Inflammatory Mediator Profiling of n-butanol Exposed Upper Airways in Individuals with Multiple Chemical Sensitivity

A Comprehensive Review of Experimental Models of Stress: Pragmatic Insight Into Psychoneuroimmunology

Psychoneuroimmunology is a scientific discipline exploring the interconnectedness of the nervous system, emotion state, and immune system. The current review examines the distinct mechanisms through which the mind and body interact when subjected to stress. Manifestations of psychoneuroimmunological stress encompass symptoms such as depression, aggression, fear, and social withdrawal, which can exert a profound impact on physiological well-being. Some observations suggest that humans and nonhuman animals exhibit similar stress-related symptoms, aiding in the identification of pharmacological pathways and potential clinical implications of therapeutic interventions. Animal stress models are predicated on varying approaches aimed at eliciting a motivational state to navigate and confront aversive circumstances. The current review describes the diverse stress induction models that have been investigated internationally, incorporating an ethological perspective that involves evaluating innate and unpunished behaviors through methodologies like the elevated plus maze, elevated zero maze, light-dark box, and open field test. Additionally, conditioned operant conflict tests, such as the Vogel conflict test, fall under the purview of learning and punishment models. This category encompasses classic conditioning models like fear conditioning, psychosocial models such as social defeat, and physical and chronic unpredictable stress paradigms. In this review, we critically evaluate existing cognitive and behavioral frameworks underpinning the development and perpetuation of stress-related disorders, while also elucidating the impact of immune system responses on the mental and physical health of animals. The primary objective of this review is to elucidate the array of animal models employed in previous research and the testing protocols used to assess animal performance in stress induction scenarios, with the ultimate aim of reducing mortality rates among research animals.

Exposure limits for indoor volatile substances concerning the general population: The role of population-based differences in sensory irritation of the eyes and airways for assessment factors

Assessment factors (AFs) are essential in the derivation of occupational exposure limits (OELs) and indoor air quality guidelines. The factors shall accommodate differences in sensitivity between subgroups, i.e., workers, healthy and sick people, and occupational exposure versus life-long exposure for the general population. Derivation of AFs itself is based on empirical knowledge from human and animal exposure studies with immanent uncertainty in the empirical evidence due to knowledge gaps and experimental reliability. Sensory irritation in the eyes and airways constitute about 30-40% of OELs and is an abundant symptom in non-industrial buildings characterizing the indoor air quality and general health. Intraspecies differences between subgroups of the general population should be quantified for the proposal of more 'empirical' based AFs. In this review, we focus on sensitivity differences in sensory irritation about gender, age, health status, and vulnerability in people, based solely on human exposure studies. Females are more sensitive to sensory irritation than males for few volatile substances. Older people appear less sensitive than younger ones. However, impaired defense mechanisms may increase vulnerability in the long term. Empirical evidence of sensory irritation in children is rare and limited to children down to the age of six years. Studies of the nervous system in children compared to adults suggest a higher sensitivity in children; however, some defense mechanisms are more efficient in children than in adults. Usually, exposure studies are performed with healthy subjects. Exposure studies with sick people are not representative due to the deselection of subjects with moderate or severe eye or airway diseases, which likely underestimates the sensitivity of the group of people with diseases. Psychological characterization like personality factors shows that concentrations of volatile substances far below their sensory irritation thresholds may influence the sensitivity, in part biased by odor perception. Thus, the protection of people with extreme personality traits is not feasible by an AF and other mitigation strategies are required. The available empirical evidence comprising age, lifestyle, and health supports an AF of not greater than up to 2 for sensory irritation. Further, general AFs are discouraged for derivation, rather substance-specific derivation of AFs is recommended based on the risk assessment of empirical data, deposition in the airways depending on the substance's water solubility and compensating for knowledge and experimental gaps. Modeling of sensory irritation would be a better 'empirical' starting point for derivation of AFs for children, older, and sick people, as human exposure studies are not possible (due to ethical reasons) or not generalizable (due to self-selection). Dedicated AFs may be derived for environments where dry air, high room temperature, and visually demanding tasks aggravate the eyes or airways than for places in which the workload is balanced, while indoor playgrounds might need other AFs due to physical workload and affected groups of the general population.

