A combination of local inflammation and central memory T cells potentiates immunotherapy in the skin

Early memory differentiation and cell death resistance in T cells predicts melanoma response to sequential anti-CTLA4 and anti-PD1 immunotherapy

Immune checkpoint blockers (ICBs)-based immunotherapy has revolutionised oncology. However, the benefits of ICBs are limited to only a subset of patients. Herein, the biomarkers-driven application of ICBs promises to increase their efficacy. Such biomarkers include lymphocytic IFNγ-signalling and/or cytolytic activity (granzymes and perforin-1) footprints, whose levels in pre-treatment tumours can predict favourable patient survival following ICB-treatment. However, it is not clear whether such biomarkers have the same value in predicting survival of patients receiving first-line anti-CTLA4 ICB-therapy, and subsequently anti-PD1 ICB-therapy (i.e., sequential ICB-immunotherapy regimen). To address this, we applied highly integrated systems/computational immunology approaches to existing melanoma bulk-tumour transcriptomic and single-cell (sc)RNAseq data originating from immuno-oncology clinical studies applying ICB-treatment. Interestingly, we observed that CD8⁺/CD4⁺T cell-associated IFNγ-signalling or cytolytic activity signatures fail to predict tumour response in patients treated with anti-CTLA4 ICB-therapy as a first-line and anti-PD1 ICB-therapy in the second-line setting. On the contrary, signatures associated with early memory CD8⁺/CD4⁺T cells (integrating TCF1-driven stem-like transcriptional programme), capable of resisting cell death/apoptosis, better predicted objective response rates to ICB-immunotherapy, and favourable survival in the setting of sequential ICB-immunotherapy. These observations suggest that sequencing of ICB-therapy might have a specific impact on the T cell-repertoire and may influence the predictive value of tumoural immune biomarkers.

Enhanced local and systemic anti-melanoma CD8+ T cell responses after memory T cell-based adoptive immunotherapy in mice

Adoptive cell transfer (ACT) melanoma immunotherapy typically employs acutely activated effector CD8+ T cells for their ability to rapidly recognize and clear antigen. We have previously observed that effector CD8+ T cells are highly susceptible to melanoma-induced suppression, whereas memory CD8+ T cells are not. Although memory T cells have been presumed to be potentially advantageous for ACT, the kinetics of local and systemic T cell responses after effector and memory ACT have not been compared. B16F10 melanoma cells stably transfected to express very low levels of the lymphocytic choriomeningitis virus (LCMV) peptide GP33 (B16GP33) were inoculated into syngeneic C57BL/6 mice. Equal numbers of bona fide naïve, effector, or memory phenotype GP33-specific CD8+ T cells were adoptively transferred into mice 1 day after B16GP33 inoculation. The efficacy of ACT immunotherapy was kinetically assessed using serial tumor measurements and flow cytometric analyses of local and systemic CD8+ T cell responses. Control of B16GP33 tumor growth, persistence of adoptively transferred CD8+ cells, intratumoral infiltration of CD8+ T cells, and systemic CD8+ T cell responsiveness to GP33 were strongest after ACT of memory CD8+ T cells. Following surgical tumor resection and melanoma tumor challenge, only mice receiving memory T cell-based ACT immunotherapy exhibited durable tumor-specific immunity. These findings demonstrate how the use of non-expanded memory CD8+ T cells may enhance ACT immunotherapeutic efficacy.

Melanoma Immunotherapy in Mice Using Genetically Engineered Pluripotent Stem Cells

