Blastocystis Research News
December 2017


IBS Patients Infected with Blastocystis Show Statistically Significant Immune Differences

Some Irritable Bowel Syndrome (IBS) patients can be shown to have Blastocystis infection, while others do not, so there is a question as to whether the finding is clinically significant, and if scientific investigation of the Blastocystis infection would yield promising results.  Researchers at Aga Khan University analyzing Peripheral Blood Mononuclear Cells (PBMC) have identified which cytokines are produced in significantly different levels in IBS patients infection with Blastocystis.  The study analyzed PBMC’s from 80 D-IBS (diarrhea predominant IBS patients) without Blastocystis infection, with Blastocystis sp. subtype 1, and with Blastocystis sp. subtype 3.  The researchers reported that although IL-8 expression was similar in the groups,  in Blastocystis sp. subtype 1, IL-8 mRNA expression was increased compared with subtype 3 and controls (P=0.001).   A statistically significantly lower level of IL-10 was found in PBMC’s from D-IBS infected with Blastocystis sp. subtype 1, when compared to controls and Blastocystis sp. subtype 3 (P<0.001), and this low IL-10 production was associated with lymphocyte and plasma cell infiltration (P=0.015 and 0.002 respectively).  In both Blastocystis sp. subtype 1 and 3, IL-12 was associated with goblet cell depletion.  The full study is available in the journal Parasitology.


Blastocystis Plus Stress (but not stress alone) Produces More Significant Immune Inhibition

A number of researchers have suggested that gastrointestinal disease may be due to infection, stress, or a combination of both, but disentangling these causes can be difficult, as classical scientific method of controlled experimentation is not feasible with human subjects.  Researchers at the University of Malaysia have reported results from an animal study that was able to shed some light on the topic.  Three-week old Wistar rats were divided into four groups, mainly and subjected to (a) no stress or infection (control); (b) stress alone; (c) infection with Blastocystis alone; and (d) both stress and infection with Blastocystis.  The study reported that while the stress group gained more weight, there were no significant immunological differences between the stress and control group.  The group infected with Blastocystis showed lower levels of oxidants.  Additionally, infection with Blastocystis was associated with lower peripheral blood mononuclear cell counts.  The group exposed to stress and Blastocystis infection had higher levels of parasite count in stool samples, serum IgE, and oxidized protein compared to the Blastocystis group alone.  The full paper is available from PLOS-One.


Co-culture of Blastocystis and human epithelial cells suggests mechanism for gastrointestinal disease

Researchers working at the University of Singapore report that co-culture of human epithelial cells with Blastocystis sp. subtype 7 (but not Blastocystis sp. subtype 4) results in a statistically significant increase in apoptosis (spontaneous cell death) and produces changes in epithelial resistance, permeability, and tight junction localization.  The full text of the study is available from Biomed Research International.  


Large study (n=10,466) reports statistically higher incidence of low serum iron, high c-reactive protein, and occult blood in Blastocystis-positive patients

A study of 10,466 patients seen at an Iran hospital reports that patients with stool samples positive for Blastocystis infection were statistically more likely to have low serum iron levels.  Additionally, occult blood was positive in 0.93% of Blastocystis-positive cases, and none of the control (p < 0.05).  C-reactive protein was positive in 1.46% of the cases and 0.5% of controls.  Erythrocyte sedimentation rate level was significantly higher in cases with Blastocystis infection as well (p < 0.05).  The full free text is available from Przeglad Gastroenterology.


Blastocystis isolates from symptomatic humans behave differently from those from asymptomatic individuals

Researchers from the University of Malaysia report that Blastocystis cultures from symptomatic individuals report different behavior with respect to capase-like proteases.  Fluorescence intensity for active capase-like proteases was significantly greater in isolates from symptomatic individuals in the 72-hour in vitro culture (p < 0.001).  Treatment with metronidazole inhibited the capase activation.  The full free text is available from Parasites and Vectors.


Fecal IgA reactivity to >250 kDa Blastocystis protein more common in immunosuppressed pigs, but no intestinal histopathology

An Australian team has used fecal IgA study to characterize the immune response of 233 pigs to Blastocystis antigens.   The team reports that a majority of the pigs (81.5%) show fecal IgA reactivity against Blastocystis proteins of molecular weight 17.5-120kDa, but reactivity to a higher weight protein (>250kDa) was found in only 18.5% of the pigs.  Immunosuppressed pigs and piglets were much more likely to show reactivity to the high molecular weight protein.  The full free text of the paper is available from Parasite Immunology.


Study of 275 Columbian children shows higher prevalence of diarrhea in children infected with Blastocystis

Columbian researchers studying 275 children attending under 5 attending day care centers in Calarca, Columbia report that children infected with Blastocystis had a significantly higher prevalence of diarrhea (OR=1.95, 95% CI, p < 0.05), with 45% of Blastocystis-positive children reporting diarrhea vs. 33% of Blastocystis-negative children.  Etiological study suggested that Blastocystis infection may come from contamination of a sugar cane beverage, floors, or foods other than bottled milk.  The full free text is available from Biomedica.


Multiplex DNA panel identifies many gastrointestinal pathogen not found in microscopy from pediatric patients returning from the tropics

Researchers in Switzerland studying 312 stool samples from pediatric patients returning from trips to the tropics report that conventional laboratory methods failed to identify most of the norovirus-positive and Giardia-positive samples identified by Luminex’s xTag gastrointestinal pathogen panel.  The Luminex panel covers 15 diarrhea-causing organisms using PCR amplification.  All adenovirus, rotavirus, C. diff, and Cryptosporidium samples were confirmed in external labs, but norovirus and Giarida positive samples were only idneitifes 40% and 29% of the time respectively.  For more information, refer to the paper published in the journal Infection.


Blastocystis found in both small intestine and large intestine of pigs

A report from a research team at the from the University of Queensland, Australia has identified Blastocystis infection in both the small and large intestines of pigs.  By studying a total of 28 pigs infected with Blastocystis, the authors found that the primary types observed were Blastocystis sp. subtypes 3 and 1.  The researchers suggested that pigs may provide suitable animals models for Blastocystis infection in humans.  The full text of the study is available from PLOS-One.


Blastocystis activates variety of pro-inflammatory cytokines in variety of mice cells

A research team from the National University of Singapore reports that Blastocystis antigens stimulate the production of a variety of cytokines, such as 1β (IL-1β), IL-6, and tumor necrosis factor alpha (TNF-α), in mouse intestinal explants, in mouse colitis colon, and in macrophages.  Further investigation utilizing RAW264.7 murine macrophages showed that Blastocystis treatment in RAW264.7 macrophages induced the activation of ERK, JNK, and p38, the three major groups of mammalian mitogen-activated protein (MAP) kinases that play essential roles in the expression of proinflammatory cytokines. ERK inhibition in macrophages significantly suppressed both mRNA and protein expression of IL-6 and TNF-α and mRNA expression of IL-1β.  For the full text of the study, refer to the journal Infection and Immunity


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