Humidity-regulated CLCA2 protects the epidermis from hyperosmotic stress.

Low environmental humidity aggravates symptoms of the inflammatory skin disease atopic dermatitis (AD). Using mice that develop AD-like signs, we show that an increase in environmental humidity rescues their cutaneous inflammation and associated epidermal abnormalities. Quantitative proteomics analysis of epidermal lysates of mice kept at low or high humidity identified humidity-regulated proteins, including chloride channel accessory 3A2 (CLCA3A2), a protein with previously unknown function in the skin. The epidermis of patients with AD, organotypic skin cultures under dry conditions, and cultured keratinocytes exposed to hyperosmotic stress showed up-regulation of the nonorthologous human homolog CLCA2. Hyperosmolarity-induced CLCA2 expression occurred via p38/c-Jun N-terminal kinase-activating transcription factor 2 signaling. CLCA2 knockdown promoted keratinocyte apoptosis induced by hyperosmotic stress through impairment of cell-cell adhesion. These findings provide a mechanistic explanation for the beneficial effect of high environmental humidity for AD patients and identify CLCA3A2/CLCA2 up-regulation as a mechanism to protect keratinocytes from damage induced by low humidity.

A novel three-dimensional heterotypic spheroid model for the assessment of the activity of cancer immunotherapy agents.

The complexity of the tumor microenvironment is difficult to mimic in vitro, particularly regarding tumor-host interactions. To enable better assessment of cancer immunotherapy agents in vitro, we developed a three-dimensional (3D) heterotypic spheroid model composed of tumor cells, fibroblasts, and immune cells. Drug targeting, efficient stimulation of immune cell infiltration, and specific elimination of tumor or fibroblast spheroid areas were demonstrated following treatment with a novel immunocytokine (interleukin-2 variant; IgG-IL2v) and tumor- or fibroblast-targeted T cell bispecific antibody (TCB). Following treatment with IgG-IL2v, activation of T cells, NK cells, and NKT cells was demonstrated by increased expression of the activation marker CD69 and enhanced cytokine secretion. The combination of TCBs with IgG-IL2v molecules was more effective than monotherapy, as shown by enhanced effects on immune cell infiltration; activation; increased cytokine secretion; and faster, more efficient elimination of targeted cells. This study demonstrates that the 3D heterotypic spheroid model provides a novel and versatile tool for in vitro evaluation of cancer immunotherapy agents and allows for assessment of additional aspects of the activity of cancer immunotherapy agents, including analysis of immune cell infiltration and drug targeting.

Antitumour activity of the glycoengineered type II anti-CD20 antibody obinutuzumab (GA101) in combination with the MDM2-selective antagonist idasanutlin (RG7388).

OBJECTIVES: To investigate whether the glycoengineered type II anti-CD20 monoclonal antibody obinutuzumab (GA101) combined with the selective MDM2 antagonist idasanutlin (RG7388) offers superior efficacy to monotherapy in treating B-lymphoid malignancies in preclinical models. METHODS: The combined effect of obinutuzumab or rituximab plus idasanutlin on direct cell death/apoptosis induction and antibody-dependent cellular cytotoxicity (ADCC) was evaluated using p53 wild-type Z-138 and DoHH-2 lymphoma cells. Furthermore, whole blood B-cell depletion was analysed, and tumour growth inhibition was evaluated in subcutaneous xenograft models. RESULTS: Idasanutlin induced concentration-dependent death of Z-138 and DoHH-2 cells. At concentrations >10-100 nm, idasanutlin enhanced obinutuzumab-induced death of DoHH-2 and Z-138 cells without negatively impacting obinutuzumab-mediated ADCC, natural killer cell activation or whole blood B-cell depletion. In the Z-138 xenograft model, a suboptimal dose of obinutuzumab with idasanutlin yielded substantial tumour growth inhibition and prolonged survival in a time-to-event analysis. In the DoHH-2 model, idasanutlin plus obinutuzumab showed superior tumour growth inhibition to idasanutlin plus rituximab. CONCLUSIONS: Obinutuzumab plus idasanutlin enhanced cell death of p53 wild-type tumour cells vs. rituximab plus idasanutlin without affecting obinutuzumab-mediated ADCC or B-cell depletion and showed robust antitumour efficacy in xenograft models, strongly supporting the investigation of this combination in clinical trials.

