Simultaneous assessment of intestinal permeability and lactose tolerance with orally administered raffinose, lactose and L-arabinose

Gender-specific insights into the irritable bowel syndrome pathophysiology. Focus on gut dysbiosis and permeability

Irritable bowel syndrome (IBS) is the most common functional gastrointestinal disorder involving the brain-gut interaction. IBS is characterized by persistent abdominal pain and changes in bowel habits. IBS exerts significant impacts on quality of life and imposes huge economic costs. Global epidemiological data reveal variations in IBS prevalence, both globally and between genders, necessitating comprehensive studies to uncover potential societal and cultural influences. While the exact pathophysiology of IBS remains incompletely understood, the mechanism involves a dysregulation of the brain-gut axis, leading to disturbed intestinal motility, local inflammation, altered intestinal permeability, visceral sensitivity, and gut microbiota composition. We reviewed several gender-related pathophysiological aspects of IBS pathophysiology, by focusing on gut dysbiosis and intestinal permeability. This perspective paves the way to personalized and multidimensional clinical management of individuals with IBS.

Intestinal barrier dysfunction in irritable bowel syndrome: a systematic review

BACKGROUND AND AIM

Irritable bowel syndrome (IBS) is a complex and heterogeneous disorder. Sensory, motor and barrier dysfunctions are the key physiological endophenotypes of IBS. Our aim is to review studies evaluating barrier dysfunction in adults and children with IBS, as well as to link those changes with IBS symptomatology and quality of life.

METHODS

A comprehensive and systematic review of multiple databases was performed up to March 2020 to identify studies comparing intestinal permeability in IBS patients with healthy controls. Both in vivo and in vitro studies were considered.

RESULTS

We identified 66 studies, of which 27 used intestinal probes to quantify barrier function. The prevalence of barrier dysfunction differed between PI-IBS (17-50%), IBS-D (37-62%) and IBS-C (4-25%). At a group level, permeability was increased compared with healthy controls in IBS-D (9/13 studies) and PI-IBS (4/4 studies), but only a minority of IBS-C (2/7 studies) and not in the only IBS-M study. All four studies in children with IBS demonstrated loss of barrier function. A heterogeneous set of tight junction genes were found to be altered in small and large intestines of adults with IBS, but these have not been evaluated in children. Positive associations were identified between barrier dysfunction and bowel disturbances (6/9 studies), abdominal pain (9/13 studies), overall symptom severity (1/6 studies), depression and anxiety (1/1 study) and quality of life (1/4 studies). Fecal slurry or supernatants of IBS patients were found to induce barrier disruption in animal models (5/6 studies).

CONCLUSIONS

Barrier dysfunction is present in a significant proportion of adult and all pediatric IBS studies, especially in the IBS-D and PI-IBS subtype. The majority of studies indicated a positive association between loss of barrier function and symptoms such as abdominal pain and changes in the bowel function.

Role for diet in normal gut barrier function: developing guidance within the framework of food-labeling regulations

A reduction in intestinal barrier function is currently believed to play an important role in pathogenesis of many diseases, as it facilitates passage of injurious factors such as lipopolysaccharide, peptidoglycan, whole bacteria, and other toxins to traverse the barrier to damage the intestine or enter the portal circulation. Currently available evidence in animal models and in vitro systems has shown that certain dietary interventions can be used to reinforce the intestinal barrier to prevent the development of disease. The relevance of these studies to human health is unknown. Herein, we define the components of the intestinal barrier, review available modalities to assess its structure and function in humans, and review the available evidence in model systems or perturbations in humans that diet can be used to fortify intestinal barrier function. Acknowledging the technical challenges and the present gaps in knowledge, we provide a conceptual framework by which evidence could be developed to support the notion that diet can reinforce human intestinal barrier function to restore normal function and potentially reduce the risk for disease. Such evidence would provide information on the development of healthier diets and serve to provide a framework by which federal agencies such as the US Food and Drug Administration can evaluate evidence linking diet with normal human structure/function claims focused on reducing risk of disease in the general public.

Capacity To Utilize Raffinose Dictates Pneumococcal Disease Phenotype

S. pneumoniae is a component of the commensal nasopharyngeal microflora of humans, but from this reservoir, it can progress to localized or invasive disease with a frequency that translates into massive global morbidity and mortality. However, the factors that govern the switch from commensal to pathogen, as well as those that determine disease tropism, are poorly understood. Here we show that capacity to utilize raffinose can determine the nature of the disease caused by a given pneumococcal strain. Moreover, our findings provide an interesting example of convergent evolution, whereby pneumococci belonging to two unrelated serotypes/lineages exhibit SNPs in separate genes affecting raffinose uptake and utilization that correlate with distinct pathogenic profiles in vivo. This further underscores the critical role of differential carbohydrate metabolism in the pathogenesis of localized versus invasive pneumococcal disease.

