Preliminary evaluation of whole-blood gamma interferon release for clinical assessment of cellular immunity in patients with active coccidioidomycosis

Challenges to Implementing a Vaccine for Coccidioidomycosis

A vaccine for coccidioidomycosis is likely to undergo trials in the near future. In this paper, we raise 4 questions that should be answered before its use and offer our solutions to these questions. These include defining the goals of vaccination, determining who should be vaccinated, how to measure vaccine immunity and protection, and how to address vaccine hesitancy and denial.

Challenges Facing Antimicrobial Stewardship Programs in the Endemic Region for Coccidioidomycosis

Coccidioidomycosis poses a significant cost and morbidity burden in the United States. Additionally, coccidioidomycosis requires constant decision-making related to prevention, diagnosis, and management. Delays in diagnosis lead to significant consequences, including unnecessary diagnostic workup and antibacterial therapy. Antifungal stewardship considerations regarding empiric, prophylactic, and targeted management of coccidioidomycosis are also complex. In this review, the problems facing antimicrobial stewardship programs (ASPs) in the endemic region for coccidioidomycosis, consequences due to delayed or missed diagnoses of coccidioidomycosis on antibacterial prescribing, and excess antifungal prescribing for prevention and treatment of coccidioidomycosis are elucidated. Finally, our recommendations and research priorities for ASPs in the endemic region for coccidioidomycosis are outlined.

Review of Clinical and Laboratory Diagnostics for Coccidioidomycosis

Coccidioidomycosis is a fungal disease associated with soil exposure that frequently goes undiagnosed due at least in part to its nonspecific presentation and the lack of clinical suspicion by health care providers. Currently available diagnostics for coccidioidomycosis offer qualitative results that can suffer from low specificity, while semiquantitative assays are labor-intensive and complex and can require multiple days to complete. Furthermore, significant confusion exists regarding the optimal diagnostic algorithms and appropriate usage of available diagnostic tests. This review aims to inform clinical laboratorians and treating clinicians about the current diagnostic landscape, appropriate diagnostic strategies, and future diagnostic directions for coccidioidomycosis, which is expected to become more prevalent due to increased migration into areas of endemicity and climate changes.

Diagnostic Approach to Coccidioidomycosis in Solid Organ Transplant Recipients

Coccidioidomycosis is a fungal infection endemic in the southwestern United States, Mexico, and parts of Central and South America. While coccidioidomycosis is associated with mostly mild infections in the general population, it can lead to devastating infections in immunocompromised patients, including solid organ transplant (SOT) recipients. Early and accurate diagnosis is important in achieving better clinical outcomes in immunocompromised patients. However, the diagnosis of coccidioidomycosis in SOT recipients can be challenging due to the limitations of diagnostic methods including cultures, serology, and other tests in providing a timely and accurate diagnosis. In this review, we will discuss the available diagnostic modalities and approaches when evaluating SOT recipients with coccidioidomycosis, from the use of conventional culture methods to serologic and molecular testing. Additionally, we will discuss the role of early diagnosis in assisting with the administration of effective antifungal therapy to reduce infectious complications. Finally, we will discuss ways to improve the performance of coccidioidomycosis diagnostic methods in SOT recipients with an option for a combined testing approach.

Evaluation of Host Constitutive and Ex Vivo Coccidioidal Antigen-Stimulated Immune Response in Dogs with Naturally Acquired Coccidioidomycosis

