Epidemiological characteristics of acute hepatitis A, 2013-2016: a cross-sectional study in Morocco

BACKGROUND

Hepatitis A virus (HAV) is the common cause of acute hepatitis worldwide. Indeed, hepatitis A is endemic in developing countries such in Morocco and most residents are exposed in childhood. The characterisation of circulating strains of HAV remains crucial to understand the virological evolution and geo-temporal characteristics, which are essential for controlling infections and outbreaks. The purpose of the current study was the detection and characterisation of HAV strains circulating in Morocco by performing serological test, RT-PCR, sequencing and phylogenetic analysis.

METHODS

In this cross-sectional study, 618 suspected acute hepatitis cases were examined by Architect HAV abIgM. Of the 162 positives, 64 underwent RNA extraction. None of the suspected cases was immune to HAV and none of them had received a blood transfusion. Samples found positive by RT-PCR using primers targeting the VP1/VP2A junction and the VP1/VP3 capsid region of HAV were subjected to sequencing and phylogenetic analyses.

RESULTS

HAV Acute infection rate was 26.2% [95% CI, 22.8-29.9], while viraemia reached 45% (29/64) after amplification of the VP3/VP1 region. Phylogenetic analysis of the VP1/2A segment revealed the presence of sub-genotypes IA and IB. Eighty-seven percent of the strains belonged to the subgenotype IA, while twelve percent to IB subgenotype.

CONCLUSION

This first molecular study of acute hepatitis A in Morocco provided information about genetic diversity of HAV, revealing the co-circulating of only two subgenotypes (IA and IB). Notably, subgenotype IA was found to be the predominant subgenotype in Morocco.

Kinetics of specific anti-SARS-CoV-2 IgM, IgA, and IgG responses during the first 12 months after SARS-CoV-2 infection: A prospective longitudinal study

Coronavirus 2019 (COVID-19) is a global health threat. The kinetics of antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) need to be assessed, as the long-term duration of these immunoglobulins remains largely controversial. The aim of this study was to assess the longitudinal dynamics of anti-SARS-CoV-2 antibodies against the nucleocapsid (N) protein and the receptor-binding domain (RBD) of the spike protein up to one year in a cohort of 190 COVID-19 patients. Between March and September 2021, we enrolled patients from two regional hospitals in Casablanca, Morocco. Blood samples were collected and analyzed for antibody levels. We used the commercial Euroimmun ELISA for the determination of anti-N IgM, the Abbott Architect™ SARS-CoV-2 IgG test for the detection of anti-RBD IgG, and an in-house kit for the assay of anti-N IgG and anti-N IgA. IgM and IgA antibodies were assessed 2-5, 9-12, 17-20 and 32-37 days after symptom onset. IgG antibodies were also assessed 60, 90, 120 and 360 days after symptom onset. One-third of patients developed IgM (32%), while two-thirds developed IgA (61%). One month of symptom onset, most patients developed IgG, with 97% and 93% positivity for anti-RBD IgG and anti-N IgG, respectively. The anti-RBD IgG positivity rate remained high up to one year of follow-up. However, the anti-N IgG positivity rate decreased over time, with only 41% of patients testing positive after one year's follow-up. IgG levels were significantly higher in older people (over 50 years) than in other study participants. We also found that patients who had received two doses of ChAdOx1 nCoV-19 vaccine prior to infection had a lower IgM response than unvaccinated patients. This difference was statistically significant two weeks after the onset of symptoms. We present the first study in Africa to measure the kinetics of antibody response (IgA, IgM and IgG) to SARS-CoV-2 over one year. Most participants remained seropositive for anti-RBD IgG after one year but showed a significant decline in antibody titers.

CXCL-8 as a signature of severe Helicobacter pylori infection and a stimulator of stomach region-dependent immune response

Helicobacter pylori infection is involved in development of diverse gastro-pathologies. Our aim is to investigate potential signature of cytokines-chemokine levels (IL-17A, IL-1β, and CXCL-8) in H. pylori-infected patients and their impact on immune response in both corpus and antrum. Multivariate level analysis with machine learning model were carried out using cytokines/chemokine levels of infected Moroccan patients. In addition, Geo dataset was used to run enrichment analysis following CXCL-8 upregulation. Our analysis showed that combination of cytokines-chemokine levels allowed prediction of positive H. pylori density score with <5% of miss-classification error, with fundus CXCL-8 being the most important variable for this discrimination. Furthermore, CXCL-8 dependent expression profile was mainly associated to IL6/JAK/STAT3 signaling in the antrum, interferons alpha and gamma responses in the corpus and commonly induced transcriptional /proliferative activities. To conclude, CXCL-8 level might be a signature of Moroccan H. pylori-infected patients and an inducer of regional-dependent immune response at the gastric level. Larger trials must be carried out to validate the relevance of these results for diverse populations.

Type I and III interferons are good markers to monitor COVID-19 pathophysiology

The COVID-19 pandemic has caused millions of deaths and has resulted in disastrous societal and economic impacts worldwide. During SARS-CoV-2 infection, abnormal levels of pro-inflammatory cytokines have been observed and were associated to the severity of the disease. Type I (-α/β) and Type III (IFN-λ) interferons are family members of cytokines that play an important role in fighting viral replication during the early phases of infection. The location and timing of the IFNs production have been shown to be decisive for the COVID-19 outcome. Despite the effectiveness of COVID-19 vaccines and with the emergence of new SARS-CoV-2 variants, a better understanding of the involvement of IFNs as players in antiviral immunity in the COVID-19 pathophysiology is necessary to implement additional potent prophylactic and/or therapeutic approaches. In this study, we investigated the role of type I and III IFN in COVID-19 pathophysiology. We first analyzed the IFN-α, IFN-β and IFN- λ mRNA expression in nasopharyngeal swabs and blood samples from Moroccan patients infected with SARS-CoV-2 and secondly correlated these IFNs expressions with COVID-19 clinical and biological parameters. Our results showed that in the upper airways of patients with mild, non-severe, or severe COVID-19 manifestations, the IFN- α, - β and - λ are expressed in the same manner as in controls. However, in blood samples their expression was downregulated in all groups. Univariate linear models with interferons as predictors to evaluate clinical-biological parameters highlighted that the main clinical-biological relations were found when testing: FiO2, Lymphocyte values and virus load. Furthermore, the multivariate models confirmed that quantifications of interferons during COVID-19 are good biological markers for tracking COVID-19 pathophysiology.

