-5.25; first intercourse 1.5% versus 0.5%, adjOR 5.75, 95% CI 1.13-29.3). Although the total number of semen exposures was lower in SGA, SGA was not associated with a shorter duration of sexual relationship. On post hoc analysis, the subgroup of SGA with abnormal uterine artery Doppler at 20 weeks (N=58) were more likely to have had a short sexual relationship compared with controls (< or =6 months adjOR 2.33, 95% CI 1.09-4.98; < or =3 months adjOR 3.22, 95% CI 1.18-8.79; first intercourse adjOR 8.02, 95% CI 1.58-40.7). We conclude that compared to uncomplicated pregnancies, short duration of sexual relationship is more common in women who develop preeclampsia and women with abnormal uterine artery Doppler waveforms who deliver an SGA baby.

Is the use of donor sperm associated with a higher incidence of preeclampsia in women who achieve pregnancy after intrauterine insemination?

OBJECTIVE

To evaluate the incidence of preeclampsia after intrauterine insemination (IUI) with either donor's or partner's sperm in women with primary infertility.

DESIGN

Retrospective cohort study.

SETTING

Tertiary referral center.

PATIENTS

Between January 1999 and December 2006, 823 women who achieved pregnancy after IUI and delivered at > or =24 weeks of gestation were reviewed. Only women with primary infertility and no known medical disorders were included. On the basis of the available outcome data, the final analysis was performed in 713 pregnancies (438 pregnancies using donor's sperm and 275 pregnancies using partner's sperm).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

The incidence of preeclampsia.

RESULT(S)

The incidence of preeclampsia in pregnancies resulting from donor sperm was higher than in the partner insemination group: 10.9% (48/438) versus 7.2% (20/275), respectively (difference, 3.7; 95% confidence interval -0.8 to +7.8). Logistic regression was performed controlling for the following parameters: type of sperm, number of previous cycles, and number of babies. In the final model, the variables that significantly predicted the risk of preeclampsia were the type of sperm used for insemination and the number of previous IUI cycles performed. The fewer cycles that were performed, the higher the incidence of preeclampsia that was observed.

CONCLUSION(S)

IUI with donor sperm appears to increase the incidence of preeclampsia when pregnancy is achieved. A protective effect of multiple cycles appears also to be present in this respect.

Murine models for HIV vaccination and challenge

HIV-1 only infects humans and chimpanzees. SIV or SHIV are, therefore, used as models for HIV in rhesus, cynomologus and pigtail macaques. Since conducting experiments in primate models does not fully mimic infection or vaccination against HIV-1 and is expensive, there is a great need for small-animal models in which it is possible to study HIV-1 infection, immunity and vaccine efficacy. This review summarizes the available murine models for studying HIV-1 infection with an emphasis on our experience of the HIV-1-infected-cell challenge as a model for evaluating candidate HIV-1 vaccines. In the cell-based challenge model, several important factors that, hopefully, can be related to vaccine efficacy in humans were discovered: the efficiency of combining plasmid DNA representing several of the viral genes originating from multiple clades of HIV-1, the importance of adjuvants activating innate and induced immunity and the enhanced HIV eradication by drug-conjugated antibody.

Combining human antisera to human leukocyte antigens, HIVgp120 and 70 kDa heat shock protein results in broadly neutralizing activity to HIV-1

OBJECTIVE

To elicit broadly neutralizing antibody activity by combining polyclonal human serum IgG antibodies with HIVgp120, human leukocyte antigen (HLA) class I or class II and 70 kDa heat shock protein.

DESIGN

: In addition to HIV antigens, HIV-1 virions express HLA class I, HLA class II and 70 kDa heat shock protein molecules, which have quantitative and functional significance. The complementary effect of combining human polyclonal IgG antibodies with these antigens may result in effective broad spectrum neutralizing activity.

METHODS

Polyclonal human sera with IgG antibodies and monoclonal antibody to HLA class I or class II, HIVgp120 and 70 kDa heat shock protein were selected and used in single, double or triple combinations. Dose-dependent inhibition studies of HIV-1 clades A, B, C and D were carried out using human CD4 T cells treated with the combinations of human sera and with monoclonal antibodies for clade B. The results are presented as half maximal (IC50) inhibitory concentration and maximum inhibition by these sera.

RESULTS

The half maximal (IC50) inhibitory concentration of clade B HIV-1 infection with single or a combination of two antisera was higher than those with three antisera, which also showed maximum inhibition of HIV-1. Further investigations of human sera with HIV-1 clades C and D also showed lower half maximal (IC50) inhibitory concentrations and higher maximum inhibition with combinations of the three antisera, but this was not seen with clade A.

CONCLUSION

A novel vaccination strategy eliciting broadly neutralizing antibody activity to the CCR5-using HIV-1 clades B, C and D has been demonstrated by the trimolecular complex of human antisera with HLA class II or class I, HIVgp120 and 70 kDa heat shock protein.

