Divergent neuroimmune signatures in the cerebrospinal fluid predict differential gender-specific survival among patients with HIV-associated cryptococcal meningitis

Introduction

Survival among people with HIV-associated cryptococcal meningitis (CM) remains low, particularly among women, despite the currently optimal use of antifungal drugs. Cryptococcus dissemination into the central nervous system [brain, spinal cord, and cerebrospinal fluid (CSF)] elicits the local production of cytokines, chemokines, and other biomarkers. However, no consistent diagnostic or prognostic neuroimmune signature is reported to underpin the risk of death or to identify mechanisms to improve treatment and survival. We hypothesized that distinct neuroimmune signatures in the CSF would distinguish survivors from people who died on antifungal treatment and who may benefit from tailored therapy.

Methods

We considered baseline clinical features, CSF cryptococcal fungal burden, and CSF neuroimmune signatures with survival at 18 weeks among 419 consenting adults by "gender" (168 women and 251 men by biological sex defined at birth).

Results

Survival at 18 weeks was significantly lower among women than among men {47% vs. 59%, respectively; hazard ratio (HR) = 1.4 [95% confidence interval (CI), 1.0 to 1.9; p = 0.023]}. Unsupervised principal component analysis (PCA) demonstrated divergent neuroimmune signatures by gender, survival, and intragender-specific survival. Overall, women had lower levels of programmed death ligand 1, Interleukin (IL) (IL-11RA/IL-1F30, and IL-15 (IL-15) than men (all p < 0.028). Female survivors compared with those who died expressed significant elevations in levels of CCL11 and CXCL10 chemokines (both p = 0.001), as well as increased T helper 1, regulatory, and T helper 17 cytokines (all p < 0.041). In contrast, male survivors expressed lower levels of IL-15 and IL-8 compared with men who died (p < 0.044).

Conclusions

Survivors of both genders demonstrated a significant increase in the levels of immune regulatory IL-10. In conclusion, the lower survival among women with CM was accompanied by distinct differential gender-specific neuroimmune signatures. These female and male intragender-specific survival-associated neuroimmune signatures provide potential targets for interventions to advance therapy to improve the low survival among people with HIV-associated CM.

Divergent Neuroimmune Signatures in the Cerebrospinal Fluid Predict Differential Gender-Specific Survival Among Patients With HIV-Associated Cryptococcal Meningitis

Survival among people with HIV-associated cryptococcal meningitis (CM) remains low, exceptionally among women with the increased threat of death on current optimal use of antifungal drugs. Cryptococcus dissemination into the central nervous system (CNS) prompts a neuroimmune reaction to activate pathogen concomitant factors. However, no consistent diagnostic or prognostic immune-mediated signature is reported to underpin the risk of death or mechanism to improve treatment or survival. We theorized that the distinct neuroimmune cytokine or chemokine signatures in the cerebrospinal fluid (CSF), distinguish survivors from people who died on antifungal treatment, who may benefit from tailored therapy. We considered the baseline clinical disease features, cryptococcal microbiologic factors, and CSF neuroimmune modulated signatures among 419 consenting adults by gender (biological sex assigned at birth) (168 females and 251 males) by 18 weeks of survival on antifungal management. Survival at 18 weeks was inferior among females than males (47% vs. 59%; hazard ratio HR=1.4, 95% CI: 1.0 to 1.9, and p=0.023). Unsupervised principal component analysis (PCA) demonstrated the divergent neuroimmune signatures by gender, survival, and intragender-specific survival. Overall, females displayed lower levels of PD-L1, IL-1RA, and IL-15 than males (all p≤0.028). Female survivors compared with those who died, expressed significant fold elevations in levels of CSF (CCL11 - myeloid and CXCL10 - lymphoid chemokine (in both p=0.001), and CSF Th1, Th2, and Th17 cytokines. In contrast, male survivors expressed distinctly lower levels of CSF IL-15 and IL-8 compared with those who died. Survivors of either gender demonstrated a significant increase in the levels of immune regulatory element, IL-10. In the finale, we classified divergent neuroimmune key signatures in CSF by gender, survival, and intragender-specific survival among people with HIV-associated cryptococcal meningitis. These intragender-specific survival associated-neuroimmune signatures, suggests the discrete role of gender immune regulating mechanisms as the possible targets for interventions to advance therapy to improve survival among people with HIV-associated cryptococcal meningitis.