Therapeutic Potential of Clove Essential Oil in Diabetes: Modulation of Pro-Inflammatory Mediators, Oxidative Stress and Metabolic Enzyme Activities

Type 1 diabetes is characterized by insulin deficiency due to the destruction of pancreatic β cells, leading to hyperglycemia, which in turn induces vascular complications. In the current study, we investigated the effect of intraperitoneal administration of clove essential oil (CEO: 20 mg/kg body weight) on certain oxidative stress and glucose metabolism enzymes, as well as the expression of proinflammatory mediators. Administration of CEO to diabetic rats showed a significant decline in blood glucose levels, total cholesterol, and xanthine oxidase, compared to the streptozotocin group. Furthermore, these treated rats elicited a notable attenuation in the levels of lipid peroxides, and thiols groups in both liver and brain tissues. The activities of antioxidant and metabolic enzymes were reverted to normality in diabetic upon CEO administration. In addition to its protective effects on red blood cell hemolysis, CEO is a potent α-amylase inhibitor with an IC₅₀ =298.0±2.75 μg/mL. Also, treatment of diabetic rats with CEO significantly reduced the iNOS expression in the spleen. Our data showed that CEO has potential beneficial effects on diabetes, which can possibly prevent the pathogenesis of diabetic micro- and macrovascular complications.

IL-1 Polymorphism and Helicobacter pylori Infection Features: Highlighting VNTR's Potential in Predicting the Susceptibility to Infection-Associated Disease Development

Genetic polymorphisms at the IL-1 cluster are associated with increased Helicobacter pylori (H. pylori)-associated disease risk in an ethnically dependent manner. Due to the corroborated role of IL-1β in H. pylori infection progression, our aim is to depict the impact of IL1B rs1143627 and rs16944 as well as the IL1RN variable number of identical tandem repeats (VNTR) on the clinical and biological features of Moroccan H. pylori-infected patients. A total of 58 patients with epigastralgic pain were referred to the gastroenterology department for histopathological and clinical analysis. DNA extraction from antrum and fundus biopsies and PCR-RFLP were performed to detect polymorphisms. As a result, VNTR was significantly associated with IL-1β antrum levels (p-value = 0.029), where the *1/*4 genotype showed a positive association with upregulated cytokine levels in the antrum and was clustered with H. pylori-infected patients' features and higher levels of IL-1β in the antrum and fundus. Likewise, *1/*1 genotype carriers clustered with severe gastritis activity and H. pylori density scores along with low levels of IL-1β in the antrum and fundus, while the *1/*2 genotype was clustered with non-infected-patient features and normal IL-1β levels. In conclusion, VNTR might be an interesting predictor to identify patients at risk of developing H. pylori-associated pathologies.

Kinetics of SARS-CoV-2 IgM and IgG Antibodies 3 Months after COVID-19 Onset in Moroccan Patients

Coronavirus disease (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) poses serious global public health problems. Characterization of the immune response, particularly antibodies to SARS-CoV-2, is important for establishing vaccine strategies. The purpose of this study was to evaluate longitudinally the kinetics of anti-SARS-CoV-2 antibodies against spike protein (S1) for up to 3 months in a cohort of 169 COVID-19 patients. We enrolled COVID-19 patients at two regional hospitals in Casablanca, Morocco, between March and September 2021. Blood samples were collected and N-specific IgM and S-specific IgG levels were measured by a commercial Euroimmun ELISA. IgM antibodies were assessed 2-5 (D00), 9-12 (D07), 17-20 (D15), and 32-37 (D30) days after symptom onset; IgG antibodies were assessed at these time points plus 60 (D60) and 90 (D90) days after symptom onset. We found that at 3 months after symptom onset, 79% of patients had detectable SARS-CoV-2-specific IgG antibodies, whereas their IgM seropositivity was 19% by 1 month after symptom onset. The IgM level decreased to 0.34 (interquartile range [IQR] 0.19-0.92) at 1 month after symptom onset, whereas the IgG level peaked at D30 (3.10; IQR 1.83-5.64) and remained almost stable at D90 (2.95; IQR 1.52-5.19). IgG levels were significantly higher in patients older than 50 years than in those younger than 50 at all follow-up time points (P < 0.05). Statistical analysis showed no significant difference in median anti-S1 antibody levels among infected patients based on gender or comorbidities. This study provides information on the longevity of anti-SARS-CoV-2 IgM and IgG antibodies in COVID-19 patients.

Inhibiting Human and Leishmania Arginases Using Cannabis sativa as a Potential Therapy for Cutaneous Leishmaniasis: A Molecular Docking Study

Cutaneous leishmaniasis (CL), a vector-borne parasitic disease caused by the Leishmania protozoan, is a serious public health problem in Morocco. The treatment of this disease is still based on pentavalent antimonials as the primary therapy, but these have associated side effects. Thus, the development of effective, risk-free alternative therapeutics based on natural compounds against leishmaniasis is urgent. Arginase, the key enzyme in the polyamine biosynthetic pathway, plays a critical role in leishmaniasis outcome and has emerged as a potential therapeutic target. The objective of this study was to test Cannabis sativa's phytochemical components (cannabinoids and terpenoids) through molecular docking against Leishmania and human arginase enzymes. Our results showed that delta-9-tetrahydrocannabinol (THC) possessed the best binding energies of -6.02 and -6.35 kcal/mol with active sites of Leishmania and human arginases, respectively. Delta-9-THC interacted with Leishmania arginase through various amino acids including His139 and His 154 and linked to human arginase via His 126. In addition to delta-9-THC, caryophyllene oxide and cannabidiol (CBD) also showed a good inhibition of Leishmania and human arginases, respectively. Overall, the studied components were found to inhibit both arginases active sites via hydrogen bonds and hydrophobic interactions. These components may serve as therapeutic agents or in co-administrated therapy for leishmaniasis.

Environmental, Climatic, and Parasite Molecular Factors Impacting the Incidence of Cutaneous Leishmaniasis Due to Leishmania tropica in Three Moroccan Foci

Cutaneous leishmaniasis (CL) occurring due to Leishmania tropica is a public health problem in Morocco. The distribution and incidence of this form of leishmaniasis have increased in an unusual way in the last decade, and the control measures put in place are struggling to slow down the epidemic. This study was designed to assess the impact of climatic and environmental factors on CL in L. tropica foci. The data collected included CL incidence and climatic and environmental factors across three Moroccan foci (Foum Jemaa, Imintanout, and Ouazzane) from 2000 to 2019. Statistical analyses were performed using the linear regression model. An association was found between the occurrence of CL in Imintanout and temperature and humidity (r² = 0.6076, df = (1.18), p-value = 3.09 × 10⁻⁵; r² = 0.6306, df = (1.18), p-value = 1.77 × 10⁻⁵). As a second objective of our study, we investigated the population structure of L.tropica in these three foci, using the nuclear marker internal transcribed spacer 1 (ITS1). Our results showed a low-to-medium level of geographic differentiation among the L.tropica populations using pairwise differentiation. Molecular diversity indices showed a high genetic diversity in Foum Jemaa and Imintanout; indeed, 29 polymorphic sites were identified, leading to the definition of 13 haplotypes. Tajima’s D and Fu’s F test statistics in all populations were not statistically significant, and consistent with a population at drift–mutation equilibrium. Further analysis, including additional DNA markers and a larger sample size, could provide a more complete perspective of L. tropica’s population structure in these three regions. In addition, further research is needed to better understand the impact of climatic conditions on the transmission cycle of Leishmania, allowing both for the development of effective control measures, and for the development of a predictive model for this parasitosis.

