Hans Petter Hougen

Chronic Pseudomonas aeruginosa lung infection is more severe in Th2 responding BALB/c mice compared to Th1 responding C3H/HeN mice

The chronic Pseudomonas aeruginosa lung infection in cystic fibrosis (CF) is characterized by a pronounced antibody response and microcolonies surrounded by numerous polymorphonuclear neutrophils (PMN). Poor prognosis is correlated with a high antibody response to P. aeruginosa antigens. An animal model of this infection was established in two strains of mice: C3H/HeN and BALB/c, generally known as Th1 and Th2 responders, respectively, which were challenged with alginate‐embedded P. aeruginosa. Mortality was significantly lower in C3H/HeN compared to BALB/c mice (p<0.025). P. aeruginosa was cleared more efficiently in C3H/HeN mice and significantly more C3H/HeN mice showed normal lung histopathology (p<0.02), and we found significantly fewer microabscesses in C3H/HeN mice than in BALB/c mice (p<0.005). In supernatants from P. aeruginosa antigen and concanavalin A‐stimulated spleen cells from the two strains of mice, the interferon‐ (IFN‐) γ levels were higher, whereas IL‐4 levels were lower in C3H/HeN mice than in BALB/c mice. The implications of these findings for CF patients with chronic P. aeruginosa lung infection are discussed.

Homicide by sharp force in two Scandinavian capitals

In the Oslo and Copenhagen capital areas, 141 homicides by sharp force were committed in the ten-year period 1985-1994. This method accounted for 33% of the homicides in this period. Thirty-five percent of the victims were female, and most of the victims were between 20 and 50 years of age. The majority of the male victims were killed by an acquaintance, the females by their spouse. Sixty-five percent of the male and 37% of the female victims had alcohol in their blood. The majority of the female victims had lesions in 3-4 anatomical regions, while the males most often had lesions in only one anatomical region. Seventy-nine percent of the females and 36% of the males had self-defence injuries in the upper extremities. In 21 cases (15%) the offender was a woman, 19 of their victims being male; the weapon in these cases was most often a kitchen knife. Seventy-eight percent of the females and 49% of the males were killed in their own home. The most common circumstance was family row when the victim was female, while a fight was the most common circumstance when the victim was male. Three offenders committed suicide after having committed homicide(s) (seven victims; three offenders).

Early immune response in susceptible and resistant mice strains with chronic Pseudomonas aeruginosa lung infection determines the type of T‐helper cell response

Most cystic fibrosis (CF) patients become chronically infected with Pseudomonas aeruginosa in the lungs. The infection is characterized by a pronounced antibody response and a persistant inflammation dominated by polymorphonuclear neutrophils. Moreover a high antibody response correlates with a poor prognosis. We speculated that a change from this Th2‐like response to a Th1‐like response might decrease the lung inflammation and thus improve the prognosis in CF patients. To investigate this, we infected C3H/HeN and BALB/c mice intratracheally with P. aeruginosa. In addition, we studied the early immune response leading to different Th responses. Mortality was lower in the C3H/HeN mice (p<0.005), they cleared the bacteria faster (day 3 p<0.01, day 7 p<0.02), had a milder lung inflammation (day 7 p<0.01, day 14 p<0.0005) and had a Th1‐like IgG subclass switch. At day 3, the C3H/HeN mice produced less NO and TNF‐α, (p<0.01 and p<0.03) and had the lowest IL‐10/IL12 ratio (p<0.05). At day 7, the C3H/HeN mice had the highest IFN‐γ (p<0.02), and the lowest IL‐4 (p<0.02) production in the lungs. In conclusion, these results show that the Th1‐reacting C3H/ HeN mice with chronic P. aeruginosa lung infection have a better disease outcome compared to the Th2‐reacting BALB/c mice, indicating that a Th1 response might be beneficial in CF patients with chronic P. aeruginosa lung infection.

