Does NLRP1 Inflammasome Activation in Immune Cells in Kidney Transplantation Relate with Donor Organ Age?

Inflammation causes a wide range of health disorders. In this process, the formation of inflammasome complexes plays a key role. Although inflammasomes have been extensively studied during kidney disease, their role in kidney transplantation has not been fully elucidated. In this study, we evaluate the gene and protein expression of several components of the inflammasome pathway before and at several time points after kidney transplantation in a cohort of patients of different ages and receiving an organ from older or younger donors. Our findings indicate the activation of the NLRP1 inflammasome in several immune cell population, monocytes and CD4+ and CD8+ cells mainly, in renal transplant, and its level increases gradually in patients who receive an older organ, whereas it has the opposite effect on older patients who receive a younger organ. Despite treatment with immunosuppressants, inflammation persists in some patients. These results lead to the hypothesis that the donor's age is a critical factor in post-transplant inflammasome activation and that specific NLRP1 inflammasome inhibitors should be considered to increase the success of kidney transplantation long-term.

KLRG1 expression on natural killer cells is associated with HIV persistence, and its targeting promotes the reduction of the viral reservoir.

Human immunodeficiency virus (HIV) infection induces immunological dysfunction, which limits the elimination of HIV-infected cells during treated infection. Identifying and targeting dysfunctional immune cells might help accelerate the purging of the persistent viral reservoir. Here, we show that chronic HIV infection increases natural killer (NK) cell populations expressing the negative immune regulator KLRG1, both in peripheral blood and lymph nodes. Antiretroviral treatment (ART) does not reestablish these functionally impaired NK populations, and the expression of KLRG1 correlates with active HIV transcription. Targeting KLRG1 with specific antibodies significantly restores the capacity of NK cells to kill HIV-infected cells, reactivates latent HIV present in CD4+ T cells co-expressing KLRG1, and reduces the intact HIV genomes in samples from ART-treated individuals. Our data support the potential use of immunotherapy against the KLRG1 receptor to impact the viral reservoir during HIV persistence.

Identification of HIV-reservoir cells with reduced susceptibility to antibody-dependent immune response.

Human immunodeficiency virus (HIV) establishes a persistent infection in heterogeneous cell reservoirs, which can be maintained by different mechanisms including cellular proliferation, and represent the main obstacle to curing the infection. The expression of the Fcγ receptor CD32 has been identified as a marker of the active cell reservoirs in people on antiretroviral therapy (ART), but if its expression has any role in conferring advantage for viral persistence is unknown. Here, we report that HIV-infected cells expressing CD32 have reduced susceptibility to natural killer (NK) antibody-dependent cell cytotoxicity (ADCC) by a mechanism compatible with the suboptimal binding of HIV-specific antibodies. Infected CD32 cells have increased proliferative capacity in the presence of immune complexes, and are more resistant to strategies directed to potentiate NK function. Remarkably, reactivation of the latent reservoir from antiretroviral-treated people living with HIV increases the pool of infected CD32 cells, which are largely resistant to the ADCC immune mechanism. Thus, we report the existence of reservoir cells that evade part of the NK immune response through the expression of CD32.

Antibody cooperative adsorption onto AuNPs and its exploitation to force natural killer cells to kill HIV-infected T cells.

HIV represents a persistent infection which negatively alters the immune system. New tools to reinvigorate different immune cell populations to impact HIV are needed. Herein, a novel nanotool for the specific enhancement of the natural killer (NK) immune response towards HIV-infected T-cells has been developed. Bispecific Au nanoparticles (BiAb-AuNPs), dually conjugated with IgG anti-HIVgp120 and IgG anti-human CD16 antibodies, were generated by a new controlled, linker-free and cooperative conjugation method promoting the ordered distribution and segregation of antibodies in domains. The cooperatively-adsorbed antibodies fully retained the capabilities to recognize their cognate antigen and were able to significantly enhance cell-to-cell contact between HIV-expressing cells and NK cells. As a consequence, the BiAb-AuNPs triggered a potent cytotoxic response against HIV-infected cells in blood and human tonsil explants. Remarkably, the BiAb-AuNPs were able to significantly reduce latent HIV infection after viral reactivation in a primary cell model of HIV latency. This novel molecularly-targeted strategy using a bispecific nanotool to enhance the immune system represents a new approximation with potential applications beyond HIV.

