Severe CSF immune cell alterations in cryptococcal meningitis gradually resolve during antifungal therapy.

Cryptococcal meningitis (CM) is a severe fungal disease in immunocompromised patients affecting the central nervous system (CNS). Host response and immunological alterations in the cerebrospinal fluid (CSF) after invasion of Cryptococcus neoformans to the central nervous system have been investigated before but rigorous and comprehensive studies examining cellular changes in the CSF of patients with cryptococccal meningitis are still rare. We retrospectively collected CSF analysis and flow cytometry data of CSF and blood in patients with CM (n = 7) and compared them to HIV positive patients without meningitis (n = 13) and HIV negative healthy controls (n = 7). Within the group of patients with CM we compared those with HIV infection (n = 3) or other immunocompromised conditions (n = 4). Flow cytometry analysis revealed an elevation of natural killer cells and natural killer T cells in the CSF and blood of HIV negative patients with CM, pointing to innate immune activation in early stages after fungal invasion. HIV positive patients with CM exhibited stronger blood-CSF-barrier disruption. Follow-up CSF analysis over up to 150 days showed heterogeneous cellular courses in CM patients with slow normalization of CSF after induction of antifungal therapy.

Differences in cytokine and chemokine profiles in cerebrospinal fluid caused by the etiology of cryptococcal meningitis and tuberculous meningitis in HIV patients.

The roles of cytokines and chemokines in HIV-associated cryptococcal meningitis (HCM) and HIV-associated tuberculous meningitis (HTBM) are debatable. In sum, 34 HIV-infected patients without meningitis, 44 HCM patients and 27 HTBM patients were enrolled for study. The concentrations of 22 cytokines/chemokines in cerebrospinal fluid (CSF) were assayed at admission. Principal component analysis (PCA), Pearson's and logistic regression analyses were used to assess the role of cytokines/chemokines in HCM and HTBM. We found the levels of T helper (Th)17, Th1 [interleukin (IL)-12p40, interferon (IFN)-γ, tumor necrosis factor (TNF)-α and TNF-ß and Th2 (IL-2/4/5/6/10)] cytokines were elevated in patients with meningitis compared with those in HIV-infected patients without central nervous system (CNS) infection. Furthermore, the IL-1Ra, IL-12p40, IL-17α and monocyte chemotactic protein-1 (MCP-1) levels were higher in HCM patients, while the IFN-γ, regulated upon activation, normal T cell expressed and secreted (RANTES) and interferon-inducible protein-10 (IP)-10 levels were higher in HTBM patients. Elevated CSF concentrations of IL-17a, TNF-ß, IL-5, IL-12p40 and IL-1Rα were closely related to meningitis, but elevated IP-10, MCP-1, RANTES and IFN-γ levels and CSF white blood cells (WBCs) were protective factors against HCM. Our study suggested that HIV-infected patients with low CSF WBCs have a high risk of HCM. Th1, Th2 and Th17 cytokines/chemokines mediate differences in the pathogenesis of HCM and TBM. Overexpressed proinflammatory MCP-1, RANTES, IFN-γ and IP-10 in CSF are protective factors against HCM but not HTBM.

A preliminary study on the characteristics of Th1/Th2 immune response in cerebrospinal fluid of AIDS patients with cryptococcal meningitis.

