Preserved MHC class II antigen processing in monocytes from HIV-infected individuals

Methamphetamine induces transcriptional changes in cultured HIV-infected mature monocytes that may contribute to HIV neuropathogenesis

HIV-associated neurocognitive impairment (HIV-NCI) persists in 15-40% of people with HIV (PWH) despite effective antiretroviral therapy. HIV-NCI significantly impacts quality of life, and there is currently no effective treatment for it. The development of HIV-NCI is complex and is mediated, in part, by the entry of HIV-infected mature monocytes into the central nervous system (CNS). Once in the CNS, these cells release inflammatory mediators that lead to neuroinflammation, and subsequent neuronal damage. Infected monocytes may infect other CNS cells as well as differentiate into macrophages, thus contributing to viral reservoirs and chronic neuroinflammation. Substance use disorders in PWH, including the use of methamphetamine (meth), can exacerbate HIV neuropathogenesis. We characterized the effects of meth on the transcriptional profile of HIV-infected mature monocytes using RNA-sequencing. We found that meth mediated an upregulation of gene transcripts related to viral infection, cell adhesion, cytoskeletal arrangement, and extracellular matrix remodeling. We also identified downregulation of several gene transcripts involved in pathogen recognition, antigen presentation, and oxidative phosphorylation pathways. These transcriptomic changes suggest that meth increases the infiltration of mature monocytes that have a migratory phenotype into the CNS, contributing to dysregulated inflammatory responses and viral reservoir establishment and persistence, both of which contribute to neuronal damage. Overall, our results highlight potential molecules that may be targeted for therapy to limit the effects of meth on HIV neuropathogenesis.

Monocyte Dysfunction, Activation, and Inflammation After Long-Term Antiretroviral Therapy in an African Cohort

BACKGROUND

Monocyte dysfunction may persist during antiretroviral therapy (ART).

METHODS

Frozen peripheral blood mononuclear cells of 30 human immunodeficiency virus (HIV)-infected ART-treated adults with sustained viral suppression and CD4 counts ≥500 cells/µL were consecutively analyzed for monocyte phenotypes and function.

RESULTS

Nonclassical monocytes (CD14+, CD16++), interleukin (IL)-1β production, and expression of CD40 and CD86 were lower among ART-treated HIV-infected adults relative to age-matched HIV-negative adults (P = .01, P = .01, and P = .02, respectively). Intestinal fatty acid-binding protein, IL6, and soluble CD14 were higher among HIV-infected adults relative to HIV-negative adults (P = .0002, P = .04, and P = .0017, respectively).

CONCLUSIONS

Further investigation is required to understand drivers of persistent monocyte activation and dysfunction.

The role of innate immunity in the immunopathology and treatment of HBV infection

In this review we give a brief update on sensors recently determined to be capable of detecting HBV, and examine how the virus represses the induction of pro-inflammatory cytokines like type I interferons. We overview cellular components of innate immunity that are present at high frequencies in the liver, and discuss their roles in HBV control and/or pathogenesis. We argue that many innate effectors have adaptive-like features or can exert specific effects on HBV through immunoregulation of T cells. Finally we consider current and possible future strategies to manipulate innate immunity as novel approaches towards a functional cure for HBV.

HIV-1 gp120 protein downregulates Nef induced IL-6 release in immature dentritic cells through interplay of DC-SIGN

HIV-1 replication is a tightly controlled mechanism which demands the interplay of host as well as viral factors. Both gp120 (envelope glycoprotein) and Nef (regulatory protein) have been correlated with the development of AIDS disease in independent studies. In this context, the ability of HIV-1 to utilize immature dentritic cells for transfer of virus is pivotal for early pathogenesis. The presence of C-type lectins on dendritic cells (DCs) like DC-SIGN, are crucial in inducing antiviral immunity to HIV-1. Both gp120 and Nef induce the release of cytokines leading to multiple effects of viral pathogenesis. Our study elucidated for the first time the cross-talk of the signaling mechanism of these two viral proteins in immature monocyte derived dentritic cells (immDCs). Further, gp120 was found to downregulate the IL-6 release by Nef, depending on the interaction with DC-SIGN. A cascade of signaling followed thereafter, including the activation of SOCS-3, to mediate the diminishing effect of gp120. Our results also revealed that the anti-apoptotic signals emanated from Nef was put to halt by gp120 through inhibition of Nef induced STAT3. Thus our results implicate that the signaling generated by gp120 and Nef, undergoes a switch-over mechanism that significantly contributes to the pathogenesis of HIV-1 and widens our view towards the approach on battling the viral infection.

Production of CD4⁺ and CD8⁺ T cell hybridomas

T cell hybridomas are very useful tools to investigate antigen presenting cell (APC) function. They were developed based on the fusion technology that led to monoclonal antibody section. Antigen-specific primary T cells are generated and fused to an immortal thymoma line. Unfused thymoma cells are eliminated by engineered metabolic selection. Antigen-specific hybridomas are identified and may be characterized in detail. Primary T cells are preferable for studies of the regulatory mechanisms intrinsic to T cells, but for study of antigen presentation T cell hybridomas have advantages over primary T cell clones, including their relative uniformity, stability over time, and ready availability in large numbers for extensive antigen presentation experiments.

Preserved MHC-II antigen processing and presentation function in chronic HCV infection

Individuals with chronic HCV infection have impaired response to vaccine, though the etiology remains to be elucidated. Dendritic cells (DC) and monocytes (MN) provide antigen uptake, processing, presentation, and costimulatory functions necessary to achieve optimal immune responses. The integrity of antigen processing and presentation function within these antigen presenting cells (APC) in the setting of HCV infection has been unclear. We used a novel T cell hybridoma system that specifically measures MHC-II antigen processing and presentation function of human APC. Results demonstrate MHC-II antigen processing and presentation function is preserved in both myeloid DC (mDC) and MN in the peripheral blood of chronically HCV-infected individuals, and indicates that an alteration in this function does not likely underlie the defective HCV-infected host response to vaccination.