A novel herpesvirus in the sanctuary chimpanzees on Ngamba Island in Uganda

BACKGROUND

Recent studies in non-human primates have led to the discovery of novel primate herpesviruses. In order to get more information on herpesvirus infections in apes, we studied wild born captive chimpanzees.

METHODS

Chimpanzees of the Ngamba island sanctuary, Uganda, were analyzed with pan-herpes polymerase chain reaction (PCR) targeting the herpesvirus DNA polymerase gene and the glycoprotein B gene. The obtained sequences were connected by long-distance PCR, and analyzed phylogenetically.

RESULTS

Twenty-one of 40 individuals were infected with members of the Gammaherpesvirinae, two of them with a novel member of this subfamily. Phylogenetically, the novel virus fell into a clade of primate rhadinoviruses and the Kaposi sarcoma herpesvirus (human herpesvirus 8), representing a third distinct rhadinovirus in chimpanzees.

CONCLUSION

Non-human primates harbor several herpesviruses many of which are still unknown. This has implications to management of primates in sanctuaries requiring continuous updates on the management protocols to deal with potential occupational pathogens.

Identification of the causative organism of tuberculous lymphadenitis in ethiopia by PCR

Tuberculous lymphadenitis (TBLN) is a common form of extrapulmonary tuberculosis with multiple differential diagnoses. Demonstration of the etiologic agent by smear microscopy or culture of fine needle aspirate (FNA) specimens is often unsuccessful. FNA specimens from 40 patients presenting at a rural health center in South Ethiopia and diagnosed as positive for TBLN on the basis of clinical and cytological criteria were analyzed for mycobacterial DNA by PCR. Thirty (75%) had cervical lymphadenitis and 11 (27.5%) were seropositive for human immunodeficiency virus (HIV). Three primer sets were initially used to identify the causative agent at the genus (antigen 85 complex), complex (IS6110 insertion sequence), and species (pncA gene and allelic variation) levels. Among the forty TBLN cases, 35 (87.5%) were positive by PCR at the genus and complex levels. Based on PCR for detection of allelic variation at position 169, 24 (68.6%) of the 35 were positive for Mycobacterium tuberculosis and 6 (17.1%) were positive for M. bovis. These six were positive in additional PCR assays using the JB21-JB22 primer set, which is highly specific for M. bovis. Five (14.1%) showed amplification for both M. tuberculosis and M. bovis with the allele-specific primer set. Cooccurrence of pyrazinamide (PZA)-sensitive and -resistant M. tuberculosis in those five cases was indicated, since all were negative in assays with the JB21-JB22 primer set. This feature was seen in 3 of 11 HIV-positive and 2 of 29 HIV-negative individuals (P < 0.001).

CONCLUSION

among 35 PCR-positive cases of TBLN from southern Ethiopia, 29 (82.9%) were caused by M. tuberculosis and six (17.1%) were caused by M. bovis.

The African Green Monkey model for cutaneous and visceral leishmaniasis

Non-human primates are valuable models for biomedical research because of their similarities to human anatomy, immunology and physiology. Leishmaniasis, a disease caused by protozoan parasites, has a worldwide distribution and results in high morbidity and mortality. Availability of a non-human primate model of leishmaniasis would facilitate the study of different aspects of this disease and would accelerate the development of vaccines and new drugs. In this article, some interesting features of the vervet monkey (African Green monkey) model of human cutaneous and visceral leishmaniasis are discussed.

Circulating TNF-alpha, TGF-beta, and IL-10 in tuberculosis patients and healthy contacts

Levels of tumour necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta, and interleukin (IL)-10 in plasma of pulmonary tuberculosis (TB) patients and healthy contacts and plasma and pleural fluid of patients with tuberculous pleuritis were examined by enzyme immunoassay. Plasma TNF-alpha and IL-10 were elevated to significant levels in healthy contacts. High levels of TGF-beta and IL-10 were also detected in plasma from TB patients and healthy contacts. Pleural fluid contained all three cytokines with the level of IL-10 being highest followed by TGF-beta and TNF-alpha. Plasma of tuberculous pleuritis patients also had detectable levels of the three cytokines. Increased levels of TNF-alpha in plasma of contacts and to some extent pleural fluid of pleuritis patients, is perhaps to limit the infection, while elevated IL-10 in plasma of TB patients and contacts and pleural fluid would perhaps modulate excess proinflammation. Elevated TGF-beta in TB patients suggests its role in the immunopathogenesis.