Streptococcus pneumoniae is commonly carried asymptomatically in the human nasopharynx, but it also causes serious and invasive diseases such as pneumonia, bacteremia, and meningitis, as well as less serious but highly prevalent infections such as otitis media. We have previously shown that closely related pneumococci (of the same capsular serotype and multilocus sequence type [ST]) can display distinct pathogenic profiles in mice that correlate with clinical isolation site (e.g., blood versus ear), suggesting stable niche adaptation within a clonal lineage. This has provided an opportunity to identify determinants of disease tropism. Genomic analysis identified 17 and 27 single nucleotide polymorphisms (SNPs) or insertions/deletions in protein coding sequences between blood and ear isolates of serotype 14 ST15 and serotype 3 ST180, respectively. SNPs in raffinose uptake and utilization genes (rafR or rafK) were detected in both serotypes/lineages. Ear isolates were consistently defective in growth in media containing raffinose as the sole carbon source, as well as in expression of raffinose pathway genes aga, rafG, and rafK, relative to their serotype/ST-matched blood isolates. Similar differences were also seen between serotype 23F ST81 blood and ear isolates. Analysis of rafR allelic exchange mutants of the serotype 14 ST15 blood and ear isolates demonstrated that the SNP in rafR was entirely responsible for their distinct in vitro phenotypes and was also the determinant of differential tropism for the lungs versus ear and brain in a mouse intranasal challenge model. These data suggest that the ability of pneumococci to utilize raffinose determines the nature of disease.

Systematic review and meta-analysis of lactose digestion, its impact on intolerance and nutritional effects of dairy food restriction in inflammatory bowel diseases

BACKGROUND

Relationships between inflammatory bowel disease and lactose containing foods remain controversial and poorly defined regarding symptoms, nutritional outcomes, and epidemiologic associations for lactose maldigestion.

METHODS

A literature review was performed using Pub Med, Cochrane library and individual references, to extract data on lactose maldigestion prevalence in inflammatory bowel diseases. A meta-analysis was done using selected articles, to determine odds ratios of maldigestion. Information was collected about symptoms, impact on pattern of dairy food consumption, as well as the effects of dairy foods on the course of inflammatory bowel diseases.

RESULTS

A total of 1022 articles were evaluated, 35 articles were retained and 5 studies were added from review articles. Of these 17 were included in meta-analysis which showed overall increased lactose maldigestion in both diseases. However increased risk on sub analysis was only found in Crohn's in patients with small bowel involvement. Nine additional studies were reviewed for symptoms, with variable outcomes due to confounding between lactose intolerance and lactose maldigestion. Fourteen studies were evaluated for dairy food effects. There was a suggestion that dairy foods may protect against inflammatory bowel disease. Nutritional consequences of dairy restrictions might impact adversely on bone and colonic complications.

CONCLUSIONS

Lactose maldigestion in inflammatory bowel disease is dependent on ethnic makeup of the population and usually not disease. No bias of increased disease prevalence was noted between lactase genotypes. Intolerance symptoms depend on several parameters besides lactose maldigestion. Dairy foods may decrease risks of inflammatory bowel disease. Dairy restrictions may adversely affect disease outcome.

Evaluation of regulated delayed attenuation strategies for Salmonella enterica serovar Typhi vaccine vectors in neonatal and infant mice

