Post-infectious Inflammatory Response Syndrome Research Articles

1820. Efficacy of Pulse-Taper Corticosteroid Adjunctive Therapy for Refractory Non-HIV Cryptococcal Meningoencephalitis

BackgroundCryptococcal meningoencephalitis (CM) affects individuals with AIDS, transplants recipients and those previously healthy, with 30–50% mortality in most groups despite anti-fungal treatment. In the previously healthy, a post-infectious inflammatory response syndrome (PIIRS) analogous to cryptococcal IRIS in AIDS patients has recently been described. PIIRS is defined as a deterioration in mental status and/or audio-visual capacity despite optimal treatment for CM and negative CSF cultures. Pathophysiology is related to excessive T-cell responses to lysed fungal cells during therapy but data on effective treatment regimens are limited.MethodsBetween March 2015 and February 2019, 11 consecutive patients with PIIRS who evidenced clinical deterioration over a period of up to 10 weeks despite effective antifungals were referred to the NIH clinical center. Patients were prospectively treated with adjunctive pulse solumedrol 1 g daily for 1 week followed by prednisone 1 mg/kg/day, tapered based on clinical and radiological response plus oral fluconazole. Montreal cognitive assessments (MOCA) scores at baseline and 1 month were the primary endpoints and CSF parameters including WBC, glucose, HLA DR4+ CD4 and CD8 cells and cytokines were also determined at baseline and after 1 week of solumedrol. Paired nonparametric t-tests were conducted using GraphPad Prism 7.0.ResultsAll patients demonstrated clinical improvement despite 7 being initiated at the point of stupor and 6 having received ventriculoperitoneal shunts without clinical response. MOCA scores at 1 month showed significant improvement (P = 0.002), accompanied by significant improvements in CSF: serum glucose ratios, CSF WBC, protein and HLADR4 positive T cells 1 week after receiving corticosteroids (P < 0.02). Patients with hearing or visual deficits exhibited clinical improvement. CSF cultures remained negative.ConclusionOur findings in this small observational cohort of refractory non-HIV CM with PIIRS demonstrated significant clinical benefit of high dose adjunctive pulse-taper corticosteroids. The study also demonstrates the utility of physiology-based immunophenotyping to guide therapy in neuroinflammation associated with infectious diseases.Disclosures All Authors: No reported Disclosures.

Immunology of Cryptococcal Infections: Developing a Rational Approach to Patient Therapy.

Cryptococcal meningoencephalitis is responsible for upwards of 15% of HIV-related deaths worldwide and is currently the most common cause of non-viral meningitis in the US, affecting both previously healthy and people with immune suppression caused by cancer chemotherapy, transplantation, and biologic therapies. Despite a continued 30–50% attributable mortality, recommended therapeutic strategies have remained largely unchanged since the 1950s. Recent murine models and human studies examining the role of the immune system in both susceptibility to the infection as well as host damage have begun to influence patient care decisions. The Damage Framework Response, originally proposed in 1999, was recently used to discuss dichotomous etiologies of host damage in cryptococcal disease. These include patients suffering microbiological damage with low host immunity (especially those immunosuppressed with HIV) and those having low (live) microbiological burden but high immune-mediated damage (HIV-related immune reconstitution syndrome and non-HIV-related postinfectious inflammatory response syndrome). Cryptococcal disease in previously healthy hosts, albeit rare, has been known for a long time. Immunophenotyping and dendritic cell-T cell signaling studies on cerebral spinal fluid of these rare patients reveal immune capacity for recognition and T-cell activation pathways including increased levels of HLA-DR and CD56. However, despite effective T-cell signals, brain biopsy and autopsy specimens demonstrated an M2 alternative macrophage polarization and poor phagocytosis of fungal cells. These studies expand the paradigm for cryptococcal disease susceptibility to include a prominent role for immune-mediated damage and suggest a need for careful individual consideration of immune activation during therapy of cryptococcal disease in diverse hosts.

CD4+ T Cells Orchestrate Lethal Immune Pathology despite Fungal Clearance during Cryptococcus neoformans Meningoencephalitis.

ABSTRACTCryptococcus neoformans is a major fungal pathogen that disseminates to the central nervous system (CNS) to cause fatal meningoencephalitis, but little is known about immune responses within this immune-privileged site. CD4+ T cells have demonstrated roles in anticryptococcal defenses, but increasing evidence suggests that they may contribute to clinical deterioration and pathology in both HIV-positive (HIV+) and non-HIV patients who develop immune reconstitution inflammatory syndrome (IRIS) and post-infectious inflammatory response syndrome (PIIRS), respectively. Here we report a novel murine model of cryptococcal meningoencephalitis and a potential damaging role of T cells in disseminated cryptococcal CNS infection. In this model, fungal burdens plateaued in the infected brain by day 7 postinfection, but activation of microglia and accumulation of CD45hi leukocytes was significantly delayed relative to fungal growth and did not peak until day 21. The inflammatory leukocyte infiltrate consisted predominantly of gamma interferon (IFN-γ)-producing CD4+ T cells, conventionally believed to promote fungal clearance and recovery. However, more than 50% of mice succumbed to infection and neurological dysfunction between days 21 and 35 despite a 100-fold reduction in fungal burdens. Depletion of CD4+ cells significantly impaired IFN-γ production, CD8+ T cell and myeloid cell accumulation, and fungal clearance from the CNS but prevented the development of clinical symptoms and mortality. These findings conclusively demonstrate that although CD4+ T cells are necessary to control fungal growth, they can also promote significant immunopathology and mortality during CNS infection. The results from this model may provide important guidance for development and use of anti-inflammatory therapies to minimize CNS injury in patients with severe cryptococcal infections.

Post-infectious inflammatory response syndrome (PIIRS): Dissociation of T-cell-macrophage signaling in previously healthy individuals with cryptococcal fungal meningoencephalitis.

Cryptococcus is an important cause of central nervous system infections in both immunocompromised patients such as those with HIV/AIDS as well as previously healthy individuals. Deficiencies in T-cell activation are well-known to be highly associated with host susceptibility in HIV/AIDS as well in animal modeling studies, resulting in poor microbiological control and little host inflammation. However, recent studies conducted in human patients have demonstrated roles for macrophage signaling defects as an important association with disease susceptibility. For example, an autoantibody to granulocyte monocyte stimulating factor (GMCSF) resulted in defective STAT5 signaling and susceptibility to cryptococcosis. In addition, severe cases of cryptococcal meningo-encephalitis in previously healthy patients, with or without anti-GMCSF autoantibody, developed a highly activated intrathecal T-cell population but had defects in effective macrophage polarization. Intrathecal inflammation correlated with neurological damage, measured by the axonal damage protein, neurofilament light chain 1. Based on these studies, we propose a new syndrome of cryptococcal post-infectious inflammatory response syndrome (PIIRS) defined in previously healthy patients with cryptococcal meningo-encephalitis as the presence of a poor clinical response in the setting of at least 1 month of amphotericin-based fungicidal therapy and sterile cerebrospinal cultures. These findings are discussed in light of the potential for improving therapy.