The early innate immune response to coccidioidomycosis has proven to be pivotal in directing the adaptive immune response and disease outcome in mice and humans but is unexplored in dogs. The objectives of this study were to evaluate the innate immune profile of dogs with coccidioidomycosis and determine if differences exist based on the extent of infection (i.e., pulmonary or disseminated). A total of 28 dogs with coccidioidomycosis (pulmonary, n = 16; disseminated, n = 12) and 10 seronegative healthy controls were enrolled. Immunologic testing was performed immediately, without ex vivo incubation (i.e., constitutive), and after coccidioidal antigen stimulation of whole blood cultures. Whole blood cultures were incubated with a phosphate-buffered solution (PBS) (negative control) or a coccidioidal antigen (rCTS1 (105-310); 10 µg/mL) for 24 h. A validated canine-specific multiplex bead-based assay was used to measure 12 cytokines in plasma and cell culture supernatant. Serum C-reactive protein (CRP) was measured with an ELISA assay. Leukocyte expression of toll-like receptors (TLRs)2 and TLR4 was measured using flow cytometry. Dogs with coccidioidomycosis had higher constitutive plasma keratinocyte chemotactic (KC)-like concentrations (p = 0.02) and serum CRP concentrations compared to controls (p < 0.001). Moreover, dogs with pulmonary coccidioidomycosis had higher serum CRP concentrations than those with dissemination (p = 0.001). Peripheral blood leukocytes from dogs with coccidioidomycosis produced higher concentrations of tumor necrosis factor (TNF)-α (p = 0.0003), interleukin (IL)-6 (p = 0.04), interferon (IFN)-γ (p = 0.03), monocyte chemoattractant protein (MCP)-1 (p = 0.02), IL-10 (p = 0.02), and lower IL-8 (p = 0.003) in supernatants following coccidioidal antigen stimulation when compared to those from control dogs. There was no detectable difference between dogs with pulmonary and disseminated disease. No differences in constitutive or stimulated leukocyte TLR2 and TLR4 expression were found. These results provide information about the constitutive and coccidioidal antigen-specific stimulated immune profile in dogs with naturally acquired coccidioidomycosis.

Host-Pathogen Interactions in Coccidioidomycosis: Prognostic Clues and Opportunities for Novel Therapies

PURPOSE

Coccidioidomycosis (CM) is a systemic fungal disease caused by the dimorphic fungi Coccidioides immitis and Coccidioides posadasii. In its endemic areas of the United States, CM is growing as a public health challenge with a marked increase in incidence in the last 15 years. Although Coccidioides infection is asymptomatic in most cases, symptomatic pulmonary disease occurs in ~40% and disseminated coccidioidomycosis (DCM) occurs in ~1% of previously healthy children and adults. DCM is markedly more common in immunocompromised people, who often experience life-threatening disease despite use of antifungal medications. Although options for antifungal therapy have improved, lifelong therapy is needed for those who develop coccidioidal meningitis. The purpose of this article was to review the state of antifungal therapy and recent studies of host-pathogen interactions in CM in light of advances in immunomodulatory therapy.

METHODS

The study included a review of PubMed and abstracts of the Coccidioidomycosis Study Group (years 2000-2019).

FINDINGS

Current therapy for CM relies upon azole and polyene antifungal agents. Murine models and studies of DCM in patients with monogenic primary immunodeficiency states and acquired immunodeficiency have revealed the importance of both innate and adaptive immune responses in the control of infections with Coccidioides species. In particular, defects in sensing of fungi and induction of cellular immune responses have been frequently reported. More recently, polymorphisms in key signaling pathways and in the generation of Th17 and Th1 immune responses have been linked with DCM.

IMPLICATIONS

Antifungal therapy is sufficient to control disease in most cases of CM, but treatment failure occurs in cases of severe pulmonary disease and nonmeningeal disseminated disease. Lifelong therapy is recommended for meningitis in view of the very high risk of recurrence. Corticosteroid therapy is advised by some experts for severe pulmonary disease and for some neurologic complications of DCM. DCM is only rarely the result of a severe monogenic immunodeficiency. Case studies suggest that reorienting cellular immune responses or augmenting effector immune responses may help resolve DCM. Systematic investigation of immunotherapy for coccidioidomycosis is advisable and may help to address the recent marked increase in reports of the disease in endemic areas.

Ex Vivo Cytokine Release, Determined by a Multiplex Cytokine Assay, in Response to Coccidioidal Antigen Stimulation of Whole Blood among Subjects with Recently Diagnosed Primary Pulmonary Coccidioidomycosis

Coccidioidomycosis, commonly known as Valley fever, is a common pneumonia in the southwestern United States. In this paper, we examined the release of 30 inflammatory proteins in whole-blood samples obtained from persons with coccidioidal pneumonia after the blood samples were incubated with a preparation made from the causative fungus, Coccidioides. We found that six of these proteins, all cytokines, were specifically released in high concentrations in these patients. Three of the cytokines were seen very early in disease, and an assay for all six might serve as a marker for the early diagnosis of Valley fever.