Adoptive cell transfer (ACT) of antigen (Ag)-specific CD8(+) cytotoxic T lymphocytes (CTLs) is a highly promising treatment for a variety of diseases. Naive or central memory T-cell-derived effector CTLs are optimal populations for ACT-based immunotherapy because these cells have a high proliferative potential, are less prone to apoptosis than terminally differentiated cells, and have the higher ability to respond to homeostatic cytokines. However, such ACT with T-cell persistence is often not feasible due to difficulties in obtaining sufficient cells from patients. Here we present that in vitro differentiated HSCs of engineered PSCs can develop in vivo into tumor Ag-specific naive CTLs, which efficiently suppress melanoma growth. Mouse-induced PSCs (iPSCs) were retrovirally transduced with a construct encoding chicken ovalbumin (OVA)-specific T-cell receptors (TCRs) and survival-related proteins (i.e., BCL-xL and survivin). The gene-transduced iPSCs were cultured on the delta-like ligand 1-expressing OP9 (OP9-DL1) murine stromal cells in the presence of murine recombinant cytokines (rFlt3L and rIL-7) for a week. These iPSC-derived cells were then intravenously adoptively transferred into recipient mice, followed by intraperitoneal injection with an agonist α-Notch 2 antibody and cytokines (rFlt3L and rIL-7). Two weeks later, naive OVA-specific CD8(+) T cells were observed in the mouse peripheral lymphatic system, which were responsive to OVA-specific stimulation. Moreover, the mice were resistant to the challenge of B16-OVA melanoma induction. These results indicate that genetically modified stem cells may be used for ACT-based immunotherapy or serve as potential vaccines.

Controlled release strategies for modulating immune responses to promote tissue regeneration

Advances in the field of tissue engineering have enhanced the potential of regenerative medicine, yet the efficacy of these strategies remains incomplete, and is limited by the innate and adaptive immune responses. The immune response associated with injury or disease combined with that mounted to biomaterials, transplanted cells, proteins, and gene therapies vectors can contribute to the inability to fully restore tissue function. Blocking immune responses such as with anti-inflammatory or immunosuppressive agents are either ineffective, as the immune response contributes significantly to regeneration, or have significant side effects. This review describes targeted strategies to modulate the immune response in order to limit tissue damage following injury, promote an anti-inflammatory environment that leads to regeneration, and induce antigen (Ag)-specific tolerance that can target degenerative diseases that destroy tissues and promote engraftment of transplanted cells. Focusing on targeted immuno-modulation, we describe local delivery techniques to sites of inflammation as well as systemic approaches that preferentially target subsets of immune populations.

Modes of action of TLR7 agonists in cancer therapy

From the numerous Toll-like receptor agonists, only TLR7 agonists have been approved for cancer treatment, although they are current restricted to topical application. The main target cells of TLR7 agonists are plasmacytoid dendritic cells, producing IFN-α and thus acting on other immune cells. Thereby dendritic cells acquire enhanced costimulatory and antigen-presenting capacity, priming an adaptive immune response. Besides NK cells, antigen-specific T cells are the main terminal effectors of TLR7 agonists in tumor therapy. This qualifies TLR7 agonists as vaccine adjuvants, which is currently being tested in clinical trials. However, the systemic application of TLR7 agonists shows insufficient efficacy, most likely owing to toxicity-limited dosing. The use of TLR7 agonists in combinational therapy holds the promise of synergistic activity and lower required doses.

Neurotoxin from Naja naja atra venom inhibits skin allograft rejection in rats

BACKGROUND

Recent studies reported that Naja naja atra venom (NNAV) regulated immune function and had a therapeutic effect on adjunctive arthritis and nephropathy. We hypothesized that NNAV and its active component, neurotoxin (NTX), might inhibit skin allograft rejection.

METHODS

Skin allografts were used to induce immune rejection in rats. In addition, mixed lymphocyte culture (MLC) was used to mimic immune rejection reaction in vitro. Both NNAV and NTX were orally given starting from 5days prior to skin allograft surgery.

RESULTS

The results showed that oral administration of NNAV or NTX prolonged the survival of skin allografts and inhibited inflammatory response. The production of Th1 cytokines (IFN-γ, IL-2) was also suppressed. NTX inhibited T-cell proliferation and CD4(+) T cell division induced by skin allografts. NTX also showed immunosuppressive activity in mixed lymphocyte culture. Atropine alone inhibited Con A-induced proliferation of T cells and potentiated NTX' s inhibitory effects on T cells, while pilocarpine only slightly enhanced Con A-induced T cell proliferation and partially reversed the inhibitory effect of NTX. On the other hand, neither nicotine nor mecamylamine had an influence on NTX's inhibitory effects on Con A-induced T cell proliferation in vitro. NTX inhibited T cell proliferation by arresting the cell cycle at the G0/G1 phase.

