Migration Patterns of Nonspecifically Activated Versus Nonactivated Nonhuman Primate T Lymphocytes: Preferential Homing of Activated Autologous CD8+ T Cells in the Rectal Mucosa

Cell-Associated Simian Immunodeficiency Virus Accelerates Initial Virus Spread and CD4+ T-Cell Depletion in the Intestinal Mucosa

Cell-free and cell-associated human immunodeficiency virus (HIV) may differently affect the immune system and the efficacy of prevention strategies. Here we examined mucosal events in simian immunodeficiency virus (SIV) infection, using infected cells together with cell-free virus and cell-free virus alone. Intravenously inoculated SIV-infected cells disseminated virus to the intestine within 16 hours. Infection with both virus forms accelerated viral dissemination in the intestinal mucosa and the loss of mucosal CD4+ T cells as compared to infection with cell-free virus only. As all natural sources of HIV infection contain both virus forms, future prevention studies should focus on efficacy against both cell-free and cell-associated virus.

Standardizing immunophenotyping for the Human Immunology Project

The heterogeneity in the healthy human immune system, and the immunological changes that portend various diseases, have been only partially described. Their comprehensive elucidation has been termed the 'Human Immunology Project'. The accurate measurement of variations in the human immune system requires precise and standardized assays to distinguish true biological changes from technical artefacts. Thus, to be successful, the Human Immunology Project will require standardized assays for immunophenotyping humans in health and disease. A major tool in this effort is flow cytometry, which remains highly variable with regard to sample handling, reagents, instrument setup and data analysis. In this Review, we outline the current state of standardization of flow cytometry assays and summarize the steps that are required to enable the Human Immunology Project.

Intravenous administration of multipotent stromal cells prevents the onset of non-alcoholic steatohepatitis in obese mice with metabolic syndrome

BACKGROUND & AIMS

Metabolic syndrome is secondary to obesity and characterized by dyslipidemia, insulin resistance, and hypertension. Non-alcoholic fatty liver disease is its hepatic manifestation, whose progression-limiting step is non-alcoholic steatohepatitis (NASH). The latter is characterized by lipid accumulation, hepatocyte damage, leukocyte infiltration, and fibrosis. NASH is a prodrome to cirrhosis and hepatocellular carcinoma. Multipotent stromal cells (MSCs) have been shown to be immunomodulatory and contribute to liver regeneration in acute failure conditions. Our aim was to evaluate whether MSC administration prevents the onset of NASH in obese mice with metabolic syndrome.

METHODS

C57BL/6 mice were chronically fed with high-fat diet. At week 33, mice received intravenously either the vehicle (obese untreated) or two doses of 0.5×10(6) syngeneic MSCs (obese MSC-treated). Four months later, liver function and structure, and metabolic syndrome markers were assessed. The persistence of donor MSCs(GFP) in obese mice was evaluated 17 weeks after their administration.

RESULTS

Obese untreated mice presented high plasma levels of hepatic enzyme, hepatomegaly, liver fibrosis, inflammatory cell infiltration, and hepatic triglyceride accumulation. Furthermore, they showed high expression levels of fibrosis markers and pro-inflammatory cytokines. By contrast, obese MSC-treated mice only presented steatosis. Mice kept obese, hypercholesterolemic, hyperglycemic, and insulin resistant irrespective of whether they received MSCs or not. Donor MSCs(GFP) were found in liver, bone marrow, heart, and kidney of obese mice.

CONCLUSIONS

MSC administration prevents the onset of NASH in obese mice. Observed hepatoprotection is not related to a reversion of the metabolic syndrome but to the preclusion of the inflammatory process.

