MD & PhD

Crosstalk between neutrophils, B-1a cells and plasmacytoid dendritic cells initiates autoimmune diabetes, Nat Med 2012 19(1) 65-73

Netting neutrophils in autoimmune small-vessel vasculitis, Nat Med 2009 15(6) 623-625

Epigenetic silencing of retinoblastoma gene regulates pathologic differentiation of myeloid cells in cancer, Nat Immunol 2013 14(3) 211-220

Cigarette Smoke-Induced Collagen Destruction; Key to Chronic Neutrophilic Airway Inflammation? PLOS one 2013 8(1) e55612

배경지식 - 문제제기 - 실험과 결과 - 문제에 대한 대답 - 질문의 과학적/임상적 의미 제시 혹은 추측

Macrophages frequently infiltrate tumors and can enhance cancer growth, yet the origins of the macrophage response are not well understood. Here we address molecular mechanisms of macrophage production in a conditional mouse model of lung adenocarcinoma. We report that overproduction of the peptide hormone Angiotensin II (AngII) in tumor-bearing mice amplifies self-renewing hematopoietic stem cells (HSCs) and macrophage progenitors. The process occurred in the spleen but not the bone marrow, and was independent of hemodynamic changes. The effects of AngII required direct hormone ligation on HSCs, depended on S1P1 signaling, and allowed the extramedullary tissue to supply new tumor-associated macrophages throughout cancer progression. Conversely, blocking AngII production prevented cancer-induced HSC and macrophage progenitor amplification and thus restrained the macrophage response at its source. These findings indicate that AngII acts upstream of a potent macrophage amplification program and that tumors can remotely exploit the hormone’s pathway to stimulate cancer-promoting immunity.

Cortez-Retamozo, V. et al. Angiotensin II Drives the Production of Tumor-Promoting Macrophages. Immunity 38, 296–308 (2013).

A₁  Regulatory T (Treg) cells, particularly those of the Foxp3+CD4+ subset, are critical regulators of immune responses. A_1-1 They were originally described as controlling the activities of other T cells but were later recognized to regulate B cells and several innate immune system players. A₂ There have also been recent reports of Treg cell control over nonimmunological processes. A_2-1 Perhaps the best-characterized example is a unique population of Treg cells residing in the visceral adipose tissue (VAT) and regulating metabolic indices. A_2-2 The prevalence, transcriptome, and T cell receptor (TCR) repertoire of this population are all distinct from those of their counterparts in lymphoid organs. A₃ Surveying a variety of tissues to see whether other nonimmuno-logical processes might be controlled by analogous Treg popu- lations, A₄ our attention was drawn to a substantial accumulation of Foxp3+CD4+ T cells in skeletal muscle undergoing repair after acute injury.

B₁ Skeletal muscle regeneration follows the same orchestrated plan regardless of the cause of muscle damage. B₂ It is driven largely by satellite cells, a pool of quiescent precursors closely associated with muscle fibers. B₃ In response to injury, these cells become activated, proliferate, differentiate, migrate, and fuse to form new myofibers. B₄ This series of events is controlled by the sequential activation and repression of specific transcription factors. B₅ With muscular dystrophies, in which chronic myofiber loss occurs due to genetic defects, the satellite cell pool is called on repeatedly, so it can exhaust or lose function over time, dampening the repair process.

C₁ Regeneration of skeletal muscle is influenced by inflammatory events that accompany repair. C₂Following an early, transient recruitment of neutrophils, myeloid mononuclear cells, mainly derived from a pool of circulating monocytes, infiltrate the injured tissue. C₃ Within days, the myeloid infiltrate transitions from a pro- to an anti-inflammatory phenotype, a shift that is critical for proper muscle repair. C₄ An initial population of proinflammatory, or M1-type, macrophages is required for clearance of apoptotic or necrotic cells and derivative debris; a subsequent population of anti-inflammatory, or M2-type, macrophages has various proregenerative functions, such as matrix remodeling and promotion of angiogenesis. C₅ Abla- tion or impaired recruitment of macrophages severely compro- mises muscle repair.