Tissue tropism: Is it an intrinsic characteristic of Leishmania species?

The genus Leishmania comprises a wide range of species, some of which are pathogenic to humans and each of which has a different tissue preference, resulting in one of the three clinical forms of human leishmaniasis: visceral, cutaneous, or mucocutaneous. Although, all pathogenic species are deposited intradermally in the mammalian host upon an infectious sand fly bite, only the viscerotropic strains can leave the skin and reach the internal organs. We assume that Leishmania tissue tropism is not only the result of Leishmania genetic determinism but is also governed by the interaction of the parasite with different vectorial and human host elements. To shed light on these elements and key steps determining the course of the infection, we describe throughout this review the disease's progression from the early stages of infection taking place in the skin to the late stages succeeding in the parasite's visceral dissemination. Hence, we address the question of Leishmania tropism, through providing relevant hypotheses and answers gathered from the literature.

Targeting IL-1β in patients with advanced Helicobacter pylori infection: a potential therapy for gastric cancer

Helicobacter pylori (H. pylori) infection is a causal factor of gastric cancer. Among the cytokines secreted during this infection, IL-1β is highly associated with promotion and progression of gastric cancer. On the therapeutic front, eradication of H. pylori was thought to be efficient to restore gastric homeostasis. However, successful H. pylori eradication in patients with advanced stages (intestinal metaplasia) failed to diminish inflammation that is due to heightened Th17 response and elevated IL-1β levels. In fact, association between these two components was established, suggesting that IL-1β is a critical target in these cases. In this review, we will discuss the functional relevance of IL-1β in advanced H. pylori infection and how its targeting may bring clinical benefit.

Anti-SARS-CoV-2 Antibody Responses 5 Months Post Complete Vaccination of Moroccan Healthcare Workers

Data about the duration of antibodies after vaccination show that the protection against SARS-CoV-2 infection begins to decline over time. This study aims to determine anti-SARS-CoV-2 anti-S IgG levels in healthcare workers five months after the second vaccination dose. We collected samples from 82 participants who were fully vaccinated with ChAdOx1 nCoV-19 or BBIBP-CorV. We assessed anti-SARS-CoV-2 IgG antibodies using a Euroimmun ELISA and an Abbott Architect ™ SARS-CoV-2 IgG test. Of the 82 participants, 65.85% were seropositive for IgG using ELISA, and 86.59% were positive for IgG according to the Abbott Architect ™ test. Individuals vaccinated with the ChAdOx1 nCoV-19 vaccine had a median anti-S1 antibody level of 1.810 AU/mL [interquartile range (IQR), 1.080-3.7340] and 171.7 AU/mL [79.9-684.6] according to the Euroimmun ELISA and Abbott Architect test, respectively. These tests indicated that people vaccinated with BBIBP-CorV had a median anti-S1 antibody level of 1.840 AU/mL [0.810-2.960] and 126.7 AU/mL [54.9-474.3], respectively. Statistical analysis showed no significant difference between the positivity rates of the vaccinated individuals, either for gender or for age. In addition, we found no significant difference between the two vaccines. Our study provides information on the longevity of the anti-SARS-CoV-2 IgG antibodies in people at least five months after vaccination.

The Modulation of NADPH Oxidase Activity in Human Neutrophils by Moroccan Strains of Leishmania major and Leishmania tropica Is Not Associated with p47phox Phosphorylation

Polymorphonuclear neutrophils (PMNs) are the first phagocyte recruited and infected by Leishmania. They synthetize superoxide anions (O2-) under the control of the NADPH oxidase complex. In Morocco, Leishmania major and L. tropica are the main species responsible for cutaneous leishmaniasis (CL). The impact of these parasites on human PMN functions is still unclear. We evaluated the in vitro capacity of primary Moroccan strains of L. major and L. tropica to modulate PMN O2- production and p47phox phosphorylation status of the NADPH oxidase complex. PMNs were isolated from healthy blood donors, and their infection rate was measured by microscopy. O2- production was measured by superoxide dismutase-inhibitable reduction of cytochrome C. P47phox phosphorylation was analyzed by Western blot using specific antibodies against Ser328 and Ser345 sites. Whereas we did not observe any difference in PMN infectivity rate, our results indicated that only L. tropica promastigotes inhibited both fMLF- and PMA-mediated O2- production independently of p47phox phosphorylation. Leishmania soluble antigens (SLAs) from both species significantly inhibited O2- induced by fMLF or PMA. However, they only decreased PMA-induced p47phox phosphorylation. L. major and L. tropica modulated differently O2- production by human PMNs independently of p47phox phosphorylation. The inhibition of ROS production by L. tropica could be a mechanism of its survival within PMNs that might explain the reported chronic pathogenicity of L. tropica CL.

Serological evidence of West Nile virus infection in human populations and domestic birds in the Northwest of Morocco

West Nile virus (WNV) was recently detected in Culex pipiens mosquitoes in Morocco. The aim of this study was to evaluate the seroprevalence of WNV in humans and in domestic birds in two regions of Morocco by the detection of IgG antibodies. Blood samples were obtained from 91 human patients and 92 domestic birds from September to December 2019. All study samples were tested using competitive enzyme-linked immunosorbent assay (cELISA) and WNV neutralization tests (VNT) were performed on positive sera. Of all samples, 4 (4.39 %) humans and 4 (4.34 %) birds were found to be seropositive for flaviviruses by the cELISA test. The VNT revealed that three of the four human samples detected positive by cELISA contained neutralizing antibodies against WNV. Two bird samples were confirmed positive by VNT. These results show a significant seroprevalence of anti-WNV antibodies and therefore suggest the active circulation and exposure of human and bird populations in the northwest of Morocco.

Entomological study in an anthroponotic cutaneous leishmaniasis focus in Morocco: Fauna survey, Leishmania infection screening, molecular characterization and MALDI-TOF MS protein profiling of relevant Phlebotomus species

In Morocco, leishmaniases are a major public health problem due to their genetic diversity and geographical distribution. Cutaneous leishmaniasis (CL) is an infectious disease caused by various species of Leishmania and transmitted typically by bite of phlebotomine sand flies. This study identifies sand fly fauna in Ibaraghen village, province of Azilal, which is a focus of CL, by combination of morphological and molecular methods (sequencing of COI gene, MALDI-TOF MS protein profiling). Nested-kDNA PCR was used to detect and identify Leishmania species within potential vector species. 432 CDC light traps were placed at different heights above ground level at four capture sites during a whole year. Traps at 1.5 m above the ground yielded capture of sand flies almost double compared to above ground level (29.33%), while the collection reached 55.09% when the traps were placed 2.5 m above ground. A total of 2,830 sand flies were collected, 2,213 unfed specimens were morphologically identified, 990 males (44.73%) and 1,223 females (55.26%) of 13 species; ten Phlebotomus species and three Sergentomyia species. Six species were analysed by MALDI-TOF MS protein profiling (4 Phlebotomus and 2 Sergentomiya species), and their identification was confirmed by COI sequencing. 1,375 unfed females were screened for the presence of Leishmania by nested-kDNA PCR in pools, 11/30 pools of P. sergenti showing a single band of 750 bp corresponding to L. tropica. Our results confirm the role of P. sergenti as a proven vector in Azilal focus of cutaneous leishmaniasis; however, the relative abundance of other species known as vectors of Leishmania species emphasizes the risk of introduction of L. infantum and L. major in this province. For the first time in Morocco, a combined approach to identify sand flies by both morphology and molecular methods based on DNA barcoding and MALDI-TOF MS protein profiling was applied.

