No abstract

Hepatitis B virus (HBV) infection has a low rate of chronicity compared to HCV infection, but chronic liver inflammation can evolve to life threatening complications. Experimental data from HBV infected chimpanzees and HBV transgenic mice have indicated that cytotoxic T cells are the main cell type responsible for inhibition of viral replication, but also for hepatocyte lysis during chronic HBV infection. Their lower activation and impaired function in later stages of infection was suggested as a possible mechanism that allowed for low levels of viral replication. The lack of an interferon response in these models also indicated the importance of adaptive immunity in clearing the infection. Increased knowledge of the signalling pathways and pathogen associated molecular patterns that govern activation of innate immunity in the early stages of viral infections in general has led to a re-evaluation of the innate immune system in HBV infection. Numerous studies have shown that HBV employs active strategies to evade innate immune responses and induce immunosuppression. Some of the immune components targeted by HBV include dendritic cells, natural killer cells, T regulatory cells and signalling pathways of the interferon response. This review will present the current understanding of innate immunity in HBV infection and of the challenges associated with clearing of the HBV infection.

Monocytic cells survive HIV replication and consequent cytopathic effects because of their decreased sensitivity to HIV-induced apoptosis. However, the mechanism underlying this resistance to apoptosis remains poorly understood. Lymphocytic cells are exposed to microbial products because of their translocation from the gut in persons with chronic HIV infections or following coinfections. We hypothesized that activation of monocytic cells by such microbial products through interaction with corresponding TLRs may confer antiapoptotic signals. Using HIV-viral protein R (Vpr)(52–96) peptide as a model apoptosis-inducing agent, we demonstrated that unlike monocyte-derived macrophages, undifferentiated primary human monocytes and promonocytic THP-1 cells are highly susceptible to Vpr(52–96)-induced apoptosis. Interestingly, monocytes and THP-1 cells stimulated with TLR9 agonist CpG induced almost complete resistance to Vpr(52–96)-induced apoptosis, albeit through a TLR9-independent signaling pathway. Moreover, CpG selectively induced the antiapoptotic cellular inhibitor of apoptosis (c-IAP)-2 protein and inhibition of the c-IAP-2 gene by either specific small interfering RNA or synthetic second mitochondrial activator of caspases mimetic reversed CpG-induced resistance against Vpr(52–96)-mediated apoptosis. We demonstrated that c-IAP-2 is regulated by the JNK and calcium signaling pathway, in particular calmodulin-dependent protein kinase-II. Furthermore, inhibition of JNK and the calcium signaling including the calmodulin-dependent protein kinase-II by either pharmacological inhibitors or their specific small interfering RNAs reversed CpG-induced protection against Vpr(52–96)-mediated apoptosis. We also show that CpG induced JNK phosphorylation through activation of the calcium signaling pathway. Taken together, our results suggest that CpG-induced protection may be mediated by c-IAP-2 through the calcium-activated JNK pathway via what appeared to be TLR9-independent signaling pathways.

AimsGrading of primary ovarian mucinous carcinoma (OMC) is inconsistent among practices. The International Collaboration on Cancer Reporting recommends grading OMC using the International Federation of Gynecology and Obstetrics (FIGO) system for endometrial endometrioid carcinoma, when needed. The growth pattern (expansile versus infiltrative), a known prognostic variable in OMC, is not considered in any grading system. We herein analysed the prognostic value of various grading methods in a well‐annotated cohort of OMC.Methods and resultsInstitutional OMCs underwent review and grading by the Silverberg and FIGO schemes and a novel system, growth‐based grading (GBG), defined as G1 (expansile growth or infiltrative invasion in ≤10%) and G2 (infiltrative growth >10% of tumour). Of 46 OMCs included, 80% were FIGO stage I, 11% stage II and 9% stage III. On follow‐up (mean = 52 months, range = 1–190), five patients (11%) had adverse events (three recurrences and four deaths). On univariate analysis, stage (P = 0.01, Cox proportional analysis), Silverberg grade (P = 0.01), GBG grade (P = 0.001) and percentage of infiltrative growth (P < 0.001), but not FIGO grade, correlated with disease‐free survival. Log‐rank analysis showed increased survival in patients with Silverberg grade 1 versus 2 (P < 0.001) and those with GBG G1 versus G2 (P < 0.001). None of the parameters evaluated was significant on multivariate analysis (restricted due to the low number of adverse events).ConclusionsSilverberg and the new GBG system appear to be prognostically significant in OMC. Pattern‐based grading allows for a binary stratification into low‐ and high‐grade categories, which may be more appropriate for patient risk stratification. Despite current practices and recommendations to utilise FIGO grading in OMC, our study shows no prognostic significance of this system and we advise against its use.