BACKGROUND: Cryptococcal Meningitis (CM) is a common opportunistic infection in the late stage of acquired immunodeficiency syndrome (AIDS). Despite the wide use of effective antiretroviral and antifungal therapy in AIDS patients, CM is still a major morbidity and mortality cause. Understanding the immune response in cryptococcal infection may help to improve the treatment strategies. METHODS: We established a prospective cohort of twelve AIDS patients with CM (HIV + CM+) admitted to the hospital from 2019 to 2020. All patients were examined at the baseline, 2 weeks, and 4 weeks thereafter. The level of 19 cytokines in cerebrospinal fluid (CSF) were recorded to analyze the characteristics and dynamic changes of Th1/Th2 immune response. Meanwhile, six AIDS patients without CM (HIV + CM-) and seventeen healthy subjects (HIV-CM-) were included as control groups for CSF assessment. RESULTS: The HIV+ CM+ group had higher CSF IFN-γ, TNF-α, IL-6, IL-7, IL-8, IL-10, IL-12 (P40), IL-15, IL-18, CCL2 levels but lower IL-4 when compared with the HIV-CM- group at baseline. And they also had a higher level of IL-12 (P40) and IL-17A compared with HIV + CM- patients. Except one patient dropped out of the study, eleven HIV + CM+ patients received induction antifungal therapy and regular CSF testing, and the mortality rate was 9.1% (1/11) and 18.2% (2/11) respectively at week 2 and week 4. Compared with baseline CSF cytokines, IL-2, IL-13, IL-17A, and VEGF-A decreased in week 2, and the VEGF-A levels further decreased in week 4. But there was no difference in the levels of all cytokines between survivors and the dead. CONCLUSION: No evidence of Th1/Th2 imbalance was found in AIDS patients with CM. However, the CSF cytokine network may provide new clues for the treatment of AIDS patients with CM. TRIAL REGISTRATION: This trial was prospectively registered in 2019.7.16. The registered number is ChiCTR1900024565 .

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.

Cryptococcal antigenemia is associated with meningitis or death in HIV-infected adults with CD4 100-200 cells/mm3.

BACKGROUND: Cryptococcal antigen (CrAg) screening with fluconazole prophylaxis has been shown to prevent cryptococcal meningitis and mortality for people living with HIV (PLWH) with CD4 < 100 cells/mm3. While cryptococcal meningitis occurs in individuals with CD4 100-200 cells/mm3, there is limited evidence that CrAg screening predicts cryptococcal meningitis or mortality among this group with moderate immunosuppression. Current IDSA and WHO clinical guidelines recommend restricting CrAg screening to PLWH with CD4 < 100 cells/mm3. METHODS: We conducted a prospective cohort study of PLWH 18+ years who had not initiated ART in South Africa. We followed participants for 14 months to determine onset of cryptococcal meningitis or all-cause mortality. At study completion, we retrospectively tested stored serum samples for CrAg using an enzyme immunoassay (EIA). We calculated CD4-stratified incidence rates of outcomes and used Cox proportional hazards to measure associations between CrAg positivity and outcomes. RESULTS: We enrolled 2383 PLWH, and 1309 participants had serum samples tested by CrAg EIA. The median CD4 was 317 cells/mm3 (interquartile range: 173-491 cells/mm3). By CD4 count at baseline, there were 209 individuals with a CD4 count of 100-200 cells/mm3 and available CrAg test results. Of these, four (1.9%) tested positive. Two of four (IR: 58.8 per 100 person-years) CrAg+ participants and 11 of 205 (IR: 5.6 per 100 person-years) CrAg- participants developed cryptococcal meningitis or died for an overall rate of death or cryptococcal meningitis that was 10.0-times higher for those who were CrAg+ (95% confidence interval: 2.2-45.3). Among those with CD4 < 100 cell/mm3 and CrAg EIA test results (N = 179), ten (5.6%) participants tested CrAg+. Among this group, seven of ten (IR: 137.6 per 100 person-years) CrAg+ participants and 26 of 169 (IR: 17.8 per 100 person-years) CrAg- participants developed cryptococcal meningitis or died, for a rate of death or cryptococcal meningitis that was 6.3-times higher for those who were CrAg+ (95% confidence interval: 2.7-14.6). CONCLUSIONS: Although few PLWH with moderate immunosuppression screened CrAg positive, a positive CrAg test was predictive of increased risk of cryptococcal meningitis or death. Similar to those with a CD4 < 100 cell/mm3, systematic CrAg screening may reduce morbidity and mortality in PLWH with CD4 100-200 cells/mm3.

The prevalence of cryptococcal antigen (CrAg) and benefits of pre-emptive antifungal treatment among HIV-infected persons with CD4+ T-cell counts < 200 cells/µL: evidence based on a meta-analysis.

