Activation of the C3a anaphylatoxin receptor inhibits keratinocyte proliferation by regulating keratin 6, keratin 16, and keratin 17 in psoriasis.

Emerging evidence suggests that signaling through the C3a anaphylatoxin receptor (C3aR) protects against various inflammation-related diseases. However, the role of C3aR in psoriasis remains unknown. The purpose of this study was to investigate the possible protective role of C3aR in psoriasis and to explore the underlying molecular mechanisms. We initially found that the psoriatic epidermis exhibited significantly decreased C3aR expression. C3aR showed protective roles in mouse models of imiquimod (IMQ)- and interleukin-23-induced psoriasis. Furthermore, increased epidermal thickness and keratin 6 (K6), K16, and K17 expression occurred in the ears and backs of C3aR-/- mice. Pharmacological treatment with a C3aR agonist ameliorated IMQ-induced psoriasiform lesions in mice and decreased the expression of K6, K16, and K17. Additionally, the signal transducer and activator of transcription 3 (STAT3) pathway participated in the protective function of C3aR. More importantly, the expression levels of K6, K16, and K17 in keratinocytes were all restored in HaCaT cells transfected with a C3aR-overexpression plasmid after treating them with colivelin (a STAT3 activator). Our findings demonstrate that C3aR protects against the development of psoriasis and suggest that C3aR confers protection by negatively regulating K6, K16, and K17 expression in a STAT3-dependent manner, thus inhibiting keratinocyte proliferation and helping reverse the pathogenesis of psoriasis.

Identification of KRT16 as a target of an autoantibody response in complex regional pain syndrome.

OBJECTIVE: Using a mouse model of complex regional pain syndrome (CRPS), our goal was to identify autoantigens in the skin of the affected limb. METHODS: A CRPS-like state was induced using the tibia fracture/cast immobilization model. Three weeks after fracture, hindpaw skin was homogenized, run on 2-d gels, and probed by sera from fracture and control mice. Spots of interest were analyzed by liquid chromatography-mass spectroscopy (LC-MS) and the list of targets validated by examining their abundance and subcellular localization. In order to measure the autoantigenicity of selected protein targets, we quantified the binding of IgM in control and fracture mice sera, as well as in control and CRPS human sera, to the recombinant protein. RESULTS: We show unique binding between fracture skin extracts and fracture sera, suggesting the presence of auto-antigens. LC-MS analysis provided us a list of potential targets, some of which were upregulated after fracture (KRT16, eEF1a1, and PRPH), while others showed subcellular-redistribution and increased membrane localization (ANXA2 and ENO3). No changes in protein citrullination or carbamylation were observed. In addition to increased abundance, KRT16 demonstrated autoantigenicity, since sera from both fracture mice and CRPS patients showed increased autoantibody binding to recombinant kRT16 protein. CONCLUSIONS: Pursuing autoimmune contributions to CRPS provides a novel approach to understanding the condition and may allow the development of mechanism-based therapies. The identification of autoantibodies against KRT16 as a biomarker in mice and in humans is a critical step towards these goals, and towards redefining CRPS as having an autoimmune etiology.

Id4 protein is highly expressed in triple-negative breast carcinomas: possible implications for BRCA1 downregulation.