Macrophages are cells of the immune system that protect organisms against invading pathogens by fulfilling critical roles in innate and adaptive immunity and inflammation. They originate from circulating monocytes and show a high degree of heterogeneity, which reflects the specialization of function given by different anatomical locations. Differentiation of monocytes towards a macrophage phenotype is also accompanied by an increase of resistance against various apoptotic stimuli, a required characteristic that allows macrophages to accomplish their function in a stressful environment.Apoptosis, a form of programmed cell death, is a tightly regulated process, needed to maintain homeostasis by balancing proliferation with cellular demise. Caspases, a family of cysteine proteases that are highly conserved in multicellular organisms, function as central regulators of apoptosis. FLIP (FLICE-inhibitory protein), anti-apoptotic members of the Bcl2 family and inhibitors of apoptosis (IAP) are the main three groups of anti-apoptotic genes that counteract caspase activation through both the extrinsic and intrinsic apoptotic pathways.Modulation of the apoptotic machinery during viral and bacterial infections, as well as in various malignancies, is a wellestablished mechanism that promotes the survival of affected cells. The involvement of anti-apoptotic genes in the survival of monocytes/macrophages, either physiological or pathological, will be described in this review. How viral and bacterial infections that target cells of the monocytic lineage affect the expression of anti-apoptotic genes is important in understanding the pathological mechanisms that lead to manifested disease. The latest therapeutic approaches that target anti-apoptotic genes will also be discussed.

IL-7 plays an important role in T cell survival, function, and memory cell development, yet the role of cytokine signaling pathways in these processes has not been fully elucidated. Moreover, the underlying mechanisms for the observed impairment of IL-7 activity in diseases, such as HIV infection, breast cancer, and autoimmunity, are not well understood. It was therefore hypothesized that IL-7-induced signaling molecules could be linked with distinct IL-7-associated activities. To address this, the activation and functional associations of IL-7-induced signaling pathways, specifically antigen-independent activities that are relevant to T cell homeostasis, were examined. Low concentrations of IL-7 (100 pg/ml) are capable of activating the Jak-STAT and PI3K signaling pathways, whereas higher concentrations (500-1000 pg/ml) were required to induce Bcl-2 production and glucose uptake. Even higher concentrations of IL-7 (10,000 pg/ml) were needed to induce cell proliferation and intracellular accumulation of perforin. Inhibition of Jak activation reduced IL-7-induced Bcl-2 and perforin production, whereas inhibition of Jak/STAT or PI3K pathways reduced glucose uptake and proliferation. This study suggests a complex control of IL-7-associated activities in the absence of antigen stimulation. These data may provide insights into mechanisms of impaired IL-7 signaling and function in disease and could be relevant for the study of IL-7-based immunotherapeutics. Specifically, this study has linked STAT5 and PI3K activation to shared and distinct IL-7-associated activities in human CD8+ T cells.

Undifferentiated endometrial carcinoma arising in the background of high-grade endometrial carcinoma-Expanding the definition of dedifferentiated endometrial carcinoma Dedifferentiated endometrial adenocarcinoma (DEC) is defined by the coexistence of undifferentiated carcinoma with low-grade (FIGO grade 1 or 2) endometrioid carcinoma. Few cases of DEC arising in the background of high-grade carcinoma (DEC-HG) have been reported, however, this phenomenon is poorly characterized. In this study we describe the morphologic, immunohistochemical and clinico-pathologic characteristics of DEC-HG. 18 DECs were diagnosed at our institution between 2008-2019, and in 11 (61%), the undifferentiated component was associated with high-grade carcinoma (8 endometrioid FIGO grade 3, 2 with ambiguous features, 1 serous). The remaining 7 (39%) represented DEC-LG (3 FIGO grade 1 and 4 FIGO grade 2). 7/11 (64%) patients with DEC-HG presented with advanced stage (FIGO stage III/IV), whereas most with DEC-LG (6/7, 86%) were stage I. On follow up, 2 patients in the DEC-HG group died of disease and 2 had progressive disease within 2 months of surgery. There was only one recurrence in the DEC-LG, 6 months post-surgery. The DEC component in both groups showed similar morphology and immunophenotype, with predominantly focal or complete loss of expression of pan-keratin, EMA, E-cadherin, CK8/18, PAX8 and ER. The DEC component in the DEC-HG group had wild-type p53 expression in 8/11 (73%) cases, loss of MLH1 and PMS2 in 6/11 (55%) and loss of SMARCA4 in 3/ 9 (33%). Although numbers are small, we show that DEC-HG is a previously under-recognized phenomenon, with morphologic and immunophenotypic similarities to DEC-LG, which supports expanding the definition of DEC to include DEC-HG. DEC-HG may be more aggressive than DEC-LG.

Resistance to apoptosis is an important characteristic that human macrophages acquire during differentiation from monocytes. However, the intracellular mechanisms that mediate the development of resistance are not well understood. We have used M-CSF-stimulated primary human monocytes and PMA-treated THP1 cells to study apoptosis resistance during differentiation of human macrophages. Our results indicate that PI3K/Akt distinctively regulates survival of macrophages during and after differentiation. More specifically, a signaling pathway consisting of PI3K/Akt-NF-κB-Bcl-xL regulates cell survival during the differentiation process. PI3K/Akt-mediated activation of NF-κB plays a key role in survival of differentiating macrophages by specifically sustaining antiapoptotic Bcl-xL expression. With the use of pharmacological inhibitors and siRNA for Akt and Bcl-xL, we show that in the absence of Akt-dependent Bcl-xL expression during differentiation, cells undergo caspase-mediated apoptosis. In contrast, in differentiated macrophages, Bcl-xL expression is independent of PI3K/Akt activation. Taken together, these results suggest that survival of macrophages is distinctly regulated during and after differentiation. Our results also suggest new, potential therapeutic targets to modulate differentiation and survival of this cell type.