Vervet monkeys vaccinated with killed Leishmania major parasites and interleukin-12 develop a type 1 immune response but are not protected against challenge infection

Leishmania major is a protozoan parasite that causes chronic cutaneous lesions that often leave disfiguring scars. Infections in mice have demonstrated that leishmanial vaccines that include interleukin-12 (IL-12) as an adjuvant are able to induce protective immunity. In this study, we assessed the safety, immunopotency, and adjuvant potential of two doses of IL-12 when used with a killed L. major vaccine in vervet monkeys. The induction of cell-mediated immunity following vaccination was determined by measuring delayed-type hypersensitivity, in vitro lymphocyte proliferation, and gamma interferon (IFN-gamma) production. Protection was assessed by challenging the animals with L. major parasites and monitoring the course of infection. At low doses of IL-12 (10 microg), a small increase in the parameters of cell-mediated immunity was observed, relative to those in animals that received antigen without IL-12. However, none of these animals were protected against a challenge infection. At higher doses of IL-12 (30 microg), a substantial increase in Leishmania-specific immune responses was observed, and monkeys immunized with antigen and IL-12 exhibited an IFN-gamma response that was as great as that in animals that had resolved a primary infection and were immune. Nevertheless, despite the presence of correlates of protection, the disease course was only slightly altered, and protection was low compared to that in self-cured monkeys. These data suggest that protection against leishmaniasis may require more than the activation of Leishmania-specific IFN-gamma-producing T cells, which has important implications for designing a vaccine against leishmaniasis.

The presence of Cryptosporidium oocysts in stools of clinically diarrhoeic and normal nonhuman primates in Kenya

A total of 114 nonhuman primates comprising 51 vervet monkeys (Cercopithecus aethiops) and 63 olive baboons (Papio anubis) were examined for Cryptosporidium oocysts using the modified Kinyoun's acid-fast staining technique. About 51.7% (59/114) of all the specimens examined, representing 78.4% (40/51) of the vervet monkeys and 30.1% (19/63) of the olive baboons were positive. Bright red, refractile Cryptosporidium oocysts were observed in the stained faecal smears against a blue background. Up to 4/6 (66.7%) of the diarrhoeic vervets and 2/3 (66.7%) baboons, respectively, were positive while the rest were negative. To the best of our knowledge, this report is the first on cryptosporidiosis in old world nonhuman primates in Kenya and probably the first report of the infection in olive baboons. Given the high frequency of oocysts in diarrhoeal specimens, the parasite may have been associated with clinical diarrhoea in the sampled animals. Cryptosporidium, which has been reported in humans in Kenya, is also suspected to occur in livestock. Its isolation from clinically ill, normal colony-borne and newly caught feral nonhuman primates has significant implications for both public health and animal agriculture in Kenya.

Heterologous protection by Leishmania donovani for Leishmania major infections in the vervet monkey model of the disease

The study was aimed at analyzing immunological cross-reactivity between Leishmania major and Leishmania donovani and possible cross-protection between the two parasite species in the vervet monkey model of the disease. Nine vervet monkeys (Cercopithecus aethiops) from the institute animal colony were sued in the study. Five of the animals had been previously infected with L. donovani but had remained asymptomatic while the other four animals were naive and comprised the control group. Immunological responses to both L. major and L. donovani antigens in the five animals with prior exposure to L. donovani were examined before challenge. High antibody titers to the two antigens were demonstrated in an enzyme-linked immunosorbent assay, but the antibody titers to L. donovani were significantly higher than those to L. major (P < 0.005). Positive in vitro peripheral blood leucocyte (PBL) proliferation to L. major and L. donovani antigens was also demonstrated, but there was no significant difference in the response to the two antigens (P > 0.1). High and varying levels of interferon gamma (IFN-gamma) were secreted in PBL from the five vervet monkeys when stimulated with L. major antigen, but vervet monkey 1296 secreted marginal levels of IFN-gamma. When the animals were challenged intradermally with 1 x 10(5) virulent L. major promastigotes mixed with sandfly vector salivary gland lysate all four vervet monkeys in the control group developed nodules of varying sizes at the inoculation sites that eventually ulcerated. However, nodule formation and ulceration occurred at different times among these animals. The other five animals (animals with prior exposure to L. donovani) did not pick up the infection at all, but one animal from this group, vervet monkey 1296, developed a transient lesion that healed within 9 weeks, the same animal that had been shown to secrete low levels of IFN-gamma. The results demonstrate high cross-reactivity between L. donovani and L. major and that L. donovani protects against L. major infections. This finding is important for vaccine development studies against leishmaniasis.

