Action of ANG II and ANP on colon epithelial cells

The interaction of angiotensin II (ANG II) and atrial natriuretic peptide (ANP) on intracellular pH (pH_i) and calcium ([Ca²⁺]_i) was investigated in T84 cells (a permanent cell line derived from human colon epithelium) using the fluorescent stains BCECF/AM and Fluo 4/AM, respectively. pH_i recovery rate mediated by the Na⁺/H⁺ exchanger (NHE) was examined following an NH₄Cl pulse. Under control conditions pH_i recovered at 0.114±0.005 pH units/min (n=35). ANG II (10^–12 or 10^–9 M) increased this value, whilst ANG II (10^–7 M) decreased it. These effects of ANG II were impaired by simultaneous addition of 1 M or 25 M HOE-694, indicating that the stimulatory and inhibitory effects of ANG II on pH_i recovery are mediated in part via the NHE1 and NHE2 isoforms. ANG II increased [Ca²⁺]_i concentration-dependently. ANP (10^–6 M) or dimethyl-BAPTA/AM (50 M) blocked the effects of ANG II on [Ca²⁺]_i and on the rate of pH_i recovery. Thapsigargin (10^–5 M) enhanced the effect of ANG II on [Ca²⁺]_i and reversed its stimulatory effect on the rate of pH_i recovery to an inhibitory one. External Ca²⁺-free solution did not affect the effects of ANG II on these parameters. These data suggest that the [Ca²⁺]_i increase induced by ANG II is dependent on intracellular calcium stores. They are compatible with the demonstration of two sites on the C-terminal of the Na⁺/H⁺ exchanger, one stimulating Na⁺/H⁺ activity by increases of [Ca²⁺]_i in the lower range (at 10^–12 or 10^–9 M ANG II) and the other inhibiting this activity at high [Ca²⁺]_i levels (at 10^–7 M ANG II). ANP or dimethyl-BAPTA/AM, by impairing the pathway mediating the increase in [Ca²⁺]_i, block both the stimulatory and inhibitory effects of ANG II.     

CD40-mediated lymphotoxin α expression in human B cells is tyrosine kinase dependent

The cytokine lymphotoxin (LT)α is known to play a role in B cell activation. As the engagement of the B cell antigen CD40 is known to lead to B cell proliferation and differentiation, we studied LTα expression in human B cells after CD40 ligation. We demonstrate that anti-CD40 monoclonal antibody (mAb) induces strong LTα mRNA and surface expression in human tonsil B cells. Induction of LTα mRNA and surface expression by CD40 ligation is inhibited by the protein tyrosine kinase (PTK) inhibitors herbimycin and genistein in a dose-dependent manner. The protein kinase C (PKC)-specific inhibitors sphingosine and bisindolylmaleimide caused negligible inhibition of anti-CD40-induced LTα mRNA and surface expression. No inhibition is observed with the protein kinase (PKA) inhibitors H89 and HA1004. Cross-linking of the transmembrane phosphatase CD45 to CD40 by using goat-anti-mouse F(ab')₂ fragments strongly inhibits CD40-mediated LTα expression in human B cells, confirming the role of PTK activation in CD40-mediated induction of LTα expression. Inhibitors of the serine/threonine protein phosphatases PP1 and PP2A, okadaic acid and calyculin induce LTα mRNA expression. In contrast, cyclosporin A, an inhibitor of the serine/threonine phosphatase calcineurin has no effect on anti-CD40-induced LTα expression. These results suggest that induction of LTα expression in B cells following engagement of CD40 involves activation of protein tyrosine kinases.     

Mast cell–derived IL-13 downregulates IL-12 production by skin dendritic cells to inhibit the TH1 cell response to cutaneous antigen exposure

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Impaired antibody responses in the hyperimmunoglobulin E syndrome

Patients with the hyper-IgE (HIE) syndrome have recurrent bacterial infections with Staphylococcus aureus and other polysaccharide encapsulated organisms. To determine whether an impairment of the antibody response to polysaccharide antigens contributes to infections in this syndrome, we measured serum antibody to the teichoic acid of S. aureus and to the capsular polysaccharide of Haemophilus influenzae type b. Compared to control subjects who had no history of S. aureus infections (N = 14), sera from patients with HIE (N = 9) lacked the expected elevation of serum antibody to teichoic acid (p greater than 0.05) and had significantly lower levels of this antibody than sera from 14 patients with atopic dermatitis, complicated by recurrent cutaneous S. aureus infections (p less than 0.01). After immunization with the capsular polysaccharide of Haemophilus influenzae type of vaccine, the antibody response of patients with HIE was significantly impaired compared to that of age-matched control subjects (p = 0.01). Although patients with HIE syndrome had normal total IgG levels, most patients with HIE but not patients with atopic dermatitis had IgG2 subclass deficiency. Defective antibody responses in patients with HIE were not restricted to polysaccharide antigens because the serum levels of antitetanus toxoid antibody in these patients were significantly lower than that of control subjects (p less than 0.001). Impaired antigen-specific antibody responses in patients with HIE syndrome may contribute to their increased susceptibility to infection.     

Impact of anxiety,stress and depression related to COVID-19 pandemic on the course of hereditary angioedema with C1-inhibitor deficiency

Background

Hereditary angioedema (HAE) attacks can be provoked with psychological factors. The aim of this study was to assess the effects of anxiety, depression and stress related to COVID-19 pandemic on disease activity of HAE patients during the quarantine period (QP) and the return to normal period (RTNP).

Methods

This study was conducted between March 2020 and September 2020 in four allergy centres. Demographic, clinical features and mental health status were evaluated in QP (from March to the beginning of June) and RTNP (from June to the beginning of September) applied by the government. The 10-point visual analogue scale (VAS10) was used to define the severity of HAE attacks. Depression, Anxiety and Stress Scales-21 (DASS-21) and Fear of COVID-19 (FC-19) scale were performed to assess mental health status.

Results

139 HAE patients were included in the study. In QP, median attack numbers and median VAS10 scores were 5 (min-max: 0–45) and 6 (min-max: 0–10), respectively. HAE attack numbers, DASS-21 stress, anxiety, depression and total DASS-21 scores, and FC-19 scores were higher in QP than RTNP (p = 0.001, p < 0.001, p = 0.001, p < 0.001, p < 0.001, p < 0.001, respectively). However, there was no difference in attack severity scores between the two periods (p > 0.05).

Conclusions

This study revealed that the restriction measures during COVID-19 outbreak cause an increase in the number of HAE attacks in relation to anxiety, depression, stress and fear of COVID-19 pandemic. Therefore, it is important to provide psychological support to HAE patients during the pandemic.

     

A Phenotypic Approach for IUIS PID Classification and Diagnosis: Guidelines for Clinicians at the Bedside

The number of genetically defined Primary Immunodeficiency Diseases (PID) has increased exponentially, especially in the past decade. The biennial classification published by the IUIS PID expert committee is therefore quickly expanding, providing valuable information regarding the disease-causing genotypes, the immunological anomalies, and the associated clinical features of PIDs. These are grouped in eight, somewhat overlapping, categories of immune dysfunction. However, based on this immunological classification, the diagnosis of a specific PID from the clinician’s observation of an individual clinical and/or immunological phenotype remains difficult, especially for non-PID specialists. The purpose of this work is to suggest a phenotypic classification that forms the basis for diagnostic trees, leading the physician to particular groups of PIDs, starting from clinical features and combining routine immunological investigations along the way. We present 8 colored diagnostic figures that correspond to the 8 PID groups in the IUIS Classification, including all the PIDs cited in the 2011 update of the IUIS classification and most of those reported since.