Macrophage-mediated extracellular matrix remodeling controls host Staphylococcus aureus susceptibility in the skin.

Hypodermis is the predominant site of Staphylococcus aureus infections that cause cellulitis. Given the importance of macrophages in tissue remodeling, we examined the hypodermal macrophages (HDMs) and their impact on host susceptibility to infection. Bulk and single-cell transcriptomics uncovered HDM subsets with CCR2-dichotomy. HDM homeostasis required the fibroblast-derived growth factor CSF1, ablation of which abrogated HDMs from the hypodermal adventitia. Loss of CCR2- HDMs resulted in accumulation of the extracellular matrix component, hyaluronic acid (HA). HDM-mediated HA clearance required sensing by the HA receptor, LYVE-1. Cell-autonomous IGF1 was required for accessibility of AP-1 transcription factor motifs that controlled LYVE-1 expression. Remarkably, loss of HDMs or IGF1 limited Staphylococcus aureus expansion via HA and conferred protection against cellulitis. Our findings reveal a function for macrophages in the regulation of HA with an impact on infection outcomes, which may be harnessed to limit the establishment of infection in the hypodermal niche.

Germline IKAROS dimerization haploinsufficiency causes hematologic cytopenias and malignancies.

IKAROS is a transcription factor forming homo- and heterodimers and regulating lymphocyte development and function. Germline mutations affecting the IKAROS N-terminal DNA binding domain, acting in a haploinsufficient or dominant-negative manner, cause immunodeficiency. Herein, we describe 4 germline heterozygous IKAROS variants affecting its C-terminal dimerization domain, via haploinsufficiency, in 4 unrelated families. Index patients presented with hematologic disease consisting of cytopenias (thrombocytopenia, anemia, neutropenia)/Evans syndrome and malignancies (T-cell acute lymphoblastic leukemia, Burkitt lymphoma). These dimerization defective mutants disrupt homo- and heterodimerization in a complete or partial manner, but they do not affect the wild-type allele function. Moreover, they alter key mechanisms of IKAROS gene regulation, including sumoylation, protein stability, and the recruitment of the nucleosome remodeling and deacetylase complex; none affected in N-terminal DNA binding defects. These C-terminal dimerization mutations are largely associated with hematologic disorders, display dimerization haploinsufficiency and incomplete clinical penetrance, and differ from previously reported allelic variants in their mechanism of action. Dimerization mutants contribute to the growing spectrum of IKAROS-associated diseases displaying a genotype-phenotype correlation.

Expression of CD40 Ligand on T Cells and Soluble CD40 Ligand in Children With Kawasaki Disease: A Single-Center Preliminary Study From North India.

BACKGROUND/OBJECTIVE: This study was done to examine the role of CD40 ligand (CD40L) in children with Kawasaki disease (KD). There is paucity of literature on this aspect of KD. METHODS: This was a case-control study of patients with KD diagnosed at the Allergy Immunology Unit, Postgraduate Institute of Medical Education and Research, Chandigarh, India. CD40L expression on activated CD3+ T cells was measured using flow cytometry, and soluble CD40L (sCD40L) was measured using enzyme-linked immunosorbent assay. RESULTS: We included 14 children with KD, 14 healthy controls, and 12 febrile controls for the purpose of this study. Mean percentage CD40L expression was higher in patients with KD (before administration of intravenous immunoglobulin [IVIg]) as compared with normal and febrile controls. This difference was statistically significant when compared with normal control (p = 0.00; confidence interval [CI], 8.92-20.30), but was not statistically significant when compared with febrile controls (p = 0.138; CI, -3.50 to 22.08). CD40L expression decreased after giving IVIg, but the difference was not statistically significant (p = 0.073; CI, -1.04 to 19.73). Mean sCD40L values increased significantly after giving IVIg (when repeated after a median period of 11 days; p = 0.001; CI, -0.77 to -0.29). There was no statistically significant difference between mean sCD40L in patients with KD (before giving IVIg) as compared with normal and febrile controls (p = 0.42; CI, -1.11 to -0.51 and p = 0.641; CI, -0.37 to 0.57, respectively). CONCLUSIONS: CD40L may have important role in the pathogenesis of KD. However, these results need to be validated in larger multicenter studies.

Clinical and molecular features of X-linked hyper IgM syndrome - An experience from North India.

X-linked hyper IgM Syndrome (XLHIGM), the most frequent form of the Hyper IgM syndromes is a primary immune deficiency resulting from a mutation in the CD40 ligand gene (CD40LG). We analyzed the clinical and laboratory features of ten patients with XLHIGM, who were diagnosed at a tertiary care hospital in North India. Most common infections were sinopulmonary infections (80%) and diarrhea (50%). Sclerosing cholangitis and necrotising fasciitis were noted in one patient each. Three novel mutations in CD40LG (c.429_429 delA, p. G144DfsX5; c.500 G > A, p.G167E and c.156 G > C, p.K52 N) were detected. In addition, we found one missense mutation, two splice site mutations and two large deletions, which have been previously reported. Four (4) patients had expired at the time of analysis. We report the first series of XLHIGM from North India where we have documented unique features such as pulmonary alveolar proteinosis and infections with Mycobacterium sp.