D₁ Though far less markedly, lymphocytes also accumulate in skeletal muscle after acute injury, as well as in the dystrophin-deficient muscles of mice harboring the mdx mutation or humans with Duchenne muscular dystrophy (DMD). D₂Their function has not been well studied, although both CD4+ and CD8+ T cells seem to promote the mdx pathology. D₃Even less is known about the composition and function of infiltrating T cell populations in models of acute muscle injury. D₄ In particular, the contribution of Treg cells is yet to be addressed.

E Here, we uncover a unique population of CD4+Foxp3+ Treg cells that accumulates in skeletal muscle shortly after acute injury. We address the impact of this population on muscle repair, its implication in genetically determined muscle aberrancies, and the potential therapeutic effects of modulating this population and one of the proregenerative factors it produce

Burzyn, D. et al. A Special Population of Regulatory T Cells Potentiates Muscle Repair. Cell 155, 1282–1295 (2013).

In the 20 control subjects, the mean resting blood pressure was 85 ± 5 mmHg. In comparison, in the 30 tennis players, the mean resting blood pressure was 94 ± 3 mmHg.

The mean resting blood pressure was higher in the 30 tennis players than in the 20 control subjects (94 ± 3 vs. 85 ± 5 mmHg, p < 0.02) 

질문A → 질문을 해결하기 위한 실험의 개요 → 실험의 결과/질문에 대한 대답 → 질문 B → 반복 

미리 디자인된 연구에서 관찰한 것 중 가장 중요한 것 → 다음으로 중요한 것

Efficacy analyses were performed on the intention-to-treat population. A survival analysis was performed after 414 deaths occurred, 37 months after the last patient was enrolled. The median overall survival in the ipilimumab–dacarbazine group was 11.2 months (95% confidence interval [CI], 9.4 to 13.6), as compared with 9.1 months (95% CI, 7.8 to 10.5) in the dacarbazine group, with estimated survival rates in the two groups, respec- tively, of 47.3% and 36.3% at 1 year, 28.5% and 17.9% at 2 years, and 20.8% and 12.2% at 3 years (hazard ratio for death with ipilimumab–dacarbazine, 0.72; P<0.001) (Fig. 1A). Ipilimumab was associated with improved overall survival across patient subgroups, including those defined according to age, sex, ECOG performance status, baseline serum lactate dehydrogenase level, and substage of metastatic disease (Fig. 2).

There was a 24% reduction in the risk of progression in the ipilimumab–dacarbazine group as compared with the dacarbazine group (hazard ratio for progression, 0.76; P=0.006). The median values for progression-free survival were similar in the two groups because the first assessment of progression occurred at week 12 after the true median. After the first tumor assessment, the Kaplan–Meier curves separated (Fig. 1B).

The safety analysis included all patients who underwent randomization and received at least one dose of the assigned study drug (498 patients). The adverse events reported in the safety popula- tion are listed in Table 3. Adverse events (all grades) for which there was a higher incidence in the ipilimumab–dacarbazine group than in the dacarbazine group included elevation of alanine aminotransferase levels (in 33.2% of patients vs. 5.6%), elevation of aspartate aminotransferase lev- els (29.1% vs. 5.6%), diarrhea (36.4% vs. 24.7%), pruritus (29.6% vs. 8.8%), and rash (24.7% vs. 6.8%). Grade 3 or 4 adverse events occurred in 56.3% of patients receiving ipilimumab plus dacarbazine and in 27.5% of patients receiving pla- cebo plus dacarbazine (P<0.001).

Robert, C. et al. Ipilimumab plus dacarbazine for previously untreated metastatic melanoma. N Engl J Med 364, 2517–2526 (2011).

