Die Progression der HIV Infektion ist vermutlich bedingt von einer unspezifischen generalisierten Immunaktivierung des Patienten (Sousa, Carneiro et al. 2002; Hazenberg, Otto et al. 2003). Somit könnte ein immunsuppressives Medikament wie das Kortisonpräparat Prednisolon die Progression der Erkrankung verlangsamen. Im Rahmen nicht-kontrollierter Studien konnte die Stabilisierung der CD4+ T-Lymphozyten in HIV-Patienten durch den Einsatz von Kortison beobachtet werden (Andrieu, Lu et al. 1995; Lu, Salerno-Goncalves et al. 1995). Dieser Effekt konnte auch mit niedrig dosiertem Prednisolon (5 mg/Tag) nachgewiesen werden (Ulmer, Muller et al. 2005). Jedoch zeigen neuere Ergebnisse, dass der CD4+ T-Lymphozytenwert bei Studien zu Immunmodulatoren kein verlässlicher Surrogatmarker für die Progression ist (Abrams, Levy et al. 2009). In der vorliegenden Arbeit sollte untersucht werden, ob sich zum Einen der stabilisierende Effekt von niedrig dosiertem Prednisolon (5 mg pro Tag) auf CD4+ T-Lymphozyten in einer kontrollierten Studie bestätigt, ob zum Zweiten die CD4+ T-Lymphozytenstabilisierung auf eine Senkung der Immunaktivierung zurückgeführt werden kann und ob zum Dritten die CD4+ TLymphozytenstabilisierung die klinische Krankheitsprogression verlangsamt. Im Rahmen der ProCort-Studie sollte außerdem eine Bestimmung der Prävalenz medikamentenresistenter HIV-Infektionen bei ART unbehandelten Patienten erfolgen. Hierbei wurden die WHO Kriterien überprüft, die als Einschlusskriterien für Patienten in Resistenz-Überwachungsstudien ein Höchstalter von 25 Jahren festgelegt hat. In unserer Untersuchung wurden demgegenüber Proben von Patienten mit höherem Alter und bereits therapierten Partnern analysiert.Methoden: Im Rahmen einer doppelblinden randomisierten klinischen Studie (ProCort1) im Bugando Medical Center (BMC) in Mwanza, Tansania, wurden 326 HIV-Patienten eingeschlossen, die zuvor noch nie mit ART behandelt wurden und einen CD4+ TLymphozytenwert von mindestens 300/μl aufwiesen. In 14 Visiten wurden, während einer zweijährigen Behandlungsdauer entweder mit 5mg Prednisolon täglich oder mit Placebo, die CD4+ T-Lymphozytenwerte und das Auftreten von Progression der HIV-Infektion bestimmt. Primärer Studienendpunkt war die Krankheitsprogression, definiert als ein Unterschreiten von 200 CD4-Zellen/μl oder dem Auftreten AIDS-definierender Erkrankungen. Um die immunologische Wirkungsweise von Prednisolon in HIV-infizierten Patienten zu untersuchen wurden sowohl in den tansanischen Studienpatienten als auch in einer mit 5 mg Prednisolon behandelten deutschen Kohorte die Lymphozytenaktivierungsmarker CD38/HLADR auf CD3/CD8-Zellen, der Monozytenaktivierungsmarker sCD14 und der Entzündungsmarker suPAR bestimmt. Um die Prävalenz der HIV Medikamentenresistenz (HIVDR) in der ProCort Studienpopulation zu ermitteln wurden 88 Proben der ART unbehandelten Patienten sequenziert. Ergebnisse: Die Ergebnisse der ProCort Studie zeigten eine statistisch signifikante Stabilisierung der CD4+ T-Lymphozytenwerte im Vergleich zum Ausgangswert durch Einsatz einer niedrig dosierten Prednisolonbehandlung (5 mg täglich). In der Intent to treat Analyse wurde ein Zugewinn von +20,1 Zellen/μl pro Jahr für den Prednisolonarm (p < 0.0001) im Vergleich zu -54,2 Zellen/μl pro Jahr für den Placeboarm (p < 0.0001) bestimmt. Die CD4+ T-Lymphozytenwerte zum Zeitpunkt der Startvisite waren im Prednisolonarm statistisch signifikant niedriger (Mean 512.14 Zellen/μl ± S.E.M. 13.39) als im Placeboarm (Mean 554.40 ± S.E.M 15.75; p = 0.042). Dies bedeutet eine schlechtere Ausgangslage für die mit Prednisolon behandelten Patienten. Trotzdem entwickelten nur vier Patienten mit Prednisolonbehandlung im Vergleich zu 11 Patienten mit Placebobehandlung AIDS, was eine statistisch signifikante Verringerung der Progressionsrate bedeutet (p=0.0196). In 16 Patienten versus 18 Patienten fielen die CD4+ T-Lymphozytenwerte unter die Werte von 200 Zellen/μl. Die Behandlung mit Prednisolon war nicht mit einer höheren Rate von unerwünschten Ereignissen oder höherer Viruslast assoziiert. / Background: A combination-therapy approach with antiretroviral substances (ARVs), also called antiretroviral therapy (ART) is at present, the best and almost the only