The pro-inflammatory cytokines in COVID-19 pathogenesis: What goes wrong?

The outbreak of coronavirus disease 2019 (COVID-19), caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection, has emerged in China in December 2019 and rapidly spread to more than 196 countries worldwide.

The physiopathology of human SARS-CoV-2 has not been completely understood, but its pathogenesis has been linked to a disproportionate response of the immune system. Just as described for SARS and MERS, an uncontrolled systemic inflammatory response, known as cytokine release syndrome (CRS) was observed in severe COVID-19 patients. It results from the release by immune and non-immune effector cells of substantial amounts of pro-inflammatory cytokines and appears to contribute to SARS-CoV-2 pulmonary inflammation and extensive lung damage. In addition, hyper-coagulation and thrombosis resulted from the important release of pro-inflammatory cytokines contribute to the lethality of subjects severely infected with SARS-CoV-2. It is therefore essential to have a deep understanding of the various cytokines involved in this exacerbated immune response, and that could be targeted by potential immunological treatments.

The aim of this review was to gather the current knowledge about the role of pro-inflammatory cytokines, namely IL-1β, IL-6, IL-8, IL-17 and TNFα in SARS-CoV-2 CRS, the probable causes and clinical outcomes of this phenomenon in severe cases of COVID-19.

The role of sampling by cotton swab in the molecular diagnosis of cutaneous leishmaniasis

An appreciated sampling technique is essential for achieving optimum results from diagnostic tests of cutaneous leishmaniasis (CL); conventional sampling methods, such as skin biopsy and dermal scrapping, are painful for the patients and require qualified staff and hospital facilities, while swabbing is patient-friendly more comfortable than invasive traditional techniques and can be carried out under field conditions. The aim of this study is to evaluate a non-invasive sampling method (swab) in the cutaneous leishmaniasis diagnosis, compared to microscopic examination. The recruitment of 205 patients was done during 3 years in six regions known as endemic CL foci in the south-east, the centre, the south-west and the north of Morocco. The results showed that molecular detection of the nuclear marker ITS1 on swab materials is to be less sensitive than microscopic examination, and the difference was statistically significant (p-value = .036). Thereafter, 55 patients were randomly selected to compare the results of two molecular techniques (ITS1-PCR and nested KDNA-PCR), performed both on swab and on stained smears used for microscopic examination; ITS1-PCR results from stained smears reached 87% positivity against 65,2% for cotton swab; and it was statistically significant (p-value = .019); on the other hand for the KDNA marker, results from cotton swab reached 93% of positivity against 91% for stained smears; and statistically the difference was not significant (p-value = .5113). One can presume that rubbing over the lesion with cotton swab implies a low parasitic load collection, but the choice of the amplification target greatly influences the results obtained from cotton swab; on top of that swab remains useful in the cases of patients with multiples lesions or the latter are located in sensitive places difficult to reach with an invasive method such as the eyelids, the lips or other mucous areas.

Population structure of leishmania major in southeastern morocco

Cutaneous leishmaniasis (CL) is an infectious disease caused by various Leishmania species. It is among the most neglected tropical diseases and has been considered a major health threat over the past decades in the country. Its zoonotic form caused by Leishmania (L) major is the most prevalent in Morocco. This study investigated the population structure of L. major in southeastern Morocco. Samples (n = 67) were collected from patients with CL in five different endemic areas located in three provinces (Ouarzazate, Tinghir, and Zagora). These samples were then sequenced using two nuclear markers: internal transcribed spacer 1 (ITS1) and a fragment of the virulence factor GP63. Next, the sequences were edited and analyzed. Molecular diversity indices showed a high population genetic diversity but an overall low haplotype diversity. Our results suggest small population differentiation, indicating a low geographic structure. Tajima's D and Fu's Fs tests both suggested recent population expansion based on the significant deviations from neutrality in both tests for all populations except Tinghir, which may be due to a small sample size. Based on our findings, the region is experiencing rapid population expansion caused by recent CL outbreaks, and one of them has been recently studied. In addition, analysis of molecular variance and F_ST suggested gene flow between Zagora and both Ouarzazate and Tinghir. Nonetheless, no gene flow was observed between Tinghir and Ouarzazate. To the best of our knowledge, this is the first analysis of the population structure of L. major in Morocco. The results of this study provide crucial background information for epidemiological studies by showing the presence of gene flow between populations and clonal expansion in cases of an outbreak. This will drive authorities to reconsider the implemented control strategies.

Evidence of circulation of West Nile virus in Culex pipiens mosquitoes and horses in Morocco

West Nile virus (WNV) is one of the most widely distributed mosquito-borne viruses in the world. In North Africa, it causes human cases of meningoencephalitis with fatalities in Algeria and in Tunisia, whereas only horses were affected in Morocco. The aims of this study were to detect WNV in mosquitoes and to determine seroprevalence of WNV in Moroccan horses by the detection of IgG antibodies. A total of 1455 mosquitoes belonging to four different species were grouped by collection site, date, and sex with 10 specimens per pool and tested for 38 arboviruses using a high-throughput chip based on the BioMark Dynamic array system. Out of 146 mosquito pools tested, one pool was positive for WNV. This positive pool was confirmed by real time RT-PCR. The serosurvey showed that 33.7% (31/92) of horses were positive for competitive enzyme-linked immunosorbent assay (cELISA) test. The flavivirus-sphere microsphere immnoassay (MIA) test, targeting three flaviviruses (WNV, Usutu virus (USUV) and Tick borne encephalitic virus (TBEV)) showed that 23 sera out of 31 were positive for WNV, two for USUV, two for USUV or WNV, and four for an undetermined flavivirus. Virus neutralization tests with USUV and WNV showed that 28 of 31 sera were positive for WNV and all sera were negative for USUV. This study reports, for the first time, the detection of WNV from Culex pipiens mosquitoes in Morocco and its circulation among horses. This highlights that the detection of arboviruses in mosquitoes could serve as an early warning signal of a viral activity to prevent future outbreaks in animals and humans.