BACKGROUND: Current WHO guidelines (2018) recommend screening for cryptococcal antigen (CrAg) in HIV-infected persons with CD4+ T cell counts< 100 cells/µL, followed by pre-emptive antifungal therapy among CrAg positive (CrAg+) persons, to prevent cryptococcal meningitis related deaths. This strategy may also be considered for those persons with a CD4+ T cell count of < 200 cells/uL according the WHO guidelines. However, there is sparse evidence in the literature supporting CrAg screening and pre-emptive antifungal therapy in those HIV-infected persons with this CD4+ T cell counts< 200 cells/µL. METHOD: We conducted a meta-analysis using data extracted from randomized controlled studies (RCTs) and cohort studies found in a search of Pubmed, Web of Science, the Cochrane Library and the EMBASE/MEDLINE database. RESULTS: The pooled prevalence of CrAg positivity in HIV-infected persons with CD4+ T cell counts< 200 cells/µL was 5% (95%CI: 2-7). The incidence of CM in CrAg+ persons was 3% (95%CI: 1-6). Among those CrAg+ persons who did not receive pre-emptive treatment, or those who received placebo, the incidence of CM was 5% (95%CI: 2-9), whereas the incidence of CM among those who received pre-emptive antifungal therapy was 3% (95%CI: 1-6), which is a statistically significant reduction in incidence of 40% (RR: 7.64, 95%CI: 2.96-19.73, p < 0.00001). As for persons with CD4+ T cell counts between 101 ~ 200 cells/µL, the risk ratio for the incidence of CM among those receiving placebo or no intervention was 1.15, compared to those receiving antifungal treatment (95%CI: 0.16-8.13). CONCLUSIONS: In our meta-analysis the incidence of CM was significantly reduced by pre-emptive antifungal therapy in CrAg+ HIV-infected persons with CD4 <  200 cells/µL. However, more specific observational data in persons with CD4+ T cell counts between 101 ~ 200 cells/µL are required in order to emphasize specific benefit of CrAg screening and pre-emptive antifungal treating in CrAg+ persons with CD4+ T cell counts < 200 cells/µL.

Cryptococcus meningitis mimicking cerebral septic emboli, a case report series demonstrating injection drug use as a risk factor for development of disseminated disease.

BACKGROUND: Clinicians may be less inclined to consider a diagnosis of cryptococcal meningitis in people without HIV infection or transplant-related immunosuppression. This may lead to a delay in diagnosis particularly if disseminated cryptococcal disease mimics cerebral septic emboli in injection drug use (IDU) leading to a search for endocarditis or other infectious sources. Though, IDU has been described as a potential risk for disseminated cryptococcal disease. CASE PRESENTATIONS: We present two cases of cryptococcal meningitis in IDU without HIV or other obvious immune deficits. Both patients presented with at least 2 weeks of headache and blurred vision. They developed central nervous system (CNS) vasculitis, one of which mimicked septic cerebral emboli, but both resulted with poor neurologic outcomes. CONCLUSIONS: IDU likely induces an underappreciated immune deficit and is a risk factor for developing cryptococcal meningitis. This diagnosis, which can mimic cerebral septic emboli through involvement of a CNS vasculitis, should be considered in the setting of IDU.

Cryptococcal antigenemia prevalence and clinical data in HIV-infected patients from the reference centre at INI-FIOCRUZ, Rio de Janeiro, Southeast of Brazil.

