A novel role for tumor necrosis factor-alpha in regulating susceptibility of activated CD4+ T cells from human and nonhuman primates for distinct coreceptor using lentiviruses

A closed-culture system using a GMP-grade culture bag and anti-CD3/28 coated bead stimulation for CD4+ T cell expansion from healthy and HIV-infected donors

CD4 immunotherapy is potentially useful in immune reconstitution of CD4⁺ T cells for HIV-infected patients. Transfusion of anti-CD3/28 expanded CD4⁺ T cells is also proved to be safe and effective in both SIV-infected macaques and HIV-infected patients. However, there is no such standardized and practical protocol available for cell production in order to use in clinics. This study thus aimed to develop a closed-culture system for in vitro CD4⁺ T lymphocyte expansion by using a commercially available GMP-grade culture bag and anti-CD3/28 activation. Freshly isolated CD4⁺ T cells by immunorosette formation from healthy donors and cryopreserved CD4⁺ T cells from HIV-infected patients with CD4 count over 500 cells/μL were stimulated with anti-CD3/28 coated beads. The activated cells were then expanded in conventional culture flasks and GMP-grade culture bags for three weeks. Fold expansion, cell viability, growth kinetic and phenotypic characters were observed. Results revealed that purified CD4⁺ T cells from healthy individuals cultured in flasks showed better expansion than those cultured in bags (797-fold and 331-fold, respectively), whereas, their cell viability, growth kinetic and expanded CD4⁺ T cell purity were almost similar. A large-scale production was also conducted and supported consistency of cell proliferation in the closed-culture system. Frozen CD4⁺ T lymphocytes from the patients were able to remain their growth function and well expanded with a good yield of 415-fold, 85% viability and 96% purity of CD4⁺ T cells at the end of a 3-week culture in bags. This developed closed-culture system using culture bags and anti-CD3/28 coated beads, therefore, can achieve a large number of expanded CD4⁺ T lymphocytes with good reproducibility, suggesting a promising protocol required for adoptive immunotherapy.

Antigen stimulation induces HIV envelope gp120-specific CD4(+) T cells to secrete CCR5 ligands and suppress HIV infection

CD4(+) T cells are critical for effective immune responses against HIV, but they are also the main cell type targeted by the virus. To investigate the key factors that could protect these cells from infection, we evaluated the capacity of HIV gp120-specific human CD4(+) T cells to produce chemokines that inhibit HIV and determined their contribution in suppressing infection in the cells. Antigen stimulation of the CD4(+) T cells elicited production of high amounts of CCR5 chemokines MIP-1alpha (CCL3), MIP-1beta (CCL4), and RANTES (CCL5). Production of these CCR5 ligands was more readily and reproducibly detected than that of IFN-gamma or IL-2. Importantly, in association with secretion of the CCR5 ligands, antigen stimulation made these CD4(+) T cells more resistant to CCR5-tropic HIV-1. Conversely, in the absence of antigen stimulation, the cells were readily infected by the virus, and after infection, their capacity to produce MIP-1beta and IFN-gamma rapidly declined. Thus, vaccines that trigger HIV-specific CD4(+) T cells to elicit robust and rapid production of anti-viral chemokines would be advantageous. Such responses would protect virus-specific CD4(+) T cells from HIV infection and preserve their critical functions in mounting and maintaining long-lasting immunity against the virus.

Anti-CD3/28 mediated expansion of macaque CD4+ T cells is polyclonal and provides extended survival after adoptive transfer

BACKGROUND

Our lab has previously shown that adoptive transfer of in vitro expanded autologous purified polyclonal CD4(+) T cells using anti-CD3/CD28 coated beads induced antiviral responses capable of controlling simian immunodeficiency virus (SIV) replication in vivo.

RESULTS

Expansion on anti-CD3/28 coated beads was found to induce a true polyclonal expansion as CFSE labeled cells uniformly showed dilution of the dye over several days of culture, in contrast to aliquots of the same cells subjected to mitogen stimulation. Of interest was the finding that CD4(+) T cells collected before and during early chronic SIV infection or AIDS stage did not show any or only modest differences in proliferative response or expansion kinetics. The reason for such excellent expansion properties was analyzed by the quantitation of telomerase activity in aliquots of expanding CD4(+) T cells from sample collected at various times post-infection. First, anti-CD3/28 expanded CD4(+) T cells exhibited telomerase levels 2- to 20-fold higher than the starting population of CD4(+) T cells. Moreover, while telomerase activity in ex vivo tested CD4(+) T cells was found to decrease following SIV infection and disease progression, anti-CD3/28 expansion appeared to restore significant levels of telomerase activity as no difference was noted in telomerase expression between CD4(+) T cells expanded from samples collected before or during the chronic SIV infection. When such expanded and CFSE labeled T cells were autologously transferred to monkeys, evidence for extended survival in vivo was provided as CFSE labeled cells were detected to relatively high levels in blood and spleen at 1 week post-infection.

