Enhancement of anti-cancer immunity by a lipoteichoic-acid-related molecule isolated from a penicillin-killed group A Streptococcus

Postbiotics of Lacticaseibacillus paracasei CECT 9610 and Lactiplantibacillus plantarum CECT 9608 attenuates store-operated calcium entry and FAK phosphorylation in colorectal cancer cells

Store-operated Ca2+ entry (SOCE) is a major mechanism for Ca2+ influx in colorectal cancer (CRC) cells. This mechanism, regulated by the filling state of the intracellular Ca2+ stores, is mediated by the endoplasmic reticulum Ca2+ sensors of the stromal interaction molecules (STIM) family [stromal interaction molecule 1 (STIM1) and STIM2] and the Ca2+-release-activated Ca2+ channels constituted by Orai family members, with predominance of calcium release-activated calcium channel protein 1 (Orai1). CRC cells exhibit enhanced SOCE due to remodeling of the expression of the key SOCE molecular components. The enhanced SOCE supports a variety of cancer hallmarks. Here, we show that treatment of the colorectal adenocarcinoma cell lines HT-29 and Caco-2 with inanimate Lacticaseibacillus paracasei (CECT9610) and Lactiplantibacillus plantarum (CECT9608) attenuates SOCE, although no detectable effect is seen on SOCE in normal colon mucosa cells. The effect of Lacticaseibacillus paracasei and Lactiplantibacillus plantarum postbiotics was mediated by downregulation of Orai1 and STIM1, while the expression levels of Orai3 and STIM2 remained unaltered. Treatment of HT-29 and Caco-2 cells with inanimate Lacticaseibacillus paracasei and Lactiplantibacillus plantarum impairs in vitro migration by a mechanism likely involving attenuation of focal adhesion kinase (FAK) tyrosine phosphorylation. Cell treatment with the Orai1 inhibitor synta-66 attenuates SOCE and prevents any further effect of Lacticaseibacillus paracasei and Lactiplantibacillus plantarum postbiotics. Together, our results indicate for the first time that Lacticaseibacillus paracasei and Lactiplantibacillus plantarum postbiotics selectively exert negative effects on Ca2+ influx through SOCE in colorectal adenocarcinoma cell lines, providing evidence for an attractive strategy against CRC.

From Pre- and Probiotics to Post-Biotics: A Narrative Review

BACKGROUND AND AIMS

gut microbiota (GM) is a complex ecosystem containing bacteria, viruses, fungi, and yeasts. It has several functions in the human body ranging from immunomodulation to metabolic. GM derangement is called dysbiosis and is involved in several host diseases. Pre-, probiotics, and symbiotics (PRE-PRO-SYMB) have been extensively developed and studied for GM re-modulation. Herein, we review the literature data regarding the new concept of postbiotics, starting from PRE-PRO-SYMB.

METHODS

we conducted a search on the main medical databases for original articles, reviews, meta-analyses, randomized clinical trials, and case series using the following keywords and acronyms and their associations: gut microbiota, prebiotics, probiotics, symbiotic, and postbiotics.

RESULTS

postbiotics account for PRO components and metabolic products able to beneficially affect host health and GM. The deeper the knowledge about them, the greater their possible uses: the prevention and treatment of atopic, respiratory tract, and inflammatory bowel diseases.

CONCLUSIONS

better knowledge about postbiotics can be useful for the prevention and treatment of several human body diseases, alone or as an add-on to PRE-PRO-SYMB.

Postbiotics-A Step Beyond Pre- and Probiotics

As an imbalance in the intestinal microbiota can lead to the development of several diseases (e.g., type 1 diabetes, cancer, among others), the use of prebiotics, probiotics, and postbiotics to alter the gut microbiome has attracted recent interest. Postbiotics include any substance released by or produced through the metabolic activity of the microorganism, which exerts a beneficial effect on the host, directly or indirectly. As postbiotics do not contain live microorganisms, the risks associated with their intake are minimized. Here, we provided a critical review of postbiotics described in the literature, including their mechanisms of action, clinical characteristics, and potential therapeutic applications. We detailed the pleiotropic effects of postbiotics, including their immunomodulatory, anti-inflammatory, antioxidant, and anti-cancer properties. Although the use of postbiotics is an attractive strategy for altering the microbiome, further study into its efficacy and safety is warranted.