CONCLUSIONS

The present study revealed that NNAV and NTX suppressed skin allograft rejection by inhibiting T cell-mediated immune responses. These findings suggest both NNAV and NTX as potential immunosuppressants for preventing the immune response to skin allografts.

Recipient Myd88 Deficiency Promotes Spontaneous Resolution of Kidney Allograft Rejection

The myeloid differentiation protein 88 (MyD88) adapter protein is an important mediator of kidney allograft rejection, yet the precise role of MyD88 signaling in directing the host immune response toward the development of kidney allograft rejection remains unclear. Using a stringent mouse model of allogeneic kidney transplantation, we demonstrated that acute allograft rejection occurred equally in MyD88-sufficient (wild-type [WT]) and MyD88(-/-) recipients. However, MyD88 deficiency resulted in spontaneous diminution of graft infiltrating effector cells, including CD11b(-)Gr-1(+) cells and activated CD8 T cells, as well as subsequent restoration of near-normal renal graft function, leading to long-term kidney allograft acceptance. Compared with T cells from WT recipients, T cells from MyD88(-/-) recipients failed to mount a robust recall response upon donor antigen restimulation in mixed lymphocyte cultures ex vivo. Notably, exogenous IL-6 restored the proliferation rate of T cells, particularly CD8 T cells, from MyD88(-/-) recipients to the proliferation rate of cells from WT recipients. Furthermore, MyD88(-/-) T cells exhibited diminished expression of chemokine receptors, specifically CCR4 and CXCR3, and the impaired ability to accumulate in the kidney allografts despite an otherwise MyD88-sufficient environment. These results provide a mechanism linking the lack of intrinsic MyD88 signaling in T cells to the effective control of the rejection response that results in spontaneous resolution of acute rejection and long-term graft protection.

Blockade of PD-1/PD-L1 promotes adoptive T-cell immunotherapy in a tolerogenic environment

Adoptive cellular immunotherapy using in vitro expanded CD8+ T cells shows promise for tumour immunotherapy but is limited by eventual loss of function of the transferred T cells through factors that likely include inactivation by tolerogenic dendritic cells (DC). The co-inhibitory receptor programmed death-1 (PD-1), in addition to controlling T-cell responsiveness at effector sites in malignancies and chronic viral diseases is an important modulator of dendritic cell-induced tolerance in naive T cell populations. The most potent therapeutic capacity amongst CD8+ T cells appears to lie within Tcm or Tcm-like cells but memory T cells express elevated levels of PD-1. Based on established trafficking patterns for Tcm it is likely Tcm-like cells interact with lymphoid-tissue DC that present tumour-derived antigens and may be inherently tolerogenic to develop therapeutic effector function. As little is understood of the effect of PD-1/PD-L1 blockade on Tcm-like CD8+ T cells, particularly in relation to inactivation by DC, we explored the effects of PD-1/PD-L1 blockade in a mouse model where resting DC tolerise effector and memory CD8+ T cells. Blockade of PD-1/PD-L1 promoted effector differentiation of adoptively-transferred Tcm-phenotype cells interacting with tolerising DC. In tumour-bearing mice with tolerising DC, effector activity was increased in both lymphoid tissues and the tumour-site and anti-tumour activity was promoted. Our findings suggest PD-1/PD-L1 blockade may be a useful adjunct for adoptive immunotherapy by promoting effector differentiation in the host of transferred Tcm-like cells.

The role of CCL20/CCR6 axis in recruiting Treg cells to tumor sites of NSCLC patients

