First case of proven invasive pulmonary infection due to Trichoderma longibrachiatum in a neutropenic patient with acute leukemia

Trichoderma species are saprophytic filamentous fungi that can be found all over the word. These fungi show increasing medical importance as opportunistic human pathogens, particularly in immunocompromised patients. Invasive infections due to Trichoderma are rare and definitive diagnosis is complex to achieve because of the lack of specific diagnosis tools. We report in this work the first proven case of invasive pulmonary infection due to T. longibrachiatum in a 69-year-old white male with hematologic malignancy. The patient was successfully treated initially with voriconazole alone followed by a combination of voriconazole and caspofungine.

Developmental options and functional plasticity of innate lymphoid cells

Innate lymphoid cells (ILCs) are lineage- and antigen receptor-negative lymphocytes including natural killer (NK) cells and at least three distinguishable cell subsets (ILC1, ILC2, ILC3) that rapidly produce cytokines (IFN-γ, IL-5, IL-13, IL-17A, IL-22) upon activation. As such, ILCs can act as first-line defenders in the context of infection, inflammation and cancer. Because of the strong conservation between the expression of key transcription factors that can drive signature cytokine outputs in ILCs and differentiated helper T cells, it has been proposed that ILCs represent innate counterparts of the latter. Several distinct ILC precursors (ILCP) with pan-ILC (giving rise to all ILCs) or subset-restricted potentials have been described in both mouse and man. How and where these different ILCP give rise to more mature tissue-resident ILCs remains unclear. Recently, environmental signals have been shown to epigenetically influence canonical ILC differentiation pathways, generating substantial functional plasticity. These new results suggest that while ILC differentiation may be 'fixed' in principle, it remains 'flexible' in practice. A more comprehensive knowledge in the molecular mechanisms that regulate ILC development and effector functions may allow for therapeutic manipulation of ILCs for diverse disease conditions.

Phenotypic and Functional Plasticity of Murine Intestinal NKp46+ Group 3 Innate Lymphoid Cells

Group 3 innate lymphoid cells (ILC3) actively participate in mucosal defense and homeostasis through prompt secretion of IL-17A, IL-22, and IFN-γ. Reports identify two ILC3 lineages: a CCR6(+)T-bet(-) subset that appears early in embryonic development and promotes lymphoid organogenesis and a CCR6(-)T-bet(+) subset that emerges after microbial colonization and harbors NKp46(+) ILC3. We demonstrate that NKp46 expression in the ILC3 subset is highly unstable. Cell fate mapping using Ncr1(CreGFP) × Rosa26(RFP) mice revealed the existence of an intestinal RFP(+) ILC3 subset (Ncr1(FM)) lacking NKp46 expression at the transcript and protein levels. Ncr1(FM) ILC3 produced more IL-22 and were distinguishable from NKp46(+) ILC3 by differential CD117, CD49a, DNAX accessory molecule-1, and, surprisingly, CCR6 expression. Ncr1(FM) ILC3 emerged after birth and persisted in adult mice following broad-spectrum antibiotic treatment. These results identify an unexpected phenotypic instability within NKp46(+) ILC3 that suggests a major role for environmental signals in tuning ILC3 functional plasticity.

The chemokine receptor CXCR6 controls the functional topography of interleukin-22 producing intestinal innate lymphoid cells

Interleukin-22 (IL-22) plays a critical role in mucosal defense, although the molecular mechanisms that ensure IL-22 tissue distribution remain poorly understood. We show that the CXCL16-CXCR6 chemokine-chemokine receptor axis regulated group 3 innate lymphoid cell (ILC3) diversity and function. CXCL16 was constitutively expressed by CX3CR1(+) intestinal dendritic cells (DCs) and coexpressed with IL-23 after Citrobacter rodentium infection. Intestinal ILC3s expressed CXCR6 and its ablation generated a selective loss of the NKp46(+) ILC3 subset, a depletion of intestinal IL-22, and the inability to control C. rodentium infection. CD4(+) ILC3s were unaffected by CXCR6 deficiency and remained clustered within lymphoid follicles. In contrast, the lamina propria of Cxcr6(-/-) mice was devoid of ILC3s. The loss of ILC3-dependent IL-22 epithelial stimulation reduced antimicrobial peptide expression that explained the sensitivity of Cxcr6(-/-) mice to C. rodentium. Our results delineate a critical CXCL16-CXCR6 crosstalk that coordinates the intestinal topography of IL-22 secretion required for mucosal defense.

The WAP protein Trappin-2/Elafin: a handyman in the regulation of inflammatory and immune responses

Trappin-2/Elafin is a potent serine protease inhibitor which prevents excessive damage under inflammatory status. This "alarm-antiprotease" is locally expressed by epithelial cells and immune cells such as macrophages and γδ T cells. It has also been proven to modulate a wide range of parameters that are critical for the inflammation process like modulating the NFκB pathway, cytokine secretion and cell recruitment. In addition, Trappin-2/Elafin was shown to possess anti-microbial properties against different classes of pathogens including viruses, fungi and bacteria. Studies also linked Trappin-2/Elafin to either susceptibility or protection against inflammatory disease and infections, even though the mechanisms remains poorly understood. This review will discuss some of the pleiotropic effects displayed by Trappin-2/Elafin, and the properties that could be used to prevent infection or to protect against inflammation.