Different activities of antitumor immunomodulators to induce neutrophil adherence response

Functions of neutrophils, major participant in host defense mechanisms, are known to be regulated by various types of immunomodulators. Capacity of immunomodulators which are reported to show antitumor effect in vivo to induce neutorophil adherence response in vitro was investigated. Several bacterial immunomodulators (OK-432, Corynebacterium parvum, B.C.G.) and components of bacteria cell walls (lipopolysaccharide (LPS), lipid A, lipoteicoic acid, N-cell wall skelton (N-CWS), muramyl dipeptide (MDP)) and fungal polysaccharides (lentinan, zymosan A, etc.) were tested. Neutrophils prepared from peripheral blood of healthy men were incubated with each immunomodulator at 37°C for 60 min in 96 well plastic plates, then neutrophils adherent to substratum were stained by crystal violet and their optical density at 570 nm was measured as a parameter of neutrophil adherence. Although purified polysaccharides mainly prepared from fungi did not induce the adherent response, not only bacterial bodies and their components but also tumor necrosis factor-α (TNF-α) clearly induced it. On the base of these results, functional classification and typing of immunomodulators by different activities in neutrophil adherence was discussed.

Sweeten PAMPs: Role of Sugar Complexed PAMPs in Innate Immunity and Vaccine Biology

Innate sensors play a critical role in the early innate immune responses to invading pathogens through sensing of diverse biochemical signatures also known as pathogen associated molecular patterns (PAMPs). These biochemical signatures primarily consist of a major family of biomolecules such as proteins, lipids, nitrogen bases, and sugar and its complexes, which are distinct from host molecules and exclusively expressed in pathogens and essential to their survival. The family of sensors known as pattern recognition receptors (PRRs) are germ-line encoded, evolutionarily conserved molecules, and consist of Toll-like receptors (TLRs), RIG-I-like receptors (RLRs), NOD-like receptors (NLRs), C-type lectin-like receptors (CLRs), and DNA sensors. Sensing of PAMP by PRR initiates the cascade of signaling leading to the activation of transcription factors, such as NF-κB and interferon regulatory factors (IRFs), resulting in a variety of cellular responses, including the production of interferons (IFNs) and pro-inflammatory cytokines. In this review, we discuss sensing of different types of glycosylated PAMPs such as β-glucan (a polymeric sugar) or lipopolysaccharides, nucleic acid, and so on (sugar complex PAMPs) by different families of sensors, its role in pathogenesis, and its application in development of potential vaccine and vaccine adjuvants.

Effect of soluble factors derived from oral cancer cells on the production of interferon-γ from peripheral blood mononuclear cells following stimulation with OK-432

The streptococcal antitumor agent OK-432 is commonly used as an immunopotentiator for immunotherapy in various types of malignant tumors including oral cancer. It has been demonstrated that OK-432 elicits an antitumor effect by stimulating immunocompetent cells, thereby inducing multiple cytokines including interferon (IFN)-γ, interleukin (IL)-2 and IL-12. Serum concentrations of IFN-γ in patients with oral cancer were examined 24 h after administration of OK-432. Serum concentrations of IFN-γ in patients with advanced cancer were significantly lower than those in patients with early cancer. These results suggested that some soluble factors produced by cancer cells may inhibit IFN-γ production with OK-432. Thus, in the present study, an in vitro simulation model was established for the immune status of patients with oral cancer by adding conditioned medium (CM) derived from oral cancer cell lines into a culture of peripheral blood mononuclear cells (PBMCs) derived from a healthy volunteer. We investigated whether soluble factors derived from oral cancer cells affected IFN-γ production from PBMCs following stimulation with OK-432. PBMCs stimulated with OK-432 produced a large amount of IFN-γ; however, both IFN-γ production and cytotoxic activity from PBMCs induced by OK-432 were inhibited by the addition of CM in a dose-dependent manner. In order to examine these inhibitory effects against IFN-γ production, the contribution of inhibitory cytokines such as IL-4, IL-6, IL-10, transforming growth factor-β and vascular endothelial growth factor was investigated. However, neutralization of these inhibitory cytokines did not recover IFN-γ production inhibited by CM. These results indicated that unknown molecules may inhibit IFN-γ production from PBMCs following stimulation with OK-432.