To compare the proliferation of PMN-MDSCs and M-MDSCs and their immediate precursors in vivo, we injected 5-bromodeoxyuridine (BrdU; thymidine analog incorporated by cycling cells) intraperitoneally into EL-4 tumor-bearing mice and measured its incorporation into M-MDSCs and PMN-MDSCs in BM and spleen cells 5 or 24 h later (Fig. 1d,e). As a control, we measured BrdU incorporation in monocytes and PMNs from naive tumor-free mice. M-MDSCs had a 5–6-fold greater BrdU incorporation than PMN-MDSCs did in BM of EL-4 tumor mice (Fig. 1d). We observed no differences in BrdU uptake between PMN-MDSCs from tumor-bearing mice and PMNs from naive mice; M-MDSCs from tumor-bearing mice incorporated more than twofold more BrdU than monocytes from naive mice did (Fig. 1d). Monocytes and PMNs from spleens of naive mice and PMN-MDSCs from spleens of tumor-bearing mice had similar BrdU uptake, whereas M-MDSCs incorporated 2–3-fold more BrdU (Fig. 1e).

We next investigated GM-CSF–driven expansion of sorted populations of BM PMN-MDSCs and M-MDSCs in vitro, cultured with or without tumor explant supernatants. We evaluated the total number of recovered cells as well as cell proliferation. PMN-MDSCs and PMNs exhibited no proliferative activity and poor survival in culture. Tumor explant supernatants improved survival of PMNs and PMN- MDSCs without an effect on proliferation. In contrast, M-MDSCs proliferated and expanded much better than monocytes or PMN- MDSCs did (Supplementary Fig. 2 and Fig. 1f). However, the ratio between PMN-MDSCs and M-MDSCs remained largely unchanged in the total population of Gr-1+CD11b+ MDSCs in vitro (Fig. 1g). Thus, despite the fact that M-MDSCs and their precursors had a higher proliferation rate than monocytes did, their accumulation in tumor-bearing mice was barely detectable. In contrast, precursors of PMN-MDSCs proliferated at similar rates as the PMNs did but expanded dramatically in tumor-bearing hosts. In addition, PMN-MDSCs represented a large percentage of MDSCs during culture, despite the lack of expansion in vitro and their poor survival, suggesting that the pool of PMN-MDSCs may be replenished from M-MDSCs.

Youn, J.-I. et al. Epigenetic silencing of retinoblastoma gene regulates pathologic differentiation of myeloid cells in cancer. Nat Immunol 14, 211–220 (2013).

① 질문에 대한 대답

② 자신의 업적과 다른 사람들의 업적을 비교

③ 대답에 대한 방어

④ 관찰된 모순된 결과를 설명 

⑤ 이 논문의 참신성을 제시 

⑥ 이 논문의 괴리를 제시 

⑦ 예기치 못한 발견을 설명 

⑧ 방법의 한계/ 연구디자인 및 가설의 타당성에서의 결함에 대한 고찰

⑨ 중요성의 확립 - 임상적/과학적 관점에서 

It has recently become clear that the immune system has a crucial role in modulating tumor progression and response to therapy. Numerous anticancer agents that were used in the past for their cytotoxic properties can modulate the host immune system, and sometimes induce a long-term protective memory T cell response. We unveiled a previously unknown environment in the MZ of the spleen of tumor-bearing hosts in which immunoregulatory monocytes coexist with memory CD8+ T cells. These multipotent inflammatory monocytes are recruited to the MZ by CCL2 and crosstolerize Ag-specific lymphocytes, at least in part by sampling tumor-released of the high proliferative rate of these exosomes. Because monocytes, some chemotherapeutic agents are very active in depleting them while sparing poorly proliferating lymphocytes, and the subsequent occupation of the splenic environment by CD8+ T cells hampers the replenishment of myeloid cells fol- lowing chemotherapy. The contribution of both depletion of regulatory T lymphocytes and induction of immunogenic cancer cell death by chemotherapy to the described phenomena was negligible. These findings provide a rational explanation for the often empirical and paradoxical observation that chemotherapy is one of the most effective adjuvants for ACT, and suggest that an extensive lympho-myeloablation before ACT is likely unnecessary or even detrimental. We propose that our findings lay the foundation for defining both the dose and class of chemotherapeutic agents that will have the greatest impact on ACT.