Evidence for the cure of HIV infection by CCR5Δ32/Δ32 stem cell transplantation

HIV entry into CD4(+) cells requires interaction with a cellular receptor, generally either CCR5 or CXCR4. We have previously reported the case of an HIV-infected patient in whom viral replication remained absent despite discontinuation of antiretroviral therapy after transplantation with CCR5Δ32/Δ32 stem cells. However, it was expected that the long-lived viral reservoir would lead to HIV rebound and disease progression during the process of immune reconstitution. In the present study, we demonstrate successful reconstitution of CD4(+) T cells at the systemic level as well as in the gut mucosal immune system after CCR5Δ32/Δ32 stem cell transplantation, while the patient remains without any sign of HIV infection. This was observed although recovered CD4(+) T cells contain a high proportion of activated memory CD4(+) T cells, ie, the preferential targets of HIV, and are susceptible to productive infection with CXCR4-tropic HIV. Furthermore, during the process of immune reconstitution, we found evidence for the replacement of long-lived host tissue cells with donor-derived cells, indicating that the size of the viral reservoir has been reduced over time. In conclusion, our results strongly suggest that cure of HIV has been achieved in this patient.

Gut mucosal FOXP3+ regulatory CD4+ T cells and Nonregulatory CD4+ T cells are differentially affected by simian immunodeficiency virus infection in rhesus macaques

The gastrointestinal tract represents a major site for human and simian immunodeficiency virus (HIV and SIV) replication and CD4(+) T-cell depletion. Despite severe depletion of mucosal CD4(+) T cells, FOXP3(+) regulatory CD4(+) T cells (T(reg)) are highly increased in the gut mucosa of chronically HIV-infected individuals and may contribute to HIV pathogenesis, either by their immunosuppressive function or as a significant target cell population for virus production. Little is known about the susceptibility of mucosal T(reg) to viral infection and the longitudinal effect of HIV/SIV infection on T(reg) dynamics. In this study, we determined the level of SIV infection in T(reg) and nonregulatory CD4(+) T cells (non-T(reg)) isolated from the colon of SIV-infected rhesus macaques. The dynamics of mucosal T(reg) and alterations in the mucosal CD4(+) T-cell pool were examined longitudinally. Our findings indicate that mucosal T(reg) were less susceptible to productive SIV infection than non-T(reg) and thus were selectively spared from SIV-mediated cell death. In addition to improved survival, local expansion of T(reg) by SIV-induced proliferation of the mucosal CD4(+) T-cell pool facilitated the accumulation of mucosal T(reg) during the course of infection. High frequency of mucosal T(reg) in chronic SIV infection was strongly related to a reduction of perforin-expressing cells. In conclusion, this study suggests that mucosal T(reg) are less affected by productive SIV infection than non-T(reg) and therefore spared from depletion. Although SIV production is limited in mucosal T(reg), T(reg) accumulation may indirectly contribute to viral persistence by suppressing antiviral immune responses.

Memory T cells in Rhesus macaques

The Rhesus macaque (Macaca mulatta) is one of the best studied species of Old World monkeys. DNA sequencing of the entire Rhesus macaque genome, completed in 2007, has demonstrated that humans and macaques share about 93% of their nucleotide sequence. Rhesus macaques have been widely used for medical research including drug testing, neurology, behavioral and cognitive science, reproduction, xenotransplantation and genetics. Because of the Rhesus macaque's sensitivity to bacteria, parasites and viruses that cause similar disease in humans, these animals represent an excellent model to study infectious diseases. The recent pandemic of HIV and the discovery of SIV, a lentivirus genetically related to HIV Type 1 that causes AIDS in Rhesus macaques, have prompted the development of reagents that can be used to study innate and adaptive immune responses in macaques at the single cell level. This review will focus on the distribution of memory cells in the different immunologic compartments of Rhesus macaques. In addition, the strategies available to manipulate memory cells in Rhesus macaques to understand their trafficking and function will be discussed. Emphasis is placed on studies of memory cells in macaques infected with SIV because many studies are available. Lastly, we highlight the usefulness of the Rhesus macaque model in studies related to the aging of the immune system.