treatment option for HIV infected individuals. While combination ART is the best treatment to prevent the onset of AIDS in HIV infection, it is still not available for millions of patients in resourcelimited areas, despite the substantial improvements achieved in the past 10 years. There is a justified concern of the acceleration of HIV-drug-resistance (HIVDR) development caused by first-line ART medication available in countries with restricted resources, as the ART available often has low genetic barriers causing resistance mutations (Barth, Wensing et al. 2008). There is a strong need for treatment that is inexpensive and effective of delaying the progress of the illness in the asymptomatic phase. HIV-associated general immune activation is a strong predictor for HIV disease progression, suggesting that chronic immune activation may drive HIV pathogenesis (Sousa, Carneiro et al. 2002; Hazenberg, Otto et al. 2003). Therefore immunomodulating agents like the corticosteroid prednisolone may decelerate HIV disease progression. This is the rationale for the use of prednisolone in HIV therapy. In nonrandomised monocentric observational studies it was shown that certain corticosteroids has a stabilizing effect on the CD4+T-lymphocytes in HIV-infected patients (Andrieu, Lu et al. 1995; Lu, Salerno-Goncalves et al. 1995). This effect could also be proven with low dose prednisolone (5 mg daily) (Ulmer, Muller et al. 2005). However, recent studies demonstrate that the CD4+T-lymphocytes are not stable predicting markers for HIV progression (Abrams, Levy et al. 2009). This thesis examines, first if the CD4+T-lymphocytes stabilizing effect of 5 mg prednisolone can be proven in a double-blind controlled randomized clinical trial, second if this effect is dependent of the reducing generalized immune activation and third if the CD4+T-lymphocytes stabilizing effect reduces the clinical progression of HIV infection. A study to identify the prevalence of HIVDR was also conducted within the ProCort study. To validate the current WHO tHIVDR survey criteria, focused on patients age below 25 years, our study included also patients over 25 years with partners already on treatment as well. Methods:The ProCort Study (Progression of HIV-Disease under Low Dose Corticosteroids) was designed as a double blinded randomized clinical trial including 326 ART-naïve patients in Bugando Medical Centre in Mwanza, Tansania, with a minimum cell count of 300 CD4+Tlymphocytes per μl. Patients were treated with either 5mg prednisolone daily or with placebo for two years. The CD4+T-lymphocytes were measured in 14 visits and progression factors were evaluated. Progression was defined as qualifying for start of ART either due to CD4 Cell 11 count below 200 cells per μl or due to developing AIDS defining symptoms. Immune activation markers were determined both for the ProCort patients and for a German cohortstudy group receiving 5 mg Prednisolon. The lymphocyte activation marker CD3/CD8/CD38/HLADR, monocyte activation marker sCD14 and markers for inflammation suPAR was targeted during the study. To identify the HIVDR in the ProCort study population sequencing was conducted in 88 sequentially enrolled ART-naïve patients. Results:The results of the ProCort study showed a statistical significant stabilizing effect of CD4+T-lymphocyte count compared to baseline counts in 5 mg prednisolone treated patients. In an intent-to-treat analysis, average changes in CD4+T-lymphocyte counts versus baseline were +20,1 cells/μl per year for prednisolone (P = 0.0002) and -54,2 cells/μl per year for placebo (P = 0.0027). The Baseline CD4+T-lymphocyte count recovery were significantly lower in the prednisolone arm (mean 512.14 cells/μl ± S.E.M. 13.39) than in the placebo arm (554.40 ± 15.75 P = 0.042) which implies a disadvantage for this group. However, only four patients treated with prednisolone and 11 patients treated with placebo developed stage C opportunistic diseases (Kaplan Meyer analysis, p = 0.0196 Gehan-Breslow-Wilcoxon test). For the CD4+T-lymphocyte counts 16 patients, compared to 18 patients in the placebo group? fall under 200 cell/μl. Prednisolone treatment was not associated with an increase in adverse events or HIV viral load. A