Jan Palmblad

HAX1 deficiency causes autosomal recessive severe congenital neutropenia (Kostmann disease)

Autosomal recessive severe congenital neutropenia (SCN) constitutes a primary immunodeficiency syndrome associated with increased apoptosis in myeloid cells, yet the underlying genetic defect remains unknown. Using a positional cloning approach and candidate gene evaluation, we identified a recurrent homozygous germline mutation in HAX1 in three pedigrees. After further molecular screening of individuals with SCN, we identified 19 additional affected individuals with homozygous HAX1 mutations, including three belonging to the original pedigree described by Kostmann. HAX1 encodes the mitochondrial protein HAX1, which has been assigned functions in signal transduction and cytoskeletal control. Here, we show that HAX1 is critical for maintaining the inner mitochondrial membrane potential and protecting against apoptosis in myeloid cells. Our findings suggest that HAX1 is a major regulator of myeloid homeostasis and underline the significance of genetic control of apoptosis in neutrophil development.

Hypersensitive reactions and antibody formation during L-asparaginase treatment of children and adults with acute leukemia.

One hundred and fourteen patients with acute leukemia, 57 children (10 AML and 47 ALL) and 57 adults (37 AML and 20 ALL) were treated with L‐asparaginase (Asnase) 200 or 1000 IU/kg daily for 30 days unless withdrawn on account of side effects. Combinations with other cytotoxic drugs were used in all but eight patients. Hypersensitive reactions, decrease in Asnase activity in plasma, and bivalent antibodies to Asnase appeared more frequently in adults (28%, 46%, and 79%, respectively) than in children (16%, 17%, and 25%, respectively). There was a clear association between these three parameters. Thus hypersensitive reactions generally developed at the time of or after the decrease in plasma Asnase activity. Antibodies were detected only where Asnase activity had disappeared from the plasma. This time sequence, and in vitro experiments, suggest the formation of antigen‐antibody complexes which might be responsible for inactivation of Asnase and for the development of hypersensitive reactions. However in many cases antibodies were found without concomitant enzyme inactivation or hypersensitive reactions. Antibodies to Asnase of IgE type (reagins) were found in only 10 children and 6 adults. There was no correlation between hypersensitive reactions, decrease in Asnase activity, and IgE antibodies. The frequency of remission among patients developing bivalent antibodies to Asnase was 68% (13/19) in contrast to 27% (3/11) among patients whose sera contained no detectable antibodies to Asnase, but the difference was not statistically significant.

Late-onset neutropenia following rituximab therapy in rheumatic diseases: Association with B lymphocyte depletion and infections

OBJECTIVE Late-onset neutropenia following rituximab therapy is a well-recognized side effect in lymphoma patients, but only a few cases of late-onset neutropenia have been reported in patients with autoimmune disorders. The purpose of this study was to define the incidence, clinical features, and some of the underlying mechanisms of late-onset neutropenia in relation to rituximab use in several rheumatic diseases. METHODS We conducted a retrospective analysis of a cohort of 209 consecutive patients with rheumatic diseases who had been treated with rituximab at a university hospital between June 2003 and March 2009. RESULTS Eleven patients with late-onset neutropenia were identified. The highest incidence was observed in granulomatosis with polyangiitis (Wegeners) and systemic lupus erythematosus patients (23% and 20%, respectively), whereas the incidence in rheumatoid arthritis patients was 3%. The median time to onset of neutropenia was 102 days (range 40-362 days) and coincided with the entire period of B lymphocyte depletion; this depletion was more pronounced in patients with late-onset neutropenia (P = 0.002) than in a control group of 20 matched patients without late-onset neutropenia. Serum IgM levels decreased during the same time and to a significantly greater amount in patients with late-onset neutropenia than in controls (P = 0.027). No patient with late-onset neutropenia displayed specific antineutrophil antibodies. Seven patients were hospitalized because of infections (6 with sepsis and 1 with febrile neutropenia) that required intravenous antibiotics. Six were treated with granulocyte colony-stimulating factor. CONCLUSION In patients treated with rituximab for rheumatic diseases, late-onset neutropenia is a clinically significant adverse event associated with marked B lymphocyte depletion and severe infections. The incidence of late-onset neutropenia appears to vary with autoimmune disease type.