The active human immunodeficiency virus reservoir during antiretroviral therapy: emerging players in viral persistence.

PURPOSE OF REVIEW: To discuss the role of CD4+ T cells with active Human immunodeficiency virus (HIV), meaning infected cells with transcriptional and/or translational viral activity during antiretroviral therapy (ART), focusing on new technologies for its detection, potential cell markers for its characterization, and evidences on the contribution of the active HIV reservoir to long-term viral persistence. RECENT FINDINGS: HIV-infected cells expressing viral ribonucleic acid are systematically detected in subjects on long-term ART. In recent years, powerful new tools have provided significant insights into the nature, quantification, and identification of cells with active HIV, including the identification of new cell markers, and the presence of viral activity in specific cell populations located in different cellular and anatomical compartments. Moreover, studies on viral sequence integrity have identified cell clones with intact viral genomes and active viral transcription that could potentially persist for years. Together, new investigations support the notion that the active reservoir could represent a relevant fraction of long-term infected cells, and therefore, the study of its cell sources and mechanisms of maintenance could represent a significant advance in our understanding of viral persistence and the development of new curative strategies. SUMMARY: The presence of HIV-infected cells with viral expression during ART has been traditionally overlooked for years. Based on recent investigations, this active viral reservoir could play an important role in HIV persistence.

Peripheral and lung resident memory T cell responses against SARS-CoV-2.

Resident memory T cells (TRM) positioned within the respiratory tract are probably required to limit SARS-CoV-2 spread and COVID-19. Importantly, TRM are mostly non-recirculating, which reduces the window of opportunity to examine these cells in the blood as they move to the lung parenchyma. Here, we identify circulating virus-specific T cell responses during acute infection with functional, migratory and apoptotic patterns modulated by viral proteins and associated with clinical outcome. Disease severity is associated predominantly with IFNγ and IL-4 responses, increased responses against S peptides and apoptosis, whereas non-hospitalized patients have increased IL-12p70 levels, degranulation in response to N peptides and SARS-CoV-2-specific CCR7+ T cells secreting IL-10. In convalescent patients, lung-TRM are frequently detected even 10 months after initial infection, in which contemporaneous blood does not reflect tissue-resident profiles. Our study highlights a balanced anti-inflammatory antiviral response associated with a better outcome and persisting TRM cells as important for future protection against SARS-CoV-2 infection.

Resident memory T cells are a cellular reservoir for HIV in the cervical mucosa.

HIV viral reservoirs are established very early during infection. Resident memory T cells (TRM) are present in tissues such as the lower female genital tract, but the contribution of this subset of cells to the pathogenesis and persistence of HIV remains unclear. Here, we show that cervical CD4+TRM display a unique repertoire of clusters of differentiation, with enrichment of several molecules associated with HIV infection susceptibility, longevity and self-renewing capacities. These protein profiles are enriched in a fraction of CD4+TRM expressing CD32. Cervical explant models show that CD4+TRM preferentially support HIV infection and harbor more viral DNA and protein than non-TRM. Importantly, cervical tissue from ART-suppressed HIV+ women contain high levels of viral DNA and RNA, being the TRM fraction the principal contributor. These results recognize the lower female genital tract as an HIV sanctuary and identify CD4+TRM as primary targets of HIV infection and viral persistence. Thus, strategies towards an HIV cure will need to consider TRM phenotypes, which are widely distributed in tissues.

Expression of CD20 after viral reactivation renders HIV-reservoir cells susceptible to Rituximab.

The identification of exclusive markers to target HIV-reservoir cells will represent a significant advance in the search for therapies to cure HIV. Here, we identify the B lymphocyte antigen CD20 as a marker for HIV-infected cells in vitro and in vivo. The CD20 molecule is dimly expressed in a subpopulation of CD4-positive (CD4+) T lymphocytes from blood, with high levels of cell activation and heterogeneous memory phenotypes. In lymph node samples from infected patients, CD20 is present in productively HIV-infected cells, and ex vivo viral infection selectively upregulates the expression of CD20 during early infection. In samples from patients on antiretroviral therapy (ART) this subpopulation is significantly enriched in HIV transcripts, and the anti-CD20 monoclonal antibody Rituximab induces cell killing, which reduces the pool of HIV-expressing cells when combined with latency reversal agents. We provide a tool for targeting this active HIV-reservoir after viral reactivation in patients while on ART.