The elements of the cellular immune response in human coccidioidomycosis remain undefined. We examined the ex vivo release of an array of inflammatory proteins in response to incubation with a coccidioidal antigen preparation to ascertain which of these might be associated with diagnosis and outcome. Patients with a recent diagnosis of primary pulmonary coccidioidomycosis and a control group of healthy subjects were studied. Blood samples were incubated for 18 h with T27K, a soluble coccidioidal preparation containing multiple glycosylated antigens, and the supernatant was assayed for inflammatory proteins using the multiplex Luminex system. The presentation and course of illness were compared to the levels of the inflammatory proteins. Among the 31 subjects studied, the median time from diagnosis to assay was 15 days. Of the 30 inflammatory proteins measured, the levels of only 7 proteins, granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-1 receptor alpha (IL-1RA), interleukin-1β (IL-1β), interferon gamma (IFN-γ), IL-2, IL-13, and tumor necrosis factor alpha (TNF-α), were more than 10-fold above the levels seen without antigen stimulation. The levels of IFN-γ and IL-2 were significantly elevated in those subjects not receiving triazole antifungal therapy compared to those who were receiving triazole antifungal therapy. While the levels of IL-1RA were nonspecifically elevated, elevated levels of IL-13 were seen only in those with active pulmonary coccidioidomycosis. Only six cytokines were specifically increased in subjects with recently diagnosed primary pulmonary coccidioidomycosis. While IFN-γ, IL-2, and TNF-α have been previously noted, the finding of elevated levels of the innate cytokines GM-CSF and IL-1β could suggest that these, as well as IL-13, are early and specific markers for pulmonary coccidioidomycosis.

IMPORTANCE Coccidioidomycosis, commonly known as Valley fever, is a common pneumonia in the southwestern United States. In this paper, we examined the release of 30 inflammatory proteins in whole-blood samples obtained from persons with coccidioidal pneumonia after the blood samples were incubated with a preparation made from the causative fungus, Coccidioides. We found that six of these proteins, all cytokines, were specifically released in high concentrations in these patients. Three of the cytokines were seen very early in disease, and an assay for all six might serve as a marker for the early diagnosis of Valley fever.

Cytokine Profiles from Antigen-Stimulated Whole-Blood Samples among Patients with Pulmonary or Nonmeningeal Disseminated Coccidioidomycosis

The outcome of coccidioidomycosis depends on a robust specific cellular immune response. A T-helper type 1 (Th1) cellular immune response has been previously associated with resolution of clinical illness. However, the precise elements of this response and whether cytokines not involved with the Th1 response play a role in coccidioidomycosis are not known. Whole-blood samples were obtained from subjects with active coccidioidomycosis and controls and incubated for 18 h with T27K, a coccidioidal antigen preparation. The supernatant was then assayed for gamma interferon (IFN-γ), interleukin-2 (IL-2), tumor necrosis factor alpha (TNF-α), IL-4, IL-6, IL-10, and IL-17A. A total of 43 subjects, 16 with acute pneumonia, 9 with pulmonary sequelae of nodules and cavities, and 18 with nonmeningeal disseminated coccidioidomycosis, were studied. Compared to concentrations in healthy immune and nonimmune donors, the median concentration of IL-17A was significantly higher in those with active coccidioidomycosis (for both, P < 0.01). In addition, IL-6 concentrations were higher while IL-2 and IFN-γ concentrations were significantly lower in those with nonmeningeal disseminated disease diagnosed within 12 months than in those with acute pneumonia (for all, P < 0.05). The cytokine profile among patients with active coccidioidomycosis is distinct in that IL-17A is persistently present. In addition, those with nonmeningeal disseminated disease have an increased inflammatory cytokine response and diminished Th1 responses that modulate over time.

In vivo trafficking and immunostimulatory potential of an intranasally-administered primary dendritic cell-based vaccine

