Ching-Tai Huang

Tumor-Derived Chemokine CCL5 Enhances TGF-β–Mediated Killing of CD8+ T Cells in Colon Cancer by T-Regulatory Cells

Chemokine CCL5/RANTES is highly expressed in cancer where it contributes to inflammation and malignant progression. In this study, we show that CCL5 plays a critical role in immune escape in colorectal cancer. We found that higher levels of CCL5 expression in human and murine colon tumor cells correlated with higher levels of apoptosis of CD8+ T cells and infiltration of T-regulatory cells (T(reg)). In mouse cells, RNA interference (RNAi)-mediated knockdown of CCL5 delayed tumor growth in immunocompetent syngeneic hosts but had no effect on tumor growth in immunodeficient hosts. Reduced tumor growth was correlated with a reduction in T(reg) infiltration and CD8(+) T-cell apoptosis in tumors. Notably, we found that CCL5 enhanced the cytotoxicity of T(reg) against CD8(+) T cells. We also found tumor growth to be diminished in mice lacking CCR5, a CCL5 receptor, where a similar decrease in both T(reg) cell infiltration and CD8(+) T-cell apoptosis was noted. TGF-β signaling blockade diminished apoptosis of CD8(+) T cells, implicating TGF-β as an effector of CCL5 action. In support of this concept, CCL5 failed to enhance the production of TGF-β by CCR5-deficient T(reg) or to enhance their cytotoxic effects against CD8(+) T cells. CCR5 signaling blockade also diminished the in vivo suppressive capacity of T(reg) in inhibiting the antitumor responses of CD8(+) T cells, in the same way as CCL5 signaling blockade. Together, our findings establish that CCL5/CCR5 signaling recruits T(reg) to tumors and enhances their ability to kill antitumor CD8(+) T cells, thereby defining a novel mechanism of immune escape in colorectal cancer.

Activated but not resting regulatory T cells accumulated in tumor microenvironment and correlated with tumor progression in patients with colorectal cancer

Activated T regulatory (Treg) cells are potent suppressors that mediate immune tolerance. We investigated the relationship between activated Treg cells and the progression of human colon cancer. We designed a cross‐sectional study of CD4+Foxp3+ T cells from peripheral blood, primary tumor and nontumor colon tissue of 42 patients with colon cancer and correlated the percentages of different subgroups of Treg cells with colon cancer stage. The phenotypes, cytokine‐release patterns and suppression ability of these Treg cells were analyzed. We found that Treg cells increased significantly in both peripheral blood and cancer tissue. In addition, the Treg cells expressed significantly lower levels of CCR7, CD62L and CD45RA in comparison to normal volunteers. Further dividing Treg cells into subgroups based on Foxp3 and CD45RA expression revealed that both activated Treg cells (Foxp3hiCD45RA−) and nonsuppressive Treg cells (Foxp3loCD45RA−), but not resting Treg cells (Foxp3lowCD45RA+), increased in the peripheral blood and cancer tissue of patients with colon cancer. Only the activated Treg cells expressed significantly higher levels of tumor necrosis factor receptor 2 and cytotoxic T‐cell antigen‐4. Activated Treg cells, however, secreted significantly lower levels of effector cytokines (interleukin‐2, tumor necrosis factor‐α and interferon‐γ) than did resting Treg cells and nonsuppressive cells upon ex vivo stimulation. Activated, but not resting, Treg cells in cancer tissue correlated with tumor metastases. In summary, we confirmed that activated Treg cells are a distinct subgroup with effector memory phenotype and fully functional regulatory activity against human colorectal cancer immunity.

Influence of teicoplanin MICs on treatment outcomes among patients with teicoplanin-treated methicillin-resistant Staphylococcus aureus bacteraemia: a hospital-based retrospective study

OBJECTIVES Higher vancomycin MIC values (≥1.5 mg/L via Etest) may be associated with vancomycin treatment failure among patients with serious methicillin-resistant Staphylococcus aureus (MRSA) infections. As there were limited similar data for teicoplanin, this retrospective cohort study intended to determine the predictive value of teicoplanin MICs for treatment failure among patients with MRSA bacteraemia. PATIENTS AND METHODS All patients with at least one blood culture positive for MRSA admitted to the hospital between January 2010 and January 2011 were reviewed. Patients with an age ≥18 years and receipt of teicoplanin therapy throughout the course or receipt of <72 h of vancomycin therapy and then teicoplanin for >3 days were enrolled. Teicoplanin Etest(®) MICs and treatment outcomes for MRSA bacteraemia were reviewed to identify the breakpoint of teicoplanin MICs influencing treatment outcomes. RESULTS Of the 101 patients enrolled, 56 had a lower teicoplanin MIC (≤1.5 mg/L) for MRSA and 45 had a higher MIC (>1.5 mg/L) for MRSA. A lower teicoplanin MIC was associated with a favourable outcome [37 (66.1%) versus 13 (28.9%); P<0.001] and a lower rate of bloodstream infection-related mortality [15 (26.8%) versus 22 (48.9%); P=0.022]. Patients with chronic obstructive pulmonary disease, bacteraemic pneumonia or higher Pittsburgh bacteraemia score had an unfavourable outcome (P=0.028, 0.022 and <0.001, respectively). Multivariate analysis showed that teicoplanin MIC >1.5 mg/L, higher Pittsburgh bacteraemia score and bacteraemic pneumonia were independent risk factors for unfavourable outcome. CONCLUSIONS A higher teicoplanin MIC value (>1.5 mg/L) may predict an unfavourable outcome and higher mortality rate among teicoplanin-treated MRSA bacteraemic patients.