Chronic Pseudomonas aeruginosa lung infection in normal and athymic rats

We have compared a chronic lung infection with Pseudomonas aeruginosa embedded in alginate beads in normal and athymic rats with an acute infection with free live P. aeruginosa bacteria. The following parameters were observed and described: mortality, macroscopic and microscopic pathologic changes, and antibody responses. The rats challenged with P. aeruginosa alginate beads experienced a generally more severe lung pathology and the antibody responses were more homogeneous with less dispersion as compared to the rats having free live P. aeruginosa bacteria. In general, manifestations were more severe in the athymic rats compared to the normal rats. It is, however, notable that the athymic rats developed similar microscopic lung manifestations as the normal rats when given a large number of P. aeruginosa in the beads, with dense accumulation of neutrophil granulocytes and microcolonies comparable to the lesions seen in cystic fibrosis (CF) patients. Early transitory IgM titers were demonstrated in both normal and athymic rats. Whilst athymic rats produced much lower IgG titers than the normal rats, presumably due to the absence of CD4+ cells, higher primary IgA titers were achieved. These two models in normal and athymic rats of the chronic lung infection resembling that seen in CF lungs make it possible to study the influence of the various components of the specific and nonspecific defence systems on the course of the chronic P. aeruginosa lung infection and to evaluate the effect of various immunization schedules and immunomodulatory drugs.

Physical and psychological sequelae to torture. A controlled clinical study of exiled asylum applicants

The study comprised 24 male Lebanese refugees living in Denmark. Twelve of them alleged having been tortured in Lebanon during the period 1981-85. The remaining twelve had neither been imprisoned nor tortured and thus acted as control persons. All the testimonies were found to be valid according to a method previously used by the author. The most common forms of torture were blows against the head, body and foot soles, suspension and asphyxiation. Threats and solitary confinement were frequent, and sexual violations were also reported. At the time of examination (March-November 1986), the main complaints were headaches, various cardiopulmonary symptoms, sleep disturbances with nightmares, impaired concentration and memory, and emotional lability. Suicide attempts were reported. Prior to the torture all the probands had been healthy except for several cases of gunshot wounds. The clinical examination revealed different scars possibly related to torture in nearly all the cases. Missing or fractured teeth, peripheral nerve damage and mental depression were also found. The 12 controls had several mental and physical complaints, but significantly fewer than the probands. Almost all of them had scars from gunshot wounds. The present study clearly indicates that torture plus exilation has a more deteriorating effect on the health status than exilation alone.

Sequelae to torture. A controlled study of torture victims living in exile

Twenty-eight Turkish refugees living in Denmark were examined by the authors in the period 1984-85. Fourteen of the persons alleged having been tortured in Turkey during the period 1980-83. The remaining 14 persons reported that they had not been tortured and thus acted as controls. All the testimonies were found valid according to a method previously used by us. The most common forms of violence reported were blows and electrical torture. Blindfolding, solitary confinement and threats were also frequent. At the time of examination the main mental complaints were sleep disturbances with nightmares and impaired memory. Emotional lability and concentration disturbances were also frequent. Physically the torture victims suffered from headache, various cardio-pulmonary and muscular pains, dyspepsia and reading disturbances. All reported that they had been healthy before torture. The clinical examination revealed only a few signs related to torture, although examples of minimal scars, fractured or missing teeth, discrete neurological disorders and mental depression were found. The 14 controls had significantly fewer complaints, and almost no abnormalities were found during the clinical examination. The present study clearly demonstrates the traumatic effects of torture.

Homicides in two Scandinavian capitals

In this study we investigated homicides in the two Scandinavian capitals, Copenhagen, Denmark and Oslo, Norway, for the 10-year period from 1985 to 1994. The total number of homicides was 431; 63.8% occurred in Copenhagen and 36.2% in Oslo. The average homicide rate was 1.6/100,000 in Copenhagen and 1.8/100,000 in Oslo. Blunt force, sharp force, and strangulation were the most common methods. Firearms were also used but did not account for >20% in either of the two cities. This is probably due to strict gun laws in both countries. There was no clear difference between the homicide victim populations in the two cities with regard to age, gender, or social and marital status. The proportion of alcoholics and unemployed persons was much higher than in the background population and to a similar extent in both cities, indicating that the homicide victim populations differ from the background populations. The perpetrator knew the victim in the majority of the cases. The most frequent motives or circumstances in both cities were fights, family rows, financial controversies, or jealousy.