Possible introduction of Leishmania tropica to urban areas determined by epidemiological and clinical profiles of patients with cutaneous leishmaniasis in Casablanca (Morocco)

Leishmaniases are a group of infectious diseases caused by protozoan Leishmania parasites and are transmitted by the bites of infected phlebotomine sandflies. The heterogeneity of these diseases is influenced by both parasitic properties and host factors. Cutaneous leishmaniasis (CL) is a major public health problem in Morocco, where the geographical expansion of CL (particularly CL caused by Leishmania tropica), the heterogeneous appearance of lesions and the difficulty in diagnosing CL contribute to late diagnosis of CL and delayed treatment of patients. Therefore, the main objective of this study was to describe the epidemiological and clinical profiles of patients with CL diagnosed in Casablanca (Morocco), which is a non-endemic area for CL. A cross-sectional study was conducted between 2010 and 2016, during which epidemiological and clinical data were collected from patients that met the inclusion criteria through an information sheet. Then, samples were obtained from each patient for parasitological and molecular diagnosis, and only patients with positive polymerase chain reaction and genotyping results were included in the study. Overall, 106 cases of CL were genotyped, of which 61 (57.5%) were caused by L. tropica, 38 (35.9%) by L. major and 7 (6.6%) by L. infantum. While all age groups were affected, CL cases wherein L. tropica was the causative agent were most frequently diagnosed in children aged 0–9 years (p = 0.005), whereas those caused by L. major were more frequently diagnosed in elderly patients (p = 0.004). Multivariate logistic regression analysis showed that two clinical variables were significantly associated with CL caused by L. tropica: lesion size (p = 0.002) and occurrence of lesion on the face (p = 0.005). Furthermore, the results of our survey highlighted the association of Leishmania infection when travelling to endemic areas. The high number of endemic foci where patients with CL were infected with L. tropica illustrated the tendency of this form to spread and generate epidemics, exposing young people to a greater degree to the disease. The epidemic status of CL caused by L. tropica in Morocco and the increased movement of the population from rural to urban areas indicate a possible introduction of this species to urban areas.

Gastric IL-1β, IL-8, and IL-17A expression in Moroccan patients infected with Helicobacter pylori may be a predictive signature of severe pathological stages

INTRODUCTION

Helicobacter pylori induces acute gastritis that can progress to serious diseases such as gastric cancer. H. pylori interacts with host cells within the gastric mucosa, resulting in activation of multiple innate immune signalling pathways, leading to pro-inflammatory cytokines production and immune cells recruitment. Various studies have shown that there are ethnic- and population-related differences in the expression of these cytokines. Although the H. pylori infection is a major public health problem in Morocco, to our knowledge, no study has been carried out in gastric cytokine expression from H. pylori-infected Moroccan patients. Thus we aimed to (i) determine the IL-1β, IL-8 and IL-17A gene expression in gastric biopsies from Moroccan patients infected with H. pylori, and (ii) to determine the cytokine signature of each pathological stages associated with this infection.

MATERIAL AND METHODS

71 patients with epigastralgic pain were included in this study. The H. pylori detection on gastric biopsies was performed by histopathological and PCR analysis. The IL-1β, IL-8 and IL-17A mRNA expression in the antrun and fundus biopsies was performed by RT-qPCR.

RESULTS

The histopathological and PCR analyses revealed that 87.32% of the patients were infected with H. pylori. IL-1β mRNA expression was significantly lower in the antral mucosa of H. pylori-infected patients (p = 0.0038) than in the uninfected while there was no significant difference in the expression of IL-8 and IL-17A mRNA. The expression of the three cytokines was higher in the fundic mucosa of H. pylori-infected patients than in the uninfected patients, but only IL-8 and IL-17A expression reached statistical significance (p = 0.042 and p = 0.0179 respectively). Furthermore, the multivariate predictive analysis highlighted a cytokine signature that may predict metaplasia during the infection progression that involves a specific down-regulation of IL17A and an up-regulation of IL1β in antral and fundic metaplasia respectively.

Transcriptional Analysis of Human Skin Lesions Identifies Tryptophan-2,3-Deoxygenase as a Restriction Factor for Cutaneous Leishmania

Disease manifestation after infection with cutaneous Leishmania species is the result of a complex interplay of diverse factors, including the immune status of the host, the infecting parasite species, or the parasite load at the lesion site. Understanding how these factors impact on the pathology of cutaneous leishmaniasis (CL) may provide new targets to manage the infection and improve clinical outcome. We quantified the relative expression of 170 genes involved in a diverse range of biological processes, in the skin biopsies from patients afflicted with CL caused by infection with either L. major or L. tropica. As compared to healthy skin, CL lesions bear elevated levels of transcripts involved in the immune response, and conversely, present a significant downregulation in the expression of genes involved in epidermal integrity and arginine or fatty acid metabolism. The expression of transcripts encoding for cytotoxic mediators and chemokines in lesions was inversely correlated with the expression of genes involved in epidermal integrity, suggesting that cytotoxicity is a major mediator of CL pathology. When comparing the transcriptional profiles of lesions caused by either L. major or L. tropica, we found them to be very similar, the later presenting an aggravated inflammatory/cytotoxic profile. Finally, we identified genes positively correlated with the parasite load in lesions. Among others, these included Th2 or regulatory cytokines, such as IL4 or IL10. Remarkably, a single gene among our dataset, encoding for tryptophan-2,3-deoxygenase (TDO), presented a negative correlation with the parasite load, suggesting that its expression may restrict parasite numbers in lesions. In agreement, treatment of macrophages infected with L. major in vitro with a TDO inhibitor led to an increase in parasite transcripts. Our work provides new insights into the factors that impact CL pathology and identifies TDO as a restriction factor for cutaneous Leishmania.

Molecular identification of Leishmania infection in the most relevant sand fly species and in patient skin samples from a cutaneous leishmaniasis focus, in Morocco

BACKGROUND

Cutaneous leishmaniasis (CL) is an infectious disease caused by various species of Leishmania and transmitted by several species of sand flies. CL is among the most neglected tropical diseases, and it has represented a major health threat over the past 20 years in Morocco. The main objectives of this study were to identify relevant sand fly species and detect Leishmania infection in the most prevalent species and patient skin samples in Taza, a focus of CL in North-eastern Morocco.

METHODOLOGY AND FINDING

A total of 3672 sand flies were collected by CDC miniature light traps. Morphological identification permitted the identification of 13 species, namely 10 Phlebotomus species and 3 Sergentomyia species. P. longicuspis was the most abundant species, comprising 64.08% of the total collected sand flies, followed by P. sergenti (20.1%) and P. perniciosus (8.45%). Using nested-kDNA PCR, seven pools of P. sergenti were positive to Leishmania tropica DNA, whereas 23 pools of P. longicuspis and 4 pools of P. perniciosus tested positive for Leishmania infantum DNA. The rates of P. longicuspis and P. perniciosus Leishmania infection were 2.51% (23/915) and 7.27% (4/55), respectively, whereas the infection prevalence of P. sergenti was 3.24%. We also extracted DNA from lesion smears of 12 patients suspected of CL, among them nine patients were positive with enzymatic digestion of ITS1 by HaeIII revealing two profiles. The most abundant profile, present in eight patients, was identical to L. infantum, whereas L. tropica was found in one patient. The results of RFLP were confirmed by sequencing of the ITS1 DNA region.