Growth inhibition and apoptosis by an active component of OK-432, a streptococcal agent, via Toll-like receptor 4 in human head and neck cancer cell lines

Toll-like receptor 4 (TLR4) plays a significant role in cancer therapy as receptors of bacteria-derived immunotherapeutic agents such as OK-432, a streptococcal immunotherapeutic agent. In addition, recent reports demonstrated that TLRs, including TLR4, are also expressed in cancer cells as well as in immunocompetent cells. It is a problem in cancer therapy that the immunoadjuvant may activate survival signals such as nuclear factor (NF)-κB or mitogen-activated protein kinases (MAPKs) in cancer cells via TLRs. In the current study, we investigated responsiveness of human head and neck cancer cell lines against TLR4 ligands, OK-PSA, an active component of OK-432, and a lipopolysaccharide (LPS). Stimulation with LPS or OK-PSA resulted in the activation of NF-κB in these cell lines expressing TLR4 and MD-2 that is a significant coreceptor for TLR4 signaling. Interestingly, OK-PSA induced cell-growth inhibition, while LPS enhanced the proliferation of the cancer cells. OK-PSA induced NF-κB activation more slowly than that induced by LPS. In addition, phosphorylation of p38 MAPK by OK-PSA was only slight compared with that by LPS. OK-PSA also induced apoptosis of the cancer cells mediated by the activation of caspase 1, 3 and 8 in a p53-independent manner. These findings strongly suggest that active components of OK-432 may elicit anti-cancer effects via enhancing host immunity as well as via directly inducing the growth inhibition and apoptosis of head and neck cancer cells through TLR4 signal.

Clinical and immunologic evaluation of dendritic cell-based immunotherapy in combination with gemcitabine and/or S-1 in patients with advanced pancreatic carcinoma

OBJECTIVES

In the current study, we have evaluated the clinical and immunological responses in patients with advanced pancreatic carcinoma who received dendritic cell (DC)-based immunotherapy in combination with gemcitabine and/or S-1.

METHODS

Dendritic cell-based immunotherapy (DC vaccine alone or DC vaccine plus lymphokine-activated killer [LAK] cell therapy) in combination with gemcitabine and/or S-1 has been carried out in 49 patients with inoperable pancreatic carcinoma refractory to standard treatment.

RESULTS

Of 49 patients, 2 patients had complete remission, 5 had partial remission, and 10 had stable disease. Prolongation of survival in this cohort was highly likely (median survival, 360 days). Survival of patients receiving DC vaccine and chemotherapy plus LAK cell therapy was longer than those receiving DC vaccine in combination with chemotherapy but no LAK cells. Increased numbers of cancer antigen-specific cytotoxic T cells and decreased regulatory T cells were observed in several patients on immunotherapy, but increased overall survival time tended to be associated only with the latter. None of the patients experienced grade 3 or worse adverse events during the treatment period.

CONCLUSIONS

Dendritic cell vaccine-based immunotherapy combined with chemotherapy was shown to be safe and possibly effective in patients with advanced pancreatic cancer refractory to standard treatment.

Innate-immunity cytokines induced by very small size proteoliposomes, a Neisseria-derived immunological adjuvant

Neisserial outer membrane proteins have been combined with monosialoganglioside GM3 to form very small size proteoliposomes (VSSP), a nanoparticulated formulation used as a cancer vaccine for the treatment of cancer patients with GM3-positive tumours. VSSP were shown to elicit anti-GM3 and anti-tumour immune responses. VSSP have also been shown to be an efficient adjuvant for tumour-cell and peptide-antigen vaccines in mice. In vitro studies showed that VSSP promote maturation of both murine and human dendritic cells, suggesting that VSSP could be used as efficient adjuvants. In order to study further the capacity of VSSP to elicit innate immune responses, human peripheral blood mononuclear cells and monocytes derived thereof were assessed for in vitro secretion of interleukin (IL)-10, IL-6, IL-12 and interferon (IFN)-gamma. VSSP most prominently induced the secretion of IL-6. IL-10 was secreted at a lower level. IL-12 p40 (but no p70) was also detected. IFN-gamma response was observed in 56% of the tested samples. Cytokine secretion was not related to lipopolysaccharide (LPS) content and involved Toll-like receptor 2 (TLR2)-mediated signal transduction. VSSP also induced DC maturation and a cytokine secretion pattern (high IL-6/low IL-10) which differs from that induced by LPS. The observed proinflammatory cytokine secretion pattern and the capacity of VSSP to drive DC maturation are examined in the light of the properties of other bacterial derivatives currently being user for immunotherapy purposes. Our results suggest that VSSP could be tested in clinical settings where T helper 1-type immune responses would be beneficial.