Severe Cutaneous Adverse Reactions Related to Systemic Antibiotics

BACKGROUND Systemic antibiotics are a major cause of severe cutaneous adverse reactions (SCARs). The selection of alternative antibiotics and management for SCARs patients with underlying infections can be challenging. METHODS We retrospectively analyzed 74 cases of SCARs, including Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), drug rash with eosinophilia and systemic symptoms (DRESS), and acute generalized exanthematous pustulosis (AGEP), related to use of systemic antibiotics in Taiwan from January 2006 to January 2012. We analyzed the causative antibiotics, clinical features, organ involvements, and mortality. We also assessed patient tolerability to alternative antibiotics after the development of antibiotic-related SCARs. RESULTS The most common causes of SCARs were penicillins and cephalosporins for SJS/TEN and AGEP; glycopeptides for DRESS. Fatality was more frequent in the SJS/TEN group. In patients with SJS/TEN, higher mortality was associated with old age and underlying sepsis before the development of SCARs. The majority of patients with penicillin- or cephalosporin-related SCARs were able to tolerate quinolones, glycopeptides, and carbapenems. CONCLUSIONS Complicated underlying conditions and infections may increase mortality in patients with antibiotic-related SCARs. The selection of structurally different alternative drugs is important to avoid recurrence.

Effector/Memory but Not Naive Regulatory T Cells Are Responsible for the Loss of Concomitant Tumor Immunity

The phenomenon of concomitant tumor immunity involves a tumor-bearing host rejecting another similar tumor at a distant site and suggests the existence of tumor-specific immunity. Loss of this immunity may contribute to tumor metastasis. However, mechanisms underlying the loss of concomitant immunity are largely unknown. We set up a concomitant tumor immunity model in which this immunity is gradually lost as the primary tumor progresses. We found that CD8+ T cells, especially tumor-infiltrating CD8+ T cells, from mice that lost concomitant tumor immunity, possessed potent antitumor properties and strongly expressed effector molecules. Furthermore, effector/memory regulatory T cells (Treg cells, CD103+CD4+Foxp3+ T cells) increased as the primary tumor progressed. They initially accumulated around the tumor and in the spleen at later points. Not only did these cells more greatly express killing molecules, they also suppressed the functions of tumor-bearing CD8+ T cells in vitro and in vivo. Finally, we show that these effector/memory Treg cells inhibit concomitant tumor immunity in vivo. Taken together, data suggest that effector/memory Treg cells are responsible for the loss of concomitant tumor immunity associated with tumor progression.

Apoptosis of tumor infiltrating effector TIM-3+CD8+ T cells in colon cancer

TIM-3 functions to enforce CD8+ T cell exhaustion, a dysfunctional state associated with the tolerization of tumor microenvironment. Here we report apoptosis of IFN-γ competent TIM-3+ population of tumor-infiltrating CD8+ T cells in colon cancer. In humans suffering from colorectal cancer, TIM-3+ population is higher in cancer tissue-resident relative to peripheral blood CD8+ T cells. Both the TIM-3+ and TIM-3- cancer tissue-resident CD8+ T cells secrete IFN-γ of comparable levels, although apoptotic cells are more in TIM-3+ compared to TIM-3- population. In mouse CT26 colon tumor model, majority of tumor-infiltrating CD8+ T cells express TIM-3 and execute cytolysis function with higher effector cytokine secretion and apoptosis in TIM-3+ compared to TIM-3- population. The tumor cells secrete galectin-9, which increases apoptosis of tumor-infiltrating CD8+ T cells. Galectin-9/TIM-3 signaling blockade with anti-TIM-3 antibody reduces the apoptosis and in addition, inhibits tumor growth in mice. The blockade increases therapeutic efficacy of cyclophosphamide to treat tumor in mice as well. These results reveal a previously unexplored role of TIM-3 on tumor-infiltrating CD8+ T cells in vivo.