Analysis of a high-throughput HLA antibody screening assay for use with platelet donors

BACKGROUND

Passive infusion of HLA antibodies has been implicated in transfusion reactions. A rapid, inexpensive method of screening blood donors for HLA antibodies might reduce the incidence of reactions. A high-throughput microbead-flow analyzer HLA antibody detection technique was compared with an enzyme-linked immunosorbent assay (ELISA) method.

STUDY DESIGN AND METHODS

Ninety-six apheresis platelet (PLT) donors were tested for antibodies to Class I and II HLA antigens with mixed-antigen microbead-flow analyzer and ELISAs. For both assays, samples reactive in the mixed-antigen assay were tested with a panel-reactive antibody (PRA) assay. Samples reactive in both the mixed-antigen and the PRA assays were considered positive.

RESULTS

In the mixed-antigen microbead assay, 46 (48%) samples were reactive to Class I antigens and 20 (21%) to Class II. Further testing in the microbead PRA assay revealed that 34 (35%) had antibodies to Class I antigens, 18 (19%) to Class II, and 42 (44%) to either Class I or Class II. Class I antibodies were present in 56 percent of females and 36 percent of males. In the mixed-antigen ELISA, 4 samples were reactive with Class I antigens, 4 with Class II antigens, and 5 with Class I or Class II. All 5 reactive samples were also reactive in the ELISA PRA assay and were from females.

CONCLUSION

The microbead assay was more sensitive than the ELISA and detected antibodies in a large proportion of donors. Samples reactive in the mixed-antigen microbead assay should be confirmed by a second assay before concluding that antibodies are present.

Why circumcision is a biomedical imperative for the 21(st) century

Circumcision of males represents a surgical "vaccine" against a wide variety of infections, adverse medical conditions and potentially fatal diseases over their lifetime, and also protects their sexual partners. In experienced hands, this common, inexpensive procedure is very safe, can be pain-free and can be performed at any age. The benefits vastly outweigh risks. The enormous public health benefits include protection from urinary tract infections, sexually transmitted HIV, HPV, syphilis and chancroid, penile and prostate cancer, phimosis, thrush, and inflammatory dermatoses. In women circumcision of the male partner provides substantial protection from cervical cancer and chlamydia. Circumcision has socio-sexual benefits and reduces sexual problems with age. It has no adverse effect on penile sensitivity, function, or sensation during sexual arousal. Most women prefer the circumcised penis for appearance, hygiene and sex. Given the convincing epidemiological evidence and biological support, routine circumcision should be highly recommended by all health professionals.

Quantitation of HLA proteins incorporated by human immunodeficiency virus type 1 and assessment of neutralizing activity of anti-HLA antibodies

Human anti-human leukocyte antigen (HLA) antibodies were assessed for neutralizing activity against human immunodeficiency virus type 1 (HIV-1) carrying HLA alleles with matching specificity. Multiparous women carrying anti-HLA antibodies were identified. Plasma samples from those women were confirmed as having antibodies that specifically bound to HLA proteins expressed on the peripheral blood mononuclear cells (PBMCs) of their husbands. A primary HIV-1 isolate was cultured in the husband's PBMCs so that the virus carried matching HLA alleles. To determine the HIV-1-neutralizing activity of anti-HLA antibodies, the infectivity of the virus for GHOST cells (which express green fluorescent protein after HIV infection) was investigated in the presence of a plasma sample positive for the respective anti-HLA antibody. A neutralization assay was also performed using purified immunoglobulin G (IgG) from two plasma samples, and two plasma samples were investigated in the presence of complement. The prerequisite for anti-HLA antibody-mediated neutralization is incorporation of HLA proteins by HIV-1. Therefore, the extent of incorporation of HLA proteins by the primary HIV-1 isolate was estimated. The ratios of HLA class I protein to HIV-1 capsid (p24) protein cultured in the PBMCs of two healthy individuals were 0.017 and 0.054. These ratios suggested that the HIV-1 strain used in the assay incorporated more HLA proteins than gp160 trimers. Anti-HLA antibody-positive plasma was found to contain antibodies that specifically reacted to HIV-1 carrying cognate HLA alleles. However, incubation of HIV-1 with anti-HLA antibody- positive plasma or purified IgG did not show a reduction in viral infectivity. HIV-1-neutralizing activity was also not detected in the presence of complement. This study shows that HIV-1 primary isolates cultured in PBMCs contain significant amounts of HLA proteins. However, the binding of antibodies to those HLA proteins does not mediate a reduction in viral infectivity.