Antitumor effect of OK-432-derived DNA: one of the active constituents of OK-432, a streptococcal immunotherapeutic agent

OK-432 is a Streptococcus-derived immunotherapeutic agent for malignancies. Our group has tried to identify the effective components of OK-432 and has succeeded in isolating a lipoteichoic acid-related preparation designated as OK-PSA, which is a strong inducer of T helper 1 (T(H)1) cells, and elicits an anticancer effect via Toll-like receptor (TLR) 4. Conversely, bacterial DNA with unmethylated CpG motifs can stimulate a T(H)1-type host response via TLR9. The unmethylated CpG DNA contained in OK-432 may play a role in its anticancer effect. In the current study, we investigated the effect of OK-432-derived DNA (OK-DNA) in augmenting the anticancer immune response. Analysis of OK-DNA with the restriction enzymes Hpa II and MspI revealed that OK-DNA contained unmethylated CpG motifs. OK-DNA induced TH1-type cytokines such as interferon-gamma, tumor necrosis factor-alpha, interleukin (IL)-12, and IL-18 and augmented killer cell activities in vitro on human peripheral blood mononuclear cells, whereas the methylated OK-DNA did not. Cytokines were also produced by OK-DNA-stimulated splenocytes derived from wild-type mice but not from TLR9-deficient mice. In the in vivo study, peritumoral administration of OK-DNA resulted in a significant inhibition of tumor growth in syngeneic tumor-bearing wild-type and TLR4-deficient mice but not in TLR9-deficient mice. The antitumor effect of OK-432 in TLR9-deficient mice was significantly but partially reduced compared with that in wild-type mice, whereas the effect of OK-432 was almost completely eliminated in TLR4-deficient mice. These findings suggest that unmethylated CpG DNA in OK-432 functions as an active component in OK-432-induced anticancer immunity via TLR9.

Mechanism of anticancer host response induced by OK-432, a streptococcal preparation, mediated by phagocytosis and Toll-like receptor 4 signaling

It has previously been reported by our group that Toll-like receptor (TLR) 4 is involved in anticancer immunity induced by OK-432, a Streptococcus-derived immunotherapeutic agent. However the detailed mechanism of the OK-432-induced immune response via TLR4 remained uncertain, because it may not be possible for OK-432, which consists of whole bacterial bodies, to bind directly to TLR4. In the current study, we conducted in vitro and in vivo experiments to investigate the hypothesis that OK-432 may first be captured and dissolved by phagocytes and that the active components released by the cells may then induce host responses via TLR4. TS-2 monoclonal antibody, which recognizes an active component of OK-432 designated OK-PSA was used in the current study. First, it was observed that OK-432-induced cytokine production by dendritic cells (DCs) and macrophages was significantly inhibited in vitro by cytochalasin B, a phagocytosis inhibitor. Immunofluorescence staining using TS-2 demonstrated that OK-432 was captured and dissolved by phagocytes. OK-PSA was detected in the supernatants derived from OK-432-treated DC culture by enzyme-linked immunosorbent assay using TS-2. Supernatants from OK-432-treated DC culture increased nuclear factor (NF)-kappaB activity in TLR4-expressing cells, and the increased activity was inhibited by TS-2 antibody. OK-432 itself did not activate NF-kappaB in these cells. In in vivo experiments, the anticancer effect of OK-432 was significantly inhibited by suppression of phagocytosis activity by cytochalasin B. In this case, the amount of OK-PSA, an active component of OK-432, in the sera was also reduced by cytochalasin B. These findings elucidated the mechanism mediated by phagocytosis and TLR4 signaling in the immune effect of OK-432.