statistically significant reduction in immune activation markers were obtained by 5 mg prednisolone therapy in both the German and the Tanzanian study group. In the Tanzanian study group the lymphocyte activation change to baseline, determined by CD38/HLADR-expression on CD8+ T lymphocytes, showed a significantly reduction of activation in prednisolone-treated patients compared to an increase in the untreated patients (-4.101% compared to 2.637%, p = 0.0018). The analysis of the immune system activation markers for inflammation (suPAR) showed a significant reduced difference to baseline in prednisolone-treated patients compared to untreated patients (-0.147 ng/ml, compared to 0,325 ng/ml, p<0.0001). In the results for monocytes activation markers for soluble CD14 just failed the significant difference between prednisolone and placebo treated patients (4.030 ng/ml, vs. 3.513 ng/ml, p=0.062). In the German Study cohort lymphocyte activation determined by CD38-expression on CD8+ T lymphocytes was significantly lower in prednisolone-treated patients compared to untreated patients (55.40% versus 73.34%, p = 0.0011). Similarly, we detected for monocyte activation markers lower levels of sCD14 (3.6 ng/ml vs. 6.11 ng/ml, p = 0.0048), and of LBP (2.18 ng/ml compared to 3.45 ng/ml; p = 0.0386) and for inflammation markers suPAR antigen (2.17 ng/ml vs. 2.56 ng/ml, p = towards lower levels of sCD40L (2.70 pg/ml vs. 3.60 pg/ml, p = 0.0782). 12 Viral load in both groups were similar (0.8 x 105 copies/ml compared to 1.1 x 105 copies/ml, p = 0.3806) (Kasang, Ulmer et al. 2012). By sequencing the HIV samples of ProCort patients we identified the HIV-1 subtype frequency A1: 34%, A1D: 7%, C: 26%, CRF10_CD: 4%, D: 28%, B: 1%. Twenty patients of the 88 were aged <25 years (meeting the WHO-initiated transmitted HIVDR surveillance criteria) and 68 patients were aged 25–63 years. The frequency of HIVDR in the study population was 14.8% (95%; CI 0.072–0.223) and independent of NVP-resistance induced by prevention of mother-to-child transmission programs. Patients >25 years had a significantly higher HIVDR frequency than younger patients (19.1%, versus 0%, P = 0.0344). ART-naïve patients aged over 25 years exhibited significantly higher HIVDR than younger patients. Detection of traces of ARVs in individuals with HIVDR suggests that besides transmission, undisclosed misuse of ARVs may constitute a significant factor in the generation of the observed high HIVDR rate. Discussion: The results in the context of the ProCort Study showed that treatment with 5 mg per day prednisolone for two years in ART-naive HIV patients is safe in an African setting and was associated with a significant increase of CD4+T-lymphocyte counts compared to the placebo group. In addition, prednis olone-treated patients developed significantly fewer AIDSdefining conditions, indicating that prednisolone slows HIV disease progression. This can be explained by the justified reduction of general immune activation in low-dose prednisolone treated patients. We suggest low-dose prednisolone as a treatment option for asymptomatic HIV infection in resource-limited settings. Additionally it should be clarified if low-dose prednisolone therapy is also an option for an ART combined treatment. So far, the reported prevalence of HIVDR in eligible patient populations is below 5% across Sub-Saharan Africa (WHO 2012). Our study identified that patients over 25 years of age showed a significant higher prevalence of HIVDR than younger patients (p=0.0344). By phylogenetic alignment for two samples of treated partners and untreated patients we demonstrate a transmission of HIVDR probably achieved by treatment to the therapy naïve patient. Detection of traces of ARVs in some other individuals with HIVDR suggests that besides transmission, undisclosed misuse of ARVs may constitute a significant factor in the generation of the observed high HIVDR rate. The current WHO HIVDR survey that is solely focused on the transmission of HIVDR and that excludes patients over 25 years of age may therefore result in substantial underestimation of the prevalence of HIVDR in the therapynaïve population. A modification of WHO HIVDR survey criteria is strongly recommended