Endovenous administration of bone-marrow-derived multipotent mesenchymal stromal cells prevents renal failure in diabetic mice

Twenty-five to 40% of diabetic patients develop diabetic nephropathy, a clinical syndrome that comprises renal failure and increased risk of cardiovascular disease. It represents the major cause of chronic kidney disease and is associated with premature morbimortality of diabetic patients. Multipotent mesenchymal stromal cells (MSC) contribute to the regeneration of several organs, including acutely injured kidney. We sought to evaluate if MSC protect kidney function and structure when endovenously administered to mice with severe diabetes. A month after nonimmunologic diabetes induction by streptozotocin injection, C57BL/6 mice presented hyperglycemia, glycosuria, hypoinsulinemia, massive beta-pancreatic islet destruction, low albuminuria, but not renal histopathologic changes (DM mice). At this stage, one group of animals received the vehicle (untreated) and other group received 2 doses of 0.5 x 10(6) MSC/each (MSC-treated). Untreated DM mice gradually increased urinary albumin excretion and 4 months after diabetes onset, they reached values 15 times higher than normal animals. In contrast, MSC-treated DM mice maintained basal levels of albuminuria. Untreated DM mice had marked glomerular and tubular histopathologic changes (sclerosis, mesangial expansion, tubular dilatation, proteins cylinders, podocytes lost). However, MSC-treated mice showed only slight tubular dilatation. Observed renoprotection was not associated with an improvement in endocrine pancreas function in this animal model, because MSC-treated DM mice remained hyperglycemic and hypoinsulinemic, and maintained few remnant beta-pancreatic islets throughout the study period. To study MSC biodistribution, cells were isolated from isogenic mice that constitutively express GFP (MSC(GFP)) and endovenously administered to DM mice. Although at very low levels, donor cells were found in kidney of DM mice 3 month after transplantation. Presented preclinical results support MSC administration as a cell therapy strategy to prevent chronic renal diseases secondary to diabetes.

rBCG induces strong antigen-specific T cell responses in rhesus macaques in a prime-boost setting with an adenovirus 35 tuberculosis vaccine vector

Background

BCG vaccination, combined with adenoviral-delivered boosts, represents a reasonable strategy to augment, broaden and prolong immune protection against tuberculosis (TB). We tested BCG (SSI1331) (in 6 animals, delivered intradermally) and a recombinant (rBCG) AFRO-1 expressing perfringolysin (in 6 animals) followed by two boosts (delivered intramuscullary) with non-replicating adenovirus 35 (rAd35) expressing a fusion protein composed of Ag85A, Ag85B and TB10.4, for the capacity to induce antigen-specific cellular immune responses in rhesus macaques (Macaca mulatta). Control animals received diluent (3 animals).

Methods and Findings

Cellular immune responses were analyzed longitudinally (12 blood draws for each animal) using intracellular cytokine staining (TNF-alpha, IL-2 and IFN-gamma), T cell proliferation was measured in CD4⁺, CD8alpha/beta⁺, and CD8alpha/alpha⁺ T cell subsets and IFN-gamma production was tested in 7 day PBMC cultures (whole blood cell assay, WBA) using Ag85A, Ag85B, TB10.4 recombinant proteins, PPD or BCG as stimuli. Animals primed with AFRO-1 showed i) increased Ag85B-specific IFN-gamma production in the WBA assay (median >400 pg/ml for 6 animals) one week after the first boost with adenoviral-delivered TB-antigens as compared to animals primed with BCG (<200 pg/ml), ii) stronger T cell proliferation in the CD8alpha/alpha⁺ T cell subset (proliferative index 17%) as compared to BCG-primed animals (proliferative index 5% in CD8alpha/alpha⁺ T cells). Polyfunctional T cells, defined by IFN-gamma, TNF-alpha and IL-2 production were detected in 2/6 animals primed with AFRO-1 directed against Ag85A/b and TB10.4; 4/6 animals primed with BCG showed a Ag85A/b responses, yet only a single animal exhibited Ag85A/b and TB10.4 reactivity.

Conclusion

AFRO-1 induces qualitatively and quantitatively different cellular immune responses as compared with BCG in rhesus macaques. Increased IFN-gamma-responses and antigen-specific T cell proliferation in the CD8alpha/alpha+ T cell subset represents a valuable marker for vaccine-take in BCG-based TB vaccine trials