Cryptococcal meningitis is a several disease common in late stage of HIV infection. Detection of cryptococcal antigen (CrAg) is an important for early diagnosis of this invasive mycosis. The pre-emptive treatment for isolated antigenemia prevents the onset of meningoencephalitis. Screening CrAg in patients with low CD4 count is cost-effective in countries with prevalence of antigenemia above 3%. However, in Brazil, the number of prevalence studies on cryptococcosis and HIV is insufficient. The objective of this study is to estimate the prevalence of CrAg and describe clinical characteristics from a cohort of patients followed at a reference center in Brazil. CrAg screening was performed in 89 inpatients with CD4 count ≤200 cells/mm3 or WHO stage III/IV from the National Institute of Infecttious Disease, Rio de Janeiro. Patients with isolated antigenemia received pre-emptive therapy with fluconazole and patients with meningoencephalitis were treated with Amphotericin B. Individuals were followed up for 12 months. Prevalence of serum CrAg was 11.23%, cryptococcal meningoencephalitis 6.74% and isolated antigenemia 4.81%. None of the patients with isolated antigenemia developed meningoencephalitis during the follow up. Signs and symptoms of meningoencephalitis were unspecific or absent. Our study suggests the need of CrAg screening in Brazil and highlights that lumbar puncture is mandatory in all individuals CrAg positive to exclude asymptomatic meningoencephalitis.

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.

Association Between Plasma Antibody Responses and Risk for Cryptococcus-Associated Immune Reconstitution Inflammatory Syndrome.

Background: Initiation of antiretroviral therapy (ART) in human immunodeficiency virus (HIV)-infected individuals with cryptococcal meningitis places them at risk for Cryptococcus-associated immune reconstitution inflammatory syndrome (C-IRIS). The relationship between antibody immunity and C-IRIS risk has not been investigated. Methods: We compared plasma levels of immunoglobulins, C. neoformans glucuronoxylomannan (GXM) capsule-specific and laminarin (Lam)-binding IgM and IgG, and percentages of peripheral blood total and memory B cells between 27 HIV-infected patients with CM who developed C-IRIS and 63 who did not, and evaluated associations of these parameters with risk of C-IRIS. Results: Prior to initiation of ART, plasma IgM, Lam-binding IgM (Lam-IgM), Lam-IgG, and GXM-IgM levels were significantly lower in patients who developed C-IRIS than those who did not. Multivariate analysis revealed significant inverse associations between C-IRIS and IgM (P = .0003), Lam-IgM (P = .0005), Lam-IgG (P = .002), and GXM-IgM (P = .002) independent of age, sex, HIV viral load, CD4+ T-cell count, and cerebrospinal fluid fungal burden. There were no associations between C-IRIS and total or memory B cells. Discussion: Antibody profiles that include plasma IgM, Lam-IgM, Lam-IgG, and/or GXM-IgM may have value in furthering our understanding of C-IRIS pathogenesis and hold promise as candidate biomarkers of C-IRIS risk.

The Mouse Inhalation Model of Cryptococcus neoformans Infection Recapitulates Strain Virulence in Humans and Shows that Closely Related Strains Can Possess Differential Virulence.

Cryptococcal meningitis (CM) causes high rates of HIV-related mortality, yet the Cryptococcus factors influencing patient outcome are not well understood. Pathogen-specific traits, such as the strain genotype and degree of antigen shedding, are associated with the clinical outcome, but the underlying biology remains elusive. In this study, we examined factors determining disease outcome in HIV-infected cryptococcal meningitis patients infected with Cryptococcus neoformans strains with the same multilocus sequence type (MLST). Both patient mortality and survival were observed during infections with the same sequence type. Disease outcome was not associated with the patient CD4 count. Patient mortality was associated with higher cryptococcal antigen levels, the cerebrospinal fluid (CSF) fungal burden by quantitative culture, and low CSF fungal clearance. The virulence of a subset of clinical strains with the same sequence type was analyzed using a mouse inhalation model of cryptococcosis. We showed a strong association between human and mouse mortality rates, demonstrating that the mouse inhalation model recapitulates human infection. Similar to human infection, the ability to multiply in vivo, demonstrated by a high fungal burden in lung and brain tissues, was associated with mouse mortality. Mouse survival time was not associated with single C. neoformans virulence factors in vitro or in vivo; rather, a trend in survival time correlated with a suite of traits. These observations show that MLST-derived genotype similarities between C. neoformans strains do not necessarily translate into similar virulence either in the mouse model or in human patients. In addition, our results show that in vitro assays do not fully reproduce in vivo conditions that influence C. neoformans virulence.