ω-3 Fatty Acids in the Prevention of Cognitive Decline in Humans

The brain is a lipid-rich organ where docosahexaenoic acid (DHA) is enriched and where eicosapentaenoic acid (EPA) may have anti-inflammatory effects. The potential role for n-3 (ω-3) fatty acids such as DHA and EPA in the prevention of cognitive decline, including Alzheimers disease (AD) has attracted major interest for the past 20 y. This review presents our understanding of recent observational, interventional, and experimental studies, with the aim of providing some answers to the following question: Can n-3 FA intake modulate cognitive function during aging? In longitudinal observation studies we mainly observe inverse relations between fish intake or serum concentrations of DHA and cognitive impairment. Intervention studies of EPA and DHA supplementation in healthy old individuals have been negative so far (i.e., after up to 2 years of treatment, no differences in cognitive decline between treated and nontreated participants have been observed). In studies that provided EPA and DHA to adults with mild cognitive impairment or age-related cognitive impairment the data seem to be positive. However, when patients with established AD were supplemented with EPA and DHA it appears no benefit was gained. For studies on healthy individuals, a major concern is that the treatment periods may have been too short. There might also be subgroup effects because of the carriage of apolipoprotein Eε4 alleles or risk factor burden. Experimental studies appear to be consistently positive (i.e., n-3 FA supplementation in rodents over a substantial portion of their lives reduces amyloid-β deposition and hippocampal neuron loss and improves cognitive functioning). We are getting closer to providing evidence-based recommendations on fish and fish oil intake to facilitate memory function during old age. In the meantime it is advised to follow the general CDC dietary recommendations of 2-3 fish meals per week or the equivalent intake of long chain n-3 fatty acids, particularly DHA.

Idiosyncratic drug‐induced agranulocytosis: Possible mechanisms and management

The incidence of drug‐induced neutropenia has not changed in the western hemisphere over the last 30 years. Yet, the drug panorama has changed considerably. This implies that host factors may play an intriguing role for this idiosyncratic reaction. The knowledge as to mechanisms for the reaction has advanced with emerging understanding of neutropoiesis and immune regulation. Nonetheless, it is still remarkably difficult to pinpoint why and how a drug causes this unexpected, severe adverse event in a patient. Patient characteristics, e.g. genetics, appear to be keys for better understanding, predictions and prevention. Am. J. Hematol. 2009.

Central nervous system involvement in severe congenital neutropenia: neurological and neuropsychological abnormalities associated with specific HAX1 mutations

Objectives.  Homozygous mutations in the HAX1 gene were recently identified in severe congenital neutropenia patients belonging to the original Kostmann family in northern Sweden. Our observations suggested that these patients also develop neurological and neuropsychological symptoms.

Effects of Omega-3 Fatty Acids on Inflammatory Markers in Cerebrospinal Fluid and Plasma in Alzheimer’s Disease: The OmegAD Study

Background: ω-3 fatty acids (ω-3 FAs) found in dietary fish or fish oils are anti-inflammatory agents that may influence Alzheimer’s disease (AD). Objective: To study the effects of dietary ω-3 FA supplementation on inflammatory markers in cerebrospinal fluid (CSF) and plasma from patients with mild to moderate AD. Methods: Thirty-five patients (70.3 ± 8.2 years) were randomized to a daily intake of 2.3 g ω-3 FAs or placebo for 6 months. The inflammatory markers interleukin (IL)-6, tumour necrosis factor-α and soluble interleukin-1 receptor type II (sIL-1RII) were analysed in CSF and plasma at baseline and at 6 months. The AD markers tau-protein, hyperphosphorylated tau-protein and β-amyloid (Aβ1–42) were assessed in CSF. High-sensitivity C-reactive protein was assessed in plasma. A possible relation to the APOE genotype was investigated. Results: There was no significant treatment effect of ω-3 FAs on inflammatory and AD biomarkers in CSF or on inflammatory markers in plasma, nor was there any relation with APOE. A significant correlation was observed at baseline between sIL-1RII and Aβ1–42 levels in CSF. Conclusions: Treatment of AD patients with ω-3 FAs for 6 months did not influence inflammatory or biomarkers in CSF or plasma. The correlation between sIL-1RII and Aβ1–42 may reflect the reciprocal interactions between IL-1 and Aβ peptides.