Involvement of nitric oxide in anti-tumor effects of OK-432, a streptococcal anti-tumor immunotherapeutic agent

We examined the role of nitric oxide (NO) induced by OK-432, a streptococcal immunotherapeutic agent, in anti-tumor effects of the OK-432 by in vitro and in vivo experiments using an NO synthase inhibitor, N-monomethyl-l-arginine acetate (NMA). The in vitro treatment of mouse splenocytes with OK-432 increased the expression of inducible NO synthase (iNOS) gene and NO production in a dose-dependent manner. Although it is well known that OK-432 induces cytokines such as interferon (IFN)-gamma and tumor necrosis factor (TNF)-alpha, both of which are known to be potent NO inducers, we observed only a partial reduction of OK-432-induced NO production with the addition of anti-IFN-gamma and/or anti-TNF-alpha neutralizing antibodies. The cytotoxicity of the splenocytes increased by in vitro OK-432 stimulation was almost completely inhibited by the treatment with NMA. OK-432 administration resulted in a marked prolongation of survival and a significant inhibition of tumor growth in syngeneic tumor-bearing mice, whereas NMA significantly inhibited the anti-tumor effects of OK-432. Although the increased cytotoxicity of adherent splenocytes derived from OK-432-treated tumor-bearing mice was almost completely inhibited by NMA, only partial inhibition by NMA was observed in the cytotoxicity of the nonadherent splenocytes. These findings strongly suggest that the iNOS/NO induced by OK-432 is intimately involved in the anti-tumor effects of OK-432.

Topical streptococcal preparation, OK-432, for atopic dermatitis

Effective treatment of atopic dermatitis (AD) may in some cases prove quite difficult. OK-432, prepared from the penicillin-treated Su strain of type III Group A Streptococcus pyogenes, has been shown to be effective for treating not only cancer but verruca vulgaris as well, suggesting this agent to create the Th1 pathway through IL-12 induction. Four AD patients consented to trial use of the OK-432 ointment. OK-432 was found to bring about complete cure in the present four cases. Based on results from its use, OK-432 may be concluded to be highly effective for treating AD.

Expression of toll-like receptor 4 on dendritic cells is significant for anticancer effect of dendritic cell-based immunotherapy in combination with an active component of OK-432, a streptococcal preparation

A lipoteichoic acid-related molecule OK-PSA is an active component of OK-432, a Streptococcus-derived anticancer immunotherapeutic agent. In the present study, we first examined the effect of OK-PSA on the maturation of dendritic cells (DCs) in vitro by using the DCs derived from 5 healthy donors and 10 patients with head and neck cancer with or without expression of toll-like receptor 4 (TLR4) or MD-2 mRNA. OK-PSA treatment effectively increased the surface expression of MHC class II, CD80, CD83, and CD86. OK-PSA-stimulated DCs secreted the cytokines that can induce helper T-cell 1 (Th1)-type T-cell response, and stimulated allogeneic T cells to produce IFN-gamma and to elicit an allogeneic antigen-specific cytotoxicity. These activities almost depended on expression of TLR4 and MD-2 genes. We next investigated the in vivo anticancer effect of intratumoral administration of syngeneic DCs followed by OK-PSA against established tumors in mice. C57BL/6 mice, which express wild-type TLR4, and C57BL/6-derived TLR4-knockout (TLR4(-/-)) mice were used. Although OK-PSA accelerated the antitumor effect of intratumoral DC administration in wild-type mice bearing syngeneic tumors, the antitumor effect of OK-PSA as well as of the combination therapy with DCs and OK-PSA was not significant in TLR4(-/-) mice. Interestingly, an administration of wild-type-mouse-derived DCs followed by OK-PSA exhibited a marked antitumor effect even in the TLR4(-/-) mice. These findings suggest that OK-PSA may be a potent adjuvant for local DC therapy, and that DC therapy followed by OK-PSA is able to elicit anticancer activity even in a TLR4-deficient host when TLR4 is expressed only in DCs injected intratumorally.

Therapeutic effects of streptococcal preparation OK-432 on atopic dermatitis-like lesions in NC/Nga mice: possible shift from a Th2- to Th1-predominance

BACKGROUND

The inducement of Th1 cell-mediated immune response, possibly brought about through bacterial stimulation, may serve to control atopic disorders such as atopic dermatitis (AD). The streptococcal preparation, OK-432, has been shown a potent Th1 inducer through the action of IL-12. NC/Nga mice under ordinary conditions have been found to contract dermatitis similar to human AD.

