Recently activated CD4 T cells in tuberculosis express OX40 as a target for host-directed immunotherapy

After Mycobacterium tuberculosis (Mtb) infection, many effector T cells traffic to the lungs, but few become activated. Here we use an antigen receptor reporter mouse (Nur77-GFP) to identify recently activated CD4 T cells in the lungs. These Nur77-GFPHI cells contain expanded TCR clonotypes, have elevated expression of co-stimulatory genes such as Tnfrsf4/OX40, and are functionally more protective than Nur77-GFPLO cells. By contrast, Nur77-GFPLO cells express markers of terminal exhaustion and cytotoxicity, and the trafficking receptor S1pr5, associated with vascular localization. A short course of immunotherapy targeting OX40+ cells transiently expands CD4 T cell numbers and shifts their phenotype towards parenchymal protective cells. Moreover, OX40 agonist immunotherapy decreases the lung bacterial burden and extends host survival, offering an additive benefit to antibiotics. CD4 T cells from the cerebrospinal fluid of humans with HIV-associated tuberculous meningitis commonly express surface OX40 protein, while CD8 T cells do not. Our data thus propose OX40 as a marker of recently activated CD4 T cells at the infection site and a potential target for immunotherapy in tuberculosis.

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.

Utility of Cerebrospinal Fluid Protein Levels as a Potential Predictive Biomarker of Disease Severity in HIV-Associated Cryptococcal Meningitis

Background

Cerebrospinal fluid (CSF) protein levels exhibit high variability in HIV-associated cryptococcal meningitis from being normal to markedly elevated. However, the clinical implications of CSF protein levels in cryptococcal meningitis remain unclear.

Methods

We analysed data from 890 adults with HIV-associated cryptococcal meningitis randomized into two clinical trials in Uganda between 2015 and 2021. CSF protein was grouped into ≥100 mg/dL (n=249) and <100 mg/dL (n=641). We described baseline clinical variables and mortality by CSF protein levels.

Results

Approximately one-third of individuals had a baseline CSF protein ≥100 mg/dL. Those with CSF protein ≥100 mg/dL were more likely to present with Glasgow coma scale scores <15 (P<0.01), self-reported seizures at baseline (P=0.02), higher CD4 T-cells (p<0.001), and higher CSF white cells (p<0.001). Moreover, those with a baseline CSF protein ≥100 mg/dL also had a lower baseline CSF fungal burden (p<0.001) and a higher percentage of sterile CSF cultures at day 14 (p=0.02). Individuals with CSF protein ≥100 mg/dL demonstrated a more pronounced immune response consisting of upregulation of immune effector molecules pro-inflammatory cytokines, type-1 T-helper cell cytokines, type-3 chemokines, and immune-exhaustion marker (p<0.05). 18-week mortality risk in individuals with a CSF protein <100 mg/dL was 34% higher, (unadjusted Hazard Ratio 1.34; 95% CI, 1.05 to 1.70; p=0.02) than those with ≥100 mg/dL.

Conclusion

In cryptococcal meningitis, individuals with CSF protein ≥100 mg/dL more frequently presented with seizures, altered mental status, immune activation, and favourable fungal outcomes. Baseline CSF protein levels may serve as a surrogate marker of immune activation and prognosis.

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.

Translational research in Uganda: linking basic science to bedside medicine in a resource limited setting

BACKGROUND

Translational research is a process of applying knowledge from basic biology and clinical trials to techniques and tools that address critical medical needs. Translational research is less explored in the Ugandan health system, yet, it is fundamental in enhancing human health and well-being. With the current high disease burden in Uganda, there are many opportunities for exploring, developing and utilising translational research.

MAIN BODY

In this article, we described the current state, barriers and opportunities for translational research in Uganda. We noted that translational research is underutilised and hindered by limited funding, collaborations, laboratory infrastructure, trained personnel, equipment and research diversity. However, with active collaborations and funding, it is possible to set up and develop thriving translational research in Uganda. Researchers need to leverage existing international collaborations to enhance translational research capacity development.

CONCLUSION

Expanding the integration of clinical and translational research in Uganda health care system will improve clinical care.