Inflammatory chemokine CCL20 and its receptor CCR6 have been reported to correlate with colorectal cancer patients' metastasis. However, the role of CCL20 in patients with NSCLC is not well defined. In this study, we detected the expression of CCL20 in tumor samples and corresponding adjacent ones (n=71) from patients with NSCLC using RT-PCR and observed that CCL20 showed higher expression in tumor samples (0.28±0.17) than in adjacent ones (0.20±0.13) (n=71, P=0.0056), which was also verified in protein level using IHC. Analysis results showed that CCL20 expression was positively associated with CD4 (n=80, P=0.0046), Foxp3 (n=80, P=0.0020) and IL-10 (n=61, P=0.0003) in tumor samples. And the flow data showed that Treg cells accumulated in TIL (MFI: 961±760) compared with PBMC (MFI: 683±460) (n=40, P=0.0046); and the percentage of CCR6 - the sole receptor of CCL20 - on Treg cells was higher in TIL (MFI: 1311±1268) than in PBMC (MFI: 976±780) (n=40, P=0.0219). It was interesting to find that the expression of CCL20 in tumor sites was almost 1.5-fold higher in samples from high-stage patients (III-IV stage, 0.34±0.17) compared with those from low-stage patients (I-II stage, 0.22±0.11) (P=0.0056). Furthermore, the higher expression of CCL20 was associated with a lower overall survival (P=0.0198). The IHC data showed that tumor cells were the main source of CCL20, and after treated cell line A549 with docetaxel, we found that the secretion of CCL20 was decreased heavily (n=3, P=0.0046). Our results demonstrated that CCL20 cooperated with CCR6 could recruit Treg cells to tumor sites, and chemotherapy medicine docetaxel could decrease the expression of CCL20.

Toll-like receptor agonist imiquimod facilitates antigen-specific CD8+ T-cell accumulation in the genital tract leading to tumor control through IFNγ

PURPOSE

Imiquimod is a Toll-like receptor 7 agonist used topically to treat external genital warts and basal cell carcinoma. We examined the combination of topical imiquimod with intramuscular administration of CRT/E7, a therapeutic human papillomavirus (HPV) vaccine comprised of a naked DNA vector expressing calreticulin fused to HPV16 E7.

EXPERIMENTAL DESIGN

Using an orthotopic HPV16 E6/E7(+) syngeneic tumor, TC-1, as a model of high-grade cervical/vaginal/vulvar intraepithelial neoplasia, we assessed if combining CRT/E7 vaccination with cervicovaginal deposition of imiquimod could result in synergistic activities promoting immune-mediated tumor clearance.

RESULTS

Imiquimod induced cervicovaginal accumulation of activated E7-specific CD8(+) T cells elicited by CRT/E7 vaccination. Recruitment was not dependent upon the specificity of the activated CD8(+) T cells, but was significantly reduced in mice lacking the IFNγ receptor. Intravaginal imiquimod deposition induced upregulation of CXCL9 and CXCL10 mRNA expression in the genital tract, which are produced in response to IFNγ receptor signaling and attract cells expressing their ligand, CXCR3. The T cells attracted by imiquimod to the cervicovaginal tract expressed CXCR3 as well as CD49a, an integrin involved in homing and retention of CD8(+) T cells at mucosal sites. Our results indicate that intramuscular CRT/E7 vaccination in conjunction with intravaginal imiquimod deposition recruits antigen-specific CXCR3(+) CD8(+) T cells to the genital tract.

CONCLUSIONS

Several therapeutic HPV vaccination clinical trials using a spectrum of DNA vaccines, including vaccination in concert with cervical imiquimod, are ongoing. Our study identifies a mechanism by which these strategies could provide therapeutic benefit. Our findings support accumulating evidence that manipulation of the tumor microenvironment can enhance the therapeutic efficacy of strategies that induce tumor-specific T cells.

HPV16-E7 expression in squamous epithelium creates a local immune suppressive environment via CCL2- and CCL5- mediated recruitment of mast cells

Human Papillomavirus (HPV) 16 E7 protein promotes the transformation of HPV infected epithelium to malignancy. Here, we use a murine model in which the E7 protein of HPV16 is expressed as a transgene in epithelium to show that mast cells are recruited to the basal layer of E7-expressing epithelium, and that this recruitment is dependent on the epithelial hyperproliferation induced by E7 by inactivating Rb dependent cell cycle regulation. E7 induced epithelial hyperplasia is associated with increased epidermal secretion of CCL2 and CCL5 chemokines, which attract mast cells to the skin. Mast cells in E7 transgenic skin, in contrast to those in non-transgenic skin, exhibit degranulation. Notably, we found that resident mast cells in E7 transgenic skin cause local immune suppression as evidenced by tolerance of E7 transgenic skin grafts when mast cells are present compared to the rejection of mast cell-deficient E7 grafts in otherwise competent hosts. Thus, our findings suggest that mast cells, recruited towards CCL2 and CCL5 expressed by epithelium induced to proliferate by E7, may contribute to an immunosuppressive environment that enables the persistence of HPV E7 protein induced pre-cancerous lesions.

