Augmentation of monocyte interleukin-8 production by psoralen/UVA-treated CD4+ T cells

Extracorporeal photochemotherapy induces bona fide immunogenic cell death

Extracorporeal photochemotherapy (ECP) is employed for the management of cutaneous T cell lymphoma (CTCL). ECP involves the extracorporeal exposure of white blood cells (WBCs) to a photosensitizer, 8-methoxypsoralen (8-MOP), in the context of ultraviolet A (UVA) radiation, followed by WBC reinfusion. Historically, the therapeutic activity of ECP has been attributed to selective cytotoxicity on circulating CTCL cells. However, only a fraction of WBCs is exposed to ECP, and 8-MOP is inactive in the absence of UVA light, implying that other mechanisms underlie the anticancer effects of ECP. Recently, ECP has been shown to enable the physiological differentiation of monocytes into dendritic cells (DCs) that efficiently cross-present tumor-associated antigens (TAAs) to CD8⁺ T lymphocytes to initiate cognate immunity. However, the source of TAAs and immunostimulatory signals for such DCs remains to be elucidated. Here, we demonstrate that 8-MOP plus UVA light reduces melanoma cell viability along with the emission of ICD-associated danger signals including calreticulin (CALR) exposure on the cell surface and secretion of ATP, high mobility group box 1 (HMGB1) and type I interferon (IFN). Consistently, melanoma cells succumbing to 8-MOP plus UVA irradiation are efficiently engulfed by monocytes, ultimately leading to cross-priming of CD8⁺ T cells against cancer. Moreover, malignant cells killed by 8-MOP plus UVA irradiation in vitro vaccinate syngeneic immunocompetent mice against living cancer cells of the same type, and such a protection is lost when cancer cells are depleted of calreticulin or HMGB1, as well as in the presence of an ATP-degrading enzyme or antibodies blocking type I IFN receptors. ECP induces bona fide ICD, hence simultaneously providing monocytes with abundant amounts of TAAs and immunostimulatory signals that are sufficient to initiate cognate anticancer immunity.

Phototherapy in systemic sclerosis: Review

Systemic scleroderma-also known as systemic sclerosis (SSc)-is a chronic systemic connective tissue disease characterized by collagen deposition in cutaneous and internal organs, leading to skin sclerosis and multiple organ fibrosis. The pathogenesis is complex and remains poorly understood. Treatment is based on organ involvement and requires a multidisciplinary approach. Skin sclerosis can cause disability, leading to decreasing quality of life. Various systemic antifibrotic therapies have been used; however, most have unsatisfactory results. Recently, phototherapy and in particular ultraviolet A (UVA) has been used to treat skin sclerosis in SSc patients with satisfactory results. The main mechanisms include lymphocyte apoptosis, cytokine alteration, inhibition of collagen synthesis and increased collagenase production, and neovascularization, leading to the breakdown of collagen fibrils resulting in skin softening or even healing digital ulcers. Most studies reported that psoralen plus UVA (PUVA) and UVA1 phototherapy improved clinical outcomes vis-à-vis skin sclerosis, joint mobility, ulcers, and histopathology. PUVA and UVA1 phototherapy therefore have potential as an alternative or adjunctive therapy for patients with SSc.

Myeloid Cells as Targets for Therapy in Solid Tumors

It is well established that cancer development ensues based on reciprocal interactions between genomically altered neoplastic cells and diverse populations of recruited "host" cells co-opted to support malignant progression. Among the host cells recruited into tumor microenvironments, several subtypes of myeloid cells, including macrophages, monocytes, dendritic cells, and granulocytes contribute to tumor development by providing tumor-promoting factors as well as a spectrum of molecules that suppress cytotoxic activities of T lymphocytes. Based on compelling preclinical data revealing that inhibition of critical myeloid-based programs leads to tumor suppression, novel immune-based therapies and approaches are now entering the clinic for evaluation. This review discusses mechanisms underlying protumorigenic programming of myeloid cells and discusses how targeting of these has potential to attenuate solid tumor progression via the induction and of mobilization CD8 cytotoxic T cell immunity.

Extracorporeal photopheresis: A focus on apoptosis and cytokines

Induction of apoptosis and changes to cytokine secretion patterns have been implicated in the mechanism of action of extracorporeal photopheresis (ECP). Lymphocyte apoptosis is initially detected in significant numbers prior to re-infusion and by 48 h post-ECP the majority of treated lymphocytes are apoptotic. The early apoptosis involves changes to mitochondrial function, reversal of the Bcl-2/Bax ratio and externalisation of phosphatidylserine. Apoptotic lymphocytes, observed from 20 h post-ECP, are associated with enhanced levels of CD95 and Fas-ligand. For cutaneous T cell lymphoma (CTCL), processing of the apoptotic lymphocytes, by suitable antigen presenting cells (APCs), is suggested to induce a clonal cytotoxic response which targets the malignant T cell population. Increased levels of TNFalpha and IFNgamma, observed post-ECP in monocytes and lymphocytes, respectively, are thought to further contribute to the proposed anti-tumour reaction seen in CTCL. However, down-regulation of pro-inflammatory cytokines and enhanced anti-inflammatory responses have been reported following ECP treatment. These immune responses may contribute to the tempering of the inflammatory conditions, such as graft versus host disease, which respond to ECP. Furthermore, untreated monocytes exposed to ECP-treated lymphocytes have also demonstrated a shift in monocyte cytokine-secretory pattern, toward one associated with immune tolerance. Recently, a mechanism of ECP-induced immune tolerance has been linked to the stimulation of the anti-inflammatory cytokines IL10 and TGFbeta by T regulatory cells, following the infusion of ECP-treated CD11c(+) APCs. Ultimately, the multifaceted responses, induced by ECP, may explain the diversity of clinical conditions that benefit.