OBJECTIVE

Examination was made of the therapeutic effects of OK-432 local intra- and/or subcutaneous injections on AD-like lesions in NC/Nga mice.

METHODS

Immunohistochemical staining with IL-4/IL-12p40 and CD80/86 and phosphorylated STAT4/p-STAT6 and RT-PCR for IL-4/IL-12p40 and STAT6/STAT4 mRNA was conducted for the evaluation of OK-432 treatment of spontaneous AD-like lesions in NC/Nga mice.

RESULTS

At 5 weeks following injection of OK-432, for treating head and back lesions in NC/Nga mice, 10 of 12 OK-432 treated NC mice were found to have clinically improved quite considerably. On the head and back skin of OK-432-treated mice, IL-12p40/CD80 positive cellular infiltration was conspicuous, in contrast to non-treated mice. IL-4/CD86 positive cellular infiltrates in OK-432-treated mice had decreased significantly more than in non-treated mice and IL-4 mRNA expression was virtually absent in OK-432-treated mice. P-STAT4 positive cells could be seen abundantly present in OK-432-treated mice, and p-STAT6 positive cells were much fewer than in non-treated mice.

CONCLUSIONS

OK-432-treatment appears to induce Th1 cellular response and to down-regulate that of the Th2 pathway in AD-like lesions of NC/Nga mice. The present results demonstrate bacterial components from such Streptococcus to likely constitute an effective new therapeutic approach in the treatment of AD.

Z-100, an immunomodulatory arabinomannan extracted from Mycobacterium tuberculosis strain Aoyama B, augments anti-tumor activities of X-ray irradiation against B16 melanoma in association with the improvement of type 1T cell responses

In this study, the effects of combination therapy consisting of X-ray irradiation and Z-100 on the survival time of C57BL/6 mice inoculated with B16F10 melanoma were investigated. Survival time was significantly prolonged in B16F10 melanoma-bearing mice treated with the X-ray irradiation (5 Gy) and Z-100 (10 mg/kg s.c.) combination therapy compared with mice irradiated with X-rays alone. The weight of primary tumors and number of metastatic colonies were also significantly suppressed by the combination therapy compared with that in the X-ray irradiation group. These results indicated that Z-100 could enhance the anti-tumor effects of radiotherapy against B16F10 melanoma. On the other hand, the survival time of CD4 knockout mice bearing the same tumors was not prolonged by the combination therapy compared with mice irradiated with X-rays alone, suggesting that CD4+ cells are partly involved in augmentation of the anti-tumor effect of radiotherapy by Z-100. In addition, type 1 cytokine (IL-2, IFN-gamma) production was significantly increased and type 2 cytokine (IL-4, IL-10) production was significantly suppressed in the tumor-bearing mice treated with the combination therapy compared with the X-ray irradiation group. Moreover, interleukin-12 production by CD11c+ cells was also significantly increased in mice treated with the combination therapy compared with the X-ray irradiation group. These results indicate that Z-100 augmented the anti-tumor effects of X-ray irradiation. Moreover, we demonstrated that the effects of Z-100 were expressed at least in part, by the improvement of the T cell responses from type 2-dominant to type 1-dominant via up-regulation of IL-12 production.

Antimetastatic effect of an immunomodulatory arabinomannan extracted from Mycobacterium tuberculosis strain Aoyama B, Z-100, through the production of interleukin-12

In this study, the role of interleukin (IL)-12 on the antimetastatic effect of Z-100 was investigated using wild-type C57BL/6 mice or IL-12p40 knockout (IL-12p40 KO) mice inoculated with highly metastatic B16F10 melanoma. When C57BL/6 mice were inoculated with B16F10 melanoma (2x10(5) cells/mouse i.v.), Z-100 (10 mg/kg i.p.) significantly suppressed the pulmonary metastasis of B16F10 melanoma 14 d after tumor inoculation. On the other hand, the antimetastatic effect of Z-100 was not observed in IL-12p40 KO mice inoculated with B16F10 melanoma. These results indicate that IL-12 is essentially required for the appearance of the antimetastatic effect of Z-100. Since helper T (Th) 2 cell responses have been reported to have a role in tumor metastasis, the regulatory effect of Z-100 on the immune balance of Th1/Th2 cell responses was investigated. In both C57BL/6 mice and IL-12p40 KO mice bearing B16F10 melanoma, Th1 cytokine production (IL-2, interferon-gamma) was significantly suppressed as compared with those in normal mice. On the other hand, Th2 cytokine production (IL-4, IL-10) in these mice was increased. The administration of Z-100 (10 mg/kg i.p.) in C57BL/6 mice bearing B16F10 melanoma improved the balance of Th1/Th2 cell responses from the Th2-dominant state to the normal state. However, the improvement of Th1/Th2 cell responses by Z-100 was not observed in IL-12p40 KO mice bearing the same tumors. In addition, Z-100 significantly increased IL-12 production by macrophages in a concentration-dependent manner, while Z-100 significantly decreased IL-10 production by these cells in vitro. These results suggested that up-regulation of IL-12 production and down-regulation of IL-10 production by Z-100 are related to the improvement of Th1/Th2 cell responses from the Th2-dominant state to the normal state, which resulted in suppression of tumor metastasis.