Mucosal challenge with cell-associated or cell-free feline immunodeficiency virus induces rapid and distinctly different patterns of phenotypic change in the mucosal and systemic immune systems

The majority of human immunodeficiency virus type 1 (HIV-1) infections occur via mucosal transmission through contact with genital secretions containing cell-associated and cell-free virus. However, few studies have assessed whether exposure to cells, HIV-1 infected or uninfected, plays a role in the sexual transmission of HIV-1. This study examined phenotypic changes in mucosal and systemic lymphoid tissue 24 hr after vaginal exposure to in vitro equilibrated infectious doses of cell-associated or cell-free feline immunodeficiency virus, uninfected heterologous cells, or medium alone. We found that even at this early time-point, mucosal exposure to virus induced substantial alterations in the phenotype and distribution of leucocytes, particularly in the tissues of the mucosal immune system. Second, we found that the type of virus inoculum directly influenced the phenotypic changes seen. Vaginal exposure to cell-free virus tended to induce more generalized phenotypic changes, typically in the peripheral immune system (blood and systemic lymph nodes). In contrast, exposure to cell-associated virus was primarily associated with phenotypic shifts in the mucosal immune system (gut and mucosal/draining lymph nodes). In addition, we found that exposure to uninfected heterologous cells also induced alterations in the mucosal immune system. These data suggest that significant immune changes occur within the first 24 hr of virus exposure, well before substantial replication would be anticipated. As the mucosal immune system, and particularly the gut, is an early and persistent target for lentiviral replication, these findings have substantial implications for HIV-1 pathogenesis and vaccine development.

Circumcision and HIV transmission

PURPOSE OF REVIEW

To review the recent literature on male circumcision and its effect on HIV acquisition.

RECENT FINDINGS

The report from the randomized clinical trial of male circumcision in South Africa demonstrating a 60% protective effect in preventing HIV acquisition provided the first clinical trial evidence of efficacy of male circumcision in protecting men against HIV infection. This protective effect was consistent with both ecological and epidemiologic studies which also show a protective effect of 50-70% in men at high risk for HIV infection. Biological studies also demonstrate an increased number of HIV receptor cells in the mucosa of foreskin providing additional evidence of HIV susceptibility in the uncircumcised male. Male circumcision may also have a beneficial effect in preventing HIV acquisition in women and lowering selected sexually transmitted infections in both sexes.

SUMMARY

The results of two ongoing randomized clinical trials of male circumcision in Kenya and Uganda are awaited with interest, however male circumcision should be carefully considered as a potential public health tool in preventing HIV acquisition. If other trials confirm the results of the South African trial, implementation of this surgical procedure will need to be carefully scaled up and integrated into other prevention programs with emphasis on surgical training, aseptic techniques, acceptability, availability and cultural considerations.

Pre-eclampsia: Is the immune maladaptation hypothesis still standing? An epidemiological update

Despite much research, and clear improvement in our understanding of risk factors and pathogenetic mechanisms, the exact etiology of pre-eclampsia remains unknown. The immune maladaptation hypothesis has been challenged recently by several large epidemiological studies. One of the explanations for contradictory findings might be that the type of pre-eclampsia seen by obstetricians in developed countries mostly involves 30 and more years old, mildly obese pregnant women having near-term pre-eclampsia. It could be that this type of pre-eclampsia is primarily related to pre-existing maternal constitutional factors. This type of pre-eclampsia might be the dominant type of pre-eclampsia in the large Scandinavian and USA studies. In contrast, the epidemiology of pre-eclampsia in young women (age 15-25), so commonly seen in developing countries and certain lower socio-economic groups in developed countries, appears more in line with the immune maladaptation hypothesis. The aim here is to provide an updated review on studies supporting or challenging the immune maladaptation hypothesis.

Mechanisms of Disease: alloimmunization in renal diseases

Graft rejection has long been considered the paradigm of renal diseases induced by alloimmunization, particularly alloimmunization directed against HLA antigens. Accumulating evidence indicates that non-HLA immunity also has an important role in clinical transplantation. Targets of alloimmunization include antigens of tubular basement membrane, tubular epithelial cells and endothelial cells. They can be polymorphic allovariants (as shown in the rat) or 'hidden' antigens exposed when the graft is damaged. Alloimmunization can also occur when a person genetically deficient in a renal protein (e.g. the alpha5 (IV) collagen chain in X-linked Alport's syndrome or nephrin in Finnish-type nephrotic syndrome) is transplanted to treat end-stage renal failure. The non-mutated protein in the donor kidney is recognized as a foreign antigen, and the resulting alloimmune response can damage the graft. We have demonstrated that alloimmunity can also affect the native kidney. We have characterized a novel fetomaternal disease in which a genetic defect in the MME gene encoding neutral endopeptidase (NEP) in the mother leads to the development of membranous nephropathy in her fetus (maternal anti-NEP antibodies bind to NEP on fetal podocytes). Our findings raise the possibility that mutations or genetic polyporphisms in MME or other genes expressed by the podocyte are involved in alloimmune-mediated development of membranous nephropathy after kidney or bone marrow transplantation.