BRCA1 germline mutation carriers usually develop ER, PR and HER2 negative breast carcinoma. Somatic BRCA1 mutations are rare in sporadic breast cancers, but other mechanisms could impair BRCA1 functions in these tumors, particularly in triple-negative breast carcinomas (TNBCs). Id4, a helix-loop-helix DNA binding factor, blocks BRCA1 gene transcription in vitro and could downregulate BRCA1 in vivo. We compared Id4 immunoreactivity in 101 TNBCs versus 113 non-TNBCs, and correlated the results with tumor morphology and immunoreactivity for CK5/6, CK14, EGFR, and androgen receptor (AR). Id4 was present in 76 out of 101 (75 %) TNBCs: 40 (40 %) TNBCs displayed Id4 positivity in >50 % of neoplastic cells, 23 (23 %) in 5-50 %, and 13 (13 %) in <5 %. In contrast, only 6 (5 %) of 113 non-TNBCs showed focal Id4 positivity, limited to fewer than 5 % of the tumor (p < 0.0001). Id4 expression significantly associated with high histologic grade (p = 0.0002) and mitotic rate (p = 0.006). Id4 decorated all 12 TNBCs with large central acellular zone of necrosis in our series, with positive staining in 10-90 % of the cells. Id4 signal strongly correlated with cytokeratin CK14 reactivity (p < 0.0001), but not with CK5/6 and EGFR. All apocrine carcinomas in our series were positive for AR and most for EGFR, but they were negative for CK5/6, CK14, and Id4, with only two exceptions. Our results document substantial expression of Id4 in most TNBCs, which could result in functional downregulation of BRCA1 pathways in these tumors.

CK5 is more sensitive than CK5/6 in identifying the "basal-like" phenotype of breast carcinoma.

Multiple immunohistochemical stains, including cytokeratin (CK)5/6, are used in a panel format to identify "basal-like" carcinomas. We set out to determine the sensitivity and specificity of the CK5 antibody (clone XM26) and compared its expression with that of CK5/6 (clone D5/16B4) in a variety of breast carcinoma cases. The study was performed on 3 breast carcinoma tissue microarrays (TMAs). TMA-1 consisted of 59 consecutive breast carcinoma cases. TMA-2 (n = 16) and TMA-3 (n = 11) consisted of basal-like breast carcinomas previously characterized morphologically and immunohistochemically at our institution. Of the 86 total cases, 20 were positive for CK5 and CK5/6, 14 were positive for CK5 only, and 52 were negative for both. The sensitivity of CK5 for identifying basal-like tumors was 97% compared with 59% for CK5/6. Both antibodies had comparable specificity of more than 95%. For positive cases, the percentage and intensity of staining was much higher with CK5 than with CK5/6 (P = .0001).

Utility of WT-1, p63, MOC31, mesothelin, and cytokeratin (K903 and CK5/6) immunostains in differentiating adenocarcinoma, squamous cell carcinoma, and malignant mesothelioma in effusions.

To distinguish carcinoma, either adenocarcinoma (ADC) or squamous cell carcinoma (SCC), and malignant mesothelioma (MM) in effusion can be a diagnostic challenge based on morphology alone. This study evaluates the utility of WT-1, p63, MOC31, mesothelin, and cytokeratin (K903 and CK5/6) immunostains in effusions when ADC and SCC of the lung are in the differential diagnosis with MM. A cohort of 43 effusions consisting of lung ADC (N = 10), SCC (N = 15), and MM (N = 18, mostly (16) pleural based), was subjected to immunostains using the above mentioned antibodies. WT-1 was positive in 100% MM, 0% ADC, and 0% SCC cases while p63 was positive in 0% MM, 30% ADC, and 80% SCC cases. Stain for MOC31 was positive in 100% ADC, 67% SCC, and 35% MM cases. Similarly, mesothelin antibody stained 100% ADC, 60% SCC, and 47% MM cases. Antibodies for K903 and CK5/6 stained 100% SCC cases but fewer ADC cases (40 and 10%, respectively). In conclusion, in this cohort of mostly pleural malignant effusion, MM can be identified with positive staining for WT-1 and negative staining for p63. Conversely, negative staining with WT-1 and positive staining for p63 exclude MM. Used as part of an immunostain panel, cytokeratin markers (CK5/6 and K903) are useful in differentiating SCC from ADC when MM is already excluded, and MOC31 might have limited value in differentiating ADC from MM. A negative stain with MOC31 can exclude lung ADC. Mesothelin, on the other hand, is not useful in the differential diagnosis of ADC, SCC, and MM.