Laboratory Test Results in Patients with Workplace Moisture Damage Associated Symptoms—The SAMDAW Study

The mechanisms of health effects of moisture damage (MD) are unclear, but inflammatory responses have been suspected. The usefulness of laboratory and allergy tests among patients in secondary healthcare with symptoms associated with workplace MD were examined. Full blood count, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), total serum immunoglobulin E (IgE), fractional exhaled nitric oxide (FeNO), and skin prick testing were assessed and analyzed in relation to multiple chemical sensitivity (MCS) and perceived stress in 99 patients and 48 controls. In analysis, t-tests, Mann-Whitney tests, and chi-squared tests were used. Minor clinically insignificant differences in blood counts were seen in patients and controls, but among patients with asthma an elevated neutrophil count was found in 19% with and only in 2% of patients without asthma (p = 0.003). CRP levels and ESR were low, and the study patients’ FeNO, total IgE, or allergic sensitization were not increased compared to controls. The level of stress was high among 26% of patients and 6% of controls (p = 0.005), and MCS was more common among patients (39% vs. 10%, p < 0.001). Stress or MCS were not significantly associated with laboratory test results. In conclusion, no basic laboratory or allergy test results were characteristic of this patient group, and neither inflammatory processes nor allergic sensitization were found to explain the symptoms among these patients. While the value of basic laboratory tests should not be ignored, the use of allergy tests does not seem necessary when symptoms are indicated to be workplace-related.

Multiple Chemical Sensitivity in Patients Exposed to Moisture Damage at Work and in General Working-Age Population-The SAMDAW Study

A considerable proportion of patients having respiratory tract or voice symptoms associated with workplace moisture damage (MD) could have multiple chemical sensitivity (MCS). MCS is characterized by symptoms of different organ systems in association with low-level chemical exposure. The objective of this study was to assess the prevalence of MCS among patients referred to secondary health care because of respiratory or voice symptoms associated with workplace MD compared to the general working-age population. Using three subscales of the QEESI© questionnaire, we assessed MCS in the study patients and 1500 controls in the same district randomly selected from the Finnish Population Information System. Study patients had significantly more often high scores in chemical intolerance (39% vs. 23%, p = 0.001), symptom severity (60% vs. 27%, p < 0.001), and life impact subscales (53% vs. 20%, p < 0.001). Asthma, chronic rhinosinusitis, laryngeal problems, and atopy were not associated with the presence of MCS. MCS is common among patients referred to secondary health care with respiratory tract and/or voice symptoms associated with workplace MD, and it considerably affects their everyday life. MCS should be considered as a possible explanatory factor for MD-associated symptoms.

Low-grade systemic inflammation and the workplace

BACKGROUND

Psychosocial and physical stressors can elicit the stress response, co-ordinated by interactions between neuroendocrine and inflammatory processes. The central role of the immune system, specifically low-grade systemic inflammation, is sometimes overlooked in work-related stress research.

OBJECTIVE

To review evidence that work-related psychosocial and physical stressors can stimulate a low-grade systemic inflammation which, through interactions with the neurohormonal systems, may impact on the well-being and productivity of workers.

METHODS

Literature searches were performed by databases and by hand. Databases used included Interface - EBSCOhost Research Databases; PsycINFO; Academic Search Complete; Africa-Wide Information; CINAHL; E-Journals; MEDLINE and PsycARTICLES.

RESULTS

Psychosocial stressors, infections, poor indoor air quality, musculoskeletal injuries and chemicals can stimulate a low-grade systemic inflammation that may adversely affect workers' mental and physical health, as well as productivity. The psychological and physical effects caused by infection-induced inflammation are generally referred to as sickness behaviour and those caused by poor indoor air quality as sick building syndrome.