CONCLUSION

This is the first molecular detection of L. tropica and L. infantum in P. sergenti and P. longicuspis, respectively, in this CL focus. Infection of P. perniciosus by L. infantum was identified for the first time in Morocco. This study also underlined the predominance of L. infantum and its vector in this region, in which L. tropica has been considered the causative agent of CL for more than 20 years.

Moroccan strains of Leishmania major and Leishmania tropica differentially impact on nitric oxide production by macrophages

BACKGROUND

Cutaneous leishmaniasis (CL) is a vector-borne parasitic disease caused by protozoa of the genus Leishmania. In Morocco, CL is a public health problem mainly caused by Leishmania major and Leishmania tropica, which are responsible for zoonotic and anthroponotic CL, respectively. Macrophages are the primary cells infected by Leishmania parasites and their capacity to produce nitric oxide (NO) is of critical importance for parasite elimination. To our knowledge, the role of NO on autochthonous infections has never been investigated before. In this study, we evaluated in vitro the capacity of autochthonous primary dermotropic strains of L. major and L. tropica to modulate NO production by J774-macrophages and determine the sensitivity of both species to exogenous NO.

METHODS

The infectivity of the J774 cell line was analyzed by optical microscopy. NO production by macrophages was measured by the Griess method. The sensitivity to NO by the two strains was assessed by the MTT assay using NO donors.

RESULTS

Our results show that the percentage of infected macrophages and the average number of parasites per macrophage were similar for L. major and L. tropica strains. While L. tropica significantly inhibited NO production induced by LPS and IFN-γ stimulation in J774 macrophages, L. major did not affect it. However, soluble Leishmania antigens (SLAs) from both autochthonous primary strains significantly inhibited the production of NO by J774-macrophages in a dose-dependent manner. Finally, our results demonstrated that promastigotes and amastigotes from both strains are sensitive to SNAP NO donor in a dose-dependent manner, although L. tropica demonstrated an increased sensitivity.

CONCLUSIONS

Our results suggest a differential ability of L. major and L. tropica strains to modulate the capacity of macrophages to produce NO. The increased ability of L. tropica to inhibit NO production by macrophages might come as a necessity due to its higher sensitivity to NO donor. Our results provide one explanation for the tendency of L. tropica to cause chronic lesions and may contribute to the different physiopathology of CL in Morocco.

New epidemiological pattern of cutaneous leishmaniasis in two pre-Saharan arid provinces, southern Morocco

Three Leishmania species are responsible of cutaneous leishmaniasis (CL) in Morocco. Zoonotic CL due to Leishmania major and Leishmania infantum, the first is known as established in the eastern arid regions, whereas the latter evolves sporadically, especially in the North. While Leishmania tropica, classically considered anthroponotic, is endemic in the semi-arid regions and is largely distributed throughout the country. The aim of this study was to identify the Leishmania species causing CL in two Provinces in arid pre-Saharan region known as zoonotic CL foci, and to contribute an update to the national data concerning the distribution of Leishmania species in both regions. The recruitment of patients was done in six localities in Ouarzazate and Zagoura provinces in 2015 and 2016. Out of 81 samples collected, 66 were positive (81%) by ITS1-PCR amplification of Leishmania DNA extracted from stained smears. The highest rate of Leishmania infection was registered in children aged 9 years or less (71,2%). The ITS1-PCR- RFLP analysis revealed the predominance of L. major infecting 52 patients (79%), followed by L. tropica in 12 patients (18%) and L. infantum in 2 patients who had no history of travel outside the studied area (3%). The sequencing of the ITS1 of both L. infantum, showed 100% similarities with L. infantum strains isolated from dogs and visceral leishmaniasis patients from the south and north of Morocco. The coexistence of the 3 Leishmania species in the same focus, and the difficult distinction of infections associated to the different Leishmania species based only on clinical lesions' aspects complicate the diagnosis and then the national control strategy, as well as the therapeutic management. The epidemiological pattern of CL in the studied areas appears to have changed during the last decades, from a predominant zoonotic CL caused by L. major to a polymorphic disease that can be due to any of the 3 Leishmania species. The expansion of L. infantum and L. tropica in southern parts of Morocco, calls for in depth epidemiological investigations for a better understanding of the CL situations in Southern parts of the country and for an assessment of the climate impact and environment changes on the leishmaniasis transmission system.

Early divergence in neutrophil apoptosis between pathogenic and nonpathogenic simian immunodeficiency virus infections of nonhuman primates

We used pathogenic and nonpathogenic simian models of SIV infection of Chinese and Indian rhesus macaque (RMs) and African green monkeys (AGMs), respectively, to investigate the relationship between polymorphonuclear neutrophil (PMN) death and the extent of viral replication and disease outcome. In this study, we showed that PMN death increased early during the acute phase of SIV infection in Chinese RMs and coincided with the peak of viral replication on day 14. The level of PMN death was significantly more severe in RMs that progressed more rapidly to AIDS and coincided with neutropenia. Neutropenia was also observed in Indian RMs and was higher in non-Mamu-A*01 compared with Mamu-A*01 animals. In stark contrast, no changes in the levels of PMN death were observed in the nonpathogenic model of SIVagm-sab (sabaeus) infection of AGMs despite similarly high viral replication. PMN death was a Bax and Bak-independent mitochondrial insult, which is prevented by inhibiting calpain activation but not caspases. We found that BOB/GPR15, a SIV coreceptor, is expressed on the PMN surface of RMs at a much higher levels than AGMs and its ligation induced PMN death, suggesting that SIV particle binding to the cell surface is sufficient to induce PMN death. Taken together, our results suggest that species-specific differences in BOB/GPR15 receptor expression on PMN can lead to increased acute phase PMN death. This may account for the decline in PMN numbers that occurs during primary SIV infection in pathogenic SIV infection and may have important implications for subsequent viral replication and disease progression.

Leishmania major-mediated prevention of programmed cell death induction in infected macrophages is associated with the repression of mitochondrial release of cytochrome c

Leishmania are obligate, intracellular parasites of macrophages in their vertebrate hosts, including humans, in which they cause disease. Here, we report that in vitro infection with Leishmania major protects murine bone marrow-derived macrophages against programmed cell death (PCD) induced by deprival of macrophage-colony stimulating factor and delays PCD caused by treatment with staurosporine, a broad inducer of PCD. This preventive effect was observed in macrophages from L. major-susceptible BALB/c and L. major-resistant C57BL/6 mice, indicating that repression of PCD did not depend on genetic background-specific regulation of T helper cell type 1 (Th1)/Th2 cytokine secretion. Prevention of effector caspase activation and PCD was associated with a repression of mitochondrial release of cytochrome c and did not involve the nuclear factor-kappaB pathway. The capacity of L. major to delay PCD induction in the infected macrophages may have implications for Leishmania pathogenesis by favoring the invasion of its host and the persistence of the parasite in the infected cells.