Lymphocytes treated by extracorporeal photopheresis can down-regulate cytokine production in untreated monocytes

BACKGROUND

Pro-inflammatory cytokines are actively involved in graft-versus host-disease (GvHD) aetiology. Treatment of GvHD, using extracorporeal photopheresis (ECP), has demonstrated clinical efficacy. ECP rapidly reduces the number of T cells that produce tumour necrosis factor alpha (TNFalpha), interferon gamma (IFNgamma) and interleukin (IL)2. ECP-treated cells are re-infused immediately after completion of treatment. This study attempted to determine the influence that ECP-treated cells would have on untreated cells following re-infusion.

METHODS

Heparinized samples were taken from 10 chronic GvHD patients, pre-ECP and immediately prior to re-infusion (post-ECP). Lymphocytes and monocytes were isolated using magnetic separation. The post-ECP lymphocytes were mixed with pre-ECP monocytes, while the post-ECP monocytes and pre-ECP lymphocytes were combined. After suitable stimulation, the T cells were tested for intracellular TNFalpha, IFNgamma and IL2, while the monocytes were evaluated for TNFalpha, IL1alpha, IL1beta, IL6 and IL8.

RESULTS

Although cytokine secretion is decreased in T cells exposed to ECP, pre-ECP T cells were unaffected by post-ECP monocytes. Post-ECP monocytes demonstrated a reduction in cytokine secretion. Furthermore, untreated monocytes down-regulated cytokine production following exposure to ECP-treated lymphocytes.

CONCLUSION

ECP has both a direct and indirect immunosuppressive action, both of which may be beneficial in the treatment of GvHD.

Patients with solid tumors treated with high-temperature whole body hyperthermia show a redistribution of naive/memory T-cell subtypes

An activation of the immune system might contribute to the therapeutic effect of whole body hyperthermia (WBH) in cancer patients. We explored immune and endocrine responses in patients undergoing high-temperature WBH. Identical parameters were investigated in a separate group of healthy volunteers undergoing physical exercise to rule out effects of sympathetic activation. Lymphocyte subpopulations, lymphocytic expression of a range of adhesion molecules, and serum concentrations of a variety of hormones and cytokines were assessed in cancer patients undergoing high-temperature (60 min at 41.0-41.8 degrees C) WBH (n = 25) and in a separate group of healthy volunteers (n = 10) performing strenuous physical exercise. WBH induced an increase in human growth hormone (hGH), ACTH, and cortisol as well as in TNF-alpha, IL-6, IL-8, and IL-12R. We observed an increase in natural killer (NK) cells and CD56+ NK T cells shortly after initiation of WBH. In contrast, we found a decrease in T cells expressing L-selectin (CD62L) or alpha4beta7 integrin adhesion molecules mediating homing to lymphatic tissues. Accordingly, we observed a decrease in CD45RA+CCR7+ naive and CD45RA-CCR7+ central memory T cells. Numbers of CD45RA-CCR7- memory effector and CD45RA+CCR7 terminally differentiated T cells, on the other hand, remained unchanged. No comparable changes were observed in the group of healthy volunteers. In conclusion, patients with solid tumors treated with WBH show an increase in NK and NK T cells. In a later phase, plasma concentrations of IL-8, hGH, and cortisol increase, correlated with an influx of neutrophils into the peripheral blood. The alterations in T-cell populations suggest that WBH may induce naive and central-memory T cells to enter lymphatic tissue to await antigen exposure and effector T cells to migrate into peripheral tissues to exert their effector function. Although the exercise group may not be an appropriate control to proof the effect of WBH, these changes were not seen in the healthy volunteers performing physical exercise.

Extracorporeal photopheresis affects interleukin (IL)-10 and IL-12 production by monocytes in patients with chronic graft-versus-host disease

BACKGROUND

Chronic graft-versus-host disease (cGVHD) is a major complication of allogeneic bone marrow transplantation. Extracorporeal photopheresis (ECP) has recently been introduced as an alternative treatment for cases of cGVHD refractory to conventional immunosuppressive treatment, but its mechanism of action is not yet clear.

OBJECTIVES

To investigate in seven patients with cGVHD the effects of ECP on resistance of monocytes to apoptosis and on monocyte cytokine production.

METHODS

We designed an in vitro model that could mimic the potential in vivo effect of reinfusion of peripheral blood mononuclear cells treated by ECP. The model was based on coculture of ECP-treated lymphocytes with untreated monocytes from the same patient.

RESULTS

ECP did not accelerate spontaneous apoptosis of monocytes. However, ECP-treated monocytes produced increased amounts of interleukin (IL)-12. In contrast, IL-12 production by monocytes did not increase in cocultures, but IL-10 production was upregulated.

CONCLUSIONS

These results suggest that reinfusion of large numbers of autologous apoptotic lymphocytes is significant for the therapeutic outcome of ECP through upregulation of IL-10, which is an immunosuppressive cytokine.