CONCLUSION

In summary, the data suggest that anti-CD3/28 mediated expansion of CD4(+) T cells retains its immunotherapeutic potential not only during the early stages of lentiviral infection but also at more advanced stages of disease.

Optimization of in vitro expansion of macaque CD4 T cells using anti-CD3 and co-stimulation for autotransfusion therapy

BACKGROUND

Our laboratory has previously shown that adoptive transfer of in vitro-expanded autologous purified polyclonal CD4(+) T cells using anti-CD3/CD28-coated beads induced antiviral responses capable of controlling SIV replication in vivo.

METHODS

As CD4(+) T cells comprise several phenotypic and functional lineages, studies were carried out to optimize the in vitro culture conditions for maximal CD4(+) T-cell expansion, survival and delineate the phenotype of these expanded CD4(+) T cells to be linked to maximal clinical benefit.

RESULTS AND CONCLUSIONS

The results showed that whereas anti-monkey CD3gamma/epsilon was able to induce T-cell proliferation and expansion in combination with antibodies against multiple co-stimulatory molecules, monkey CD3epsilon cross reacting antibodies failed to induce proliferation of macaque CD4(+) T cells. Among co-stimulatory signals, anti-CD28 stimulation was consistently superior to anti-4-1BB, CD27 or ICOS while the use of anti-CD154 failed to deliver a detectable proliferation signal. Increasing the relative anti-CD28 co-stimulatory signal relative to anti-CD3 provided a modest enhancement of expansion. Additional strategies for optimization included attempts to neutralize free radicals, enhancement of glucose uptake by T cells or addition of T-cell stimulatory cytokines. However, none of these strategies provided any detectable proliferative advantage. Addition of 10 autologous irradiated feeder cells/expanding T cell provided some enhancement of expansion; however, given the high numbers of T cell needed, this approach was deemed impractical and costly, and lower ratios of feeder to expanding T cells failed to provide such benefit. The most critical parameter for efficient expansion of purified CD4(+) T cells from multiple monkeys was the optimization of space and culture conditions at culture inception. Finally, anti-CD3/28-expanded CD4(+) T cells uniformly exhibited a central memory phenotype, absence of CCR5 expression, marked CXCR4 expression in vitro, low levels of caspase 3 but also of Bcl-2 expression.

Follicular dendritic cell-mediated up-regulation of CXCR4 expression on CD4 T cells and HIV pathogenesis

Follicular dendritic cells (FDCs) represent a major reservoir of HIV, and active infection occurs surrounding these cells, suggesting that this microenvironment is highly conducive to virus transmission. Because CD4 T cells around FDCs in germinal centers express the HIV coreceptor, CXCR4, whereas CD4 lymphocytes in many other sites do not, it prompted the hypothesis that FDCs may increase CXCR4 expression on CD4 T cells, thereby facilitating infection. To test this, HIV receptor/coreceptor expression was determined on CD4 T cells cultured with or without FDCs, and its consequence to infection was assessed by measuring virus binding and entry. FDCs had little effect on CCR5 or CD4 expression but increased CXCR4 expression on CD4 T cells. FDC-mediated up-regulation of CXCR4 on CD4 T cells occurred by 24 h and was sustained for at least 96 h in vitro, and FDC-CD4 T cell contact was necessary. Importantly, increased CXCR4 expression directly correlated with increased binding and entry of HIV-1 X4 isolates. Furthermore, CD4(+)CD57(+) germinal center T cells expressed high levels of CXCR4 and supported enhanced entry of X4 HIV compared with other CD4 T cells from the same tissue. Thus, in addition to serving as a reservoir of infectious virus, FDCs render surrounding germinal center T cells highly susceptible to infection with X4 isolates of HIV-1.

Macaques with rapid disease progression and simian immunodeficiency virus encephalitis have a unique cytokine profile in peripheral lymphoid tissues

The influence of host cytokine response on viral load, disease progression, and neurologic lesions was investigated in the simian immunodeficiency virus (SIV)-infected macaque model of AIDS. Cytokine gene expression (interleukin-1beta [IL-1beta], IL-2, IL-6, IL-10, gamma interferon [IFN-gamma], and tumor necrosis factor alpha [TNF-alpha]) and viral loads were evaluated by semiquantitative reverse transcription-PCR in lymph nodes of 5 control animals and 28 animals infected with SIVmac251 at the terminal stages of AIDS. Infected animals showed higher expression of IFN-gamma, IL-6, and IL-10 mRNAs compared with controls. Levels of all cytokines were comparable between animals with rapid (survival, <200 days) or slow/normal (survival, >200 days) disease progression. However, among rapid progressors, the eight animals with SIV encephalitis had a unique cytokine profile (increased IL-2, IL-6, and IFN-gamma) that was associated with higher viral loads. These observations provide evidence that host cytokine responses may influence SIV neuropathogenesis independent of disease progression.