CONCLUSIONS

Stressor-induced low-grade systemic inflammation can be a causal factor in the physical and behavioural symptoms of work-related stress. It is therefore important that those involved with the health of workers be cognisant of inappropriate or chronic low-grade inflammation as a potential health hazard.

PON1 polymorphisms can predict generalized anxiety and depressed mood in patients with multiple chemical sensitivity

Background: Multiple chemical sensitivity (MCS) is a chronic condition with somatic, cognitive and affective symptoms that follow contact with chemical agents at usually non toxic concentrations. We aimed to assess the role of genetic polymorphisms involved in oxidative stress on anxiety and depression in MCS. Materials & methods: Our study investigated the CAT rs1001179, MPO rs2333227, PON1 rs662 and PON1 rs705379 polymorphisms in MCS. Results: The AG genotype of the PON1 rs662 and the TT and CT genotypes of the PON1 rs705379 were involved in anxiety and depression. Discussion: These results are in line with existing evidence of PON1 involvement in MCS and suggest a further role of this gene in the exhibition of anxiety and depression in this disease.

Chemical Intolerance Is Associated With Altered Response Bias, not Greater Sensory Sensitivity

Chemical intolerance is a surprisingly prevalent condition or affliction characterized by adverse reactions to low levels of chemical, often odorous stimulation. Sufferers often assume that their plight is due to an uncommon sensory acuteness, yet studies repeatedly fail to reveal altered detection thresholds. Here, we investigated whether self-reported chemical intolerance is associated with altered sensory sensitivity or response bias. The sensory acuity (sensitivity; A) and sensory decision rule (criterion; B) to n-butanol was assessed using the method of constant stimuli in 82 participants with different degrees of chemical intolerance (low to high). Higher self-reported chemical intolerance was associated with a lower criterion, but not with sensitivity.

Chemical intolerance: involvement of brain function and networks after exposure to extrinsic stimuli perceived as hazardous

Background

Chemical intolerance (CI) is a chronic condition characterized by recurring and severe symptoms triggered by exposure to low levels of odorous or pungent substances. The etiology of CI has been a controversial subject for a long time. The aim of this review is to summarize findings on the neurological processing of sensory information during and after exposure to low levels of odorous or pungent substances in individuals with CI, focusing on the brain function and networks.

Methods

Scientific studies on CI published between 2000 and 2019 in academic peer-reviewed journals were systematically searched using medical and scientific literature databases. Only peer-reviewed articles reporting original research from experimental human studies directly associated with CI, and involving related neurological responses or brain imaging after exposure to odorous or pungent substances (i.e., in chemical provocation tests), were considered.

Results

Forty-seven studies were found to be eligible for a full-text review. Twenty-three studies met the selection criteria and were included in this review. Evidence indicated that differences between subjects with CI and healthy controls were observed by brain imaging during and after exposure to odorous or pungent substances. Differences in brain imaging were also observed between initial exposure and after exposure to these substances. Neurological processing of sensory information after exposure to extrinsic stimuli in the limbic system and related cortices were altered in subjects with CI. A previous documentable exposure event was likely to be involved in this alteration.

Conclusions

This review documents consistent evidence for the altered neurological processing of sensory information in individuals with CI. Further neurophysiological research exploring the processing of extrinsic stimuli and cognition of sensation through the limbic system and related cortices in CI, and the appearance of symptoms in individuals with CI, are required.

Comorbidity of Airway Inflammatory Diseases in Chemical and Building-Related Intolerance

OBJECTIVES

This study investigated comorbidity in chemical intolerance (CI) and building- related intolerance (BRI) with (i) chronic sinusitis, chronic obstructive pulmonary disease, allergic and nonallergic asthma and allergic rhinitis, and (ii) airway inflammatory symptoms.

METHODS

Data from two population-based questionnaire surveys, the Västerbotten and Österbotten Environmental Health Studies, were used. The participants were categorized as CI or BRI and referents, and binary logistic regression analysis was applied.