Our data depict two scenarios for future approaches aimed at enhancing ACT therapeutic impact. First, metronomic chemotherapy treatment could be exploited to maintain a long- term contraction of the immunosuppressive monocyte expansion. Metronomic chemotherapy was originally developed to vercome drug resistance; however, low-dose cyclophosphomide was reported to limit regulatory T lymphocytes and increase innate immune response (Ghiringhelli et al., 2004; Ghir- inghelli et al., 2007). Second, chemotherapeutic drugs with distinct immunomodulatory properties could be combined with cancer immunotherapy. As recently reviewed, in fact, some agents can induce immunogenic cancer-cell death (Galluzzi et al., 2012; Zitvogel et al., 2011). Of interest, many of the drugs that alter the splenic immunoregulatory environment do not affect the immunogenic context of cancer death. Future devel- opments could thus be based on optimizing low-dose chemotherapy to eliminate immunosuppressive monocytes before administering a specific drug that is able to elicit immunogenic death and increase tumor-Ag uptake by APCs present in the tumor microenvironment.

A prediction based on our data is that adoptive transfer of Ag-specific CD8+ TCM would be the best choice for passive immuno- therapy, because these cells may be able to interfere with myeloid cell expansion in the spleen following chemotherapy. Indeed, this hypothesis is supported by some published experi- mental data showing that adoptively transferred CD8+ TCM were more potent than effector memory CD8+ T cells specific for a melanoma Ag in causing the eradication of large established tumors (Klebanoff et al., 2005). Of interest, this greater efficacy achieved with CD8+ TCM was related to the ability of tumor-reactive T cells to traffic better to secondary lymphoid organs than to tumor sites (Klebanoff et al., 2005).

CCL2 has multiple roles in cancer progression. Gr-1+ inflam- matory monocytes were not found at primary mammary tumor lesions, and instead were preferentially recruited by CCL2 to pulmonary metastases to assist tumor spreading. Moreover, CCL2 expression and macrophage infiltration were shown to correlate with poor prognosis and metastatic disease in human breast cancer (Qian et al., 2011). Recent evidence, however, shows that the antitumor effects of CCL2 blockade in vivo are dependent on the host immune system. In fact, administration of anti-CCL2 monoclonal antibody (mAb) induced tumor-spe- cific CD8+ T cell activation and expansion rather than a decrease in the number of tumor-associated macrophages (Fridlender et al., 2010, 2011). Moreover, the antitumor effects of CCL2 blockade was completely lost in immunodeficient mice or after CD8+ T cell depletion, clearly enforcing the concept that CCL2 blockade reestablishes the immune response in the tumor- bearing host, in similarity to the data we obtained with either 5-FU administration or ccl2/ccr2 gene knockout ablation. Moreover, we show here that CCL2 serum levels correlate with the expansion of immature myeloid cells in the blood of cancer patients, and, more importantly, with the clinical response to cancer vaccination in patients who develop broad immune responses to the tumor Ags present in the vaccine. The spleen is not easily accessible in patients, but our findings indicate that blood may be used to provide information relevant for the clinical outcomes of cancer immunotherapy.

Ugel, S. et al. Immune Tolerance to Tumor Antigens Occurs in a Specialized Environment of the Spleen. CellReports 2, 628–639 (2012).

Origins of tumor-associated marcphages and neutrophils. Proc Natl Acad Sci USA 109, 2491–2496 (2012).

Tumor induces proliferation of TAM/TAN precursors in the spleen