We developed regulated delayed attenuation strategies for Salmonella vaccine vectors. In this study, we evaluated the combination of these strategies in recombinant attenuated Salmonella enterica serovar Typhi and Salmonella enterica serovar Typhimurium vaccine vectors with similar genetic backgrounds in vitro and in vivo. Our goal is to develop a vaccine to prevent Streptococcus pneumoniae infection in newborns; thus, all strains delivered a pneumococcal antigen PspA and the impact of maternal antibodies was evaluated. The results showed that all strains with the regulated delayed attenuated phenotype (RDAP) displayed an invasive ability stronger than that of the S. Typhi vaccine strain, Ty21a, but weaker than that of their corresponding wild-type parental strains. The survival curves of different RDAP vaccine vectors in vitro and in vivo exhibited diverse regulated delayed attenuation kinetics, which was different from S. Typhi Ty21a and the wild-type parental strains. Under the influence of maternal antibody, the persistence of the S. Typhimurium RDAP strain displayed a regulated delayed attenuation trend in nasal lymphoid tissue (NALT), lung, and Peyer's patches, while the persistence of S. Typhi RDAP strains followed the curve only in NALT. The bacterial loads of S. Typhi RDAP strains were lower in NALT, lung, and Peyer's patches in mice born to immune mothers than in those born to naive mothers. In accordance with these results, RDAP vaccine strains induced high titers of IgG antibodies against PspA and against Salmonella lipopolysaccharides. Immunization of mothers with S. Typhi RDAP strains enhanced the level of vaginal mucosal IgA, gamma interferon (IFN-γ), and interleukin 4 (IL-4) and resulted in a higher level of protection against S. pneumoniae challenge.

Increased small intestinal permeability in ulcerative colitis: rather genetic than environmental and a risk factor for extensive disease?

BACKGROUND

A disturbed epithelial barrier could play a pivotal role in ulcerative colitis (UC). We performed a family-based study analyzing in vivo gastrointestinal permeability in patients with UC, their healthy relatives, spouses, and controls.

METHODS

In total, 89 patients with UC in remission, 35 first-degree relatives (UC-R), 24 nonrelated spouses (UC-NR), and 99 healthy controls (HC) were studied. Permeability was assessed by a sugar-drink test using sucrose (gastroduodenal permeability), lactulose/mannitol (intestinal permeability), and sucralose (colonic permeability). Data were correlated with clinical characteristics including medical treatment.

RESULTS

Increased intestinal permeability was detected significantly more often in UC patients in remission (25/89, 28.1%) compared with HC (6/99, 6.1%; P < 0.001). Similar results were obtained in UC-R (7/35, 20.0%; P = 0.01 compared with HC) regardless of sharing the same household with the patients or not. No difference was found between UC-NR (3/24, 12.5%) and HC. Notably, in UC patients increased intestinal permeability was found in 12/28 patients (42.9%) with pancolitis, 7/30 (23.3%) patients with left-sided colitis, and in 2/19 (10.5%) patients with proctitis (P = 0.04). Gastroduodenal and colonic permeability were similar in all groups. Among patients on azathioprine, increased intestinal permeability was only seen in 1/18 (5.6%) patients. In contrast, in 24/70 (34.3%) patients without azathioprine, an increased intestinal permeability was found (P = 0.005).

CONCLUSIONS

An increased intestinal but not colonic permeability was found in UC patients in clinical remission that could mark a new risk factor for extensive disease location. Similar findings in healthy relatives but not spouses suggest that this barrier defect is genetically determined.

Capacity for absorption of water-soluble secondary metabolites greater in birds than in rodents

Plant secondary metabolites (SMs) are pervasive in animal foods and potentially influence feeding behavior, interspecies interactions, and the distribution and abundance of animals. Some of the major classes of naturally occurring SMs in plants include many water-soluble compounds in the molecular size range that could cross the intestinal epithelium via the paracellular space by diffusion or solvent drag. There are differences among species in paracellular permeability. Using Middle Eastern rodent and avian consumers of fruits containing SMs, we tested the hypothesis that avian species would have significantly higher paracellular permeability than rodent species. Permeability in intact animals was assessed using standard pharmacological methodology to measure absorption of two radiolabeled, inert, neutral water-soluble probes that do not interact with intestinal nutrient transporters, L-arabinose (M_r = 150.1 Da) and lactulose (M_r = 342.3 Da). We also measured absorption of labeled 3-O-methyl-D-glucose (3OMD-glucose; M_r = 194.2 Da), which is a nonmetabolized analogue of D-glucose that is passively absorbed through the paracellular space but also transported across the enterocyte membranes. Most glucose was absorbed by all species, but arabinose fractional absorption (f) was nearly three times higher in birds (1.03±0.17, n = 15 in two species) compared to rodents (0.37±0.06, n = 10 in two species) (P<0.001). Surprisingly, the apparent rates of absorption in birds of arabinose exceeded those of 3OMD-glucose. Our findings are in agreement with previous work showing that the paracellular pathway is more prominent in birds relative to nonflying mammals, and suggests that birds may be challenged by greater absorption of water-soluble, dietary SMs. The increased expression of the paracellular pathway in birds hints at a tradeoff: the free energy birds gain by absorbing water-soluble nutrients passively may be offset by the metabolic demands placed on them to eliminate concomitantly absorbed SMs.