Impact of T cell selection methods in the success of clinical adoptive immunotherapy

Chemotherapy and/or radiotherapy regular regimens used for conditioning of recipients of hematopoietic stem cell transplantation (SCT) induce a period of transient profound immunosuppression. The onset of a competent immunological response, such as the appearance of viral-specific T cells, is associated with a lower incidence of viral infections after haematopoietic transplantation. The rapid development of immunodominant peptide virus screening together with advances in the design of genetic and non-genetic viral- and tumoural-specific cellular selection strategies have opened new strategies for cellular immunotherapy in oncologic recipients who are highly sensitive to viral infections. However, the rapid development of cellular immunotherapy in SCT has disclosed the role of the T cell selection method in the modulation of functional cell activity and of in vivo secondary effects triggered following immunotherapy.

Effector and central memory T helper 2 cells respond differently to peptide immunotherapy

Peptide immunotherapy (PIT) offers realistic prospects for the treatment of allergic diseases, including allergic asthma. Much is understood of the behavior of naive T cells in response to PIT. However, treatment of patients with ongoing allergic disease requires detailed understanding of the responses of allergen-experienced T cells. CD62L expression by allergen-experienced T cells corresponds to effector/effector memory (CD62L(lo)) and central memory (CD62L(hi)) subsets, which vary with allergen exposure (e.g., during, or out with, pollen season). The efficacy of PIT on different T helper 2 (Th2) cell memory populations is unknown. We developed a murine model of PIT in allergic airway inflammation (AAI) driven by adoptively transferred, traceable ovalbumin-experienced Th2 cells. PIT effectively suppressed AAI driven by unfractionated Th2 cells. Selective transfer of CD62L(hi) and CD62L(lo) Th2 cells revealed that these two populations behaved differently from one another and from previously characterized (early deletional) responses of naive CD4(+) T cells to PIT. Most notably, allergen-reactive CD62L(lo) Th2 cells were long-lived within the lung after PIT, before allergen challenge, in contrast to CD62L(hi) Th2 cells. Despite this, PIT was most potent against CD62L(lo) Th2 cells in protecting from AAI, impairing their ability to produce Th2 cytokines, whereas this capacity was heightened in PIT-treated CD62L(hi) Th2 cells. We conclude that Th2 cells do not undergo an early deletional form of tolerance after PIT. Moreover, memory Th2 subsets respond differently to PIT. These findings have implications for the clinical translation of PIT in different allergic scenarios.

Alocasia cucullata exhibits strong antitumor effect in vivo by activating antitumor immunity

Chinese herbal medicines have long been used to treat various illnesses by modulating the human immune response. In this study, we investigate the immuno-modulating effect and antitumor activity of Alocasia Cucullata (AC), a Chinese herb traditionally used to treat infection and cancer. We found that the whole water extract of AC roots could significantly attenuate tumor growth in mouse tumor models. The median survival time of the AC-treated mice was 43 days, 16 days longer than that of the control group. Moreover, the AC-treated mice showed substantially higher induction of key antitumor cytokines, such as IL-2, IFN-γ, and TNF-α, indicating that AC may exert antitumor effect by activating antitumor immunity. To further pinpoint the cellular and molecular mechanism of AC, we studied the dose response of a human monocytic cell line, THP-1, to the whole water extract of AC. Treatment of the AC extract significantly induced THP-1 differentiation into macrophage-like cells and the differentiated THP-1 showed expression of specific macrophage surface markers, such as CD11b and CD14, as well as productions of antitumor cytokines, e.g. IFN-γ and TNF-α. Our data thus point to AC as potentially a new, alternative immuno-modulating herbal remedy for anticancer treatment.