Inflammation switches the differentiation program of Ly6Chi monocytes from antiinflammatory macrophages to inflammatory dendritic cells in the colon

Blood monocytes differentiate into distinct colonic macrophage or dendritic cell subsets depending on the presence or absence of inflammation

Dendritic cells (DCs) and macrophages (MPs) are important for immunological homeostasis in the colon. We found that F4/80^hiCX3CR1^hi (CD11b⁺CD103⁻) cells account for 80% of mouse colonic lamina propria MHC-II^hi cells. Both CD11c⁺ and CD11c⁻ cells within this population were identified as MPs based on multiple criteria, including an MP transcriptome revealed by microarray analysis. These MPs constitutively released high levels of IL-10 at least partially in response to the microbiota via an MyD88-independent mechanism. In contrast, cells expressing low to intermediate levels of F4/80 and CX3CR1 were identified as DCs based on phenotypic and functional analysis and comprise three separate CD11c^hi cell populations: CD103⁺CX3CR1⁻CD11b⁻ DCs, CD103⁺CX3CR1⁻CD11b⁺ DCs, and CD103⁻CX3CR1^intCD11b⁺ DCs. In noninflammatory conditions, Ly6C^hi monocytes (MOs) differentiated primarily into CD11c⁺ but not CD11c⁻ MPs. In contrast, during colitis, Ly6C^hi MOs massively invaded the colon and differentiated into proinflammatory CD103⁻CX3CR1^intCD11b⁺ DCs, which produced high levels of IL-12, IL-23, iNOS, and TNF. These findings demonstrate the dual capacity of Ly6C^hi blood MOs to differentiate into either regulatory MPs or inflammatory DCs in the colon and that the balance of these immunologically antagonistic cell types is dictated by microenvironmental conditions.

Type I IFNs regulate effector and regulatory T cell accumulation and anti-inflammatory cytokine production during T cell-mediated colitis

We explored the function of endogenous type I IFNs (IFN-1) in the colon using the T cell adoptive transfer model of colitis. Colon mononuclear phagocytes (MPs) constitutively produced IFN-1 in a Toll/IL-1R domain-containing adapter-inducing IFN-β-dependent manner. Transfer of CD4(+)CD45RB(hi) T cells from wild-type (WT) or IFN-α/β receptor subunit 1 knockout (IFNAR1(-/-)) mice into RAG(-/-) hosts resulted in similar onset and severity of colitis. In contrast, RAG(-/-) × IFNAR1(-/-) double knockout (DKO) mice developed accelerated severe colitis compared with RAG(-/-) hosts when transferred with WT CD4(+)CD45RB(hi) T cells. IFNAR signaling on host hematopoietic cells was required to delay colitis development. MPs isolated from the colon lamina propria of IFNAR1(-/-) mice produced less IL-10, IL-1R antagonist, and IL-27 compared with WT MPs. Accelerated colitis development in DKO mice was characterized by early T cell proliferation and accumulation of CD11b(+)CD103(-) dendritic cells in the mesenteric lymph nodes, both of which could be reversed by systemic administration of IL-1R antagonist (anakinra). Cotransfer of CD4(+)CD25(+) regulatory T cells (Tregs) from WT or IFNAR1(-/-) mice prevented disease caused by CD4(+)CD45RB(hi) T cells. However, WT CD4(+)CD25(+)Foxp3(GFP+) Tregs cotransferred with CD4(+)CD45RB(hi) T cells into DKO hosts failed to expand or maintain Foxp3 expression and gained effector functions in the colon. To our knowledge, these data are the first to demonstrate an essential role for IFN-1 in the production of anti-inflammatory cytokines by gut MPs and the indirect maintenance of intestinal T cell homeostasis by both limiting effector T cell expansion and promoting Treg stability.

Protein synthesis rate measured with L-[1-11C]tyrosine positron emission tomography correlates with mitotic activity and MIB-1 antibody-detected proliferation in human soft tissue sarcomas

Protein synthesis rate (PSR) can be assessed in vivo using positron emission tomography with L-[1-11C]tyrosine (TYR-PET). Biological activity of soft tissue sarcomas (STS) can be measured in vitro by the mitotic rate and number of proliferating cells. In STS the grade of malignancy, in which the mitotic index plays a major role, is considered to be the major standard in predicting biological tumour behaviour. This study was designed to test the validity of TYR-PET in relation to different histopathological features. In 21 patients with untreated STS, the PSR was measured using TYR-PET. The number of mitoses was counted and tumours were graded according to the grading system of Coindre et al. (Cancer 1986; 58:306-309). Proliferative activity was assessed by immunohistological detection of the Ki-67 nuclear antigen using MIB-1 monoclonal antibody. To test the association between the PSR and these tumour parameters, a correlation analysis was performed. A significant (P<0.05) correlation was found between PSR and the Ki-67 proliferation index (R = 0.54), and between PSR and mitotic rate (R = 0.64). There was no correlation between PSR and tumour grade. The present study in malignant soft tissue tumours relates in vivo tumour metabolism as established with TYR-PET to tumour activity measured in vitro and indicates that the non-invasive method of TYR-PET can estimate the mitotic and proliferative activity in STS.

Hepatic Kaposi sarcoma: A case report and review of the literature

Kaposi sarcoma (KS) is an aggressive cancer caused by human herpesvirus-8, primarily seen in immunocompromised patients. As opposed to the well-described cutaneous manifestations and pulmonary complications of KS, hepatic KS is rarely reported before death as most patients with hepatic KS do not manifest symptoms or evidence of liver injury. In patients with acquired immune deficiency syndrome, hepatic involvement of KS is present in 12%-24% of the population on incidental imaging and in approximately 35% of patients with cutaneous KS if an autopsy was completed after their death. Patients with clinically significant hepatic injury due to hepatic KS usually have an aggressive course of disease with hepatic failure often progressing to multi-organ failure and death. Here we report an unusual presentation of acute liver injury due to hepatic KS and briefly review the published literature on hepatic KS.

Epidemiology of heart failure in rural Chhattisgarh, India

Background Cardiovascular diseases, including heart failure (HF), are leading causes of death and disability in India. However, most studies in India only include urban populations or rural regions with improved access and may not represent the poorest patients or regions. We studied the epidemiology of HF patients admitted to a secondary care hospital in rural Chhattisgarh, India. Methods We did a retrospective chart review of patients hospitalized with HF in 2018 to obtain their demographic data and risk factors for developing HF. We reviewed echocardio-grams to assign patients to their most probable HF category. Results We studied 88 HF patients with a mean age of 42 years including 55 (62.5%) women. The most common categories of HF were cardiomyopathy (36.8%), rheumatic heart disease (RHD; 25.3%) and right heart failure (RHF; 18.4%). Prior tuberculosis was more prevalent in patients with RHF compared with other types of HF (43.8% v. 13.9%). Conclusions HF patients in this study from rural central India were young and predominantly women. Cardiomyopathy, RHD and RHF due to past tuberculosis were common causes of HF in this population. Further studies are needed to expand upon these single centre findings to better understand the risk factors and outcomes of HF among the rural poor.