Interleukins 15 and 12 in combination expand the selective loss of natural killer T cells in HIV infection in vitro

Expansion of invariant natural killer T cells from systemic lupus erythematosus patients by alpha-Galactosylceramide and IL-15

CD1d-restricted invariant natural killer T cells (iNKT cells) may play an important role in the pathogenesis of systemic lupus erythematosus (SLE). Interleukin (IL)-15 is a pro-inflammatory cytokine which is over-expressed in SLE patients. In the present study, we investigated the iNKT cell expansion of mononuclear cells (MNCs) from SLE patients following 10 days’ culture with α-galactosylceramide (α-Galcer) and /or IL-15. We sought to determine the phenotypic and functional characteristics of the expanded iNKT cells compared to healthy controls and correlated with disease activity. We observed that 1. The percentages of Vα24+/Vβ11+ iNKT cells following 10-day incubation was lower in SLE groups compared to controls; 2. The percentages and absolute numbers of Vα24+/Vβ11+ iNKT cells were expanded by α-galactosylceramide (α-Galcer), and further enhanced with IL-15 in SLE patient, but the effect of IL-15 was much lower than controls; 3.IL-15 +α-Galcer expanded CD3+/CD56+ NKT-like cells from SLE patients, especially with active disease 4. The CD161+ Vα24+/Vβ11+ iNKT cells in SLE were more responsive to α-Galcer stimulation than the CD161- counterpart; 5. IL-15 decreased apoptosis of α-Galcer activated SLE iNKT cells; 6. IL-15 enhanced CD69, CD1d and CD11a expression on α-Galcer treated iNKT cells; 7. The IL-4 production of iNKT cells was decreased in SLE patients compared to controls; 8. IL-15 increased IFN-γ and IL-4 production of SLE iNKT cells; 8. IL-15 failed to augment the ability of iNKT cells to aid NK-mediated K562 cytolysis in SLE patients; 9. CD161 positivity, granzyme B and perforin expression of α-Galcer+IL-15 expanded iNKT cells correlated with C3 levels in SLE patients. Taken together, our results demonstrated numeric and functional deficiency of iNKT cells and their response to IL-15 in SLE patients. Our finding may provide insight for using adoptive iNKT cell therapy in autoimmune diseases.

Hemophagocytic lymphohistiocytosis in an HIV-positive patient with concomitant disseminated histoplasmosis

A 46-year-old Dominican man, known to have HIV, presented with constitutional symptoms of two week's duration. The patient was found to have cytopenias, significantly elevated ferritin level and lymphadenopathy. Biopsies and laboratory studies met the criteria for hemophagocytic lymphohistiocytosis (HLH). A concomitant diagnosis of histoplasmosis was confirmed as the trigger for HLH and treatment resulted in clinical improvement and resolution of symptoms.

Study of Natural Cytotoxicity Receptors in Patients with HIV/AIDS and Cancer: A Cross-Sectional Study

The NCR receptors play a fundamental role in the cytotoxicity mediated by NK cells against tumor cells. In the current study, we investigated possible HIV/AIDS-related changes in the expression of the NCR receptors comparing healthy donors, HIV/AIDS patients, and HIV/AIDS patients with cancer (HIV/AIDSWC). The NCRs were quantified in NK cells (NK^dim and NK^bright) and T lymphocytes from peripheral blood samples by flow cytometry. We found a significant decrease in the frequency of NK cells expressing NKp46 in HIV/AIDS group (p = 0.0012). There was a decrease in the frequency of NK cells expressing NKp46 in the HIV/AIDSWC group; however, this was not statistically significant. We found a significant decrease in the frequency of NK cells expressing NKp30 in the HIV/AIDS group (p = 0.0144). There was a decrease in the frequency of NK cells expressing NKp30 and in the HIV/AIDSWC group, but this was not statistically significant. There were no changes in the distribution of NK cells and their subtypes in both groups.