Landmark clinical observations and immunopathogenesis pathways linked to HIV and Cryptococcus fatal central nervous system co-infection

Cryptococcal meningitis remains one of the leading causes of death among HIV-infected adults in the fourth decade of HIV era in sub-Saharan Africa, contributing to 10%-20% of global HIV-related deaths. Despite widespread use and early induction of ART among HIV-infected adults, incidence of cryptococcosis remains significant in those with advanced HIV disease. Cryptococcus species that causes fatal infection follows systemic spread from initial environmental acquired infection in lungs to antigenaemia and fungaemia in circulation prior to establishment of often fatal disease, cryptococcal meningitis in the CNS. Cryptococcus person-to-person transmission is uncommon, and deaths related to blood infection without CNS involvement are rare. Keen to the persistent high mortality associated with HIV-cryptococcal meningitis, seizures are common among a third of the patients, altered mental status is frequent, anaemia is prevalent with ensuing brain hypoxia and at autopsy, brain fibrosis and infarction are evident. In addition, fungal burden is 3-to-4-fold higher in those with seizures. And high immune activation together with exacerbated inflammation and elevated PD-1/PD-L immune checkpoint expression is immunomodulated phenotypes elevated in CSF relative to blood. Lastly, though multiple Cryptococcus species cause disease in this setting, observations are mostly generalised to cryptococcal infection/meningitis or regional dominant species (C neoformans or gattii complex) that may limit our understanding of interspecies differences in infection, progression, treatment or recovery outcome. Together, these factors and underlying mechanisms are hypotheses generating for research to find targets to prevent infection or adequate therapy to prevent persistent high mortality with current optimal therapy.

B Cell Compartmentalization in Blood and Cerebrospinal Fluid of HIV-Infected Ugandans with Cryptococcal Meningitis

Activated B cells modulate infection by differentiating into pathogen-specific antibody-producing effector plasmablasts/plasma cells, memory cells, and immune regulatory B cells. In this context, the B cell phenotypes that infiltrate the central nervous system during human immunodeficiency virus (HIV) and cryptococcal meningitis coinfection are ill defined. We characterized clinical parameters, mortality, and B cell phenotypes in blood and cerebrospinal fluid (CSF) by flow cytometry in HIV-infected adults with cryptococcal (n = 31) and noncryptococcal (n = 12) meningitis and in heathy control subjects with neither infection (n = 10). Activation of circulating B cells (CD21low) was significantly higher in the blood of subjects with HIV infection than in that of healthy controls and greater yet in matched CSF B cells (P < 0.001). Among B cell subsets, elevated frequencies of memory and plasmablasts/plasma cells most clearly distinguished the CSF from blood compartments. With cryptococcal meningitis, lower frequencies of expression of the regulatory protein programmed death-1 (PD-1) on plasmablasts/plasma cells in blood (median, 7%) at presentation were associated with significantly decreased 28-day survival (29% [4/14 subjects]), whereas higher PD-1 expression (median, 46%) characterized subjects with higher survival (88% [14/16 subjects]). With HIV infection, B cell differentiation and regulatory markers are discrete elements of the circulating and CSF compartments with clinical implications for cryptococcal disease outcome, potentially due to their effects on the fungus and other local immune cells.

HIV-Associated Cryptococcal Immune Reconstitution Inflammatory Syndrome Is Associated with Aberrant T Cell Function and Increased Cytokine Responses

Cryptococcal meningitis remains a significant opportunistic infection among HIV-infected patients, contributing 15-20% of HIV-related mortality. A complication of initiating antiretroviral therapy (ART) following opportunistic infection is immune reconstitution inflammatory syndrome (IRIS). IRIS afflicts 10-30% of HIV-infected patients with cryptococcal meningitis (CM), but its immunopathogenesis is poorly understood. We compared circulating T cell memory subsets and cytokine responses among 17 HIV-infected Ugandans with CM: 11 with and 6 without CM-IRIS. At meningitis diagnosis, stimulation with cryptococcal capsule component, glucuronoxylomannan (GXM) elicited consistently lower frequencies of CD4⁺ and CD8⁺ T cell memory subsets expressing intracellular cytokines (IL-2, IFN-γ, and IL-17) among subjects who subsequently developed CM-IRIS. After ART initiation, T cells evolved to show a decreased CD8⁺ central memory phenotype. At the onset of CM-IRIS, stimulation more frequently generated polyfunctional IL-2⁺/IL-17⁺ CD4⁺ T cells in patients with CM-IRIS. Moreover, CD8⁺ central and effector memory T cells from CM-IRIS subjects also demonstrated more robust IL-2 responses to antigenic stimulation vs. controls. Thus, ART during CM elicits distinct differences in T cell cytokine production in response to cryptococcal antigens both prior to and during the development of IRIS, suggesting an immunologic foundation for the development of this morbid complication of CM infection.