Role of dihydrolipoamide dehydrogenase in regulation of raffinose transport in Streptococcus pneumoniae

Streptococcus pneumoniae strains lacking the enzyme dihydrolipoamide dehydrogenase (DLDH) show markedly reduced ability to grow on raffinose and stachyose as sole carbon sources. Import of these sugars occurs through the previously characterized raffinose ATP-binding cassette (ABC) transport system, encoded by the raf operon, that lacks the necessary ATP-binding protein. In this study, we identified the raffinose ATP-binding protein RafK and showed that it was directly involved in raffinose and stachyose import. RafK carries a C-terminal regulatory domain present in a subset of ATP-binding proteins that has been involved in both direct regulation of transporter activity (inducer exclusion) and transcription of transporter genes. Pneumococci lacking RafK showed a 50- to 80-fold reduction in expression of the raf operon genes aga (alpha-galactosidase) and rafEFG (raffinose substrate binding and permease genes), and both glucose and sucrose inhibited raffinose uptake through inducer exclusion. Like RafK, the presence of DLDH also activated the expression of raf operon genes, as DLDH-negative pneumococci showed a significantly decreased expression of aga and rafEFG, but DLDH did not regulate rafK or the putative regulatory genes rafR and rafS. DLDH also bound directly to RafK both in vitro and in vivo, indicating the possibility that DLDH regulates raffinose transport by a direct interaction with the regulatory domain of the transporter. Finally, although not as attenuated as DLDH-negative bacteria, pneumococci lacking RafK were significantly outcompeted by wild-type bacteria in colonization experiments of murine lung and nasopharynx, indicating a role for raffinose and stachyose transport in vivo.

[Alterations of intestinal epithelial barrier and flora in the irritable bowel syndrome]

The irritable bowel syndrome (IBS) is a common bowel disorder that markedly impairs quality of life of patients. The causes of IBS symptoms are not well known. Motility and sensibility disorders, a genetic susceptibility, stress, previous GI infections and food intolerance have been involved in the pathogenesis of IBS. Recent investigations suggest that alterations of the intestinal epithelial barrier integrity, in particular increased permeability, could modify the cross-talk between bacterial microflora and the host, thus leading to persitent "low-grade" inflammation and alterated GI motility and sensitivity.

Intestinal permeability and irritable bowel syndrome

Based on a systematic PubMed search, this short review addresses why intestinal permeability may be important in the pathobiology of irritable bowel syndrome (IBS), the evidence of abnormal permeability in patients with IBS, and the pros and cons of the different probe molecules available to assess intestinal permeability. While a subgroup of patients with IBS appears to have evidence of increased intestinal permeability, improvements in the methods and validation are key to further research in this field in order to better understand intestinal barrier functions in IBS.

Assessment of hypolactasia and site-specific intestinal permeability by differential sugar absorption of raffinose, lactose, sucrose and mannitol

The sugar absorption test is a non-invasive test for investigating intestinal permeability by simultaneous measurement of four probe sugars. In this study, we evaluated the utility of raffinose, lactose, sucrose and mannitol as probe sugars and calculated their urinary recovery as a percentage of ingested dose (mol/mol) and the recovery ratios of raffinose/mannitol, lactose/ raffinose and sucrose/raffinose. The reference ranges for these ratios, established from 39 healthy volunteers, are 0.005-0.015, 0.13-0.63 and 0.09-0.47, respectively. This sugar absorption test was performed in three patient groups. i) In 109 patients with aspecific gastrointestinal symptoms of whom intestinal histology was studied by duodenal biopsies: the urinary raffinose/mannitol recovery ratio highly correlated with gradation of duodenal damage; the sensitivity and specificity of the raffinose/mannitol ratio for detection of intestinal damage were 93% and 91%, respectively, using a cut-off level of 0.020. ii) In 70 patients in whom intestinal lactase activity was investigated by the lactose tolerance test: the urinary lactose/raffinose recovery ratio provided high diagnostic accuracy for hypolactasia (sensitivity 81% and specificity 89% at a cut-off level of 0.70). In analogy with the lactose/raffinose ratio, we suppose that the sucrose/raffinose ratio can be used as a marker of hyposucrasia. iii) In 40 patients with localized small intestinal damage, Crohn's disease of the ileum (n = 21) and celiac disease with histologically proven duodenal damage (n = 19): the raffinose/mannitol recovery ratio was increased in 100% of patients with celiac disease and in 81% of patients with Crohn's disease; increased lactose/raffinose recovery ratio (hypolactasia) and increased sucrose/raffinose (hyposucrasia) were present in 89% and 95% of celiac patients and 19% and 0% of Crohn's disease patients, respectively. The combination of the raffinose/mannitol ratio and sucrose/raffinose ratio appears to be an indication of the distribution of intestinal damage.