BACKGROUND

Coccidioidomycosis or Valley fever is caused by a highly virulent fungal pathogen: Coccidioides posadasii or immitis. Vaccine development against Coccidioides is of contemporary interest because a large number of relapses and clinical failures are reported with antifungal agents. An efficient Th1 response engenders protection. Thus, we have focused on developing a dendritic cell (DC)-based vaccine for coccidioidomycosis. In this study, we investigated the immunostimulatory characteristics of an intranasal primary DC-vaccine in BALB/c mouse strain that is most susceptible to coccidioidomycosis. The DCs were transfected nonvirally with Coccidioides-Ag2/PRA-cDNA. Expression of DC-markers, Ag2/PRA and cytokines were studied by flow cytometry, dot-immunoblotting and cytometric bead array methods, respectively. The T cell activation was studied by assessing the upregulation of activation markers in a DC-T cell co-culture assay. For trafficking, the DCs were co-transfected with a plasmid DNA encoding HSV1 thymidine kinase (TK) and administered intranasally into syngeneic mice. The trafficking and homing of TK-expressing DCs were monitored with positron emission tomography (PET) using 18F-FIAU probe. Based on the PET-probe accumulation in vaccinated mice, selected tissues were studied for antigen-specific response and T cell phenotypes using ELISPOT and flow cytometry, respectively.

RESULTS

We found that the primary DCs transfected with Coccidioides-Ag2/PRA-cDNA were of immature immunophenotype, expressed Ag2/PRA and activated naïve T cells. In PET images and subsequent biodistribution, intranasally-administered DCs were found to migrate in blood, lung and thymus; lymphocytes showed generation of T effector memory cell population (T(EM)) and IFN-γ release.

CONCLUSIONS

In conclusion, our results demonstrate that the intranasally-administered primary DC vaccine is capable of inducing Ag2/PRA-specific T cell response. Unique approaches utilized in our study represent an attractive and novel means of producing and evaluating an autologous DC-based vaccine.

Polyfunctional T lymphocytes are in the peripheral blood of donors naturally immune to coccidioidomycosis and are not induced by dendritic cells

Coccidioidomycosis is a fungal infection endemic in the southwestern United States that is increasing in incidence. While cellular immunity correlates with protection from clinical illness, the precise elements of that response are undefined. Using the coccidioidal antigen preparation T27K and multiparametric flow cytometry, the in vitro frequency of polyfunctional T lymphocytes in the peripheral blood of naturally immune healthy donors and those who were nonimmune was determined. Polyfunctional CD4 lymphocytes, defined as producing intracellular interleukin 2 (IL-2), gamma interferon (IFN-gamma), and tumor necrosis factor alpha simultaneously, had a frequency of 137 per 400,000 events among peripheral blood mononuclear cells (PBMC) of immune donors compared to 11 per 400,000 PBMC from nonimmune donors (P = 0.03). When monocyte-derived mature dendritic cells pulsed with T27K (mDC(T27K)) were used for antigen presentation, the frequency of polyfunctional CD4 T lymphocytes did not significantly increase for either group, although mDC(T27K) did significantly increase the concentrations of IL-2 and IFN-gamma released by PBMC from nonimmune donors (P = 0.02). After in vitro stimulation with T27K, polyfunctional CD4 and CD8 lymphocytes of PBMC from immune donors had a mixture of low- and high-expression CCR7 cells, suggesting both effector and central memory, compared with predominantly high-expression CCR7 cells when PBMC were incubated with the mitogen phytohemagglutinin (P = 0.03). These data demonstrate the presence of polyfunctional T lymphocytes in the peripheral blood of individuals with coccidioidal immunity and suggest a model for the in vitro testing of vaccine candidates for coccidioidomycosis.

An Archived Lot of Coccidioidin Induces Specific Coccidioidal Delayed-type Hypersensitivity and Correlates with in vitro Assays of Coccidioidal Cellular Immune Response

No test for assessing cellular immune response in coccidioidomycosis is currently available in the United States. In the present study, we tested 49 healthy subjects living in the coccidioidal endemic region with a 1:55.8 dilution of a single lot of coccidioidin archived since the 1970s. In this group, 23 evaluable subjects demonstrated >/=5 mm of induration at 24, 48 or 72 h, with a mean+/-SEM maximum induration of 18.4+/-4.0 mm. The induration results among 14 subjects reactive at 24 h were compared to those from 179 individuals in an historical cohort studied in the 1980s using a reference lot of coccidioidin. Results were within 5% and not significantly different (P=0.924). The maximum induration response of all evaluable subjects correlated significantly with the results of in vitro tests of coccidioidal cellular immunity using supernatant interferon-gamma concentration and CD69 expression on T cells (Spearman rank correlation coefficients 0.69 and 0.68, respectively; P<0.01 for both). These data suggest that archived coccidioidin retains its potency and specificity and that in vitro test of coccidioidal immunity may have utility in the measurement of coccidioidal cellular immunity.