RESULTS

Prevalence rates for the case groups were 7.2% to 40.0% for diseases and 24.3% to 68.9% for symptoms, whereas adjusted odds ratios (ORs) were 3.4 to 26.1 for diseases and 3.3 to 17.0 for symptoms, all being significantly higher than unity. Prevalence rates and ORs were in general higher in BRI than in CI.

CONCLUSION

Inflammatory airway diseases and symptoms are associated with CI and BRI, which encourages further research regarding underlying mechanisms and treatments.

Multiple Chemical Sensitivity: Review of the State of the Art in Epidemiology, Diagnosis, and Future Perspectives

OBJECTIVE

Systematic bibliography analysis of about the last 17 years on multiple chemical sensitivity (MCS) was carried out in order to detect new diagnostic and epidemiological evidence. The MCS is a complex syndrome that manifests as a result of exposure to a low level of various common contaminants. The etiology, diagnosis, and treatment are still debated among researchers.

METHOD

Querying PubMed, Web of Science, Scopus, Cochrane library, both using some specific MESH terms combined with MESH subheadings and through free search, even by Google.

RESULTS

The studies were analyzed by verifying 1) the typology of study design; 2) criteria for case definition; 3) presence of attendances in the emergency departments and hospital admissions, and 4) analysis of the risk factors.

OUTLOOK

With this review, we give some general considerations and hypothesis for possible future research.

Repeated pulmonary exposures to zinc ions enhance inflammatory responses to subsequent metal exposures

AIM OF STUDY

Metal contaminants contribute to adverse human health effects via acute and chronic exposures. Acute metal exposures followed by prolonged secondary metal exposures may elicit exaggerated inflammatory responses in certain individuals. The aim of this study is to determine whether repeated pulmonary exposures to zinc chloride (ZnCl₂) alter subsequent responses to zinc or cerium exposures.

MATERIALS AND METHODS

Rats were intratracheally (IT) instilled with physiologic saline (n = 24) or 0.05 mg/kg ZnCl₂ (n = 16) twice weekly for 4 weeks. Four days after last dosing, the saline group was divided into three subgroups, each IT-instilled with either saline, ZnCl₂ or CeCl₃ (both at 0.1 mg/kg). The ZnCl₂ pre-instilled rats were divided into two subgroups, each instilled with 0.1 mg/kg ZnCl₂ or CeCl₃. Biomarkers of lung injury/inflammation were assessed in bronchoalveolar lavage (BAL) fluid collected 24 hours later. Oxidative stress was evaluated as total and reduced glutathione in BAL.

RESULTS

Increases in inflammatory cells, LDH, albumin, leptin, MCP-1, IP-10, fractalkine, TNFα and RANTES were observed in rats instilled with multiple PBS and then with 0.1 mg/kg ZnCl₂ and CeCl₃. However, rats pre-exposed repeatedly to 0.05 mg/kg ZnCl₂ and then challenged with 0.1 mg/kg ZnCl₂ or CeCl₃ showed even more eosinophils, lymphocytes, and increased concentrations of hemoglobin and MIP-1α. Significant reduction in GSH/GSSG ratios in BAL in response to all ZnCl₂ or CeCl₃ exposures indicated oxidative stress.

CONCLUSION

Previous exposure to zinc ions increases responsiveness to subsequent exposures to zinc and cerium ions. These findings suggest enhanced sensitization possibly due to a reduction in antioxidant defenses.

Building-Related Environmental Intolerance and Associated Health in the General Population

People frequently attribute adverse symptoms to particular buildings when exposure to pollutants is low, within nonhazardous levels. Our aim was to characterize building-related intolerance (BRI) in the general population. Data were derived from two population-based questionnaire surveys, the Västerbotten and Österbotten Environmental Health Study. We identified cases of BRI if respondents reported symptoms emerging from residing in certain buildings, when most other people had none. The questionnaires covered lifestyle factors, perceived general health, BRI duration and symptom frequency, the emotional and behavioral impact of BRI, coping strategies, and physician-diagnosed diseases. From the total of 4941 participants, we formed two case groups, 275 (5.6%) fulfilled criteria for self-reported BRI, and 123 (2.5%) for BRI with wide-ranging symptoms. Individuals in both case groups were significantly more often female, single, and perceived their general health as poorer than the referents, i.e., those reporting no BRI symptoms. The mean duration of BRI was 12 years. In both case groups, avoidance behavior was found in over 60%, and nearly half of the sample had sought medical care. BRI with wide-ranging symptoms was associated with elevated odds for all studied comorbidities (somatic and psychiatric diseases and functional somatic syndromes). The perceived health of individuals with BRI is poorer and comorbidities are more frequent than among referents. BRI seems to be similar to other environmental intolerances and shares features with functional somatic syndromes.