Intestinal passive absorption of water-soluble compounds by sparrows: effect of molecular size and luminal nutrients

We tested predictions that: (1) absorption of water-soluble probes decreases with increasing molecular size, consistent with movement through effective pores in epithelia, and (2) absorption of probes is enhanced when measured in the presence of luminal nutrients, as predicted for paracellular solvent drag. Probes (L-arabinose, L-rhamnose, perseitol, lactulose; MW 150.1-342.3 Da) were gavaged in nonanesthetized House sparrows ( Passer domesticus), or injected into the pectoralis, and serially measured in plasma. Bioavailability was calculated as F=AUC by gavage/AUC by injection, where AUC is the area under the curve of plasma probe concentration vs. time. Consistent with predictions, F declined with probe size by 75% from the smallest to the largest probe, and absorption of probes increased by 40% in the presence of luminal glucose or food compared to a mannitol control. Absorption of water-soluble probes by sparrows is much higher than in humans, which is much higher than in rats. These differences seem mainly attributable to differences in paracellular solvent flux and less to differences in effective paracellular pore size.

Assessment of intestinal permeability: enzymatic determination of urinary mannitol, raffinose, sucrose and lactose on Hitachi analyzer

The sugar absorption test is the usual test for measurement of intestinal permeability. After intestinal absorption of probe sugars the subsequently excreted sugars are measured in urine. We have developed four enzymatic methods for the measurement of the urinary concentration of the probe sugars mannitol, raffinose, lactose and sucrose. Mannitol, lactose and sucrose are directly measured on Hitachi 917 using mannitol dehydrogenase, beta-galactosidase and invertase, respectively, as enzyme reagents. Raffinose measurement needs a three hours preincubation with alpha-galactosidase, after which the liberated sucrose is measured. The analytical performances such as within- and between-run precision, linearity, lowest detection limit, interference of other sugars and comparison with a gas chromatographic method are described for the four methods. These methods are accurate an can easily be performed in any clinical laboratory.

L-Arabinosuria: a new defect in human pentose metabolism

A female patient, the first child of healthy non-consanguineous parents, presented at the age of 16 months with delayed motor development and facial dysmorphism. In addition she displayed a palatoschizis and multiple skeletal abnormalities as hypoplastic scapulae, hypoplastic os ilea, and an extreme cervical kyphosis. Biochemical investigation of urine revealed no abnormalities except for the presence of large amounts of reducing sugars. The sugar was identified as L-arabinose, which mainly originated from fruit formula in her diet. In addition highly elevated levels of L-arabitol were found in urine, plasma, and cerebrospinal fluid. Although little is known about human arabinose metabolism, we presume that L-arabitol dehydrogenase is deficient in our patient. As polyols are potentially toxic to the central nervous system there could be deleterious long-term effects of this disorder. Withdrawal of dietary fruit led to normalization of polyol levels. The above-mentioned clinical abnormalities are probably not related to this new inborn error of metabolism and should be considered as a separate entity.

Evaluation of human intestinal absorption data and subsequent derivation of a quantitative structure–activity relationship (QSAR) with the Abraham descriptors

The human intestinal absorption of 241 drugs was evaluated. Three main methods were used to determine the human intestinal absorption: bioavailability, percentage of urinary excretion of drug-related material following oral administration, and the ratio of cumulative urinary excretion of drug-related material following oral and intravenous administration. The general solvation equation developed by Abraham's group was used to model the human intestinal absorption data of 169 drugs we considered to have reliable data. The model contains five Abraham descriptors calculated by the ABSOLV program. The results show that Abraham descriptors can successfully predict human intestinal absorption if the human absorption data is carefully classified based on solubility and administration dose to humans.