Symptomatic Cryptococcal Antigenemia Presenting as Early Cryptococcal Meningitis With Negative Cerebral Spinal Fluid Analysis.

BACKGROUND: Individuals with cryptococcal antigenemia are at high risk of developing cryptococcal meningitis if untreated. The progression and timing from asymptomatic infection to cryptococcal meningitis is unclear. We describe a subpopulation of individuals with neurologic symptomatic cryptococcal antigenemia but negative cerebral spinal fluid (CSF) studies. METHODS: We evaluated 1201 human immunodeficiency virus-seropositive individuals hospitalized with suspected meningitis in Kampala and Mbarara, Uganda. Baseline characteristics and clinical outcomes of participants with neurologic-symptomatic cryptococcal antigenemia and negative CSF cryptococcal antigen (CrAg) were compared to participants with confirmed CSF CrAg+ cryptococcal meningitis. Additional CSF testing included microscopy, fungal culture, bacterial culture, tuberculosis culture, multiplex FilmArray polymerase chain reaction (PCR; Biofire), and Xpert MTB/Rif. RESULTS: We found 56% (671/1201) of participants had confirmed CSF CrAg+ cryptococcal meningitis and 4% (54/1201) had neurologic symptomatic cryptococcal antigenemia with negative CSF CrAg. Of those with negative CSF CrAg, 9% (5/54) had Cryptococcus isolated on CSF culture (n = 3) or PCR (n = 2) and 11% (6/54) had confirmed tuberculous meningitis. CSF CrAg-negative patients had lower proportions with CSF pleocytosis (16% vs 26% with ≥5 white cells/µL) and CSF opening pressure >200 mmH2O (16% vs 71%) compared with CSF CrAg-positive patients. No cases of bacterial or viral meningitis were detected by CSF PCR or culture. In-hospital mortality was similar between symptomatic cryptococcal antigenemia (32%) and cryptococcal meningitis (31%; P = .91). CONCLUSIONS: Cryptococcal antigenemia with meningitis symptoms was the third most common meningitis etiology. We postulate this is early cryptococcal meningoencephalitis. Fluconazole monotherapy was suboptimal despite Cryptococcus-negative CSF. Further studies are warranted to understand the clinical course and optimal management of this distinct entity. CLINICAL TRIALS REGISTRATION: NCT01802385.

Do Intracerebral Cytokine Responses Explain the Harmful Effects of Dexamethasone in Human Immunodeficiency Virus-associated Cryptococcal Meningitis?

BACKGROUND: The CryptoDex trial showed that dexamethasone caused poorer clinical outcomes and slowed fungal clearance in human immunodeficiency virus-associated cryptococcal meningitis. We analyzed cerebrospinal fluid (CSF) cytokine concentrations from participants over the first week of treatment to investigate mechanisms of harm and test 2 hypotheses: (1) dexamethasone reduced proinflammatory cytokine concentrations, leading to poorer outcomes and (2) leukotriene A4 hydrolase (LTA4H) genotype influenced the clinical impact of dexamethasone, as observed in tuberculous meningitis. METHODS: We included participants from Vietnam, Thailand, and Uganda. Using the Luminex system, we measured CSF concentrations of the following: interferon γ, tumor necrosis factor (TNF) α, granulocyte-macrophage colony-stimulating factor, monocyte chemoattractant 1, macrophage inflammatory protein 1α, and interleukin 6, 12p70, 8, 4, 10, and 17. We determined the LTA4H genotype based on the promoter region single-nucleotide polymorphism rs17525495. We assessed the impact of dexamethasone on cytokine concentration dynamics and the association between cytokine concentration dynamics and fungal clearance with mixed effect models. We measured the influence of LTA4H genotype on outcomes with Cox regression models. RESULTS: Dexamethasone increased the rate TNF-α concentration's decline in (-0.13 log2pg/mL/d (95% confidence interval, -.22 to -.06 log2pg/mL/d; P = .03), which was associated with slower fungal clearance (correlation, -0.62; 95% confidence interval, -.83 to -.26). LTA4H genotype had no statistically significant impact on outcome or response to dexamethasone therapy. Better clinical outcomes were associated with higher baseline concentrations of interferon γ. CONCLUSIONS: Dexamethasone may slow fungal clearance and worsen outcomes by increasing TNF-α concentration's rate of decline.