Levels of oxylipins, endocannabinoids and related lipids in plasma before and after low-level exposure to acrolein in healthy individuals and individuals with chemical intolerance

Oxylipins and endocannabinoids play important biological roles, including effects upon inflammation. It is not known whether the circulating levels of these lipids are affected by inhalation of the environmental pollutant acrolein. In the present study, we have investigated the consequences of low-level exposure to acrolein on oxylipin, endocannabinoid and related lipid levels in the plasma of healthy individuals and individuals with chemical intolerance (CI), an affliction with a suggested inflammatory origin. Participants were exposed twice (60min) to heptane and a mixture of heptane and acrolein. Blood samples were collected before exposure, after and 24h post-exposure. There were no overt effects of acrolein exposure on the oxylipin lipidome or endocannibinoids detectable in the bloodstream at the time points investigated. No relationship between basal levels or levels after exposure to acrolein and CI could be identified. This implicates a minor role of inflammatory mediators on the systemic level in CI.

Gene expression profiling in persons with multiple chemical sensitivity before and after a controlled n-butanol exposure session

OBJECTIVES

To investigate the pathophysiological pathways leading to symptoms elicitation in multiple chemical sensitivity (MCS) by comparing gene expression in MCS participants and healthy controls before and after a chemical exposure optimised to cause symptoms among MCS participants.The first hypothesis was that unexposed and symptom-free MCS participants have similar gene expression patterns to controls and a second hypothesis that MCS participants can be separated from controls based on differential gene expression upon a controlled n-butanol exposure.

DESIGN

Participants were exposed to 3.7 ppm n-butanol while seated in a windowed exposure chamber for 60 min. A total of 26 genes involved in biochemical pathways found in the literature have been proposed to play a role in the pathogenesis of MCS and other functional somatic syndromes were selected. Expression levels were compared between MCS and controls before, within 15 min after being exposed to and 4 hours after the exposure.

SETTINGS

Participants suffering from MCS and healthy controls were recruited through advertisement at public places and in a local newspaper.

PARTICIPANTS

36 participants who considered themselves sensitive were prescreened for eligibility. 18 sensitive persons fulfilling the criteria for MCS were enrolled together with 18 healthy controls.

OUTCOME MEASURES

17 genes showed sufficient transcriptional level for analysis. Group comparisons were conducted for each gene at the 3 times points and for the computed area under the curve (AUC) expression levels.

RESULTS

MCS participants and controls displayed similar gene expression levels both at baseline and after the exposure and the computed AUC values were likewise comparable between the 2 groups. The intragroup variation in expression levels among MCS participants was noticeably greater than the controls.

CONCLUSIONS

MCS participants and controls have similar gene expression levels at baseline and it was not possible to separate MCS participants from controls based on gene expression measured after the exposure.

Experiences of persons with multiple chemical sensitivity with mental health providers

In this paper, we summarize the results of an online survey of persons in the United States with chemical intolerance/multiple chemical sensitivity who sought help from mental health providers, including counselors, psychologists, psychiatrists, and others. Respondents reported on their most recent contact with a provider, describing reasons for the contact, accommodations requested and received, and suggestions for how the experience could be more helpful. Overall, though clients were accommodated in small ways, some received no accommodation, and many felt that the providers needed to be more knowledgeable regarding chemical intolerance. Results are discussed in terms of the importance of providers becoming more aware of multiple chemical sensitivity and more willing to make their services accessible to these clients.