Polymorphonuclear neutrophils (PMNs) can contribute to the regulation of the host immune response by crosstalk with innate and adaptive leukocytes, including NK cells. Mechanisms by which this ...immunoregulation process occurs remain incompletely understood. Here, we focused on the effect of human neutrophil‐derived serine proteases on NKp46, a crucial activating receptor expressed on NK cells. We used flow cytometry, Western blotting, and mass spectrometry (MS) analysis to reveal that cathepsin G CG; and not elastase or proteinase 3 (PR3) induces a time‐ and concentration‐dependent, down‐regulatory effect on NKp46 expression through a restricted proteolytic mechanism. We also used a functional assay to demonstrate that NKp46 cleavage by CG severely impairs NKp46‐mediated responses of NK cells, including IFN‐γ production and cell degranulation. Importantly, sputa of cystic fibrosis (CF) patients, which have high concentrations of CG, also alter NKp46 on NK cells. Hence, we have identified a new immunoregulatory mechanism of neutrophils that proteolytically disarms NK cell responses.
Immuno‐regulatory mechanism of PMNs that proteolytically disarms NK cell response.
The role of PKCδ and ERK during molecular mechanism of myeloid differentiation in bipotent progenitors.
M‐CSF and G‐CSF are instructive cytokines that specifically induce differentiation of bipotent ...myeloid progenitors into macrophages and granulocytes, respectively. Through morphology and colony assay studies, flow cytometry analysis of specific markers, and expression of myeloid transcription factors, we show here that the Eger/Fms cell line is composed of cells whose differentiation fate is instructed by M‐CSF and G‐CSF, thus representing a good in vitro model of myeloid bipotent progenitors. Consistent with the essential role of ERK1/2 during macrophage differentiation and defects of macrophagic differentiation in native ERK1−/− progenitors, ERK signaling is strongly activated in Eger/Fms cells upon M‐CSF‐induced macrophagic differentiation but only to a very small extent during G‐CSF‐induced granulocytic differentiation. Previous in vivo studies indicated a key role of Fli‐1 in myeloid differentiation and demonstrated its weak expression during macrophagic differentiation with a strong expression during granulocytic differentiation. Here, we demonstrated that this effect could be mediated by a differential regulation of protein kinase Cδ (PKCd) on Fli‐1 expression in response to M‐CSF and G‐CSF. With the use of knockdown of PKCd by small interfering RNA, we demonstrated that M‐CSF activates PKCd, which in turn, inhibits Fli‐1 expression and granulocytic differentiation. Finally, we studied the connection between ERK and PKCd and showed that in the presence of the MEK inhibitor U0126, PKCd expression is decreased, and Fli‐1 expression is increased in response to M‐CSF. Altogether, we demonstrated that in bipotent myeloid cells, M‐CSF promotes macrophagic over granulocytic differentiation by inducing ERK activation but also PKCd expression, which in turn, down‐regulates Fli‐1 expression and prevents granulocytic differentiation.
The PI3K signaling pathway regulates cell growth and movement and is heavily mutated in cancer. Class I PI3Ks synthesize the lipid messenger PI(3,4,5)P
. PI(3,4,5)P
can be dephosphorylated by 3- or ...5-phosphatases, the latter producing PI(3,4)P
. The PTEN tumor suppressor is thought to function primarily as a PI(3,4,5)P
3-phosphatase, limiting activation of this pathway. Here we show that PTEN also functions as a PI(3,4)P
3-phosphatase, both in vitro and in vivo. PTEN is a major PI(3,4)P
phosphatase in Mcf10a cytosol, and loss of PTEN and INPP4B, a known PI(3,4)P
4-phosphatase, leads to synergistic accumulation of PI(3,4)P
, which correlated with increased invadopodia in epidermal growth factor (EGF)-stimulated cells. PTEN deletion increased PI(3,4)P
levels in a mouse model of prostate cancer, and it inversely correlated with PI(3,4)P
levels across several EGF-stimulated prostate and breast cancer lines. These results point to a role for PI(3,4)P
in the phenotype caused by loss-of-function mutations or deletions in PTEN.
The PI3K signaling pathway regulates cell growth and movement and is heavily mutated in cancer. Class I PI3Ks synthesize the lipid messenger PI(3,4,5)P3. PI(3,4,5)P3 can be dephosphorylated by 3- or ...5-phosphatases, the latter producing PI(3,4)P2. The PTEN tumor suppressor is thought to function primarily as a PI(3,4,5)P3 3-phosphatase, limiting activation of this pathway. Here we show that PTEN also functions as a PI(3,4)P2 3-phosphatase, both in vitro and in vivo. PTEN is a major PI(3,4)P2 phosphatase in Mcf10a cytosol, and loss of PTEN and INPP4B, a known PI(3,4)P2 4-phosphatase, leads to synergistic accumulation of PI(3,4)P2, which correlated with increased invadopodia in epidermal growth factor (EGF)-stimulated cells. PTEN deletion increased PI(3,4)P2 levels in a mouse model of prostate cancer, and it inversely correlated with PI(3,4)P2 levels across several EGF-stimulated prostate and breast cancer lines. These results point to a role for PI(3,4)P2 in the phenotype caused by loss-of-function mutations or deletions in PTEN.