The Indispensable Role of CCR5 for In Vivo Suppressor Function of Tumor-Derived CD103+ Effector/Memory Regulatory T Cells

CD103 is a marker for identification of effector/memory regulatory T cells (Tregs). CD103+ Tregs are potent suppressors of tissue inflammation in several infectious diseases, autoimmune diseases, and cancers. However, the underlying mechanisms for this potent suppression ability remain unclear. The current study was designed to clarify this issue. Unexpectedly, we found both CD103+ and CD103− Tregs had similar suppression capacity in vitro. We then chose a murine tumor model for investigation of the in vivo behavior of these Tregs. The suppression ability in vivo against the anti-tumor ability of CD8+ T cells was restricted to CD103+ Tregs although both Tregs had equal in vitro suppression ability. In addition, CD103+ Tregs expressed significantly higher levels of CCR5 than those of CD103− Tregs and accumulated more in tumors than did CD103− Tregs. Furthermore, blockade of CCR5 signaling, either by CCR5−/−CD103+ Tregs or by CCL5 knockdown tumor, could reduce the migration of CD103+ Tregs into tumors and impair their in vivo suppression ability. In conclusion, these results indicate that the potent in vivo suppression ability of CD103+ Tregs is due to the tissue-migration ability through CCR5 expression.

Fusidic acid for the treatment of bone and joint infections caused by meticillin-resistant Staphylococcus aureus

There is a lack of surveillance data on resistance to fusidic acid (FA) in Asia, and no reviews of FA usage for the treatment of orthopaedic infections have been conducted since the year 2000. In this study, we present a systemic literature review of FA resistance in Asia and the clinical use of FA for the treatment of bone and joint infections (BJIs). The in vitro activity of FA against meticillin-resistant Staphylococcus aureus (MRSA) isolates remains good, with low (<10%) resistance rates in most Asian countries. FA in Asia appears to be a better oral anti-MRSA agent than trimethoprim/sulfamethoxazole and clindamycin. More than 80 cases of FA use for BJI have been reported since 2000 and the recurrence or failure rate is <10%. There is much evidence supporting the use of FA in combination with other antibiotics (e.g. rifampicin) as an oral treatment following intravenous glycopeptide treatment for BJIs.

Liver injury is associated with enhanced regulatory T-cell activity in patients with chronic hepatitis B

Summary.  Chronic hepatitis B virus (HBV) infection is associated with impairment of HBV‐specific immune responses. Recently, it has been shown that regulatory T (Treg) cells downregulate HBV‐specific immune responses but their role in chronic hepatitis B is still controversial. We hypothesized that liver injury enhances the influence of Treg cells on HBV‐specific immune responses. The frequency of Treg cell and the in vitro expansion of HBV‐specific CD8+ T cell detected by the tetramer method were investigated in 79 patients with chronic hepatitis B. Thirty‐three healthy volunteers were enrolled to measure the frequency of Treg cell as controls. The results showed that in chronic hepatitis B cases, the frequency of Treg cells in peripheral blood was significantly higher than that in normal volunteers. The higher level of serum transaminase was associated with higher frequency of Treg cells, which both had a linear correlation relationship. HBV‐DNA level, HBe status, age and sex had no statistical association with Treg cell frequency. Furthermore, in patients with higher serum transaminase levels, the expansion of HBV‐specific CD8+ T cells was higher after removal of Treg cells when compared with patients with lower serum transaminase levels. In conclusion, our data indicate a significant association between serum transaminase level and frequency/activity of Treg cells. Based on this observation, we propose that liver‐injury enhances Treg cell frequency/activity in chronic hepatitis B patients.

Blockade of TNF-α signaling benefits cancer therapy by suppressing effector regulatory T cell expansion

Effector but not naive regulatory T cells (Treg cells) can accumulate in the peripheral blood as well as the tumor microenvironment, expand during tumor progression and be one of the main suppressors for antitumor immunity. However, the underlying mechanisms for effector Treg cell expansion in tumor are still unknown. We demonstrate that effector Treg cell-mediated suppression of antitumor CD8+ T cells is tumor-nonspecific. Furthermore, TNFR2 expression is increased in these Treg cells by Affymetrix chip analysis which was confirmed by monoclonal antibody staining in both hepatocellular carcinoma (HCC) and colorectal cancer (CRC) patients and murine models. Correspondingly, increased levels of TNF-α in both tissue and serum were also demonstrated. Interestingly, TNF-α could not only expand effector Treg cells through TNFR2 signaling, but also enhanced their suppressive activity against antitumor immunity of CD8+ T cells. Furthermore, targeting TNFR2 signaling with a TNF-α inhibitor could selectively reduce rapid resurgence of effector Treg cells after cyclophosphamide-induced lymphodepletion and markedly inhibit the growth of established tumors. Herein, we propose a novel mechanism in which TNF-α could promote tumor-associated effector Treg cell expansion and suggest a new cancer immunotherapy strategy using TNF-α inhibitors to reduce effector Treg cells expansion after cyclophosphamide-induced lymphodepletion.