Myeloid-derived suppressor cells (MDSCs) have been identified in humans and mice as a population of immature myeloid cells with the ability to suppress T cell activation. They accumulate in tumor-bearing mice and humans and have been shown to contribute to cancer development. Here, we have isolated tumor-derived exosomes (TDEs) from mouse cell lines and shown that an interaction between TDE-associated Hsp72 and MDSCs determines the suppressive activity of the MDSCs via activation of Stat3. In addition, tumor-derived soluble factors triggered MDSC expansion via activation of Erk. TDE-associated Hsp72 triggered Stat3 activation in MDSCs in a TLR2/MyD88-dependent manner through autocrine production of IL-6. Importantly, decreasing exosome production using dimethyl amiloride enhanced the in vivo antitumor efficacy of the chemotherapeutic drug cyclophosphamide in 3 different mouse tumor models. We also demonstrated that this mechanism is relevant in cancer patients, as TDEs from a human tumor cell line activated human MDSCs and triggered their suppressive function in an Hsp72/TLR2-dependent manner. Further, MDSCs from cancer patients treated with amiloride, a drug used to treat high blood pressure that also inhibits exosome formation, exhibited reduced suppressor functions. Collectively, our findings show in both mice and humans that Hsp72 expressed at the surface of TDEs restrains tumor immune surveillance by promoting MDSC suppressive functions.

Chemotherapeutic agents are widely used for cancer treatment. In addition to their direct cytotoxic effects, these agents harness the host's immune system, which contributes to their antitumor activity. Here we show that two clinically used chemotherapeutic agents, gemcitabine (Gem) and 5-fluorouracil (5FU), activate the NOD-like receptor family, pyrin domain containing-3 protein (Nlrp3)-dependent caspase-1 activation complex (termed the inflammasome) in myeloid-derived suppressor cells (MDSCs), leading to production of interleukin-1β (IL-1β), which curtails anticancer immunity. Chemotherapy-triggered IL-1β secretion relied on lysosomal permeabilization and the release of cathepsin B, which bound to Nlrp3 and drove caspase-1 activation. MDSC-derived IL-1β induced secretion of IL-17 by CD4(+) T cells, which blunted the anticancer efficacy of the chemotherapy. Accordingly, Gem and 5FU exerted higher antitumor effects when tumors were established in Nlrp3(-/-) or Casp1(-/-) mice or wild-type mice treated with interleukin-1 receptor antagonist (IL-1Ra). Altogether, these results identify how activation of the Nlrp3 inflammasome in MDSCs by 5FU and Gem limits the antitumor efficacy of these chemotherapeutic agents.

Based on these findings, PRP can be recommended for fast delivery of growth factors whereas A-PRF is better-suited for long-term release.

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In about one third of patients, psoriasis starts in the first or second decade of life. In the beginning, involvement is often atypical or mild, and a confident diagnosis may be difficult to establish. Plaque psoriasis is the most frequent type, also in children, but lesions are often smaller, thinner, and less scaly than in adults. Treatment can be a challenge because many therapeutic options have drawbacks or are not approved in childhood. Because psoriasis is a life-long disease, affected children and their parents need special support and guidance. We herein focus on the peculiarities of clinical presentations and of the management of psoriatic children and adolescents.

Liver X receptors (LXRs) have been proposed to have some anticancer properties, through molecular mechanisms that remain elusive. Here we report for the first time that LXR ligands induce caspase-1-dependent cell death of colon cancer cells. Caspase-1 activation requires Nod-like-receptor pyrin domain containing 3 (NLRP3) inflammasome and ATP-mediated P2 Â 7 receptor activation. Surprisingly, LXRb is mainly located in the cytoplasm and has a non-genomic role by interacting with pannexin 1 leading to ATP secretion. Finally, LXR ligands have an antitumoral effect in a mouse colon cancer model, dependent on the presence of LXRb, pannexin 1, NLRP3 and caspase-1 within the tumor cells. Our results demonstrate that LXRb, through pannexin 1 interaction, can specifically induce caspase-1-dependent colon cancer cell death by pyroptosis.

Summary Background  Intolerably high doses of systemic corticosteroids and additional immunosuppressants may be required to control disease activity in autoimmune bullous skin diseases. New therapeutic options are needed for such patients. Objectives  To determine the efficacy and adverse effects of adjuvant rituximab. Methods  Seven patients with refractory autoimmune blistering diseases (pemphigus vulgaris, PV, n = 4; bullous pemphigoid, BP, n = 2; mucous membrane pemphigoid, MMP, n = 1) were treated four times with rituximab at an individual dose of 375 mg m−2 at weekly intervals. Results  All lesions cleared in three patients (two PV, one BP), while they were reduced by more than 50% in three others (two PV, one BP). The concomitant immunosuppressive medication was reduced in five patients (four PV, one BP). The patient with MMP developed bilateral blindness while nasopharyngeal lesions resolved. Three patients (two BP, one PV) experienced severe adverse events including fatal pneumonia. Conclusions  Adjuvant B‐cell depletion by rituximab is effective in otherwise therapy‐resistant bullous autoimmune disorders but may be associated with substantial adverse effects including fatal outcomes.

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