Vaccination of vervet monkeys against cutaneous leishmaniosis using recombinant Leishmania 'major surface glycoprotein' (gp63)

Vervet monkeys (Cercopithicus aethiops) were shown to give a positive delayed-type hypersensitivity (DTH) reaction to gp63, a major surface glycoprotein of Leishmania parasites, and also produce antibodies to the molecule following a triple vaccination with a total dose of 150 micrograms of recombinant gp63 mixed with Bacille Calmette Guerin (BCG). However, peripheral blood leucocytes (PBL) from these animals neither proliferated nor produced any interferon-gamma (IFN-gamma) following in vitro stimulation with the antigen. Analysis of lymphocyte subsets following vaccination did not reveal any striking phenotypic alteration of cellular sub-populations in PBL. When vaccinated animals were rechallenged, via the needle, with virulent Leishmania major promastigotes containing salivary gland extracts from vector sandflies, only partial protection was achieved. We concluded from these studies that rgp63 produced in Escherichia coli is a safe vaccine molecule which gives only partial protection following vaccination in the vervet monkey host. The molecule requires further improvement for vaccine and/or immunodiagnosis application.

The chemotactic effect of Phlebotomus duboscqi (Diptera: Psychodidae) salivary gland lysates to murine monocytes

The possibility that salivary gland lysates of Phlebotomus duboscqi are able to attract vertebrate monocytes was investigated. In vitro studies showed that salivary gland lysates of P. duboscqi, the vector of Leishmania major in Kenya, are chemotactic to mouse peritoneal monocytes. This attraction of monocytes by vector salivary gland lysates may form part of the mechanisms through which sandfly saliva ensures successful parasitization of macrophages in a susceptible host by Leishmania parasites.

Evaluation of immune associated cells in lesions of L. major infected vervet monkeys (Cercopithecus aethiops)

Vervet monkeys were used to characterize immune associated cell types recruited into lesion sites as a result of experimental primary and secondary infections with Leishmania major. A heavy cellular infiltration consisting primarily of CD8+ (cytotoxic/suppressor) T cells were observed in the lesions. A small number of B lymphocytes and NK cells were also stained. Changes in cell type populations observed in the lesions were similarly reflected in the draining lymph nodes. Studies from control sites in all the animals revealed the presence of CD8+ T cells both in the epidermis and dermal layers of the normal skin. B cells, CD16 (NK cells) and CD4 (helper T cells) positive cells were virtually absent in the normal skin. It was concluded that CD8+ T cells were the predominant cells in the lesions. It also appeared that similar cell types were restricting the parasites at the lesion site both in primary and secondary L. major infections in vervet monkeys.

Visceral leishmaniasis in vervet monkeys: immunological responses during asymptomatic infections

Nine vervet monkeys (Cercopithecus aethiops) were infected intradermally with 8 x 10(7) virulent L. donovani promastigotes. Four animals developed clinical visceral leishmaniasis and died over a period of 18 months. The remaining five animals have remained asymptomatic for a period of 3 years now. Attempts to isolate parasites from spleen and liver through biopsies were fruitless. Immunological responses of these subclinically infected animals were examined. Enzyme-linked immunosorbent assay (ELISA) and western blot analyses demonstrated Leishmania specific antibodies in these animals, but the antibody titres were low. When proliferation of peripheral blood monocytes (PBMC) to Concanavalin A (Con A) of these animals was compared with control 'disease free animals' there were no significant differences in response. However, L. donovani antigen (fixed promastigotes) specific proliferation was demonstrated in the five subclinically infected animals. High and varying levels of interferon gamma (IFN-gamma) were secreted in PBMC cultures from the five vervet monkeys when stimulated with either Con A or L. donovani antigens. In control animals, IFN-gamma was only detected when PBMC were stimulated with Con A. Marked delayed-type hypersensitivity (DTH) responses were demonstrated in the five subclinically infected animals 48 h after injection with formalin fixed promastgotes. It was concluded that the visceral Leishmania disease spectrum due to L. donovani observed in humans could be induced in vervet monkeys and that L. donovani asymptomatic/cryptic infected animals have competent humoral and cellular responses to homologous parasites.