Long-term follow-up of kidney transplant patients with posttransplant lymphoproliferative disorder: duration of posttransplant lymphoproliferative disorder-induced operational graft tolerance, interleukin-18 course, and results of retransplantation

BACKGROUND

Posttransplant lymphoproliferative disorder (PTLD) can be resolved in many transplant patients by the reduction or cessation of immunosuppression, after which many grafts continue to function as the result of a form of operational tolerance. When graft function deteriorates, retransplantation may be an option. Cytokines such as interleukin (IL)-10 and IL-18 may play a role in PTLD tolerance induction and tumor regression. We report long-term follow-up on the duration of graft tolerance and the course of retransplantation in a series of patients who underwent kidney transplantation and demonstrated PTLD, and in whom we were able to perform IL-18 analyses.

RESULTS

Patients were followed for up to 7 years after PTLD diagnosis. Treatment consisted of immunosuppression cessation with radiation therapy in cases with overt monomorphic lymphomas. All patients' PTLDs were resolved, and all patients but one (whose graft was removed) demonstrated a period of operational graft tolerance of up to 5 years. Five patients underwent retransplantation without sign of recurrence of the PTLD up to 3 years after transplantation. In the eight patients analyzed, IL-18 increased significantly during PTLD regression and follow-up in those with long-term operational tolerance.

CONCLUSION

We report on a series of patients with resolved PTLDs demonstrating long-term recurrence-free survival, of whom most experienced a long period of operational graft tolerance. IL-18 seems to play a role in the resolution of the PTLDs. Five patients underwent retransplantation with standard immunosuppression without recurrence. A previous diagnosis of PTLD should not be regarded as a contraindication for later retransplantation.

Anti-tumor immune response induced by the fractions derived from OK-432, a streptococcal preparation, by using a monoclonal antibody TS-2 that neutralizes the interferon-gamma-inducing activity of OK-432: comparison between the TS-2-binding and TS-2-unbinding fraction

We have previously isolated a lipoteichoic acid (LTA)-related molecule (OK-PSA) from OK-432, a streptococcal agent, by affinity chromatography on a CNBr-activated Sepharose 4B bound TS-2 monoclonal antibody (mAb) that neutralizes the interferon (IFN)-gamma-inducing activity of OK-432. In the current study, we compared the cytokine-inducing and anti-tumor activities of OK-PSA, a TS-2-binding fraction, with those of OK-PTF, a TS-2-unbinding fraction, in order to determine the efficacy of OK-PSA for clinical use in affinity chromatography using TS-2. In the in vitro experiments using human peripheral blood mononuclear cells (PBMCs), OK-PSA markedly induced Th1-type cytokines, while interleukin (IL)-6 and IL-10, Th2-type cytokines, were induced by OK-PTF. Th1-cytokine induction by OK-PTF was not dose-dependent and was suppressed when PBMCs were treated with a high concentration of OK-PTF. In a mouse model, Th1 cytokines were also induced by OK-PSA and Th2 cytokines were induced by OK-PTF. Th2 cytokine-inducing activity of OK-PTF was accelerated in tumor-bearing mice relative to that in healthy mice. Although the anti-tumor effect of OK-PTF was statistically significant, it was much weaker than that of OK-PSA. A significant difference between the anti-tumor effect of OK-PSA and that of OK-PTF was observed (P<0.05). Finally, OK-PSA elicited its cytokine-inducing effect via Toll-like receptor (TLR) 4, whereas OK-PTF-induced signaling was mediated by both TLR2 and TLR4. These findings strongly suggested that the affinity chromatography using TS-2 is a useful strategy to separate the effective component for cancer therapy (OK-PSA) from other components.