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•PTEN is a PI(3,4)P2 3-phosphatase•PTEN and INPP4B regulate PI(3,4)P2 accumulation downstream of class I PI3K•PTEN regulates PI(3,4)P2-dependent activation of Akt and formation of invadopodia•PI(3,4)P2 signaling may play a role in the tumor suppressor function of PTEN
Malek et al. show that the tumor suppressor PTEN acts as a PI(3,4)P2 3-phosphatase within the growth factor-stimulated PI3K signaling network, in addition to its accepted role as a PI(3,4,5)P3 3-phosphatase. This suggests that specific PI(3,4)P2 effector functions, such as invadopodia formation, play a role in the PTEN-loss-of-function phenotype.
Polymorphonuclear neutrophils (PMNs) can contribute to the regulation of the host immune response by crosstalk with innate and adaptive leukocytes, including NK cells. Mechanisms by which this ...immunoregulation process occurs remain incompletely understood. Here, we focused on the effect of human neutrophil-derived serine proteases on NKp46, a crucial activating receptor expressed on NK cells. We used flow cytometry, Western blotting, and mass spectrometry (MS) analysis to reveal that cathepsin G CG; and not elastase or proteinase 3 (PR3) induces a time- and concentration-dependent, down-regulatory effect on NKp46 expression through a restricted proteolytic mechanism. We also used a functional assay to demonstrate that NKp46 cleavage by CG severely impairs NKp46-mediated responses of NK cells, including IFN-γ production and cell degranulation. Importantly, sputa of cystic fibrosis (CF) patients, which have high concentrations of CG, also alter NKp46 on NK cells. Hence, we have identified a new immunoregulatory mechanism of neutrophils that proteolytically disarms NK cell responses.
The neonatal Fc receptor (FcRn) is responsible for the recycling and transcytosis of IgG and albumin. FcRn level was found altered in cancer tissues and implicated in tumor immunosurveillance and ...neoplastic cell growth. However, the consequences of FcRn down-regulation in the anti-tumor immune response are not fully elucidated. By using the B16F10 experimental lung metastasis model in an FcRn-deficient microenvironment (FcRn-/- mice), we found lung metastasis associated with an abnormal natural killer (NK) cell phenotype. In FcRn-/- mice, NK cells were immature, as shown by their surface marker profile and their decreased ability to degranulate and synthesize interferon γ after chemical and IL-2 or IL-12, IL-15 and IL-18 activation. These new findings support the critical role of FcRn downregulation in the tumor microenvironment in anti-tumor immunity, via NK cell maturation and activation.
The neonatal Fc receptor (FcRn) is responsible for the recycling and transcytosis of IgG and albumin. FcRn level was found altered in cancer tissues and implicated in tumor immunosurveillance and ...neoplastic cell growth. However, the consequences of FcRn down-regulation in the anti-tumor immune response are not fully elucidated. By using the B16F10 experimental lung metastasis model in an FcRn-deficient microenvironment (FcRn-/- mice), we found lung metastasis associated with an abnormal natural killer (NK) cell phenotype. In FcRn-/- mice, NK cells were immature, as shown by their surface marker profile and their decreased ability to degranulate and synthesize interferon γ after chemical and IL-2 or IL-12, IL-15 and IL-18 activation. These new findings support the critical role of FcRn downregulation in the tumor microenvironment in anti-tumor immunity, via NK cell maturation and activation.
Recent
studies suggested that the transcription cofactor LIM-only protein FHL2 is a major transcriptional regulator of mouse natural killer (NK) cells. However, the expression and role of FHL2 in NK ...cell biology are unknown. Here, we confirm that FHL2 is expressed in both mouse and human NK cells. Using FHL2
mice, we found that FHL2 controls NK cell development in the bone marrow and maturation in peripheral organs. To evaluate the importance of FHL2 in NK cell activation, FHL2
mice were infected with
. FHL2
mice are highly susceptible to this infection. The activation of lung NK cells is altered in FHL2
mice, leading to decreased IFNγ production and a loss of control of bacterial burden. Collectively, our data reveal that FHL2 is a new transcription cofactor implicated in NK cell development and activation during pulmonary bacterial infection.
Infants at high-risk of unilateral Cerebral Palsy (UCP) may have asymmetry in upper extremity movement and function, which should be identified as soon as possible for management.
To explore the ...feasibility of using two AX3 Axivity monitors in wrist-worn bracelets to quantify movements, and to identify whether accelerometry parameters are consistent with hand function.
6 infants at high risk of UCP (aged 3 to −12 months) were included in a Single-Case Experimental Design to explore the impact of an 8-week bimanual stimulation home program.
Each week of the baseline (randomized duration 4–7 weeks) and 8-week program, the Hand Assessment for Infants (HAI) was performed and accelerometry parameters were collected during HAI and also during spontaneous activity, several times a week.
Actimetry was analyzed during HAI and 238 spontaneous activity sessions (mean 42 ± 21 min). Actimetry ratios distribution and evolution show a high variability, especially for spontaneous activity. No strong correlation was found between HAI scores and accelerometry parameters, either collected during HAI, or during spontaneous activity times.
Despite its feasibility, using accelerometry bracelets looks unreliable for detecting and monitoring hand function in infants under one year.
•The use of two custom-made soft bracelets containing accelerometers is feasible in infants.•Accelerometry identifies upper limb differences in babies with unilateral brain damage.•Actimetry parameters show a high variability, even for ratios between upper limbs.•There is very little correlation between the intensity of movement and hand function.
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