Cell-mediated responses of immunized vervet monkeys to defined Leishmania T-cell epitopes

A population of vervet monkeys was immunized with killed parasites and infected with Leishmania major promastigotes either by needle or by infected-fly bite. The responses of recovered monkeys to mitogens, killed parasites, and molecularly defined T-cell epitopes were then compared with those of control animals. Peripheral blood mononuclear cells (PBMC) from both naive and recovered animals proliferated strongly in response to both B- and T-cell mitogens, although the responses of the recovered animals were less strong than those of the naive animals. Cells from recovered vervets, but not those from naive vervets, also proliferated in response to parasite antigens and synthetic T-cell epitopes. Likewise, cells from recovered animals released gamma interferon and either interleukin 2 (IL-2) or IL-4 into culture media in response to both of the above-mentioned antigens, whereas cells from control animals did not. The fact that no IL-5 could be measured following parasite antigen or synthetic T-cell epitope stimulation of PBMC suggested that cells proliferating in response to these molecules belonged to the Th1 subset. Phenotypic analysis of the PBMC showed a marked increase in T-cell but not B-cell populations in recovered animals. Among this population was an increased number of CD45R0+ memory cells. The data from this study are in keeping with the earlier finding that vervet monkeys provide an excellent model system for leishmaniasis. Further, these data support the contention that synthetic T-cell epitopes are prime candidates for molecularly defined Leishmania vaccines.

IFN-gamma and delayed-type hypersensitivity are associated with cutaneous leishmaniasis in vervet monkeys following secondary rechallenge with Leishmania major

IFN-gamma levels and delayed-type hypersensitivity (DTH) responses were evaluated in vervet monkeys, following secondary infection with Leishmania major (L. major). The animals had previously been vaccinated with leishmanial antigen, exposed to a primary infection and allowed to self-cure. Supernatants of peripheral blood mononuclear cell (PBMC) cultures, stimulated with either L. major antigen or Concanavalin A (Con A), were examined for the presence of IFN-gamma in a double sandwich enzyme-linked immunosorbent assay (ELISA). Significant levels of IFN-gamma were detected during active disease and following self-cure in both antigen and Con A supernatants. Higher levels of IFN-gamma were, however, present during active disease as compared with after self-cure. Positive and strong DTH responses were elicited in all experimental animals, following intradermal injection of fixed promastigotes (5 x 10(7)/animal) before rechallenge, during active infection and following self-cure. Again, strongest DTH responses were obtained during active infection as compared with the other sampling points. There was a correlation between IFN-gamma levels and DTH responses. It was concluded that IFN-gamma secretion and positive DTH responses are associated with secondary L. major infection and represent specific immunological correlates of protection in this disease model.

Reactivity of some monoclonal antibodies specific for human lymphocytes with vervet monkey peripheral blood mononuclear cells

Reactivities of some monoclonal antibodies to human lymphocyte surface antigens were tested on vervet monkey peripheral blood mononuclear cells (PBMC), using flow cytometry and immunoperoxidase techniques. A number of antibodies were identified which reacted with similar populations of lymphocytes from vervet monkeys. These included antibodies that define T cells, suppressor/cytotoxic cell subset, pan B cells, monocytes and MHC class I and II. A number of anti-CD4 markers examined were unsuitable for use in the vervet system.