Involvement of Toll-like receptor 4 signaling in interferon-gamma production and antitumor effect by streptococcal agent OK-432

BACKGROUND

The streptococcal agent OK-432 has been used for immunotherapy of head and neck cancer, among other malignancies, but its mechanism of action is unknown. Because the Toll-like receptor 4 (TLR4)/MD-2 complex is important in enabling the mammalian immune system to recognize bacterial components, we investigated whether expression of the TLR4 and MD-2 genes is associated with OK-432-induced anticancer immunity.

METHODS

Peripheral blood mononuclear cells (PBMCs) from 28 patients with head and neck cancer were analyzed for TLR4 and MD-2 mRNA expression by reverse transcription-polymerase chain reaction (RT-PCR) analysis. PBMCs were treated in vitro with OK-432 or with OK-PSA (a lipoteichoic-acid-related molecule that is an active component of OK-432), and interferon-gamma (IFN-gamma) mRNA expression, an immune response measure, was analyzed by RT-PCR. Patient sera collected 24 hours after OK-432 administration were examined for IFN-gamma protein using an enzyme-linked immunosorbent assay. Lewis lung carcinoma-bearing wild-type C57BL/6 and TLR4-deficient mice (four mice per group) received intraperitoneal injections of OK-432, and tumor volumes and sera IFN-gamma levels were measured over time. All statistical tests were two-sided.

RESULTS

Twenty patients expressed both TLR4 and MD-2. Expression of TLR4 and MD-2 genes was associated with the in vivo IFN-gamma induction in 19 patients administered OK-432 (Fisher's exact test P<.001). Although both OK-432 and OK-PSA induced IFN-gamma expression from PBMCs in vitro, expression of TLR4 and MD-2 was associated only with IFN-gamma expression induced by OK-PSA (P<.001). In vivo intraperitoneal administration of OK-432 resulted in an increase of IFN-gamma in sera from wild-type mice but not in sera from TLR4-deficient mice. Tumors in wild-type mice treated with OK-432 were statistically significantly smaller than those in mice treated with saline (P =.007). By contrast, in TLR4-deficient mice, there was no difference in tumor volume between the two treatment groups.

CONCLUSIONS

TLR4 and MD-2 may mediate OK-432-induced anticancer immunity.

Role of lipoteichoic acid in infection and inflammation

Lipoteichoic acid (LTA) is a surface-associated adhesion amphiphile from Gram-positive bacteria and regulator of autolytic wall enzymes (muramidases). It is released from the bacterial cells mainly after bacteriolysis induced by lysozyme, cationic peptides from leucocytes, or beta-lactam antibiotics. It binds to target cells either non-specifically, to membrane phospholipids, or specifically, to CD14 and to Toll-like receptors. LTA bound to targets can interact with circulating antibodies and activate the complement cascade to induce a passive immune kill phenomenon. It also triggers the release from neutrophils and macrophages of reactive oxygen and nitrogen species, acid hydrolases, highly cationic proteinases, bactericidal cationic peptides, growth factors, and cytotoxic cytokines, which may act in synergy to amplify cell damage. Thus, LTA shares with endotoxin (lipopolysaccharide) many of its pathogenetic properties. In animal studies, LTA has induced arthritis, nephritis, uveitis, encephalomyelitis, meningeal inflammation, and periodontal lesions, and also triggered cascades resulting in septic shock and multiorgan failure. Binding of LTA to targets can be inhibited by antibodies, phospholipids, and specific antibodies to CD14 and Toll, and in vitro its release can be inhibited by non-bacteriolytic antibiotics and by polysulphates such as heparin, which probably interfere with the activation of autolysis. From all this evidence, LTA can be considered a virulence factor that has an important role in infections and in postinfectious sequelae caused by Gram-positive bacteria. The future development of effective antibacteriolitic drugs and multidrug strategies to attenuate LTA-induced secretion of proinflammatory agonists is of great importance to combat septic shock and multiorgan failure caused by Gram-positive bacteria.