The Early Innate Immune Response to, and Phagocyte-Dependent Entry of, Cryptococcus neoformans Map to the Perivascular Space of Cortical Post-Capillary Venules in Neurocryptococcosis.

The innate immune system is the primary defense against cryptococcal infection, but paradoxically it promotes infection of the central nervous system. We performed a detailed longitudinal study of neurocryptococcosis in normal, chimeric, green fluorescent protein phagocyte-positive mice and phagocyte-depleted mice and interrogated the central nervous system innate immune response to Cryptococcus neoformans H99 using confocal microscopy, histology, flow cytometry, and quantification of brain cytokine/chemokines and fungal burdens. C. neoformans was present in the perivascular space (PVS) of post-capillary venules. This was associated with a massive influx of blood-derived monocytes, neutrophils, and T lymphocytes into the PVS and a predominantly proinflammatory cytokine/chemokine response. Phagocytes containing cryptococci were present only in the lumen and corresponding PVS of post-capillary venules. Free cryptococci were observed breaching the glia limitans, the protective barrier between the PVS and the cerebral parenchyma. Parenchymal cryptococcomas were typically in direct contact with post-capillary venules and lacked surrounding immune cell infiltrates. Phagocyte depletion abrogated cryptococcoma formation and PVS infiltrates. Together, these observations suggest that cryptococcomas can originate via phagocyte-dependent transport across post-capillary venular endothelium into the PVS and thence via passage of free cryptococci into the brain. In conclusion, we demonstrate for the first time that the PVS of cortical post-capillary venules is the major site of the early innate immune response to, and phagocyte-dependent entry of, C. neoformans.

Shedding light on IRIS: from Pathophysiology to Treatment of Cryptococcal Meningitis and Immune Reconstitution Inflammatory Syndrome in HIV-Infected Individuals.

OBJECTIVES: The aim of this work was to review current treatment options and propose alternatives for immune reconstitution inflammatory syndrome (IRIS) in HIV-infected individuals with cryptococcal meningitis (CM) (termed 'HIV-CM IRIS'). As a consequence of the immunocompromised state of these individuals, the initial immune response to CM is predominantly type 2 T helper (Th2) /Th17 rather than Th1, leading to inefficient fungal clearance at the time of antiretroviral initiation, and a subsequent overexaggeration of the Th1 response and life-threatening IRIS development. METHODS: An article-based and clinical trial-based search was conducted to investigate HIV-CM IRIS pathophysiology and current treatment practices. RESULTS: Guidelines for CM treatment, based on the Cryptococcal Optimal Antiretroviral Timing (COAT) trial, recommend delayed antiretroviral therapy (ART) following antifungal treatment. The approach aims to decrease fungal burden and allow immune balance restoration prior to ART initiation. If the initial immune balance is not restored, the fungal burden is not sufficiently reduced and there is a risk of developing IRIS post-ART, highlighted by a Th1 immune overcompensation, leading to increased mortality. The mainstay treatment for Th1-biased IRIS is corticosteroids; however, this treatment has been shown to correlate with increased mortality and significant associated adverse events. We emphasize targeting a more specific Th1 mechanism via the tumour necrosis factor (TNF)-α cytokine antagonist thalidomide, as it is the only TNF-α antagonist currently approved for use in infectious disease settings and has been shown to decrease Th1 overreaction, restoring immune balance in HIV-CM IRIS. CONCLUSIONS: Although the side effects and limitations of thalidomide must be considered, it is currently being successfully used in infectious disease settings and warrants mainstream application as a therapeutic option for treatment of IRIS in HIV-infected patients with CM.

T11TS immunotherapy augments microglial and lymphocyte protective immune responses against Cryptococcus neoformans in the brain.