CD95 engagement induces disseminated endothelial cell apoptosis in vivo: immunopathologic implications

Fas (CD95) is a death receptor involved in apoptosis induction on engagement by Fas ligand (CD95L). Although CD95L-mediated apoptosis has been proposed as a pathogenic mechanism in a wide range of diseases, including graft-versus-host disease, systemic CD95 engagement in mice by agonistic CD95-specific antibodies or by soluble multimeric CD95L (smCD95L), though lethal, has been reported to cause apoptosis only in a limited range of cell types, that is, hepatocytes, hepatic sinusoidal endothelial cells, and lymphocytes. Another member of the tumor necrosis factor (TNF)/CD95L family, TNF-alpha, induces disseminated vascular endothelial cell apoptosis, which precedes apoptosis of other cell types and lethal multiorgan failure. Here we show that systemic CD95 engagement in vivo by agonistic CD95-specific antibody or smCD95L causes rapid, extensive, and disseminated endothelial cell apoptosis throughout the body, by a mechanism that does not depend on TNF-alpha. Disseminated endothelial cell apoptosis was also the first detectable lesion in a murine model of acute tissue damage induced by systemic transfer of allogeneic lymphocytes and did not occur when allogeneic lymphocytes were from CD95L-defective mice. Both vascular and additional tissue lesions induced by agonistic CD95-specific antibody, smCD95L, or allogeneic lymphocytes were prevented by treatment with an inhibitor of caspase-8, the upstream caspase coupled to CD95 death signaling. Vascular lesions are likely to play an important role in the pathogenesis of allogeneic immune responses and of other diseases involving circulating CD95L-expressing cells or smCD95L, and the prevention of CD95-mediated death signaling in endothelial cells may have therapeutic implications in these diseases.

On the evolution of programmed cell death: apoptosis of the unicellular eukaryote Leishmania major involves cysteine proteinase activation and mitochondrion permeabilization

Leishmania major is a protozoan parasite from one of the most ancient phylogenic branches of unicellular eukaryotes, and containing only one giant mitochondrion. Here we report that staurosporine, that induces apoptosis in all mammalian nucleated cells, also induces in L. major a death process with several cytoplasmic and nuclear features of apoptosis, including cell shrinkage, phosphatidyl serine exposure, maintenance of plasma membrane integrity, mitochondrial transmembrane potential (DeltaPsim) loss and cytochrome c release, nuclear chromatin condensation and fragmentation, and DNA degradation. Nuclear apoptosis-like features were prevented by cysteine proteinase inhibitors, and cell free assays using dying L. major cytoplasmic extracts indicated that the cysteine proteinases involved (i) also induced nuclear apoptosis-like features in isolated mammalian nuclei, and (ii) shared at least two nuclear substrates, but no cleavage site preference, with human effector caspases. Finally, isolated L. major mitochondria released cytochrome c and cysteine proteinases with nuclear pro-apoptotic activity when incubated with human recombinant Bax, even (although much less efficiently) when Bax was deleted of its transmembrane domain required for insertion in mitochondrial outermembranes, implying that L. major mitochondrion may express proteins able to interact with Bax. The recruitment of cysteine proteinases and mitochondria to the cell death machinery may be of very ancient evolutionary origin. Alternately, host/parasite interactions may have exerted selective pressures on the cell death phenotype of kinetoplastid parasites, resulting in the more recent emergence of an apoptotic machinery through a process of convergent evolution.

Gamma-interferon induces apoptosis of the B lymphoma WEHI-279 cell line through a CD95/CD95L-independent mechanism

Gamma-interferon (IFN-gamma) a cytokine produced by CD4+ T helper type 1 cells, CD8+ T cells and natural killer (NK) cells, plays a central role in the development of humoral and cell-mediated immunity. IFN-gamma participates in the maturation and differentiation of B cells, but it has been previously reported that IFN-gamma may inhibit the early stages of B cell activation. We report that the inhibition of the B lymphoma cell WEHI-279-proliferation induced by IFN-gamma, involves the induction of typical features of apoptosis (nuclear chromatin condensation and fragmentation, cell shrinkage, phosphatidyl-serine (PS) exposure and mitochondrial membrane potential (delta psim) loss). IFN-gamma-mediated B cell apoptosis was decreased by the addition of the T helper type 2 cytokine, IL-4. WEHI-279 cells express CD95 and undergo apoptosis after treatment with either an agonistic anti-CD95 Ab or with a soluble recombinant CD95L. However, incubation with CD95-Fc or TRAIL-R1-Fc fusion proteins, did not prevent IFN-gamma-mediated apoptosis, suggesting that IFN-gamma-mediated apoptosis occurs independently of CD95/CD95L and TRAIL-R/TRAIL interactions. IFN-gamma-mediated apoptosis is associated with caspase-3 activation that can be prevented by the addition of the broad caspase inhibitor zVAD-fmk. These data indicate that IFN-gamma may play a major role in the regulation of B cell apoptosis, and suggest the involvement of an alternative pathway which is independent of the death receptors.

The Th1 to Th2 shift induced by Schistosoma mansoni does not exacerbate murine aids (MAIDS)

Schistosoma mansoni infection in mice is associated with a switch from a Th1 to a Th2-type cytokine response. The role of Th1 and Th2 responses in immune dysregulations associated with AIDS and murine AIDS (MAIDS) is controversial, but a Th2 bias could be associated with disease progression, raising the hypothesis that helminth infections might accelerate the retroviral disease progression. Here, we used the murine model of AIDS to evaluate the course of the viral disease during co-infection with S. mansoni. C57BL/6 mice were infected with S. mansoni cercariae 8 weeks before intravenous challenge with the LP-BM5 retroviral complex. MAIDS did not progress faster in co-infected mice, in terms of spleen and inguinal lymphadenopathy size, ecotropic virus titres in the spleen, or in vitro proliferative responses to mitogen. Th2 cytokine production was not enhanced in co-infected animals, except for an isolated increase in IL-4 production 21 weeks after LP-BM5 infection. Co-infected animals had significantly lower lymph node and spleen weights than mice infected with LP-BM5 only. MAIDS did not influence the granulomatous response to S. mansoni in the liver of co-infected mice. Finally, infection with S. mansoni neither enhanced Th2 cytokine production nor accelerated MAIDS progression in animals subsequently challenged with LP-BM5.

Competitive reverse transcription-polymerase chain reaction for quantifying murine AIDS virus

The causative agent of murine AIDS (MAIDS) is the defective murine leukemia virus BM5d, that requires the replication-competent ecotropic MuLV (BM5e) helper virus. We developed a competitive quantitative PCR method including specific internal standards to quantify the expression of BM5d in the spleen of infected mice and to characterize BM5d expression kinetics following experimental infection. Specimen RNA was reverse-transcribed and co-amplified with a competitive template containing a gag sequence specific for BM5d that can be discriminated from that corresponding to wild-type cDNA by the presence of a unique restriction site, Bg/II. PCR products were quantified by means of densitometric analysis after ethidium bromide staining of gels. To standardise the RNA extraction and reverse transcription steps, the amount of defective-virus mRNA was compared to a constant copy number of murine beta actin mRNA. LP-BM5 production was measured in the spleen of infected mice. Defective gag mRNA production was compared to that of the ecotropic virus. The mRNA level of the defective virus and the titre of replicative virus increased with the duration of infection, and the amount of defective virus mRNA correlated with the titre of replicating virus.