Ontogeny of CD4+ T Lymphocytes With Phenotypic Susceptibility to HIV-1 During Exclusive and Nonexclusive Breastfeeding in HIV-1-Exposed Ugandan Infants

Background

Among infants exposed to human immunodeficiency virus (HIV) type 1, mixed breastfeeding is associated with higher postnatal HIV-1 transmission than exclusive breastfeeding, but the mechanisms of this differential risk are uncertain.

Methods

HIV-1-exposed Ugandan infants were prospectively assessed during the first year of life for feeding practices and T-cell maturation, intestinal homing (β7hi), activation, and HIV-1 coreceptor (CCR5) expression in peripheral blood. Infants receiving only breast milk and those with introduction of other foods before 6 months were categorized as exclusive and nonexclusive, respectively.

Results

Among CD4+ and CD8+ T cells, the expression of memory, activation, and CCR5 markers increased rapidly from birth to week 2, peaking at week 6, whereas cells expressing the intestinal homing marker increased steadily in the central memory (CM) and effector memory T cells over 48 weeks. At 24 weeks, when feeding practices had diverged, nonexclusively breastfed infants showed increased frequencies and absolute counts of β7hi CM CD4+ and CD8+ T cells, including the HIV-1-targeted cells with CD4+β7hi/CCR5+ coexpression, as well as increased activation.

Conclusions

The T-cell phenotype associated with susceptibility to HIV-1 infection (CCR5+, gut-homing, CM CD4+ T cells) was preferentially expressed in nonexclusively breastfed infants, a group of infants at increased risk for HIV-1 acquisition.

Cellular immune activation in cerebrospinal fluid from ugandans with cryptococcal meningitis and immune reconstitution inflammatory syndrome

Background. Human immunodeficiency virus (HIV)-associated cryptococcal meningitis (CM) is characterized by high fungal burden and limited leukocyte trafficking to cerebrospinal fluid (CSF). The immunopathogenesis of CM immune reconstitution inflammatory syndrome (IRIS) after initiation of antiretroviral therapy at the site of infection is poorly understood.

Methods. We characterized the lineage and activation status of mononuclear cells in blood and CSF of HIV-infected patients with noncryptococcal meningitis (NCM) (n = 10), those with CM at day 0 (n = 40) or day 14 (n = 21) of antifungal therapy, and those with CM-IRIS (n = 10).

Results. At diagnosis, highly activated CD8⁺ T cells predominated in CSF in both CM and NCM. CM-IRIS was associated with an increasing frequency of CSF CD4⁺ T cells (increased from 2.2% to 23%; P = .06), a shift in monocyte phenotype from classic to an intermediate/proinflammatory, and increased programmed death ligand 1 expression on natural killer cells (increased from 11.9% to 61.6%, P = .03). CSF cellular responses were distinct from responses in peripheral blood.

Conclusions. After CM, T cells in CSF tend to evolve with the development of IRIS, with increasing proportions of activated CD4⁺ T cells, migration of intermediate monocytes to the CSF, and declining fungal burden. These changes provide insight into IRIS pathogenesis and could be exploited to more effectively treat CM and prevent CM-IRIS.

AIDS-related mycoses: the way forward

The contribution of fungal infections to the morbidity and mortality of HIV-infected individuals is largely unrecognized. A recent meeting highlighted several priorities that need to be urgently addressed, including improved epidemiological surveillance, increased availability of existing diagnostics and drugs, more training in the field of medical mycology, and better funding for research and provision of treatment, particularly in developing countries.