Mechanisms of Control of Mycobacterium tuberculosis by NK Cells: Role of Glutathione

Tuberculosis (TB), caused by Mycobacterium tuberculosis (M. tb), continues to be one of the most prevalent infectious diseases in the world. There is an upward trend in occurrence due to emerging multidrug resistant strains and an increasingly larger proportion of immunocompromised patient populations as a result of the acquired immunodeficiency syndrome pandemic. The complex and often deadly combination of multidrug resistant M. tb (MDR-M. tb) along with human immunodeficiency virus (HIV) puts a significant number of people at high risk for pulmonary and extra-pulmonary TB without sufficient therapeutic options available. Natural killer (NK) cells and macrophages are major components of the body's innate immune system, contributing significantly to the body's ability to synergistically inhibit the growth of M. tb in immune compromised individuals lacking a sufficient T cell response. Direct mechanisms of control are largely through the secretory products perforin, granulysin, and granzymes, as well as multiple membrane-bound death receptors that facilitate target directed lysis. NK cells also have a role in indirectly stimulating an immune response through activation of macrophages and monocytes with multiple signaling pathways, including both reactive oxygen species and reactive nitrogen species. Glutathione (GSH) has been shown to play a part in inhibiting the growth of intracellular M. tb through bacteriostatic mechanisms. Enhancing cellular GSH through several cytokines and N-acetyl cysteine has been shown to increase these effects, at least in part, through their action on NK cells. Taken together, there is substantial evidence for a mechanistic correlation between NK cell activity and functionality in combating M. tb in HIV infection mediated through adequate GSH production and use.

Regulation of NKT Cell Localization in Homeostasis and Infection

Natural killer T (NKT) cells are a specialized subset of T lymphocytes that regulate immune responses in the context of autoimmunity, cancer, and microbial infection. Lipid antigens derived from bacteria, parasites, and fungi can be presented by CD1d molecules and recognized by the canonical T cell receptors on NKT cells. Alternatively, NKT cells can be activated through recognition of self-lipids and/or pro-inflammatory cytokines generated during infection. Unlike conventional T cells, only a small subset of NKT cells traffic through the lymph nodes under homeostatic conditions, with the largest NKT cell populations localizing to the liver, lungs, spleen, and bone marrow. This is thought to be mediated by differences in chemokine receptor expression profiles. However, the impact of infection on the tissue localization and function of NKT remains largely unstudied. This review focuses on the mechanisms mediating the establishment of peripheral NKT cell populations during homeostasis and how tissue localization of NKT cells is affected during infection.

Histoplasmosis-Induced Hemophagocytic Syndrome: A Case Series and Review of the Literature

Background. Histoplasmosis-associated hemophagocytic lymphohistiocytosis (HLH) is a relatively rare disorder for which data are limited regarding optimal treatment and clinical outcomes in adults. We describe the clinical features, treatment, and outcomes of patients with histoplasmosis-associated HLH at our institution.

Methods. We performed a retrospective chart review of all inpatients at Parkland Hospital diagnosed with HLH associated with Histoplasma capsulatum from 2003 to 2013.

Results. Eleven cases of histoplasmosis-associated HLH over this time period were identified. Nine of eleven cases were males (82%). Nine of these patients had human immunodeficiency virus (HIV)/acquired immune deficiency syndrome (AIDS), 1 was a renal transplant patient on immunosuppressants, and the other had no documented immunocompromise. The most common HLH criteria were splenomegaly (n = 10), fever (n = 10), and ferritin >500 ng/dL (n = 9). Urine Histoplasma antigen was positive in every patient tested (n = 9 of 9), and most antibodies for Histoplasma were positive if checked (n = 4 of 5). A majority of patients received liposomal amphotericin B (n = 9) with an average treatment duration of 11 days, and 5 patients also received prednisone, intravenous immunoglobulin (IVIG), or both. Overall, 5 patients died within 30 days (45.5%), and 7 patients died within 90 days (63.6%). Of the 5 patients that received immunosuppression, 4 died (80%), whereas in the group not given additional immunosuppression (n = 5), 2 died (40%).

Conclusions. Histoplasmosis-associated HLH among adults is a lethal disease of highly immunocompromised patients, especially patients with HIV/AIDS. Clinical features such as splenomegaly, elevated ferritin, and cytopenias should prompt evaluation for HLH in this population. Further data are needed to define the role of immunosuppression, IVIG, and highly active antiretroviral therapy in treating this condition.