Absence of involvement of nitric oxide in LP-BM5-induced immunodeficiency syndrome

To examine the role of nitric oxide (NO) in murine AIDS (MAIDS) pathogenesis, we determined NO production and inducible NOS (iNOS) mRNA expression in the macrophages of LP-BM5-infected mice, together with the in vivo effects of L-NAME, a competitive inhibitor of NO synthase. LP-BM5 infection induced neither spontaneous nitrite production nor iNOS mRNA expression. No differences in IFN gamma + LPS-induced nitrite production or iNOS mRNA expression were observed in macrophages, from non-infected or infected mice. Spleen weight, ecotropic MuLV replication, the blood lymphocyte phenotype and proliferative response of splenocytes were not modified by L-NAME. LP-BM5 infection did not increase macrophage NO production and NO production did not appear to protect against LP-BM5-induced immunodeficiency.

Inhibitory effect of nitric oxide on the replication of a murine retrovirus in vitro and in vivo

Nitric oxide (NO) exerts microbicidal effects on a broad spectrum of pathogens, including viruses, but its antiretrovirus properties have not yet been described. The purpose of this study was to determine whether NO inhibits murine Friend leukemia virus (FV) replication in vitro and to what extent NO may play a role in defenses against FV infection in mice. Three NO-generating compounds were studied: 3-morpholino-sydononimine (SIN-1), sodium nitroprusside (SNP), and S-nitroso-N-acetylpenicillamine (SNAP). The effects of these three compounds were compared with those of their controls (SIN-1C, potassium ferricyanide, and N-acetylpenicillamine, respectively), which do not generate NO and with that of sodium nitrite (NaNO2). SIN-1, SNP, and SNAP inhibited FV replication in dunni cells in a concentration-dependent manner. In contrast, no significant inhibitory effect was observed with the three controls or NaNO2. Furthermore, the addition of superoxide dismutase did not alter the inhibitory effect of SIN-1, which is also known to generate superoxide anions. No dunni cell toxicity was observed in the range of concentrations tested. We also assessed the effect of NO produced by activated macrophages on FV replication. Macrophages activated by gamma interferon and lipopolysaccharide inhibited FV replication in a concentration-dependent manner. This inhibition was due in part to NO production, since it was reversed by NG-monomethyl L-arginine, a competitive inhibitor of NO synthase. In vivo administration of NG-nitro-L-arginine methyl ester, a competitive inhibitor of NO synthase, significantly increased the viral load in spleen cells of FV-infected mice. These results suggested that NO may play a role in defenses against the murine Friend leukemia retrovirus.

Kinetics of ex-vivo cytokine production by splenocytes during murine acquired immunodeficiency syndrome (MAIDS)

The role of T helper 1 (Th1) and T helper 2 (Th2) responses in the murine acquired immunodeficiency syndrome (MAIDS) is unclear. It has been suggested that differential activation of T cell subsets, particularly a shift to Th2 cytokine production, may be associated with disease progression. To clarify the regulation of the cytokine network in the course of MAIDS, we examined the kinetics of cytokine production by isolated splenocytes. C57/BL6 mice were infected with the LP-BM5 mixture. The spleen cell proliferative response, together with IL-2, IFN-gamma, IL-10 and IL-4 production by unstimulated and ConA or anti-CD3 MoAb-stimulated spleen cells, were determined at various times after inoculation (weeks 1, 3, 6 and 9). Spleen cells isolated from murine leukemia virus complex (LP-BM5) infected mice spontaneously produced significant amounts of IL-2 and IFN-gamma one and three weeks post-infection, compared to uninfected controls. The capacity of isolated T cells to produce the Th1 cytokines IL-2 and IFN-gamma in response to stimulation with ConA and anti-CD3 MoAb decreased after 3 weeks of infection. The fall in IL-2 production ran parallel to the fall in the T cell proliferative response to ConA. IL-10 production in response to ConA and anti-CD3 MoAb increased after three weeks post-inoculation, and followed the reverse kinetic pattern to IFN-gamma and IL-2. In contrast, no significant spontaneous IL-4 production and no increase in IL-4 production in response to ConA or anti-CD3 MoAb occurred during the course of MAIDS, relative to uninfected controls. These results suggest that LP-BM5 infection leads to a fall in Th1 cytokine production rather than a clear switch to Th2 cytokine production.

Protective effect of LPS and poly A:U against immune oxidative injury: role of thiols released by activated macrophages

Oxidative injury of immune cells has been observed both at inflammatory sites and in pathologic situations, such as human immunodeficiency virus infection. We used an ex vivo model of immune oxidative injury to test the antioxidant effect of two immunomodulating agents administered to C57B1/6 mice. Lipopolysaccharide (LPS) and the synthetic polyribonucleotide poly A:U preserved the ConA-induced proliferative response of spleen T cells against oxidative injury ex vivo. The glutathione and thiol contents of fresh spleen T cells from LPS- and poly A:U-treated mice were significantly higher than control values. In addition, spleen T cells from LPS- and poly A:U-treated mice were protected against the oxidative injury-induced decrease in glutathione content after 48 h of ConA stimulation. Because LPS and poly A:U both activate macrophages, we sought an antioxidant effect of macrophage-released compounds. Neither rhIL-1 alpha nor rhTNF alpha protected against oxidative injury in vitro. In contrast, LPS and poly A:U induced macrophages to release acid-soluble thiols, which have been reported to participate in the regulation of glutathione levels in lymphocytes and could therefore protect against immune oxidative injury.

Modulation of saccharin preference by morphine and naloxone: inversion of drug effects as a function of saccharin concentration

The aim of the present study was to verify and extend a recent, isolated observation showing that, in rats, a moderate dose of morphine may induce either an increase or a decrease in preference for saccharin, the direction of the response depending apparently on the concentration of the sweetener. Two experiments were performed successively. First, we showed that the preference threshold for saccharin (0.3 mM, two-bottle procedure) of rats placed on a schedule of restricted water access was significantly decreased following injection of 1 mg/kg of morphine. In the second experiment, three groups of naive rats were submitted to the preference test but the concentration of saccharin solution was different for each group, namely 0.3, 1 and 1.7 mM. After stabilization of the baseline responses the effect of morphine (1 mg/kg) was tested in each of the 3 groups. As observed previously morphine decreased the preference of the rats tested with the 0.3 mM solution, but markedly increased the preference of the two other groups tested with the 1 and 1.7 mM solutions respectively. The effects of low doses of naloxone (0.01, 0.1 and 1 mg/kg) were then tested on the same groups of rats with the same saccharin concentrations. The 0.01 mg/kg dose of the antagonist increased the preference for the groups of rats tested with the 0.3 and 1 mM solutions. The other two doses of naloxone decreased saccharin intake whatever the saccharin concentration used. It is suggested that these apparently paradoxical effects of morphine and naloxone could result either from the stimulation of opioid autoreceptors or from the differential stimulation of different opioid receptor subtypes.