Urinary excretion of lactose and oligosaccharides in preterm infants fed human milk or infant formula

At present, not much is known about the absorption and metabolism of human milk (HM) oligosaccharides in term and preterm infants. We investigated the renal excretion of lactose and complex oligosaccharides in preterm infants fed HM (n = 9, mean actual body weight 2290 g) or a cow's milk-based infant formula (n = 9, mean actual body weight 2470 g). We found that the renal excretion of lactose in HM-fed infants was slightly lower than in formula-fed infants (14.0 +/- 7.4 versus 20.4 +/- 8.7 mg kg-1 day-1, mean +/- SD). The excretion of neutral sugars deriving from oligosaccharides was similar in HM-fed and formula-fed infants (3.8 +/- 2.1 versus 2.9 +/- 0.9 mg kg-1 day-1); the difference between means was not statistically significant. The separation and characterization of oligosaccharides by high-pH anion exchange chromatography with pulsed amperometric detection (HPAE-PAD) and subsequent analysis by fast atom bombardment-mass spectrometry (FAB-MS) revealed a more complex pattern in HM-fed infants compared to the formula-fed group. Lactose-derived oligosaccharides characteristic for HM (e.g. lacto-N-tetraose, and lacto-N-fucopentaoses I and II) were excreted in HM-fed but not in formula-fed infants. These results indicate that nutrition has a significant impact on the oligosaccharide composition in urine of preterm infants.

A novel HPLC method for the simultaneous quantification of monosaccharides and disaccharides used in tests of intestinal function and permeability

The quantification of monosaccharides and disaccharides used as probes in intestinal function and permeability tests can be technically demanding, detracting from the value of this approach to the indirect assessment of intestinal damage. In this study, a procedure is described for the simultaneous quantification of rhamnose, lactulose, 3-O-methyl-D-glucose and xylose in urine by HPLC using an anion exchange column with pulsed amperometric detection. This method is relatively fast and simple to perform, requiring no pre-treatment of urine samples or post-column derivatization. Accuracy and precision of determinations are illustrated by analytical recoveries (mean percentage +/- S.D., CV., n = 30) for multiple batch analyses of a diluted urine sample containing 20 mg/l of rhamnose (100 +/- 6.8, 6.2%), lactulose (100 +/- 6.1, 5.5%), 3-O-methyl-D-glucose (98 +/- 5.9, 5.5%) and xylose (104 +/- 7.1, 6.5%). Linearity of standard curves indicated that the lower limit for accurate quantification was 0.1 mg/l for all four sugars. Urinary recoveries following oral administration of these sugars to control dogs were determined as a baseline for the investigation of intestinal damage in this species and comparison of chromatograms illustrated enhanced permeability in dogs with gluten-sensitive enteropathy.

A new diffusion chamber system for the determination of drug permeability coefficients across the human intestinal epithelium that are independent of the unstirred water layer

A new method for determining permeability coefficients, that are independent of the unstirred water layer (UWL), has been developed. The method was used to determine the cellular permeability coefficient of the rapidly absorbed drug testosterone in monolayers of the human intestinal epithelial cell line, Caco-2. Using a new diffusion cell with an effective stirring system based on a gas lift, the cellular permeability coefficient for testosterone was (1.98 +/- 0.13).10(-4) cm/s which is 3.5-times higher than the permeability coefficient obtained in the unstirred system. The thickness of the UWL obtained with the well stirred diffusion cell was 52 +/- 4 microns. This value is much lower than those previously reported in various well stirred in vitro models. The calculated cellular permeability of testosterone was 13-23-times lower than that for an UWL of the same thickness as the epithelial cell (17-30 microns). We conclude that the permeability of the epithelial monolayer must be included in calculations of the thickness of the UWL.

Intestinal nematode infections in children: the pathophysiological price paid

The mechanism by which small animals such as rodents resist or eliminate nematode parasites requires mucosal inflammation as the final effector of the immune response. The resulting freedom from chronic infection may be worth the price of short-term illness. Putative vaccines which attempt to enhance the natural effect will have to take into account the inflammatory cost to the host. Human helminthiases involve a more stable equilibrium between host and parasite. The medical literature on hookworm disease and clinical ascariasis describes, for the former, some chronic inflammatory effects correlated with worm burden, but for the latter a less quantified or predictable set of detrimental effects. We describe a current, systematic study of the inflammatory response to whipworm infection, in which anaemia, growth retardation and intestinal leakiness are viewed as predictable consequences related to infection intensity. There is evidence for the absence of cell-mediated immunopathology. However, a specific, IgE-mediated local anaphylaxis may, at least partly, mediate the deleterious effects. Increased numbers of mucosal macrophages may also contribute to the chronic, systemic effects through their output of cytokines. Similar attempts to show the mechanisms of pathogenesis and quantify the effects of hookworm disease should be undertaken.