Pseudomonas aeruginosa biofilm aggravates skin inflammatory response in BALB/c mice in a novel chronic wound model

Chronic wounds are presumed to persist in the inflammatory state, preventing healing. Emerging evidence indicates a clinical impact of bacterial biofilms in soft tissues, including Pseudomonas aeruginosa (PA) biofilms. To further investigate this, we developed a chronic PA biofilm wound infection model in C3H/HeN and BALB/c mice. The chronic wound was established by an injection of seaweed alginate‐embedded P. aeruginosa PAO1 beneath a third‐degree thermal lesion providing full thickness skin necrosis, as in human chronic wounds. Cultures revealed growth of PA, and both alginate with or without PAO1 generated a polymorphonuclear‐dominated inflammation early after infection. However, both at days 4 and 7, there were a more acute polymorphonuclear‐dominated and higher degree of inflammation in the PAO1 containing group (p < 0.05). Furthermore, PNA‐FISH and supplemented DAPI staining showed bacteria organized in clusters, resembling biofilms, and inflammation located adjacent to the PA. The chronic wound infection showed a higher number of PAO1 in the BALB/c mice at day 4 after infection as compared to C3H/HeN mice (p < 0.006). In addition, a higher concentration of interleukin‐1beta in the chronic wounds of BALB/c mice was observed at day 7 (p < 0.02), despite a similar number of bacteria in the two mouse strains. The present study succeeded in establishing a chronic PA biofilm infection in mice. The results showed an aggravating impact of local inflammation induced by PA biofilms. In conclusion, our findings indicate that improved infection control of chronic wounds reduces the inflammatory response and may improve healing.

Novel experimental Pseudomonas aeruginosa lung infection model mimicking long-term host–pathogen interactions in cystic fibrosis

The dominant cause of premature death in patients suffering from cystic fibrosis (CF) is chronic lung infection with Pseudomonas aeruginosa. The chronic lung infection often lasts for decades with just one clone. However, as a result of inflammation, antibiotic treatment and different niches in the lungs, the clone undergoes significant genetic changes, resulting in diversifying geno‐ and phenotypes. Such an adaptation may generate different host responses. To experimentally reflect the year‐long chronic lung infection in CF, groups of BALB/c mice were infected with clonal isolates from different periods (1980, 1988, 1997, 1999 and 2003) of the chronic lung infection of one CF patient using the seaweed alginate embedment model. The results showed that the non‐mucoid clones reduced their virulence over time, resulting in faster clearing of the bacteria from the lungs, improved pathology and reduced pulmonary production of macrophage inflammatory protein‐2 (MIP‐2) and granulocyte colony‐stimulating factor (G‐CSF). In contrast, the mucoid clones were more virulent and virulence increased with time, resulting in impaired pulmonary clearing of the latest clone, severe inflammation and increased pulmonary MIP‐2 and G‐CSF production. In conclusion, adaptation of P. aeruginosa in CF is reflected by changed ability to establish lung infection and results in distinct host responses to mucoid and non‐mucoid phenotypes.

Faster activation of polymorphonuclear neutrophils in resistant mice during early innate response to Pseudomonas aeruginosa lung infection.

Polymorphonuclear neutrophils (PMNs) are crucial for the outcome of Pseudomonas aeruginosa lung infection in patients with cystic fibrosis. We compared PMNs and inflammatory cytokines in the lungs and blood from susceptible BALB/c and resistant C3H/HeN mice 1 and 2 days after intratracheal challenge with alginate embedded P. aeruginosa. These parameters were correlated with the quantitative bacteriology and histopathology of the lungs. After challenge, the content of granulocyte colony‐stimulating factor (G‐CSF) and macrophage inflammatory protein‐2 (MIP‐2) was increased in the lungs and the sera and the percentage of PMNs was increased in the blood. However, 2 days after challenge the concentration of G‐CSF and MIP‐2 was higher in the lungs and sera of BALB/c mice. CD11b expression was higher on the PMNs of the C3H/HeN mice. The expression of CD62L on PMNs of both strains of mice was decreased 1 day after bacterial challenge, whereas the expression was increased after 2 days of challenge on PMNs of C3H/HeN mice only. These changes were accompanied by a more severe lung inflammation in BALB/c mice and faster clearance of the bacteria in C3H/HeN mice. In conclusion, the rapid early bacterial clearance in the lungs of C3H/HeN mice could be explained by faster activation of the PMNs, as indicated by the higher up‐regulation of CD11b. The severe lung inflammation in BALB/c mice may be caused by the early higher content of G‐CSF in the sera mobilizing PMNs from the bone marrow and the persistent chemotactic gradient provided by MIP‐2 in the lungs.