Generation of bovine intraspecies hybridomas with initial suppressed growth

Bovine B-cell hybrids were generated by fusing pokeweed mitogen (PWM) activated normal bovine peripheral blood lymphocytes (PBL) with an aminopterin-sensitive bovine B-cell line BL20. The fusion partner was derived by irradiation and growth in medium containing increasing concentrations of 6-thioguanine (6TG). Resultant cells were designated ATS/BL20. Polyethylene glycol-induced (PEG) fusion was used and hybrids were selected in hypoxanthine-aminopterin-thymidine (HAT) medium. Hybrid cell growth was noticed after 4 to 6 weeks of fusion following a period of quiescence. Hybrid formation was confirmed by selection in HAT medium, expression of cytoplasmic IgM (cIgM) and surface antigens and karyotype analysis.

Experimental transmission of Leishmania major to vervet monkeys (Cercopithecus aethiops) by bites of Phlebotomus duboscqi (Diptera: Psychodidae)

Experimental transmission of Leishmania major to vervet monkeys (Cercopithecus aethiops) was accomplished by bites of Phlebotomus duboscqi sandflies. Three-day-old, laboratory-reared P. duboscqi were fed on leishmanial lesions on hamsters infected with L. major. The flies were re-fed on monkeys 10 d after infection. Five adult male vervet monkeys were used in concurrent transmission trials. Two of the monkeys received subcutaneous inoculations with stationary-phase promastigotes (2 x 10(6) promastigotes in 0.1 ml of medium) on the base of the tail. Putatively infected P. duboscqi were allowed to feed on the remaining 3 monkeys at sites on the base of the tail and on the right eyebrow. Challenges by sandfly bites resulted in multiple leishmanial lesions at all bite sites and, consequently, more lesion area than was produced by needle challenges. Post-feeding dissection of sandflies indicated that multiple lesions could be caused by bites of a single fly, and that probing alone, without imbibing blood, was sufficient for transmission. These first experimental transmissions of L. major to vervets by bites of P. duboscqi demonstrate that sandfly challenge is an efficient alternative to needle challenge, making available a unique Leishmania-sandfly-non-human primate model for use in vaccine development.

Selected phenotypic and cloning properties of a bovine lymphoblastoid cell line, BL20

A bovine lymphoblastoid cell line, BL20, was shown to express a BoLA antigen and surface IgM, implying that it was probably of B-cell origin. At low density (less than 10(5)/ml), the cells failed to grow. Inclusion of growth factor-containing supernatants from concanavalin A or pokeweed mitogen (PWM)-activated bovine lymphocytes or from thymus fibroblast-like cells did not improve cloning of the cells. Feeder cells also did not enhance cloning of the cells except for bovine thymus fibroblast-like cell monolayer.

In vitro secretion of bovine immunoglobulins during pokeweed mitogen or pokeweed mitogen and antigen activation of lymphocytes

Activation of bovine peripheral blood mononuclear cells (PBM) towards immunoglobulin (Ig) synthesis and secretion was examined in vitro using pokeweed mitogen (PWM) or PWM plus sheep red blood cells (SRBC). Bovine PBM were composed of 7-30% B cells, 25-56% T cells and 1-4% macrophages. Cell density and PWM concentrations were critical parameters for obtaining reproducible maximum lymphocyte proliferation and polyclonal B cell activation. Inclusion of aminopterin, a folic acid antagonist, reduced cellular proliferation and viability but had no apparent effect on the time of appearance of peak proliferation. Co-culture of PBM with SRBC and PWM generated anti-SRBC specific antibodies.

Antibodies to Leishmania tropica promastigotes during infection in mice of various genotypes

After intradermal injection of 10(7) promastigotes of a particular isolate of the intramacrophage protozoan parasite, Leishmania tropica, the development of disease (cutaneous lesions) is much more severe in BALB/c than in three other mouse strains, C57BL/6,C3H/He and CBA/H. Using fixed promastigotes and 125I-labelled protein A in a solid-phase radioimmunoassay (RIA), titres of antibody were shown to increase up to about day 50 of infection. However, titres were not markedly different in BALB/c mice compared with the other three resistant strains, although antibody levels were highest in sera from the diseased BALB/c mice at late time points. Using isotype-specific antisera in the RIA, and sera from the day 50 time point, the isotype distribution of anti-promastigote antibodies was not noticeably different in sera from mice of the four genotypes with IgG1 and IgG2a (+/- IgG2b) antibodies predominating. It is concluded that differences in susceptibility to disease in this murine model of cutaneous leishmaniasis do not correlate with any decrease or increase in any particular antibody response to the promastigote.