Transfer of omega‐3 fatty acids across the blood–brain barrier after dietary supplementation with a docosahexaenoic acid‐rich omega‐3 fatty acid preparation in patients with Alzheimer's disease: the OmegAD study

Little is known about the transfer of essential fatty acids (FAs) across the human blood–brain barrier (BBB) in adulthood. In this study, we investigated whether oral supplementation with omega‐3 (n‐3) FAs would change the FA profile of the cerebrospinal fluid (CSF).

Effects of DHA- Rich n-3 Fatty Acid Supplementation on Gene Expression in Blood Mononuclear Leukocytes : The OmegAD Study

Background Dietary fish oil, rich in n-3 fatty acids (n-3 FAs), e.g. docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), regulate inflammatory reactions by various mechanisms, e.g. gene activation. However, the effects of long-term treatment with DHA and EPA in humans, using genome wide techniques, are poorly described. Hence, our aim was to determine the effects of 6 mo of dietary supplementation with an n-3 FA preparation rich in DHA on global gene expression in peripheral blood mononuclear cells. Methods and Findings In the present study, blood samples were obtained from a subgroup of 16 patients originating from the randomized double-blind, placebo-controlled OmegAD study, where 174 Alzheimer disease (AD) patients received daily either 1.7 g of DHA and 0.6 g EPA or placebo for 6 months. In blood samples obtained from 11 patients receiving n-3 FA and five placebo, expressions of approximately 8000 genes were assessed by gene array. Significant changes were confirmed by real-time PCR. At 6 months, the n-3 FAs group displayed significant rises of DHA and EPA plasma concentrations, as well as up- and down-regulation of nine and ten genes, respectively, was noticed. Many of these genes are involved in inflammation regulation and neurodegeneration, e.g. CD63, MAN2A1, CASP4, LOC399491, NAIP, and SORL1 and in ubiqutination processes, e.g. ANAPC5 and UBE2V1. Down-regulations of ANAPC5 and RHOB correlated to increases of plasma DHA and EPA levels. Conclusions We suggest that 6 months of dietary n-3 FA supplementation affected expression of genes that might influence inflammatory processes and could be of significance for AD. Trial Registration ClinicalTrials.gov NCT00211159

Docosahexaenoic acid stabilizes soluble amyloid-β protofibrils and sustains amyloid-β induced neurotoxicity in vitro

Enrichment of diet and culture media with the polyunsaturated fatty acid docosahexaenoic acid has been found to reduce the amyloid burden in mice and lower amyloid‐β (Aβ) levels in both mice and cultured cells. However, the direct interaction of polyunsaturated fatty acids, such as docosahexaenoic acid, with Aβ, and their effect on Aβ aggregation has not been explored in detail. Therefore, we have investigated the effect of docosahexaenoic acid, arachidonic acid and the saturated fatty acid arachidic acid on monomer oligomerization into protofibrils and protofibril fibrillization into fibrils in vitro, using size exclusion chromatography. The polyunsaturated fatty acids docosahexaenoic acid and arachidonic acid at micellar concentrations stabilized soluble Aβ42 wild‐type protofibrils, thereby hindering their conversion to insoluble fibrils. As a consequence, docosahexaenoic acid sustained amyloid‐β‐induced toxicity in PC12 cells over time, whereas Aβ without docosahexaenoic acid stabilization resulted in reduced toxicity, as Aβ formed fibrils. Arachidic acid had no effect on Aβ aggregation, and neither of the fatty acids had any protofibril‐stabilizing effect on Aβ42 harboring the Arctic mutation (AβE22G). Consequently, AβArctic‐induced toxicity could not be sustained using docosahexaenoic acid. These results provide new insights into the toxicity of different Aβ aggregates and how endogenous lipids can affect Aβ aggregation.