STAT3-Mediated Transcriptional Regulation of Osteopontin in STAT3 Loss-of-Function Related Hyper IgE Syndrome.

Background: Hyper-IgE syndrome (HIES) caused by loss-of-function (LOF) mutations in STAT3 gene (STAT3 LOF HIES) is associated with dental and facial abnormalities in addition to immunological defects. The role of STAT3 in the pathogenesis of the dental/facial features is, however, poorly elucidated. Objectives: Since mechanism of cellular resorption of mineralized tissues such as bone and teeth are similar, we attempted to study the expression of genes involved in bone homeostasis in STAT3 LOF HIES. Methods: Peripheral blood mononuclear cells from healthy controls (HCs), STAT3 LOF HIES patients, STAT3-/- PC-3 cells and STAT3+/+ LNCaP cells were stimulated with IL-6 and quantitative PCR array was performed to study the relative mRNA expression of 43 pre-selected genes. PCR array finding were further evaluated after stattic induced STAT3 inhibition. Results: Osteopontin (OPN) gene was seen to be significantly upregulated after IL-6 stimulation in HC (mean fold change 18.6, p = 0.01) compared with HIES subjects. Inhibition of STAT3 signaling by stattic followed by IL-6 stimulation abrogated the OPN response in HCs suggesting that IL-6-induced STAT3 signaling regulates OPN expression. Bioinformatics analysis predicted the presence of STAT3 response element TTCCAAGAA at position -2005 of the OPN gene. Conclusion: Regulation of OPN gene through IL-6-mediated STAT3 activation and its significant dysregulation in STAT3 LOF HIES subjects could make OPN a plausible candidate involved in the pathogenesis of dental/facial manifestations in HIES.

Expression of γH2AX may help in defining a genetically more stable subtype of infiltrating ductal carcinoma of breast.

BACKGROUND & OBJECTIVES: Gamma H2AX, a marker of DNA double stranded breaks (DSB) has been found to be over expressed in various tumours. The objective of the present work was to study the expression of γH2AX in infiltrating ductal carcinoma (IDC) and fibroadenoma (FA) cases and to associate the expression in IDC with cytomorphological features and DNA ploidy. METHODS: The expression of γH2AX was studied in fine needle aspirates of 16 cases of IDC and 15 FA cases. The expression in IDC was correlated with the cytological grade, apoptotic (AI) and mitotic indices (MI) and ploidy status. RESULTS: A high γH2AX expression was noted in IDC as compared to FA. Amongst the IDC cases the γH2AX was found to be significantly over expressed in DNA diploid IDC cases as compared to the aneuploid ones. INTERPRETATION & CONCLUSIONS: The study suggests a role of γH2AX in breast carcinogenesis which needs to be explored further. Moreover, the γH2AX expression together with ploidy status may serve as a means of assigning the patients of IDC to a better prognostic category irrespective of the cytomorphogical parameters.

Spontaneously occurring micronuclei in infiltrating ductal carcinoma of breast: a potential biomarker for aggressive phenotype detection?

Chromosomal instabilities (CIN) manifesting as structural or numerical alterations in the chromosomes are common in malignancies like breast cancer. Assessment of CIN in breast cancer may help to understand its etiopathogenesis. Micronucleus (MN) scoring and aneuploidy have been used to assess the presence of CIN in lymphocytes of various malignancies in the past. In this study, spontaneously occurring MN were counted in epithelial cells on fine needle aspiration cytology (FNAC) smears from 50 patients with benign and malignant breast lesions. Further, the ploidy status and S-phase fraction (SPF) of the samples was determined by flow cytometry. All these were then correlated with grades of breast cancer at cytology. Most IDC cases showed variable number of MN (n = 16, MN mean = 9.3), in contrast to the benign lesions (n = 26) where they were consistently absent. Aneuploidy and SPF analysis also showed a significant difference between benign (n = 10, mean DNA index [DI] = 0.96 ± 0.04, mean SPF= 8.07% ± 2.93) and malignant (n = 10, mean DI = 1.5 ± 0.41, mean SPF = 25.05% ± 10.35) lesions. On statistical analysis, a positive correlation was observed between the grades of IDC and presence of aneuploidy and high SPF (P-values < 0.05); however, the difference between the MN scores of grade 2 and 3 cancers was not significant. The study suggests that MN scoring and aneuploidy may be used to assess the presence of underlying CIN in IDC on FNAC smears. Further, collectively they may be explored for their role as biomarkers for predicting the tumor behavior in the breast cancer patients.