Accumulation and activation of epidermal γδ T cells in a mouse model of chronic dermatitis is not required for the inflammatory phenotype.

Chronic skin inflammation resulting from a defective epidermal barrier is a hallmark of atopic dermatitis (AD). We previously demonstrated that mice lacking FGF receptors 1 and 2 in keratinocytes (K5-R1/R2 mice) develop an AD-like chronic dermatitis as a result of an impaired epidermal barrier. Here, we show that γδ T cells, which rapidly respond to various insults, accumulate in the epidermis of K5-R1/R2 mice before the development of histological abnormalities. Their number and activation further increase as the phenotype progresses, most likely as a consequence of increased expression of Il-2 and Il-7 and the stress-induced proteins Rae-1, H60c, Mult1, PlexinB2, and Skint1. To determine the role of γδ T cells in the skin phenotype, we generated quadruple mutant K5-R1/-R2 mice lacking γδ T cells. Surprisingly, loss of γδ T cells did not or only marginally affect keratinocyte proliferation, epidermal thickness, epidermal barrier function, and accumulation and activation of different immune cells in the skin of K5-R1/R2 mice, possibly due to partial compensation by αß T cells. These results demonstrate that γδ T cells do not contribute to the development or maintenance of chronic inflammation in response to a defect in the epidermal barrier.

Mast cells are dispensable in a genetic mouse model of chronic dermatitis.

Chronic inflammatory skin diseases, such as atopic dermatitis, affect a large percentage of the population, but the role of different immune cells in the pathogenesis of these disorders is largely unknown. Recently, we found that mice lacking fibroblast growth factor receptor 1 (Fgfr1) and Fgfr2 (K5-R1/R2 mice) in the epidermis have a severe impairment in the epidermal barrier, which leads to the development of a chronic inflammatory skin disease that shares many features with human atopic dermatitis. Using Fgfr1-/Fgfr2-deficient mice, we analyzed the consequences of the loss of mast cells. Mast cells accumulated and degranulated in the skin of young Fgfr1-/Fgfr2-deficient mice, most likely as a consequence of increased expression of the mast cell chemokine Ccl2. The increase in mast cells occurred before the development of histological abnormalities, indicating a functional role of these cells in the inflammatory skin phenotype. To test this hypothesis, we mated the Fgfr1-/Fgfr2-deficient mice with mast cell-deficient CreMaster mice. Surprisingly, loss of mast cells did not or only mildly affect keratinocyte proliferation, epidermal thickness, epidermal barrier function, accumulation and activation of different immune cells, or expression of different proinflammatory cytokines in the skin. These results reveal that mast cells are dispensable for the development of chronic inflammation in response to a defect in the epidermal barrier.

The role of chronic inflammation in cutaneous fibrosis: fibroblast growth factor receptor deficiency in keratinocytes as an example.

Fibrosis is associated with a variety of skin diseases and causes severe aesthetic and functional impairments. Functional studies in rodents, together with clinical observations, strongly suggest a crucial role of chronic injury and inflammation in the pathogenesis of fibrotic diseases. The phenotype of mice lacking fibroblast growth factor (FGF) receptors 1 and 2 in keratinocytes supports this concept. In these mice, a defect in keratinocytes alone initiated an inflammatory response, which in turn caused keratinocyte hyperproliferation and dermal fibrosis. As the mechanism underlying this phenotype, we identified a loss of FGF-induced expression of claudins and occludin, which caused abnormalities in tight junctions with concomitant deficits in epidermal barrier function. This resulted in severe transepidermal water loss and skin dryness. In turn, activation of keratinocytes and epidermal γδ T cells occurred, which produced IL-1 family member 8 and S100A8 and S100A9. These cytokines attracted immune cells and activated fibroblasts, resulting in a double paracrine loop through production of keratinocyte mitogens by dermal cells. In addition, a profibrotic response was induced in fibroblasts. Our results highlight the importance of an intact epidermal barrier for the prevention of inflammation and fibrosis and the role of chronic inflammation in the pathogenesis of fibrotic diseases.