Cryptococcus neoformans, the encapsulated yeast acquired through inhalation, remains localized in lungs, but harbours the CNS in immunocompromised individuals. Several treatment regimes have failed combating this disease totally, but long-term usage of drugs leads to organ damage. As T11-target structure (T11TS) has documented profound immune potentiation, we aimed to investigate the role of microglia, pivotal immune cells of brain in ameliorating cryptococcosis, with T11TS immunotherapy. Murine model with C neoformans infection was prepared by intraperitoneal injection and the brains of rats examined 7 days post-infections for histopathology by PAS and Alcian blue staining corroborated with organ fungal burden evidencing restorative T11TS action on Cryptococcal meningitis. Immunotherapy with three doses of T11TS, a CD2 ligand, in C neoformans infected rats, upregulates toll-like receptors 2, -4 and -9 of microglia, indicating increased phagocytosis of the fungus. Flowcytometric analysis revealed increased numbers of T11TS treated brain infiltrating CD4+ and CD8+ T-lymphocytes along with increased MHC I and MHC II on microglia, activating the infiltrating lymphocytes aiding the killing mechanism. Present study also indicated that T11TS increased production of Th1 inflammatory cytokines conducive to fungal elimination while the inhibitory Th2 cytokines were dampened. This preclinical study is first of its kind to show that T11TS effected profound immune stimulation of microglial activity of C neoformans infected rats eradicating residual fungal burden from the brain and can be a useful therapeutic strategy in fighting against this deadly disease.

Case report: chronic relapsing cryptococcal meningitis in a patient with low mannose-binding lectin and a low naïve CD4 cell count.

BACKGROUND: Cryptococcal meningitis is most commonly found in HIV-infected patients. In HIV-negative patients, its low incidence can lead to prolonged time to diagnosis. Detailed case reports of chronic cryptococcal meningitis are scarce, but could provide clues for earlier diagnosis in this patient category. CASE PRESENTATION: A 60-year old man presented June 2015 with intermittent headaches for several months without any fever. Initial work-up showed a leukocytosis, raised CSF opening pressure and raised leukocytes and protein in the CSF. An MRI revealed leptomeningeal contrast enhancement and cerebellar oedema. While malignancy and various infectious causes were excluded, the patient had a spontaneous clinical and radiological recovery. One year later, the patient returned with complaints of headaches. Also, cerebellar oedema and leptomeningeal contrast enhancement had recurred. Eventually in March 2017, the novel cryptococcal antigen lateral flow assay (CrAg LFA) was positive on CSF, and one colony of Cryptococcus neoformans was cultured from CSF. The patient was treated with the standard antifungal regimen which resulted in resolution of his headaches. In retrospect, the cryptococcal antigen test was already positive on a serum sample from June 2015. Interestingly, post-treatment immunological analysis revealed both a low mannose-binding lectin (MBL) concentration and low naïve CD4 counts. CONCLUSIONS: We present a patient with cryptococcal meningitis in an HIV-negative patient with low MBL and low naïve CD4 count suffering a chronic relapsing meningo-encephalitis with relatively mild symptoms for around 2 years. In patients with an unexplained meningo-encephalitis such as this case, early performance of CrAg LFA on serum and/or CSF is an inexpensive and rapid method to reduce time-to diagnosis.

"Mercedes-Benz Sign" on CSF Cytology.

Cryptococcus meningitis is a potentially lethal disease, and cerebrospinal fluid cytology is crucial in establishing diagnosis. We report a novel and interesting morphological sign of Cryptococcus neoformansin CSF cytology resembling the logo of Mercedes-Benz. The sign is highly suggestive of Cryptococcus infection and is a strong indicator for more specific tests and timely treatment.

The significance of anti-granulocyte-macrophage colony-stimulating factor antibodies in cryptococcal infection: case series and review of antibody testing.

We report two cases of cryptococcosis, associated with anti-granulocyte-macrophage colony-stimulating factor antibodies. We review this recently identified acquired form of autoimmune immune deficiency and discuss the potential applications of granulocyte-macrophage colony-stimulating factor antibody testing by enzyme-linked immunosorbent assay.